Method and arrangement for providing control information of a waste water treatment process

Abstract

A method for providing control information of a waste water treatment process for controlling an emission load to be emitted from the waste water treatment process within a predetermined time interval is disclosed.

Description

[0001] METHOD AND ARRANGEMENT FOR PROVIDING CONTROL INFORMATION OF A WASTE WATER TREATMENT PROCESS

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to a method and arrangement for providing control information of a waste water treatment process and to a computer program .

[0004] BACKGROUND

[0005] In industrial processes , environmental regulations for emis sions to be released from the industrial processes may be in place . Typically, such regulations involve environmental licenses or permits that define how much emissions of certain compounds or components may be released to the environment without penalties . An optimal treatment level for waste water obtained from such industrial processes is typically sought in order to keep emissions within the environmental license and, on the other hand, not to use unnecessary amounts of treatment chemicals . Such treatment chemicals may be costly, and their excessive use may not be sustainable . Further, the chemical treatment for reducing the emissions may pose environmental challenges of their own . For example , such a chemical treatment may produce sludges containing aluminium or iron, which may be challenging to dewater and which may not be allowed to be landfilled .

[0006] Further, in certain processes , emission loads may be quite variable , which may make it more challenging to select optimal treatment levels .

[0007] SUMMARY

[0008] This Summary is provided to introduce a selection of concepts in a s implif ied form that are further described below in the Detailed Description . This Summary is not intended to identify key features or essential features of the claimed subj ect matter, nor is it intended to be used to limit the scope of the claimed subj ect matter .

[0009] A method for providing control information of a waste water treatment process for controlling an emission load to be emitted from the waste water treatment process within a predetermined time interval is disclosed . The method may comprise obtaining at a plurality of instants within the predetermined time interval a value of a current cumulative emission load emitted from the waste water treatment process , determining at each of the plurality of instants within the predetermined time interval an estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval , wherein the estimate of the cumulative emission load is determined based on at least the value of the current cumulative emission load and on data of the emiss ion load emitted from the waste water treatment process obtained earlier, determining at each of the plurality of instants a control threshold of the emission concentration and / or load at which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below a predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , and / or determining at each of the plurality of instants a control time interval for the duration of which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below the predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , and providing the control information for implementing the one or more control actions in the waste water treatment process based on at least one of the estimate of the cumulative emiss ion load to be emitted from the waste water treatment proces s within the predetermined time interval , the determined control threshold of the emission concentration and / or load, or the control time interval .

[0010] An arrangement for providing control information of a waste water treatment proces s for control ling an emission load to be emitted from the waste water treatment process within a predetermined time interval is disclosed . The arrangement may comprise means for obtaining at a plurality of instants within the predetermined time interval a value of a current cumulative emission load emitted from the waste water treatment process , means for determining at each of the plurality of instants within the predetermined time interval an estimate of the cumulative emiss ion load to be emitted from the waste water treatment proces s within the predetermined time interval , wherein the estimate of the cumulative emission load is determined based on at least the value of the current cumulative emission load and on data of the emission load emitted from the waste water treatment process obtained earlier, means for determining at each of the plurality of instants a control threshold of the emission concentration and / or load at which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below a predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , and / or means for determining at each of the plurality of instants a control time interval for the duration of which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below the predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , and means for providing the control information for implementing the one or more control actions in the waste water treatment process based on at least one of the estimate of the cumulative emiss ion load to be emitted from the waste water treatment process within the predetermined time interval , the determined control threshold of the emission concentration and / or load, or the control time interval .

[0011] A computer program is also disclosed, the computer program comprising instructions which, when executed by an apparatus , cause the apparatus to perform at least the following : obtaining at a plurality of instants within the predetermined time interval a value of a current cumulative emission load emitted from the waste water treatment process , determining at each of the plurality of instants within the predetermined time interval an estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval , wherein the estimate of the cumulative emission load is determined based on at least the value of the current cumulative emission load and on data of the emis sion load emitted from the waste water treatment process obtained earlier, determining at each of the plurality of instants a control threshold of the emission concentration and / or load at which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below a predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , and / or determining at each of the plurality of instants a control time interval for the duration of which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below the predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , and providing the control information for implementing the one or more control actions in the waste water treatment process based on at least one of the estimate of the cumulative emiss ion load to be emitted from the waste water treatment proces s within the predetermined time interval , the determined control threshold of the emission concentration and / or load, or the control time interval .

[0012] BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings , which are included to provide a further understanding of the described embodiments and constitute a part of this specification, illustrate various advantageous features and examples of their combinations . In the drawings : Figure 1 illustrates a flow chart representation of a method for providing control information of a waste water treatment process for controlling an emission load to be emitted from the waste water treatment process within a predetermined time interval according to an embodiment ;

[0014] Figure 2 illustrates a block diagram of an arrangement according to an embodiment ;

[0015] Figure 3 illustrates an arrangement according to an embodiment as a block diagram and schematically a waste water treatment process according to an embodiment ;

[0016] Figure 4 shows a historical COD load distribution data obtained over almost a year as a histogram;

[0017] Figure 5 illustrates incoming COD concentration values during a time interval of a month;

[0018] Figure 6 shows the evolution of the allowable ( cumulative ) emission load calculated every hour during the simulation ;

[0019] Figure 7 shows the control thresholds found by the optimi zer ; and

[0020] Figure 8 shows the cumulative COD emissions calculated at each hour and the monthly predetermined limit for the emissions .

[0021] DETAILED DESCRIPTION

[0022] A method for providing control information of a waste water treatment process for controlling an emission load to be emitted from the waste water treatment process within a predetermined time interval is disclosed .

[0023] The method may comprise obtaining at a plurality of instants within the predetermined time interval a value of a current cumulative emission load emitted from the waste water treatment process , determining at each of the plurality of instants within the predetermined time interval an estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval , wherein the estimate of the cumulative emission load is determined based on at least the value of the current cumulative emission load and on data of the emis sion load emitted from the waste water treatment process obtained earlier, determining at each of the plurality of instants a control threshold of the emission concentration and / or load at which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below a predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , and / or determining at each of the plurality of instants a control time interval for the duration of which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below the predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , and providing the control information for implementing the one or more control actions in the waste water treatment process based on at least one of the estimate of the cumulative emiss ion load to be emitted from the waste water treatment proces s within the predetermined time interval , the determined control threshold of the emission concentration and / or load, or the control time interval . An arrangement for providing control information of a waste water treatment proces s for control ling an emission load to be emitted from the waste water treatment process within a predetermined time interval is also disclosed .

[0024] The arrangement may comprise means for obtaining at a plurality of instants within the predetermined time interval a value of a current cumulative emission load emitted from the waste water treatment process , means for determining at each of the plurality of instants within the predetermined time interval an estimate of the cumulative emiss ion load to be emitted from the waste water treatment proces s within the predetermined time interval , wherein the estimate of the cumulative emission load is determined based on at least the value of the current cumulative emission load and on data of the emission load emitted from the waste water treatment process obtained earlier, means for determining at each of the plurality of instants a control threshold of the emission concentration and / or load at which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below a predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , and / or means for determining at each of the plurality of instants a control time interval for the duration of which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below the predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , and means for providing the control information for implementing the one or more control actions in the waste water treatment proces s based on at least one of the estimate of the cumulative emiss ion load to be emitted from the waste water treatment process within the predetermined time interval , the determined control threshold of the emission concentration and / or load, or the control time interval .

[0025] A computer program comprising instructions is also disclosed . The instructions , when executed by an apparatus , cause the apparatus to perform at least the following : obtaining at a plurality of instants within the predetermined time interval a value of a current cumulative emission load emitted from the waste water treatment process , determining at each of the plurality of instants within the predetermined time interval an estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval , wherein the estimate of the cumulative emission load is determined based on at least the value of the current cumulative emission load and on data of the emis sion load emitted from the waste water treatment process obtained earlier, determining at each of the plurality of instants a control threshold of the emission concentration and / or load at which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below a predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , and / or determining at each of the plurality of instants a control time interval for the duration of which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below the predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , and providing the control information for implementing the one or more control actions in the waste water treatment process based on at least one of the estimate of the cumulative emiss ion load to be emitted from the waste water treatment proces s within the predetermined time interval , the determined control threshold of the emission concentration and / or load, or the control time interval .

[0026] The method, arrangement and computer program may be used to select and optionally implement suitable control actions in the waste water treatment process based on the control information even in processes in which the emission loads may be quite variable e . g . within the predetermined time interval . For example , in waste water obtainable from pulping processes , emission loads such as COD and phosphorus loads in waste water streams obtainable from the pulping processes may vary in a cyclical manner .

[0027] Further, the method, arrangement and computer program may allow for implementing an on-off control strategy and for selecting an optimal control threshold of the emiss ion load . Then one or more control actions may be implemented when the control threshold is met ( for example , reached or exceeded) .

[0028] The method and arrangement may be a method and arrangement for controlling waste water treatment process for controlling an emiss ion load to be emitted from the waste water treatment process within a predetermined time interval.

[0029] The waste water treatment process may have a predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process e.g. within the predetermined time interval. For example, the predetermined limit of the cumulative emission load may be a limit allowed by an environmental license or permit or by an environmental regulation within the predetermined time interval, such as a monthly limit.

[0030] The predetermined time interval may be e.g. a month, or an interval of at least a month. The predetermined time interval may however also be shorter or longer, such as at least a week, or several weeks, or several months, or at least a year, or a year. The predetermined time interval may be determined by an environmental license or permit that sets the limit of the cumulative emission load that may be emitted from the waste water treatment process, or it may be a predetermined time interval imposed by the waste water treatment process itself.

[0031] The instants of the plurality of instants within the predetermined time interval may occur e.g. every 24 hours, or every 48 hours, or every 72 hours, or every four days, or once a week. Or, the plurality of instants may comprise or be e.g. at least four, or at least five, or at least 8, or at least 10, or at least 15 instants within the predetermined time interval. The instants may occur at regular or irregular intervals from each other. Thus the value of the current cumulative emission load emitted from the waste water treatment process may be obtained e.g. every 24 hours, or every 48 hours, or every 72 hours, or every four days, or once a week. Very short intervals between the instants may not be practical; at the same time, very long intervals between the instants may not allow for reacting to sudden changes in the emission load to a sufficient extent . It is also possible to obtain values of the current cumulative emission load emitted from the waste water treatment process at shorter intervals , for example every hour, several times a day or once a day . Then the value of the current cumulative emis sion load emitted from the waste water treatment process at each specific instant may be obtained, e . g . calculated, from these values obtained at the shorter intervals .

[0032] The value of the current cumulative emission load emitted from the waste water treatment process may thus be understood as the value of the current cumulative emi ssion load emitted from the waste water treatment process from the beginning of the predetermined time interval until the specific instant at which the value is determined .

[0033] The emis sion load may compri se or be at least one of chemical oxygen demand (COD) load or phosphorus load . In other words , the term "emis sion load" may in this specification refer to COD load, phosphorus load, or both COD load and phosphorus load . Likewise , the emission concentration may compri se or be at least one of chemical oxygen demand (COD) concentration or phosphorus concentration , the term "emission concentration" may in this specification refer to COD concentration, phosphorus concentration, or both COD concentration and phosphorus concentration . In embodiments in which both COD load and phosphorus load are used in the method or arrangement , the method and arrangement may be applied to COD load and phosphorus load separately .

[0034] COD and phosphorus are emissions the load of which may be quite variable ; for example in waste water streams obtainable from the pulping processes COD and phosphorus loads may vary in a cycl ic manner . COD and phosphorus may in certain situations be controlled by implementing similar or the same control actions . Both may also be subj ect to environmental permits , licenses or regulations . The emission load may comprise or be COD load . COD may be understood as referring to a measure of the amount of oxygen that can be consumed by chemical reactions in the waste water . COD (COD concentration) is commonly expressed in mass of oxygen consumed over volume of waste water as milligrams per litre (mg / 1 ) . It may be used as a quantitative indication of oxidi zable organic matter in the waste water . COD load may be expressed as kg / d ( i . e . kg / day) . Many governments impose strict regulations regarding the maximum COD allowed in waste water before it may be discharged to the environment . Likewise , phosphorus concentration may be expressed e . g . as mg / 1 and the phosphorus load as kg / day .

[0035] In the context of this specification, the waste water treatment process may be a process to which waste water incoming from one or more sources are directed and in which they are treated so that the waste water may be emitted, e . g . discharged, from the waste water treatment process .

[0036] The waste water treatment process may comprise a primary treatment, a secondary treatment , and optionally a tertiary treatment .

[0037] In the context of this specification, the term "primary treatment" may be understood as referring to a treatment intended to remove coarse , suspended and floating solids from raw waste water . It may comprise screening for trapping solid obj ects and sedimentation for removing suspended solids .

[0038] In the context of this specification, the term "secondary treatment" may be understood as referring to a treatment including a biological treatment and intended to remove dissolved organic matter, phosphorus and nitrogen remaining after the primary treatment . The secondary treatment may comprise a biological treatment ( including e . g . an aeration tank) and a secondary clarification ( sedimentation) stage . In the context of this specification, the term "tertiary treatment" may be understood as referring to a treatment that may follow the primary and secondary treatment and that is intended to at least partially remove dissolved organic matter, phosphorus and nitrogen that may remain after primary and secondary treatment . The tertiary treatment may increase the quality of the waste water before it i s emitted (discharged) from the waste water treatment process . Tertiary treatment may involve physical-chemical separation techniques such as f locculation / precipitation, carbon adsorption, membranes for advanced filtration, ion exchange , dechlorination, and / or reverse osmosis , depending e . g . on the required quality of the resulting waste water to be emitted from the wastewater treatment process . The tertiary treatment may thus comprise e . g . a flocculation stage and / or a precipitation stage . The tertiary treatment may comprise a control treatment , in which at least one control chemical is added to the waste water in order to f locculate / precipitate at least a part of the emission load, such as COD and / or phosphorus load .

[0039] The waste water incoming to the waste water treatment process may be obtained from a pulping process , for example from a pulp bleaching process . Such waste water obtained from a pulping process may typically contain so-called hard COD, i . e . COD that is refractory to biological treatment . Thus such waste water may contain significant concentrations and / or loads of COD after primary and secondary treatment . The hard COD may include organic aromatic compounds originating from plants , such as lignin and / or compounds derived from lignin, or from soil-based material , such as humic acid and / or fulvic acid . Such waste water obtained from a pulping process , such as a pulp bleaching process , may also contain significant concentrations and / or loads of phosphorus . The waste water incoming to the waste water treatment process may be obtained from a single waste water stream, or it may be obtained by combining a plurality of waste water streams , including waste water streams e . g . from a pulping process , such as a pulp bleaching process , before they enter the waste water treatment process . The plurality of the waste water streams may be combined e . g . in a primary sedimentation tank of the waste water treatment process .

[0040] The value of the current cumulative emission load emitted from the waste water treatment process may be obtained e . g . from measurements , such as online measurements , of the emi ssion concentration in and flow of the waste water emitted from the waste water treatment process as from the beginning of the predetermined time interval until the specific instant . When the values of the concentration of the emission in the waste water emitted from the waste water treatment proces s and the flow of the waste water emitted from the waste water treatment process are obtained, it is possible to determine , e . g . calculate or estimate , the emission load in the waste water emitted from the waste water treatment process . In general , an emiss ion load within a time interval may be calculated when the emission concentration ( s ) and flow ( s ) within the time interval are known . When the emission concentration and / or load in the waste water emitted from the waste water treatment process until each instant as from the beginning of the predetermined time interval is known, the value of the current cumulative emission load may be calculated therefrom .

[0041] In some embodiments , when the emission concentration in the waste water emitted from the waste water treatment process at each instant as from the beginning of the predetermined time interval is known, the value of the current cumulative emission load at said instant may be calculated therefrom based on the average flow as from the beginning of the predetermined time interval . The emission concentration and / or load (e . g . COD and / or phosphorus concentration and / or COD and / or phosphorus load) may be determined from the waste water e . g . immediately before the waste water i s emitted from the waste water treatment process , for example after a tertiary treatment , or in embodiments in which the waste water treatment process does not comprise a tertiary treatment , after the secondary treatment .

[0042] The method may further comprise measuring the emission concentration and / or load in the waste water emitted from the waste water treatment process , for example measuring the emission load as from the beginning of the predetermined time interval . The method may comprise measuring the flow of the waste water emitted from the waste water treatment process as from the beginning of the predetermined time interval and thereby measuring the emission load in the waste water emitted from the waste water treatment process as from the beginning of the predetermined time interval . The method may comprise measuring e . g . the average flow of the waste water emitted to and / or from the waste water treatment process .

[0043] The arrangement may comprise means for measuring the emission concentration and load in the waste water emitted from the waste water treatment process , for example as from the beginning of the predetermined time interval . The arrangement may comprise means for measuring the flow of the waste water emitted from the waste water treatment process as from the beginning of the predetermined time interval and thereby for measuring the emission load in the waste water emitted from the waste water treatment process as from the beginning of the predetermined time interval . The arrangement may comprise means for measuring e . g . the average flow of the waste water emitted to and / or from the waste water treatment process . The method may further comprise using a measurement apparatus to measure the emission concentration and optionally load in the waste water emitted from the waste water treatment process as from the beginning of the predetermined time interval . The arrangement may thus further comprise a measurement apparatus for measuring or configured to measure the emission concentration and optionally load in the waste water emitted from the waste water treatment process as from the beginning of the predetermined time interval .

[0044] The method may further comprise using a measurement apparatus to measure the flow of the waste water emitted from the waste water treatment process , for example as from the beginning of the predetermined time interval . The arrangement may thus further comprise a measurement apparatus for measuring or configured to measure the flow of the waste water emitted from the waste water treatment process , for example as from the beginning of the predetermined time interval .

[0045] The emission concentration and / or load (e . g . COD and / or phosphorus concentration and / or COD and / or phosphorus load) may be determined and / or measured from the waste water e . g . immediately before the waste water is emitted from the waste water treatment process , and / or before tertiary treatment ( i . e . between secondary treatment and tertiary treatment ) . The emission concentration and / or load (e . g . COD and / or phosphorus concentration and / or COD and / or phosphorus load) may in some embodiments be determined and / or measured from the waste water before and after the tertiary treatment .

[0046] The measurement ( s ) may be done using a method and / or apparatus for monitoring and controlling a treatment of a waste water stream as described in WO 2020 / 099723 , which is herein incorporated in its entirety . In said method and / or apparatus , the COD concentration may be measured by measuring ultraviolet (UV) light absorbance and optionally turbidity of the waste water and determining the COD concentration (dissolved organics ) in the waste water based on the measured UV absorbance and optionally on the measured turbidity . Said method and / or apparatus may be an online ( realtime ) method and / or an online apparatus . The arrangement may further comprise such an apparatus .

[0047] The measurement ( s ) may be done using a method and / or apparatus for controlling a coagulant dosage in a water treatment system as described in WO 2023 / 052681 , which is herein incorporated in its entirety . The arrangement may further comprise such an apparatus .

[0048] The estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval may be determined based on at least the value of the current cumulative emiss ion load and on data of the emis sion load emitted from the waste water treatment process obtained earlier . The data of the emission load emitted from the waste water treatment process may have been obtained earlier e . g . by online measurements of the emission concentrations and / or emis sion loads ( either in the waste water incoming to the waste water treatment process and / or in the waste water to be emitted from the waste water treatment process ) . The data of the emission load obtained earlier may have been stored e . g . in a database . The data of the emission load ( s ) obtained earlier may thus be understood as referring to data obtained earlier, i . e . historical data or long-term data, that includes data on the emission load emitted from the waste water treatment process obtained before the method and / or arrangement described herein is used or applied .

[0049] The data obtained earlier may be gathered e . g . in the form of a distribution of emission loads emitted from the waste water treatment process or incoming to the waste water treatment process , or in the form of a distribution of emission concentrations emitted from the waste water treatment process or incoming to the waste water treatment process . The data obtained earlier may have been gathered over a long period of time , such as for a plurality of predetermined time intervals . For example , wherein the predetermined time interval is a month, the data obtained earlier may have been obtained over at least a month, or over at least two months , or over at least three months , or e . g . over a year . Further data of the emission load obtained earlier may be gathered e . g . after each predetermined time interval and added to the data obtained earlier for future predetermined time intervals .

[0050] The arrangement may thus comprise means for gathering and / or storing the data obtained earlier .

[0051] The data of the emission load obtained earlier may exhibit cyclical variation . For example , waste water incoming to the waste water treatment process that is obtained from a pulping process , such as from a pulp bleaching process , may often exhibit cyclical variation . In such embodiments , the data of the emi ssion load obtained earlier may be obtained from a time interval exhibiting the cyclical variation for a plurality of cycles .

[0052] For example , in embodiments in which a plurality of cycles are exhibited during a time interval of a month, the data obtained earlier may have been obtained over at least a month, or at least two months , or over at least three months , or e . g . over a year .

[0053] The method may comprise determining at each of the plurality of instants an allowable cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , wherein the allowable cumulative emission load is determined based on the value of the current cumulative emi ssion load and the predetermined l imit of the cumulative emission load that may be emitted from the waste water treatment process , and by determining the control threshold and / or the control time interval based on the allowable cumulative emission load .

[0054] The arrangement may further comprise means for determining at each of the plurality of instants an allowable cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , wherein the allowable cumulative emission load is determined based on the value of the current cumulative emission load and the predetermined limit of the cumulative emission load that may be emitted from the waste water treatment proces s , and by determining the control threshold and / or the control time interval based on the allowable cumulative emission load .

[0055] The allowable cumulative emission load may be determined e . g . by subtracting the value of the current cumulative emission load from the predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval . The allowable cumulative emission load is thus the emission load that may still be emitted from the waste water treatment process within the predetermined time interval , for example without breaching an environmental license , permit or regulations . A safety marginal , for example a safety marginal of e . g . 5 % or 10 % , may be taken into account when determining the allowable cumulative emission load, if desired .

[0056] Then, at each of the plurality of instants , the control threshold of the emission concentration and / or load, or the control time interval , may be determined such that the estimate of the cumulative emis sion load to be emitted from the waste water treatment process within the predetermined time interval remaining remains below the allowable cumulative emission load .

[0057] It may be possible to estimate a proportion of the estimate of the cumulative emission load to be reduced in the waste water treatment process by implementing the one or more control actions in the waste water treatment process . In other words , when the proportion of the estimate of the cumulative emission load to be reduced has been estimated, i . e . it is estimated how much of the emission load will be removed, by implementing the one or more control actions , it may be possible to calculate ( or at least estimate ) the proportion of the estimated cumulative emission load that will be reduced / removed and the proportion of the estimated cumulative emission that will remain after implementing the one or more control actions . The proportion of the estimated cumulative emission that will remain after implementing the one or more control actions may then be considered as the estimate of the cumulative emission load to be emitted from the waste water treatment process . The estimate of the cumulative emission load may thus be determined also on the basis of the proportion of the estimate of the cumulative emission load to be reduced in the waste water treatment process by implementing the one or more control actions in the waste water treatment process .

[0058] The control threshold of the emission load may be considered to be e . g . a load or a concentration of the emiss ion , at which the one or more control actions in the waste water treatment process may or should be implemented in order to control that the emiss ion load to be emitted from the waste water treatment process within the predetermined time interval remains under the predetermined limit . The control threshold may be the highest value of the control threshold at which the one or more control actions in the waste water treatment process may or should be implemented such that the emission load to be emitted from the waste water treatment process within the predetermined time interval remains under the predetermined limit .

[0059] For example , when the control threshold is reached or exceeded, the control information provided may include an indication that the one or more control actions in the waste water treatment process may or should be implemented . For example , when the emission is COD, the control threshold may be a COD concentration (mg / 1 ) or COD load which, when reached or exceeded, indicates that the one or more control actions in the waste water treatment process should be implemented . Then the control information provided may include an indication that the one or more control actions in the waste water treatment process should be implemented . Subsequently, the one or more control actions in the waste water treatment process may be implemented .

[0060] The control threshold of the emission load may be determined based on the allowable cumulative emission load, on the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval , and on the proportion of the estimate of the cumulative emission load to be removed by implementing the one or more control actions in the waste water treatment process .

[0061] For example , the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval may be calculated using a number of possible emission loads as tentative control thresholds and selecting the highest emission load / tentative control threshold that leads to an estimate of the cumulative emission load to be emitted from the waste water treatment proces s that is still within the predetermined limit of the cumulative emission load . The highest emission load / tentative control threshold thereby selected may be selected as the control threshold of the emission load . Alternatively, a corresponding emission concentration may be calculated from the highest emission load based on e . g . the average flow and used as the control threshold . A suitable optimi zation algorithm may be applied for determining the control threshold, e . g . a derivative-free optimi zation method, such as golden-section search or pattern search .

[0062] A safety marginal , for example a safety marginal of e . g . 5 % or 10 % , may be taken into account when determining the control threshold, if desired . For example, then the predetermined limit of the cumulative emission load may be e . g . 90 % or 95 % of a limit allowed by an environmental license or permit or by an environmental regulation within the predetermined time interval , such as a monthly limit .

[0063] The control time interval may be a time interval , for the duration of which the at least one control actions may or should be implemented such that that the estimate of the cumulative emiss ion load to be emitted from the waste water treatment proces s within the predetermined time interval remains below the predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval . The control time interval may be the shortest control time interval for the duration of which the one or more control actions in the waste water treatment process may or should be implemented such that the emiss ion load to be emitted from the waste water treatment process within the predetermined time interval remains under the predetermined limit .

[0064] For example , the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval may be calculated using a number of possible control time intervals as tentative control time intervals and selecting the shortest tentative control time interval that leads to an estimate of the cumulative emission load to be emitted from the waste water treatment process that is still within the predetermined limit of the cumulative emission load . The shortest tentative control time interval thereby selected may be selected as the control time interval of the emission load. A suitable optimization algorithm may be applied for determining the control time interval, e.g. a derivative-free optimization method, such as golden-section search or pattern search.

[0065] A safety marginal, for example a safety marginal of e.g. 5 % or 10 % , may be taken into account when determining the control time interval, if desired. For example, then the predetermined limit of the cumulative emission load may be e.g. 90 % or 95 % of a limit allowed by an environmental license or permit or by an environmental regulation within the predetermined time interval, such as a monthly limit.

[0066] The emission concentration and / or load (e.g. COD and / or phosphorus concentration and / or COD and / or phosphorus load) may be determined from the waste water e.g. (immediately) before the waste water is emitted from the waste water treatment process, and / or before tertiary treatment (i.e. between the secondary treatment and the tertiary treatment) . Whether the control threshold is reached and / or exceeded may thus also be determined from the emission concentration and / or load (e.g. COD and / or phosphorus concentration and / or COD and / or phosphorus load) determined from the waste water e.g. (immediately) before the one or more control actions in the waste water treatment process would be implemented. For example, in embodiments in which the one or more control actions would be implemented in the tertiary treatment, the emission concentration and / or load (e.g. COD and / or phosphorus concentration and / or COD and / or phosphorus load) may be determined from the waste water before the tertiary treatment (and after the secondary treatment) . In embodiments in which the one or more control actions would be implemented in the secondary treatment, the emission concentration and / or load (e.g. COD and / or phosphorus concentration and / or COD and / or phosphorus load) may be determined from the waste water before the secondary treatment ( and after the primary treatment ) .

[0067] Whether the control threshold is met may then be determined from the emission concentration and / or load thus determined .

[0068] Providing the control information may be understood e . g . as outputting the control information . The control information may be provided or output e . g . to a display for an operator of the waste water treatment process . The control information may be provided or output e . g . in the form of an alert , a control signal , and / or a suggestion to the operator of the waste water treatment process . The control information may be provided or output e . g . to an apparatus for implementing the one or more control actions in the waste water treatment process based on at least the control information, for example as a control signal . The control information may be provided or output e . g . to an apparatus for monitoring and controlling a treatment of a waste water stream as described in WO 2020 / 099723 , which is herein incorporated in its entirety . The control information may be provided or output e . g . to an apparatus for controlling a coagulant dosage in a water treatment system as described in WO 2023 / 052681 , which is herein incorporated in its entirety .

[0069] The method may further comprise using the control information for controlling the emission load to be emitted from the waste water treatment process within the predetermined time interval . The arrangement may further comprise means for using the control information for controlling the emission load to be emitted from the waste water treatment process within the predetermined time interval .

[0070] The method may further comprise implementing one or more control actions in the waste water treatment process based on at least the control information, such as the determined control threshold of the emiss ion load . For example , when the control threshold is met , the one or more control actions may be implemented . Or, when the control time interval is determined, the one or more control actions may be implemented for the duration of the control time interval .

[0071] The arrangement may further comprise means for implementing one or more control actions in the waste water treatment process based on at least the control information, such as the determined control threshold of the emission load .

[0072] The one or more control actions may comprise at least one of starting a control treatment of the emission load in the waste water treatment process , controlling dosing of at least one control chemical in a control treatment of the emission load in the waste water treatment process , adj usting a parameter of a secondary treatment in the waste water treatment process , or adj usting a parameter of a tertiary treatment in the waste water treatment process .

[0073] In the context of this specification, the term "control treatment" may be understood as referring to a treatment that is intended to control the emission load, e . g . to remove or reduce the emission load at least partially . The control treatment may comprise or be a chemical control treatment , a physical control treatment , or a combination of a chemical and physical control treatment . For example , the control treatment may comprise dosing of at least one control chemical and subsequent removal of suspended solids in the waste water treatment process . In other words , the control treatment may comprise or be dosing of at least one control chemical . The control treatment may comprise a physical control treatment , such as sedimentation, clarification, flocculation, membrane purification, and / or ultraviolet light treatment . The one or more control actions may comprise starting a control treatment of the emission load in the waste water treatment process . For example , the one or more control actions may comprise starting dosing of at least one control chemical in the waste water treatment process .

[0074] The one or more control actions may comprise starting and / or controlling dosing of at least one control chemical in a control treatment of the emission load in the waste water treatment process .

[0075] The one or more control actions may comprise adj usting a parameter of a secondary treatment in the waste water treatment process .

[0076] The one or more control actions may comprise adj usting a parameter of a tertiary treatment in the waste water treatment process .

[0077] The one or more control actions may be implemented e . g . in tertiary treatment . A parameter of the tertiary treatment may be adj usted in embodiments in which the waste water treatment process comprises a tertiary treatment . In embodiments in which the tertiary treatment comprises a flotation stage, the parameter of a tertiary treatment may include e . g . a rate of aeration of the f lotation stage and / or a parameter of a scraper of the flotation stage .

[0078] Starting a control treatment of the emission load in the waste water treatment process may refer to starting a control treatment process within the waste water treatment process that i s intended to reduce and thereby control the emission load in the waste water to be emitted from the waste water treatment proces s . For example, the control treatment may be started only when the control threshold is met ( reached and / or exceeded) . In this manner, the control treatment may be started only when necessary, for example in situations in which the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval typically remains below or close to the predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process.

[0079] The control treatment of the emission load may be started in the secondary treatment and / or in the tertiary treatment of the waste water treatment process.

[0080] The starting of the control treatment may comprise e.g. starting dosing of at least one control chemical in the control treatment of the emission load in the waste water treatment process.

[0081] Such control chemicals may flocculate and / or precipitate COD and / or phosphorus, such that they may be removed at least partially by clarification, sedimentation, flotation and / or filtration.

[0082] Controlling the dosing of at least one control chemical in a control treatment of the emission load in the waste water treatment process may comprise or be e.g. increasing the dosing of the at least one control chemical .

[0083] The at least one control chemical may be dosed e.g. in the secondary treatment. In embodiments in which the waste water treatment process comprises a secondary treatment, which comprises a biological treatment (and e.g. an aeration tank) and a secondary clarification (sedimentation) stage, and at least a part of sludge from the secondary clarification is returned to the biological treatment (e.g. in the aeration tank) in the secondary treatment as return sludge (i.e. return activated sludge) , the at least one control chemical, such as a coagulant, may be dosed in the return sludge. Additionally or alternatively, the at least one control chemical, such as a polymer or an inorganic coagulant, may be added to the secondary clarification, e.g. to the waste water incoming to the secondary clarification.

[0084] The at least one control chemical may, additionally or alternatively, be dosed e.g. in the tertiary treatment . The parameter of the secondary treatment in the waste water treatment process may include or be e.g. a rate of aeration of the biological treatment in the secondary treatment and / or dosing of a nutrient supplement to the biological treatment in the secondary treatment. The nutrient supplement may include one or more nutrients for the microbial population involved in the biological treatment.

[0085] The at least one control chemical may comprise or be at least one of a coagulant, such as aluminium- based coagulant or an iron-based coagulant, or of a flocculant, such as a polymer. The at least one control chemical may comprise a coagulant, such as an inorganic coagulant, and a flocculant. The capability of coagulants to remove the emission at least partially may be improved by the flocculant.

[0086] The coagulant may comprise or be an inorganic (anionic or cationic) coagulant, an organic (polyelec- trolytic) coagulant or any mixture or combination thereof. The inorganic coagulant may comprise or be e.g. a salt of aluminium, iron, magnesium, calcium, zirconium, zinc, or any mixture or combination thereof. The inorganic coagulant may comprise or be e.g. a chloride, sulphate, chlorosulphate, chlorohydrate, silicate, nitrate, or any mixture or combination thereof. The inorganic coagulant may comprise or be e.g. aluminium sulphate, polyaluminium sulphate, iron sulphate, aluminium chloride, polyaluminium chloride, polyaluminium chlorosulfate, polyaluminium hydroxychlorosulfate, aluminium chlorohydrate, sodium aluminate, ferric sulfate, polyferric sulfate, ferric chloride, ferric chlorosulphate, polyferric chloride, ferrous sulfate, ferrous chlorosulphate, ferrous chloride, aluminium triformate, polyaluminium formate, polyaluminium nitrate, polyaluminum silicate, magnesium chloride calcium chloride, calcium sulphate, zinc chloride, or any mixture or combination thereof. The organic (polyelectrolytic) coagulant may comprise or be e . g . polyacrylamide , polyamine , polyDADMAC, polyethyleneimine , dicyandiamide , polyvinyl amine , or any mixture or combination thereof .

[0087] The flocculant may comprise or be e . g . an inorganic polymer, such as activated silica ; a natural polymer, such as starch or alginate ; a synthetic polymer, or any mixture or combination thereof . Polymers may be cationic, anionic, nonionic, or amphoteric . The synthetic polymer may comprise or be e . g . polyacrylamide , polyamine , polydiallyldimethylammoniumchloride (polyDADMAC) , or any mixture or combination thereof .

[0088] In embodiments in which the emission load comprises or is chemical oxygen demand (COD) load and phosphorus load, the method may comprise obtaining at a plurality of instants within the predetermined time interval a value of a current cumulative COD load and a value of a current cumulative phosphorus load emitted from the waste water treatment process , determining at each of the plurality of instants within the predetermined time interval an estimate of the cumulative COD load and an estimate of the cumulative phosphorus load to be emitted from the waste water treatment process within the predetermined time interval , wherein the estimate of the cumulative COD load is determined based on at least the value of the current cumulative COD load and on data of the COD load emitted from the waste water treatment process obtained earlier, and the estimate of the cumulative phosphorus load is determined based on at least the value of the current cumulative phosphorus load and on data of the phosphorus load emitted from the waste water treatment process obtained earlier, optionally determining at each of the plurality of instants an allowable cumulative COD load and an allowable cumulative phosphorus load that may be emitted from the waste water treatment process within the predetermined time interval , wherein the allowable cumulative COD load is determined based on the current cumulative COD load and a predetermined l imit of the cumulative COD load that may be emitted from the waste water treatment process , and the allowable cumulative phosphorus load is determined based on the current cumulative phosphorus load and a predetermined limit of the cumulative phosphorus load that may be emitted from the waste water treatment process , determining at each of the plurality of instants a control threshold of the COD concentration and / or load at which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative COD load to be emitted from the waste water treatment process within the predetermined time interval remains below a predetermined limit of the cumulative COD load that may be emitted from the waste water treatment process within the predetermined time interval , and a control threshold of the phosphorus concentration and / or load at which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative phosphorus load to be emitted from the waste water treatment process within the predetermined time interval remains below a predetermined limit of the cumulative phosphorus load that may be emitted from the waste water treatment process within the predetermined time interval ; and / or determining at each of the plurality of instants a control time interval during which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative COD load to be emitted from the waste water treatment process within the predetermined time interval remains below the predetermined limit of the cumulative COD load that may be emitted from the waste water treatment process within the predetermined time interval , and determining at each of the plurality of instants a control time interval during which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative phosphorus load to be emitted from the waste water treatment process within the predetermined time interval remains below the predetermined limit of the cumulative phosphorus load that may be emitted from the waste water treatment process within the predetermined time interval , and providing the control information for implementing one or more control actions in the waste water treatment process based on at least one of the estimate of the cumulative COD load to be emitted from the waste water treatment process within the predetermined time interval , the estimate of the cumulative phosphorus load to be emitted from the waste water treatment process within the predetermined time interval , the determined control threshold of the COD concentration and / or load, the determined control threshold of the phosphorus concentration, or the control time interval .

[0089] The waste water treatment process thus may have a predetermined limit of the cumulative COD load and a predetermined limit of the cumulative phosphorus load that may be emitted from the waste water treatment process e . g . within the predetermined time interval . It may be of interest to ensure that both the cumulative COD load and the cumulative phosphorus load that are eventually emitted from the waste water treatment process within the predetermined time interval remain below the predetermined limits .

[0090] In such an embodiment , the control thresholds of the COD and phosphorus loads may be selected such that both the estimate of the cumulative COD load remains below the predetermined limit of the cumulative COD load and the estimate of the cumulative phosphorus load to be emitted from the waste water treatment process within the predetermined time interval remain below the predetermined limit of the cumulative phosphorus load that may be emitted from the waste water treatment process . For example , from the separately determined COD and phosphorus control thresholds , the control threshold that leads to a higher proportion of the estimates of the cumulative COD and phosphorus loads to be removed by implementing one or more control actions in the waste water treatment process may be selected as the control threshold . In a similar manner, from the separately determined COD and phosphorus control time intervals , the control time interval that leads to a higher proportion of the estimates of the cumulative COD and phosphorus loads to be removed by implementing one or more control actions in the waste water treatment process may be selected as the control time interval .

[0091] The various means described in this specification may comprise or be the same or different means , for example the same apparatus , computing unit or processor, or different apparatuses , computing units or processors , which may arranged at one or more locations .

[0092] The means may comprise at least one processor and at least one memory including computer program code . The at least one memory and the computer program code may be conf igured to , with the at least one processor, cause the arrangement to perform the method according to one or more embodiments described in this specification .

[0093] The arrangement may comprise at least one processor and at least one memory including computer program code , the at least one memory and the computer program code conf igured to , with the at least one processor, cause the arrangement to perform the method according to one or more embodiments described in this specification, e . g . : obtain at a plurality of instants within the predetermined time interval a value of a current cumulative emission load emitted from the waste water treatment process , determine at each of the plurality of instants within the predetermined time interval an estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval , wherein the estimate of the cumulative emission load is determined based on at least the value of the current cumulative emi ssion load and on data of the emission load emitted from the waste water treatment process obtained earlier, determine at each of the plurality of instants a control threshold of the emission concentration and / or load at which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emiss ion load to be emitted from the waste water treatment process within the predetermined time interval remains below a predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , and / or determine at each of the plurality of instants a control time interval during which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below the predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , and provide the control information for implementing the one or more control actions in the waste water treatment process based on at least one of the estimate of the cumulative emiss ion load to be emitted from the waste water treatment process within the predetermined time interval , the determined control threshold of the emission concentration and / or load, or the control time interval .

[0094] The at least one memory and the computer program code may be further configured to , with the at least one processor, cause the arrangement to : measure the emission concentration and load in the waste water emitted from the waste water treatment process , for example as from the beginning of the predetermined time interval .

[0095] The at least one memory and the computer program code may be further configured to , with the at least one processor, cause the arrangement to : measure the flow of the waste water emitted from the waste water treatment process as from the beginning of the predetermined time interval and thereby measure the emission load in the waste water emitted from the waste water treatment process as from the beginning of the predetermined time interval .

[0096] The at least one memory and the computer program code may be further configured to , with the at least one processor, cause the arrangement to : implement one or more control actions in the waste water treatment process based on at least the control information, such as the determined control threshold of the emission load .

[0097] There is provided a computer program comprising instructions which, when executed by an apparatus , cause the apparatus to perform the method according to one or more embodiments described in this specification .

[0098] There is further provided a computer-readable medium comprising instructions which, when executed by an apparatus , cause the apparatus to perform the method according to one or more embodiments described in this specification .

[0099] EXAMPLES Reference will now be made in detail to various embodiments , an example of which is il lustrated in the accompanying drawings .

[0100] The description below discloses some embodiments in such a detail that a person skilled in the art is able to utili ze the embodiments based on the disclosure . Not all steps or features of the embodiments are discussed in detail , as many of the steps or features will be obvious for the person skilled in the art based on this specification .

[0101] Figure 1 illustrates a flow chart representation of a method for providing control information of a waste water treatment process (WWTP) 101 for controlling an emission load to be emitted from the waste water treatment process 101 within a predetermined time interval according to an embodiment .

[0102] At 102 , at an instant of a plurality of instants within the predetermined time interval , a value of a current cumulative emi ssion load emitted from the waste water treatment process is obtained and / or received . The value of the current cumulative emission load may be obtained or received in various ways . In some embodiments , the method may comprise measuring the concentration of the emission, for example using a suitable online measurement , in the waste water emitted from the waste water treatment process . The method may further comprise measuring the flow or the average flow of the waste water emitted from the waste water treatment process and calculating the value of the current cumulative emission load from the measured concentration of the emission ( or measured concentrations of the emission e . g . once an hour or daily) . As a further example , in arrangements comprising at least one processor and at least one memory including computer program code , the value of the current cumulative emission load may be obtained from the at least one memory of the arrangement , where it may have been stored ( for example , in a database ) .

[0103] At 103 , at each of the plurality of instants within the predetermined time interval an estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval is determined . The estimate of the cumulative emiss ion load may be determined based on at least the value of the current cumulative emission load, determined at 102 , and on data of the emission load emitted from the waste water treatment process obtained earlier . In arrangements comprising at least one processor and at least one memory including computer program code , the data of the emiss ion load emitted from the waste water treatment process obtained earlier may be obtained from the at least one memory of the arrangement , where it may have been stored ( for example , in a database ) .

[0104] At 104 , at each of the plurality of instants an allowable cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval may be determined . The allowable cumulative emission load may be determined based on the value of the current cumulative emission load and a predetermined limit of the cumulative emis sion load that may be emitted from the waste water treatment process . The allowable cumulative emission load may be determined e . g . by subtracting the value of the current cumulative emission load, determined at 102 , from the predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval .

[0105] At 105 , a control threshold of the emission load is determined based on the allowable cumulative emission load and on the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval . The control threshold of the emission load may be determined based on the allowable cumulative emission load, on the estimate of the cumulative emiss ion load to be emitted from the waste water treatment proces s within the predetermined time interval , and on the proportion of the estimate of the cumulative emi ssion load to be removed by implementing one or more control actions in the waste water treatment process . The control threshold of the emission concentration and / or load is determined such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below a predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval .

[0106] Additionally or alternatively, at 105 , a control time interval may be determined . The control time interval , for the duration of which one or more control actions in the waste water treatment process should be implemented, may be selected such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below the predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval .

[0107] At 106, the control information for implementing one or more control actions in the waste water treatment process is provided or output based on at least the allowable cumulative emiss ion load and / or the estimate of the cumulative emiss ion load to be emitted from the waste water treatment proces s within the predetermined time interval and the determined control threshold of the emission load . The control information may be provided or output e . g . to the waste water treatment process 101 , for example to an operator of the waste water treatment process 101 . The control information may be provided or output e . g . in the form of an alert and / or suggestions to the operator of the waste water treatment process 101 , or in the form of a control signal .

[0108] After 106 , at a further instant within the predetermined time interval , the method may be repeated at 102 .

[0109] Thus the method at 102 - 106 may be repeated at a plurality of instants until the end of the predetermined time interval is reached .

[0110] However, as indicated earlier, it may not be necessary to determine the allowable cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval . The estimate of the cumulative emission load to be emitted from the waste water treatment proces s within the predetermined time interval may also be calculated using a number of possible emission loads as tentative control thresholds and selecting the highest emission load / ten- tative control threshold that leads to an estimate of the cumulative emission load to be emitted from the waste water treatment process that is still within the predetermined limit of the cumulative emission load . The highest emission load / tentative control threshold thereby selected may be selected as the control threshold of the emission load . Alternatively, a corresponding emission concentration may be calculated from the highest emission load based on e . g . the average flow and used as the control threshold . A suitable optimi zation algorithm may be applied for determining the control threshold, such as any optimi zation algorithm described in this specification .

[0111] Figure 2 illustrates a block diagram of an arrangement 200 according to an exemplary embodiment . The arrangement 200 comprises one or more processors 201 , and one or more memories 202 that comprise computer program code 203 . The arrangement 200 may also include an input / output module (not shown in Fig . 2 ) , and / or a communication interface 204 for wired and / or wireless communication . Although the arrangement 200 is depicted as including only one processor 201 , the arrangement 200 may include more than one processor . In an exemplary embodiment , the memory 202 is capable of storing instructions , such as an operating system and / or various applications . The memory 202 may additionally be capable of storing the value of a current cumulative emission load emitted from the waste water treatment process and other data, such as data of the emission load emitted from the waste water treatment process obtained earlier . For example , the arrangement 200 may comprise a database for storing or configured to store the data of the emission load emitted from the waste water treatment process obtained earlier .

[0112] Furthermore , the processor 201 is capable of executing the stored instructions . In an exemplary embodiment , the processor 201 may be embodied as a multi-core processor, a single core processor, or a combination of one or more multi-core processors and one or more single core processors . For example , the processor 201 may be embodied as one or more of various processing devices , such as a coprocessor, a microprocessor, a controller, a digital signal processor ( DSP) , a processing circuitry with or without an accompanying DSP, or various other processing devices including integrated circuits such as , for example , an application specific integrated circuit (AS IC) , a field programmable gate array ( FPGA) , a microcontroller unit (MCU) , a hardware accelerator, a special-purpose computer chip, or the like . In an exemplary embodiment , the processor 201 may be configured to execute hard- coded functionality . In an exemplary embodiment , the processor 201 may be embodied as an executor of software instructions , wherein the instructions may specifically configure the processor 201 to perform the algorithms and / or operations described herein when the instructions are executed, for example, the steps discussed with respect to Fig. 1.

[0113] The memory 202 may be embodied as one or more volatile memory devices, one or more non-volatile memory devices, and / or a combination of one or more volatile memory devices and non-volatile memory devices. For example, the memory 202 may be embodied as semiconductor memories (such as mask ROM, PROM (programmable ROM) , EPROM (erasable PROM) , flash ROM, RAM (random access memory) , etc . ) .

[0114] In an embodiment, the at least one memory 202 may store program instructions (program code) 203 that, when executed by the at least one processor 201, cause the arrangement 200 to perform the functionality of the various embodiments discussed herein. Further, in an embodiment, at least one of the processor 201 and the memory 202 may constitute means for implementing the discussed functionality. Further, the arrangement 200 may be configured to perform at least some of the examples and embodiments discussed above.

[0115] Exemplary embodiments may be implemented in software, hardware, application logic or a combination of software, hardware and application logic. The exemplary embodiments can store information relating to various methods described herein. This information can be stored in one or more memories, such as a hard disk, a solid state drive (SSD) , an optical disk, a magnetooptical disk, an RAM, and the like. One or more databases can store the information used to implement the exemplary embodiments (for example, the data of the emission load emitted from the waste water treatment process obtained earlier) . The databases can be organized using data structures (e.g., records, tables, arrays, fields, graphs, trees, lists, and the like) included in one or more memories or storage devices listed herein. The methods described with respect to the exemplary embodiments can include appropriate data structures for storing data collected and / or generated by the methods of the devices and subsystems of the exemplary embodiments in one or more databases .

[0116] The components of the exemplary embodiments may include computer readable medium or memories for holding instructions programmed according to the teachings and for holding data structures , tables , records , and / or other data described herein . In an exemplary embodiment , the application logic, software or an instruction set is maintained on any one of various conventional computer-readable media . In the context of this document, a "computer-readable medium" may be any media or means that can contain, store , communicate , propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus , or device , such as a computer . A computer- readable medium may include a computer-readable storage medium that may be any media or means that can contain or store the instructions for use by or in connection with an instruction execution system, apparatus , or device , such as a computer . A computer readable medium can include any suitable medium that participates in providing instructions to a processor for execution . Such a medium can take many forms , including but not limited to , non-volatile media, volatile media, transmission media, and the like .

[0117] The functionality of the arrangement 200 may be implemented us ing a cloud computing system or other type of distributed computing system .

[0118] Figure 3 illustrates an arrangement 300 according to an exemplary embodiment . The arrangement 300 i s illustrated as a block diagram . The arrangement 300 is similar to the arrangement 200 described in Fig . 2 . Further, Figure 3 illustrates schematically a waste water treatment process 305 that may or may not be considered to be a part of the arrangement 300 . The waste water treatment process 305 comprises a primary treatment 308 , a secondary treatment 309 and optionally a tertiary treatment 310 . The primary treatment 308 may comprise e . g . screening for trapping solid obj ects and sedimentation for removing suspended solids , or other units commonly included in a primary treatment . The secondary treatment 309 comprises , in this exemplary embodiment , a biological treatment 313 ( including e . g . an aeration tank) and a secondary clarification ( sedimentation) stage 314 . However, additionally or alternatively, it could comprise other units commonly included in a secondary treatment . At least a part of sludge from the secondary clarification stage 314 may be returned to the biological treatment 313 (e . g . in the aeration tank) as return sludge 315 .

[0119] Waste water 311 incoming to the waste water treatment process 305 may be obtained e . g . from a pulping process 307 , such as from one or more pulp bleaching stages (not shown for clarity) . The incoming waste water 311 may enter the primary treatment 308 and then continue to the secondary treatment 309 and finally, if a tertiary treatment is present , to the tertiary treatment 310 , after which it is emitted from the waste water treatment process as emitted waste water 312 .

[0120] The arrangement 300 may further comprise a measurement apparatus 317 for measuring the emission concentration and optionally load in the waste water emitted from the waste water treatment process 312 . The measurement apparatus 317 may further be configured to measure e . g . the flow of the waste water 312 emitted from the waste water treatment process .

[0121] The measurement apparatus 317 may provide the measurements (values ) to the arrangement 300 . The processor 301 may be embodied as an executor of software instructions , wherein the instructions may specifically configure the processor 301 to perform the algorithms and / or operations described herein when the instructions are executed, for example , the steps discussed with respect to Fig . 1 . The arrangement 300 may further provide or output control information to the waste water treatment process 305 .

[0122] For example , the measurement apparatus 317 may further be configured to use the control information and / or to implement one or more control actions in the waste water treatment process 305 . Thus the control information may be may be provided or output by the arrangement 300 e . g . to the apparatus 317 for implementing one or more control actions in the waste water treatment process based on at least the control information .

[0123] The measurement apparatus 317 may thus be configured to implement the one or more control actions in the waste water treatment process 305 based on at least the control information, for example by starting a control treatment of the emission load in the waste water treatment process 305 , controlling dosing of at least one control chemical in a control treatment of the emission load in the waste water treatment process 305 , adj usting a parameter of the secondary treatment 309 in the waste water treatment process 305 , or adj usting a parameter of the tertiary treatment 310 in the waste water treatment process 305 . For example , the measurement apparatus 317 may be configured to control the dosing of at least one control chemical 316 at one or more stages of the waste water treatment process 305 .

[0124] The at least one control chemical 316 may be dosed e . g . in the secondary treatment 309 . The at least one control chemical 316 , such as a coagulant , may be dosed in the return sludge 315 . Additionally or alternatively, the at least one control chemical 316 may be dosed to the secondary clarification 314 , or to the waste water stream incoming to the secondary clarification 314 . The at least one control chemical may, additionally or alternatively, be dosed e . g . in the tertiary treatment 310 .

[0125] Although the measurement apparatus 317 is shown in this exemplary embodiment between the secondary treatment 309 and the tertiary treatment 310 , it could also be placed after the tertiary treatment 310 , i . e . so that it would be configured to measure the emission concentration and / or load in the waste water 312 immediately before it is emitted from the waste water treatment process 305 . The measurement apparatus 317 may also measure the emission concentration and / or load in the waste water 312 both before and after the tertiary treatment 310 .

[0126] EXAMPLE 1

[0127] The method was demonstrated using data from an industrial waste water treatment process , which utili zed an on-off control strategy in which chemical treatment ( alum, i . e . aluminium sulphate , dosage in tertiary treatment ) was started and stopped according to online measurements of incoming COD or phosphorus load . When the chemical treatment was active , the dosage of alum is adj usted based on a COD measurement value . This example considers only COD to optimi ze the control threshold .

[0128] The historical COD load distribution data was obtained from October 2021 - August 2022 and its histogram is presented in Figure 4 .

[0129] The method was tested with data from September 2022 . The incoming COD during that month was used as an input to the simulation ( see Figure 5 ) . The waste water incoming to the industrial waste water treatment process was obtained from a chemical pulping process . The incoming COD concentration exhibited cyclical variation . A control algorithm calculated the current cumulative COD emissions in the waste water to be emitted from the waste water treatment process at every hour using the online measurements . The cumulative emissions at the end of the time interval (month) and a new control threshold were calculated at every 72 hours . The control threshold was then used to simulate the controller operation before it was updated again .

[0130] The first step was to predict the emissions at the end of the interval , for which an estimation of the future COD load was required . The load was predicted using the information stored in the historical load distribution of incoming COD . I t was as sumed that the incoming COD for the remaining interval would follow a similar distribution . The cumulative emission load at the end of the interval was calculated using the load distribution and an average flow . Next , an allowable cumulative emission load for the rest of the interval was computed by subtracting the value of the current cumulative emission from a predetermined emission limit at the end of the interval . Figure 6 shows the evolution of the allowable emission load calculated every hour during the simulation .

[0131] Then, the allowable emission load for the rest of the interval was utili zed to find the optimal control threshold . The optimization routine simulates the operation of water treatment using the historical load distribution, the average flow and an average COD reduction achieved in the tertiary treatment . The goal was to find the highest control threshold that would result in a cumulative emission below the allowable emission load ( taking into account a safety marginal of e . g . 10 % ) . For the test data , the control thresholds found by the optimi zer are presented in Figure 7 . A new threshold was calculated every 72 hours and the figure shows how the threshold value evolved during the simulation . Finally, Figure 8 shows the cumulative COD emissions calculated at each hour and the monthly predetermined limit for the emissions . It can be seen that the control strategy managed to retain the cumulative COD emissions within the predetermined monthly limit .

[0132] While there have been shown and described and pointed out fundamental novel features as applied to preferred embodiments thereof , it will be understood that various omissions and substitutions and changes in the form and details of the devices and methods described may be made by those skilled in the art without departing from the spirit of the disclosure . For example , it is expressly intended that all combinations of those elements and / or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the disclosure . Moreover, it should be recogni zed that structures and / or elements and / or method steps shown and / or described in connection with any disclosed form or embodiments may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice . Furthermore , in the claims means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents , but also equivalent structures .

[0133] The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features , to the extent that such features or combinations are capable of being carried out based on the present specification as a whole , in the light of the common general knowledge of a person skilled in the art , irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims . The applicant indicates that the disclosed aspects / embodiments may consist of any such individual feature or combination of features . In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the disclosure .

[0134] It is obvious to a person skil led in the art that with the advancement of technology, the basic idea may be implemented in various ways . The embodiments are thus not limited to the examples described above ; instead they may vary within the scope of the claims .

[0135] The embodiments described hereinbefore may be used in any combination with each other . Several of the embodiments may be combined together to form a further embodiment . A method, a product , an arrangement , or a use, disclosed herein, may comprise at least one of the embodiments described hereinbefore . It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments . The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages . It will further be understood that reference to ' an' item refers to one or more of those items . The term "comprising" or "including" is used in this specification to mean including the feature ( s ) or act ( s ) followed thereafter, without excluding the presence of one or more additional features or acts .

Claims

CLAIMS1 . A method for providing control information of a waste water treatment process for controlling an emission load to be emitted from the waste water treatment process within a predetermined time interval , wherein the method comprises obtaining at a plurality of instants within the predetermined time interval a value of a current cumulative emission load emitted from the waste water treatment process , determining at each of the plurality of instants within the predetermined time interval an estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval , wherein the estimate of the cumulative emission load is determined based on at least the value of the current cumulative emission load and on data of the emission load emitted from the waste water treatment process obtained earlier, determining at each of the plurality of instants a control threshold of the emission concentration and / or load at which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below a predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , and / or determining at each of the plurality of instants a control time interval for the duration of which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below the predetermined limit of the cumulative emissionload that may be emitted from the waste water treatment process within the predetermined time interval , and providing the control information for implementing the one or more control actions in the waste water treatment process based on at least one of the estimate of the cumulative emiss ion load to be emitted from the waste water treatment proces s within the predetermined time interval , the determined control threshold of the emission concentration and / or load, or the control time interval .2 . The method according to claim 1 , wherein the method comprises determining at each of the plurality of instants an allowable cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , wherein the allowable cumulative emission load is determined based on the value of the current cumulative emission load and the predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process , and by determining the control threshold or the control time interval based on the allowable cumulative emission load .3 . The method according to claim 1 or 2 , wherein the control threshold or the control time interval is determined based on a proportion of the estimate of the cumulative emiss ion load to be reduced in the waste water treatment process by implementing the one or more control actions in the waste water treatment process when the control threshold is met or by implementing the one or more control actions in the waste water treatment process for the duration of the control time interval .4 . The method according to any one of claims 1 - 3 , wherein the emission load comprises or is at least one of chemical oxygen demand (COD) load or phosphorus load .5 . The method according to any one of claims 1- 4 , wherein the emission load comprises or is COD load .6 . The method according to any one of claims 1 - 5 , wherein the waste water incoming to the waste water treatment process is obtained from a pulping process , optionally from a pulp bleaching process .7 . The method according to any one of claims 1- 6 , wherein the control threshold of the emission load is determined based on the allowable cumulative emission load and the proportion of the estimate of the cumulative emission load to be reduced by implementing one or more control actions in the waste water treatment process .8 . The method according to any one of claims 1- 7 , wherein the method further comprises implementing one or more control actions in the waste water treatment process based on at least the control information, such as the determined control threshold of the emission load .9 . The method according to claim 8 , wherein the one or more control actions comprise at least one of starting a control treatment of the emission load in the waste water treatment process , controlling dosing of at least one control chemical in a control treatment of the emission load in the waste water treatment process , adj usting a parameter of a secondary treatment in the waste water treatment process , or adj usting a parameter of a tertiary treatment in the waste water treatment process .10 . The method according to claim 9 , wherein the at least one control chemical comprises or is at least one of a coagulant, such as aluminium-based coagulant or an iron-based coagulant , or of a flocculant , such as a polymer .11 . The method according to any one of claims 1 - 10 , wherein the data of the emission load obtainedearlier exhibits cyclical variation, and the data of the emission load obtained earlier is obtained from a time interval exhibiting the cyclical variation for a plurality of cycles .12 . An arrangement for providing control information of a waste water treatment process for controll ing an emiss ion load to be emitted from the waste water treatment process within a predetermined time interval , the arrangement comprising means for obtaining at a plurality of instants within the predetermined time interval a value of a current cumulative emission load emitted from the waste water treatment process , means for determining at each of the plurality of instants within the predetermined time interval an estimate of the cumulative emiss ion load to be emitted from the waste water treatment proces s within the predetermined time interval , wherein the estimate of the cumulative emission load is determined based on at least the value of the current cumulative emission load and on data of the emission load emitted from the waste water treatment process obtained earlier, means for determining at each of the plurality of instants a control threshold of the emission concentration and / or load at which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below a predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , and / or means for determining at each of the plurality of instants a control time interval for the duration of which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emission load to be emitted from thewaste water treatment process within the predetermined time interval remains below the predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , and means for providing the control information for implementing the one or more control actions in the waste water treatment proces s based on at least one of the estimate of the cumulative emiss ion load to be emitted from the waste water treatment process within the predetermined time interval , the determined control threshold of the emission concentration and / or load, or the control time interval .13 . The arrangement according to claim 12 , wherein the arrangement further comprises means for determining at each of the plurality of instants an allowable cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , wherein the allowable cumulative emission load is determined based on the value of the current cumulative emission load and the predetermined limit of the cumulative emission load that may be emitted from the waste water treatment proces s , and by determining the control threshold or the control time interval based on the allowable cumulative emission load .14 . A computer program comprising instructions which, when executed by an apparatus , cause the apparatus to perform at least the following : obtaining at a plurality of instants within the predetermined time interval a value of a current cumulative emission load emitted from the waste water treatment process , determining at each of the plurality of instants within the predetermined time interval an estimate of the cumulative emission load to be emitted from the waste water treatment process within thepredetermined time interval , wherein the estimate of the cumulative emission load is determined based on at least the value of the current cumulative emission load and on data of the emission load emitted from the waste water treatment process obtained earlier, determining at each of the plurality of instants a control threshold of the emission concentration and / or load at which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below a predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , and / or determining at each of the plurality of instants a control time interval for the duration of which one or more control actions in the waste water treatment process should be implemented such that the estimate of the cumulative emission load to be emitted from the waste water treatment process within the predetermined time interval remains below the predetermined limit of the cumulative emission load that may be emitted from the waste water treatment process within the predetermined time interval , and providing the control information for implementing the one or more control actions in the waste water treatment process based on at least one of the estimate of the cumulative emiss ion load to be emitted from the waste water treatment proces s within the predetermined time interval , the determined control threshold of the emission concentration and / or load, or the control time interval .

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