A sludge reduction and drying method for sewage treatment
Patent Information
- Application Number
- CN202611391609.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-09
- Publication Date
- 2026-10-13
AI Technical Summary
[0005]为此，本发明提供一种用于污水处理的污泥减量干化方法，用以克服现有技术中污泥减量干化过程中破壁强度难以匹配脱水性能、异常原因难以定位和干化参数缺少前馈依据的问题
[0016]与现有技术相比，本发明的有益效果在于，本发明提供的污泥减量干化方法通过持续获取机械脱水设备的单位能耗和脱水滤液浊度，并以历史能耗数据确定的单位能耗分布范围为基准，一旦单位能耗超出正常范围即判定为能耗预警状态；这种基于实时能耗监测的预警机制，能够比人工巡检或定期取样分析更早地发现脱水阻力异常，避免因破壁过度或不足导致的滤饼堵塞、过滤压力升高和设备过载等问题持续发展；同时，在能耗预警状态下进一步结合滤液浊度与单位能耗的变化趋势和时间重叠程度，判断二者是否同步变化，从而初判破壁状态，将能耗和滤液浊度两个在线可测参数关联使用，实现了对破壁状态的动态监测，无需频繁离线采样即可快速识别潜在异常，显著提高了污泥处理流程的自动化水平和运行稳定性；通过早期预警和趋势分析，操作人员可以及时介入调整，防止异常状态进一步恶化为设备故障或出水水质超标，保障脱水设备长期稳定运行。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of wastewater treatment and sludge resource utilization technology, specifically to a sludge reduction and drying method for wastewater treatment. Background Technology
[0002] In urban sewage treatment, industrial wastewater treatment, and other biochemical treatment processes, excess sludge is typically first concentrated or conditioned, then subjected to enhanced cell wall disruption, flocculation, and mechanical dewatering. The resulting sludge cake is sent to a drying facility, while the dewatered filtrate is returned to the sewage treatment system. Enhanced cell wall disruption breaks down sludge flocs and microbial cell structures, converting some particulate organic matter into dissolved or easily degradable forms, thus creating conditions for sludge reduction.
[0003] However, the relationship between cell wall breaking strength and dehydration performance is not monotonic. When cell wall breaking is insufficient, the cell and floc structures are not fully destroyed, resulting in limited subsequent weight reduction. When cell wall breaking is excessive, more fine particles may be generated and soluble extracellular polymers may be released, which will increase dehydration resistance, filtrate turbidity and filtrate organic load, increase cake moisture content, and thus increase the moisture and heat load of the drying feed. If only a single weight reduction index or a single instantaneous energy consumption is used as the control basis, it is easy to misjudge the increase in dissolution as the actual solid weight reduction, and it is also difficult to distinguish between equipment abnormality, flocculation failure and changes in cell wall breaking state.
[0004] Therefore, it is necessary to establish a sludge treatment process that can ensure the reduction effect while suppressing the dehydration deterioration and the increase in drying energy consumption. Summary of the Invention
[0005] Therefore, the present invention provides a sludge reduction and drying method for wastewater treatment, which overcomes the problems in the prior art where the cell wall breaking strength is difficult to match the dewatering performance, the abnormal causes are difficult to locate, and the drying parameters lack feedforward basis.
[0006] To achieve the above objectives, this invention provides a sludge reduction and drying method for wastewater treatment, applied to a sludge treatment process in which excess sludge undergoes sequential enhanced cell disruption, conditioning / flocculation, and mechanical dewatering. The sludge cake and filtrate obtained from the mechanical dewatering are respectively subjected to drying and recirculation treatments, including: Continuously obtain the unit energy consumption of the dehydration equipment and the turbidity of the dehydrated filtrate during the mechanical dehydration process; The current dehydration resistance status is determined based on the unit energy consumption, and the dehydration resistance status includes normal energy consumption status and energy consumption warning status. In response to the energy consumption warning state, the changes in the turbidity of the dehydrated filtrate and the unit energy consumption are determined to preliminarily judge the cell wall breakage state. The cell wall breaking states include over-breaking state, under-breaking state, and normal breaking state. In response to the initial judgment that the sludge was not in an over-disruption state, the soluble chemical oxygen demand and capillary water absorption time of the sludge before mechanical dewatering were obtained. The cell wall breakage state is determined a second time based on the soluble chemical oxygen demand and the capillary water absorption time. Based on the results of the cell wall disruption determination, pre-dehydration adjustment measures are formulated, including adjusting the intensity of cell wall disruption, adjusting the PAM type, increasing the flocculant dosage, and calibrating the dehydration equipment. Whether to adjust the drying treatment parameters is determined based on the results of the cell wall disruption assessment.
[0007] As a preferred technical solution for sludge reduction and drying methods used in sewage treatment, based on the determination result that the unit energy consumption is greater than the unit energy consumption distribution range, the current dewatering resistance state is determined to be an energy consumption warning state. The unit energy consumption distribution range is determined based on historical energy consumption data.
[0008] As a preferred technical solution for sludge reduction and drying methods used in wastewater treatment, in response to the energy consumption warning state, determining the change state of the turbidity of the dewatered filtrate and the unit energy consumption includes: Obtain the turbidity of the dehydrated filtrate and the unit energy consumption within the monitoring period corresponding to the energy consumption early warning status; The turbidity change trend of the dehydrated filtrate and the energy consumption change trend of the unit energy consumption are determined respectively, and the time range of turbidity change and the time range of energy consumption change are determined. The overlapping time range is determined based on the turbidity change time range and the energy consumption change time range, so as to determine the overlapping time ratio; In response to the turbidity change trend being consistent with the energy consumption change trend and the overlap time ratio being not less than the reference ratio, it is determined that the synchronous change condition is met and the change state is determined to be a synchronous change state. The change states include synchronous change states and asynchronous change states.
[0009] As a preferred technical solution for sludge reduction and drying methods used in wastewater treatment, the initial determination of the cell wall disruption state based on the described changes includes: In response to the synchronous change state, the initial judgment of the cell wall breaking state is that the cell wall breaking state is excessive. In response to the asynchronous state of the change, if the initial judgment is that the cell wall breaking state is not an over-breaking state, then the soluble chemical oxygen demand and capillary water absorption time of the sludge before mechanical dewatering are obtained.
[0010] As a preferred technical solution for sludge reduction and drying methods used in wastewater treatment, the cell wall disruption state is determined to be the normal cell wall disruption state in response to the normal energy consumption state.
[0011] As a preferred technical solution for sludge reduction and drying methods used in wastewater treatment, a secondary determination of the cell wall disruption state is performed based on the soluble chemical oxygen demand and the capillary water absorption time, including: In response to the capillary water absorption time not exceeding the preset upper limit of water absorption time, the cell wall breakage state is determined to be the normal cell wall breakage state. In response to the capillary water absorption time exceeding a preset upper limit, the cell wall disruption state is determined based on the soluble chemical oxygen demand, wherein: In response to the soluble chemical oxygen demand being lower than the preset lower limit of oxygen demand, the cell wall breaking state is determined to be an insufficient cell wall breaking state. In response to the soluble chemical oxygen demand exceeding the preset upper limit of oxygen demand, the cell wall disruption state is determined to be an over-disruption state.
[0012] As a preferred technical solution for sludge reduction and drying methods used in wastewater treatment, the process of obtaining the soluble chemical oxygen demand and the capillary water absorption time includes: The soluble chemical oxygen demand and capillary water absorption time of the sludge before mechanical dewatering were tested a preset number of times, and the corresponding test results were obtained. The average value is calculated based on the test results of each soluble chemical oxygen demand (COD) test and recorded as the soluble COD. The average value is calculated based on the results of each capillary water absorption time test and recorded as the capillary water absorption time.
[0013] As a preferred technical solution for sludge reduction and drying methods used in wastewater treatment, pre-dewatering adjustment measures are formulated based on the results of the cell wall disruption determination, including: In response to the excessive cell wall disruption, pre-dehydration adjustment measures were implemented to reduce the intensified cell wall disruption intensity and increase the flocculant dosage. In response to insufficient cell wall disruption, pre-dehydration adjustment measures were formulated to enhance cell wall disruption intensity and adjust the PAM type. In response to the normal state of cell wall disruption, the adjustment measures before dehydration were to observe the dehydration equipment and calibrate the measuring instruments.
[0014] As a preferred technical solution for sludge reduction and drying methods used in wastewater treatment, the decision on whether to adjust drying parameters is based on the determination of the cell wall disruption state, including: In response to over-disruption and under-disruption, the drying feed rate is reduced and the drying temperature is increased or the residence time is extended.
[0015] As a preferred technical solution for sludge reduction and drying methods used in wastewater treatment, determining whether to adjust drying parameters based on the results of the cell wall disruption determination also includes: In response to the normal state of cell wall disruption, maintain the current drying parameters.
[0016] Compared with existing technologies, the beneficial effects of this invention are as follows: The sludge reduction and drying method provided by this invention continuously acquires the unit energy consumption and turbidity of the dewatering filtrate of the mechanical dewatering equipment, and uses the unit energy consumption distribution range determined by historical energy consumption data as a benchmark. Once the unit energy consumption exceeds the normal range, it is judged as an energy consumption warning state. This warning mechanism based on real-time energy consumption monitoring can detect abnormal dewatering resistance earlier than manual inspection or periodic sampling and analysis, avoiding the continued development of problems such as filter cake blockage, increased filtration pressure, and equipment overload caused by excessive or insufficient cell disruption. At the same time, in the energy consumption warning state, the trend and time overlap of the changes in filtrate turbidity and unit energy consumption are further combined to determine whether the two are changing synchronously, thereby initially judging the cell disruption state. By using the two online measurable parameters of energy consumption and filtrate turbidity together, dynamic monitoring of the cell disruption state is realized. Potential anomalies can be quickly identified without frequent offline sampling, which significantly improves the automation level and operational stability of the sludge treatment process. Through early warning and trend analysis, operators can intervene and adjust in a timely manner to prevent the abnormal state from further deteriorating into equipment failure or effluent water quality exceeding the standard, ensuring the long-term stable operation of the dewatering equipment.
[0017] In particular, under energy consumption warning conditions, the initial judgment of excessive cell disruption is made based on the synchronous change relationship between turbidity and energy consumption. If the change is synchronous, it is initially judged as excessive cell disruption. If it is asynchronous, the soluble chemical oxygen demand (SCOD) and capillary water absorption time (CST) of the sludge before mechanical dewatering are further obtained for secondary judgment using these two indicators that characterize the degree of cell disruption and dewatering performance. This multi-level judgment strategy effectively avoids misjudgments that may be caused by a single indicator or criterion: although energy consumption and turbidity alone can quickly identify synchronous anomalies, they cannot distinguish between insufficient cell disruption and normal cell disruption but dewatering performance affected by other factors. The combination of SCOD and CST can make a more refined judgment on the cell disruption state from two dimensions: the degree of organic matter release and filtration performance. This graded judgment mechanism takes into account both the real-time nature of online monitoring and the accuracy of offline detection. It avoids the misjudgment of attributing all asynchronous anomalies to insufficient cell disruption, and can identify excessive cell disruption in time through SCOD and CST before it is fully reflected in energy consumption, which significantly improves the reliability of cell disruption state diagnosis.
[0018] In particular, differentiated adjustment measures are formulated based on the results of the cell disruption determination: when it is determined to be over-disruption, the cell disruption intensity is reduced to decrease the continued release of fine particles and soluble EPS, while the flocculant dosage is increased to promote particle bridging and improve filtration performance; when it is determined to be under-disruption, the cell disruption intensity is increased to release bound water, and a PAM more suitable for the sludge charge and organic components is selected to improve dewaterability; when it is determined to be normal, equipment and instruments are checked first to avoid translating measurement errors into process adjustments; in addition, this method also adjusts the drying section parameters in conjunction with the cell disruption state, addressing situations where over-disruption or under-disruption leads to excessive sludge cake content... When the moisture content increases, the drying feed rate is reduced and the drying temperature is increased or the residence time is extended to compensate for the increased moisture load; under normal conditions, the drying parameters are kept stable. This strategy, which combines source control and end-of-pipe compensation based on diagnostic results, can take the most effective control measures for different cell disruption states, avoiding energy waste and excessive reagent addition caused by blind adjustment. At the same time, the matching and adjustment of drying section parameters ensures that the final sludge cake moisture content meets the standard. This achieves synergistic optimization of the entire process from cell disruption, conditioning and dewatering to drying, reduces the overall energy consumption and operating cost per unit of sludge treatment, and improves the economy and process adaptability of sludge reduction and drying. Attached Figure Description
[0019] Figure 1 This is a flowchart of a sludge reduction and drying method for wastewater treatment according to an embodiment of the present invention. Detailed Implementation
[0020] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.
[0021] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.
[0022] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.
[0023] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0024] In actual sludge treatment processes, to reduce the impact of changes in sludge influent conditions and fluctuations in the conditioning process on the assessment of dewatering effectiveness, it is usually necessary to maintain stable sludge concentration, sludge flow rate, and conditioning agent dosage. However, even when the above operating parameters remain stable, the degree of cell disruption in the enhanced sludge cell wall breaking process may still deviate from the expected state due to factors such as changes in the operating status of the cell wall breaking equipment, fluctuations in cell wall breaking energy transfer, and changes in the properties of the sludge itself.
[0025] When the degree of cell wall disruption is insufficient, the release of bound water inside the sludge is inadequate, which may lead to increased sludge filtration resistance, increased energy consumption for mechanical dewatering, and reduced subsequent drying efficiency. When the degree of cell wall disruption is too high, the cell structure is excessively damaged, and a large amount of soluble substances are released, which may cause an increase in suspended solids in the filtrate, changes in sludge floc structure, and a decrease in dewatering performance. Therefore, it is difficult to accurately determine the current state of sludge cell wall disruption based solely on external operating parameters such as sludge concentration, flow rate, and conditioner dosage. Further identification of the cell wall disruption state is still required by combining the operating characteristics of the mechanical dewatering process and sludge property indicators.
[0026] Please see Figure 1 As shown, it is a flowchart of the sludge reduction and drying method for sewage treatment according to an embodiment of the present invention.
[0027] In practice, the sludge reduction and drying method for wastewater treatment is applied to the sludge treatment system, including a waste sludge feeding unit, an enhanced cell disruption unit, a conditioning / flocculation unit, a mechanical dewatering unit, a sludge cake drying unit, a dewatered filtrate recirculation unit, an online energy consumption acquisition unit, and a filtrate turbidity acquisition unit. The enhanced cell disruption unit can employ hot water hydrolysis, ultrasound, microwave, mechanical shearing, chemical oxidation, or a combination thereof. The conditioning / flocculation unit is used to add inorganic flocculants and / or PAM. The mechanical dewatering unit can employ a belt filter press, a plate and frame filter press, a centrifugal dewatering machine, or a screw press. The energy consumption acquisition unit communicates with the electricity meter or frequency converter of the mechanical dewatering equipment, and the turbidity acquisition unit is set in the stable flow section of the filtrate. The soluble chemical oxygen demand and capillary water absorption time are both based on the sampling and testing results of sludge before mechanical dewatering. The sampling point should be located after the enhanced cell disruption and conditioning / flocculation are completed and before mechanical dewatering feed, so as to reflect the actual state of the sludge entering the dewatering equipment.
[0028] This invention provides a sludge reduction and drying method for wastewater treatment, applied to a sludge treatment process in which excess sludge undergoes sequential enhanced cell disruption, conditioning / flocculation, and mechanical dewatering. The sludge cake obtained from mechanical dewatering, being high in solids content, enters the sludge cake drying unit. The dewatered filtrate obtained from mechanical dewatering is returned to the wastewater treatment system after turbidity detection. The method includes: Step S1: During mechanical dewatering, the unit energy consumption of the dewatering equipment and the turbidity of the dewatered filtrate are continuously acquired at a fixed sampling period. It should be understood that the unit energy consumption parameter can characterize the energy consumption level of the mechanical dewatering equipment under the condition of unit sludge treatment volume, and can reflect the change in dewatering resistance during sludge dewatering: when the sludge filtration resistance increases, the operating load required for the mechanical dewatering equipment to maintain the same dewatering effect will increase accordingly, thus causing a corresponding change in the unit energy consumption parameter. In addition, filtrate samples generated by mechanical dewatering are continuously collected at the filtrate output end of the mechanical dewatering equipment, and the turbidity of the filtrate samples is detected to obtain the turbidity parameter of the dewatered filtrate. The turbidity of the dewatered filtrate can characterize the change in the content of suspended particulate matter and fine sludge flocs in the dewatered filtrate, so as to reflect the influence of sludge structure changes on dewatering performance during enhanced cell disruption. In practice, after obtaining the unit energy consumption and the turbidity of the dehydrated filtrate, the two are correlated according to the same time marker to form a unit energy consumption change sequence and a filtrate turbidity change sequence, which are used to analyze the correlation between the change trend and change time of the unit energy consumption parameter and the dehydrated filtrate turbidity parameter.
[0029] In implementation, the unit energy consumption Eu = (Pavg - Pidle) × Δt / MDS, where Pavg is the average active power of the dewatering equipment during the monitoring period (in kW), Pidle is the no-load or standby power of the equipment (in kW), Δt is the monitoring period (in hours), MDS is the mass of dry solids of sludge treated in the same period (in tons), MDS is obtained by multiplying the sludge mass flow rate by the total solids content, and the cumulative amount is used when the equipment directly outputs the cumulative dry solids amount; Pidle is measured when no sludge is fed in and the auxiliary equipment is kept under the same conditions and is checked at least once a month.
[0030] Step S2: Based on the determination result that the unit energy consumption is greater than the unit energy consumption distribution range (i.e., greater than the upper limit of the unit energy consumption distribution range), it is indicated that the comprehensive power required for mechanical dewatering to overcome filter cake resistance, adhesion and blockage exceeds the historical normal energy consumption, that is, the sludge conditioning or dewatering state has undergone substantial changes, so the current dewatering resistance state is determined to be the energy consumption warning state. Conversely, if the unit energy consumption is less than or equal to the upper limit of the unit energy consumption distribution range, then the current dehydration resistance state is determined to be the normal energy consumption state. The distribution range of unit energy consumption is determined based on historical energy consumption data. In implementation, the controller saves historical normal operation data (no less than 7 days and no less than 20 dewatering cycles). After removing data during equipment maintenance, shutdown, sensor failure, and obvious abnormal sludge feeding, a baseline is formed. After sorting by unit energy consumption, the 5th percentile to the 95th percentile is used as the initial distribution range (if there are obvious outliers, the median ± 3 × absolute median difference (MAD) is used instead of the mean ± 3 × standard deviation (σ)).
[0031] Step S3: In response to the normal energy consumption state, the cell wall breaking state is determined to be the normal cell wall breaking state; otherwise, in response to the energy consumption warning state, the output controller starts a monitoring cycle, and records the filtrate turbidity and unit energy consumption with the same timestamp during the monitoring cycle, so as to initially determine the cell wall breaking state according to steps S31 and S32. In practice, an online turbidity meter is used to output the turbidity of the filtrate; In practice, the monitoring cycle is typically 15 to 30 minutes. Step S31, determining the change in turbidity of the dehydrated filtrate and the unit energy consumption, includes: Step S311: Obtain the turbidity of the dehydrated filtrate and the unit energy consumption within the monitoring period corresponding to the energy consumption warning status; In implementation, it is also necessary to obtain the unit energy consumption data and filtrate turbidity data within the baseline time window (5min to 10min) before the energy consumption warning, and take the median as the baseline unit energy consumption E0 and the baseline turbidity NTU0 respectively. Step S312: Determine the turbidity change trend of the dehydrated filtrate and the energy consumption change trend of the unit energy consumption, and determine the time range of turbidity change and the time range of energy consumption change. In implementation, unit energy consumption and filtrate turbidity with the same timestamp are obtained synchronously within the monitoring period, i.e., (NTUi,Ei,ti). The unit energy consumption and filtrate turbidity at the same timestamp are then normalized based on the baseline unit energy consumption and baseline turbidity. The normalization formula is as follows: , Normalized filtrate turbidity X NTU,i and unit energy consumption X E,i Smoothing is performed, and sliding linear fitting is applied to the smoothed filtrate turbidity and unit energy consumption. Typically, a least-squares linear fitting is performed every 1 minute within the monitoring period for a fixed-length window (3 min to 5 min) to obtain the slope of turbidity change and the slope of unit energy consumption change at that moment. If the percentage of positive slopes for both turbidity change and unit energy consumption change is greater than 80%, it is determined that the overall trend of filtrate turbidity and unit energy consumption is upward, and the trend of turbidity change is consistent with the trend of energy consumption change. In implementation, the turbidity change slope sequence and unit energy consumption change slope sequence of the reference time window before energy consumption warning are calculated in the same way, and the 95th percentile of these two slope sequences is used as the corresponding preset slope. Step S313: Determine the overlapping time range based on the turbidity change time range and the energy consumption change time range, so as to determine the overlapping time ratio; it can be understood that the overlapping time ratio is the ratio of the overlapping duration to the joint change duration. It should be understood that each linear fit will yield the corresponding slope of turbidity change and slope of unit energy consumption change: if the slope of turbidity change or slope of unit energy consumption change is greater than the preset slope for 2 to 3 consecutive times, the first corresponding moment is recorded as the moment when the effective change of filtrate turbidity or unit energy consumption begins; if the slope of turbidity change or slope of unit energy consumption change is not greater than the corresponding preset slope for 2 to 3 consecutive times, the moment when the effective slope of turbidity change exceeds the preset slope or the moment when the effective slope of unit energy consumption change exceeds the preset slope is recorded as the moment when the effective change of filtrate turbidity ends and the moment when the effective change of unit energy consumption ends, respectively. In implementation, the time range of turbidity change is denoted as (t). Ts ,t Te ),t Ts t is the time when the turbidity of the filtrate begins to change effectively. Te The effective change time of filtrate turbidity ends; the time range of energy consumption change is denoted as (t). Es ,t Ee ), t Es t is the time when the unit energy consumption begins to change effectively. Ee Let the effective change time of unit energy consumption end; then: (1) The overlap time range is [max(t)] Ts ,t Es ),min(t Te ,t Ee Therefore, the overlap duration = max[0, min(t)], Te ,t Ee )-max(t Ts ,t Es )]; (2) The time range of the joint change is [min(t)] Ts ,t Es ),max(t Te ,t Ee Therefore, the duration of the joint change is max(t). Te ,t Ee )-min(t Ts ,t Es ); Step S314: In response to the turbidity change trend being consistent with the energy consumption change trend and the overlap time ratio being not less than the reference ratio, it is determined that the synchronous change condition is met and the change state is determined to be a synchronous change state; otherwise, it is determined that the synchronous change condition is not met and the change state is determined to be an asynchronous state. It is understandable that changes in filtrate turbidity and equipment energy consumption cannot change simultaneously; there will be some time lag. Therefore, the reference ratio in implementation is 65% to 80%.
[0032] And, step S32, preliminary determination of the cell wall breaking state based on the changes, includes: The fact that the change state is a synchronous change state indicates that excessive cell disruption increases the number of fine particles and soluble polymers in the liquid phase, causing the turbidity of the filtrate to rise. These substances clog the filter cake during filtration, increasing the filtration resistance and ultimately leading to an increase in unit energy consumption. However, synchronous changes may also be caused by other factors (such as a sudden increase in sludge concentration or fluctuations in sludge properties). But excessive cell disruption is the most typical and direct cause of synchronous changes, so it is initially judged to be an excessive cell disruption state. In response to the asynchronous state of the aforementioned change, if the initial judgment is that the cell wall breaking state is not an over-breaking state, then the soluble chemical oxygen demand and capillary water absorption time of the sludge before mechanical dewatering are obtained. It is understood that the increase in filtrate turbidity but the lack of a significant increase in unit energy consumption may only be due to a temporary increase in particulate matter in the liquid phase, but it has not yet caused filter cake blockage or is only a measurement fluctuation or sampling interference. The increase in unit energy consumption but the lack of a significant increase in filtrate turbidity may be caused by non-cell wall breaking factors such as filter cloth blockage, increased mechanical resistance of the equipment, changes in sludge feed rate, and abnormal filter plate compression. Therefore, other indicators need to be obtained for judgment in the asynchronous state.
[0033] Step S4, in response to the initial judgment that the sludge is not in an over-disruption state, obtain the soluble chemical oxygen demand and capillary water absorption time of the sludge before mechanical dewatering, specifically including: Step S41: Perform soluble chemical oxygen demand (COD) and capillary water absorption time tests on the sludge before mechanical dewatering a preset number of times (usually 3 to 5 times), and obtain the corresponding test results. Step S42: Calculate the average value based on the results of each soluble chemical oxygen demand (COD) test and record this average value as the soluble COD. It can be understood that soluble COD is the content of dissolved organic matter in the sludge liquid phase before mechanical dewatering, reflecting the degree of release of intracellular organic matter and extracellular polymers into the liquid phase after cell wall disruption. A low soluble COD indicates insufficient cell wall disruption and insufficient release of intracellular organic matter and EPS; a high soluble COD indicates a large or excessive degree of cell wall disruption, resulting in the dissolution of a large amount of intracellular organic matter and EPS. Step S43: Calculate the average value based on the results of each capillary water absorption time test and record this average value as the capillary water absorption time. It can be understood that the capillary water absorption time characterizes the filtration and dewatering performance of sludge, reflecting the ease with which sludge releases water and the filter cake filtration resistance. A lower capillary water absorption time indicates better sludge dewatering performance and easier water release, while a higher capillary water absorption time indicates poor sludge dewatering performance, difficulty in releasing water, and high filter cake filtration resistance. When the cell wall is not sufficiently broken, the capillary water absorption time will be higher, but when the cell wall is broken excessively, fine particles, colloids, and dissolved polymers will clog the filter cake pores, which will also lead to a higher CST.
[0034] Step S5, a secondary determination of the cell wall disruption state is performed based on the soluble chemical oxygen demand and the capillary water absorption time, including: If the capillary water absorption time is not higher than the preset upper limit of water absorption time, it means that there is no obvious abnormality in the sludge floc structure, the state of water presence, and the filter cake filtration resistance, and the cell wall breaking state is determined to be the normal cell wall breaking state. If the capillary water absorption time exceeds the preset upper limit, it indicates that the sludge filtration and dewatering performance has deteriorated. However, the cause may be insufficient or excessive cell disruption, which needs to be determined in conjunction with the soluble chemical oxygen demand (SCOD). In response to the soluble chemical oxygen demand being lower than the preset lower limit of oxygen demand, it indicates that the content of dissolved organic matter in the sludge liquid phase is very low and the release of intracellular organic matter and extracellular polymers during the cell disruption process is insufficient, thus determining the cell disruption state as an insufficient cell disruption state. In response to the soluble chemical oxygen demand being higher than the preset upper limit of oxygen demand, it indicates that the content of dissolved organic matter in the sludge liquid phase is too high. During the cell disruption process, a large amount of intracellular organic matter and extracellular polymers are released, and the cell disruption state is determined to be the cell disruption over-disruption state. If the soluble chemical oxygen demand (COD) is between the preset lower limit and the preset upper limit, it may be that the cell wall breaking degree is normal, but other factors (such as conditioner failure, filter cloth blockage, or changes in the properties of the sludge) are causing the CST to be high. In this case, an early warning message will be issued and the soluble chemical oxygen demand and the capillary water absorption time will be continuously monitored. If the test is performed every 5 minutes for 3 consecutive times, it is determined that the increase in CST may be due to non-cell wall breaking factors. The conditioner addition should be checked to see if it is normal, if the filter cloth is blocked, if the properties of the sludge have changed, and if the equipment parameters are abnormal. In practice, the preset lower limit of oxygen demand, the preset upper limit of oxygen demand, and the preset upper limit of water absorption time are all determined based on the historical data of the sludge treatment plant. That is, under normal cell wall breaking conditions, the 95th percentile of each historical test data is used as the corresponding preset value.
[0035] Step S6: Based on the determination of the cell wall disruption state, formulate pre-dehydration adjustment measures, including: In response to the excessive cell disruption, pre-dehydration adjustment measures were implemented to reduce the intensity of cell disruption to decrease the continued release of fine particles and soluble EPS, and to increase the flocculant dosage to promote particle bridging. In response to insufficient cell wall disruption, pre-dewatering adjustment measures were formulated to enhance cell wall disruption intensity (to moderately disrupt sludge flocs and cell walls, releasing bound water into free water and thus improving dewatering performance) and to select PAM (polyacrylamide, a water-soluble polymer widely used as a flocculant in sludge dewatering and wastewater treatment) which is more suitable for sludge charge and organic components, so as to better exert charge neutralization and adsorption bridging effects and improve dewaterability after cell / floc disruption; If the response indicates that the cell wall breaking process is normal, it means that the degree of cell wall breaking itself is not obviously abnormal. At this time, fluctuations in indicators or alarms may be due to drift or error of the measuring instrument. Therefore, you can observe the dehydration equipment and calibrate the measuring instrument regularly.
[0036] Furthermore, based on the results of the cell wall disruption determination, it is determined whether to adjust the drying treatment parameters, including: Both excessive and insufficient cell wall breaking can lead to poorer mechanical dewatering and increased cake moisture content, meaning an increased water load entering the drying section. If the drying parameters remain unchanged, the sludge moisture content after drying will not meet the target requirements. Therefore, the drying parameters should be adjusted, i.e., reducing the drying feed rate (while keeping the heat capacity and residence time of the drying equipment constant, allowing the unit sludge to obtain more heat, increasing the heat intensity of the unit sludge, which is conducive to water evaporation) and increasing the drying temperature (increasing the heat transfer temperature difference to accelerate the water evaporation rate) or extending the residence time (allowing the sludge to have more time to evaporate water in the drying equipment) to compensate for the increased water load caused by changes in cake moisture content or dewatering resistance. When the cell wall is in normal condition, the mechanical dewatering effect is basically stable, the moisture content of the mud cake does not show obvious abnormalities, and the water load entering the drying section does not change significantly. Therefore, maintaining the current drying parameters can maintain stable operation.
[0037] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.
[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A sludge reduction and drying method for wastewater treatment, applied in a sludge treatment process where excess sludge undergoes sequential enhanced cell disruption, conditioning / flocculation, and mechanical dewatering, wherein the sludge cake and filtrate obtained from the mechanical dewatering are respectively subjected to drying and recirculation treatments, characterized in that, include: Continuously obtain the unit energy consumption of the dehydration equipment and the turbidity of the dehydrated filtrate during the mechanical dehydration process; The current dehydration resistance status is determined based on the unit energy consumption, and the dehydration resistance status includes normal energy consumption status and energy consumption warning status. In response to the energy consumption warning state, the changes in the turbidity of the dehydrated filtrate and the unit energy consumption are determined to preliminarily judge the cell wall breakage state. The cell wall breaking states include over-breaking state, under-breaking state, and normal breaking state. In response to the initial judgment that the sludge was not in an over-disruption state, the soluble chemical oxygen demand and capillary water absorption time of the sludge before mechanical dewatering were obtained. The cell wall breakage state is determined a second time based on the soluble chemical oxygen demand and the capillary water absorption time. Based on the results of the cell wall disruption determination, pre-dehydration adjustment measures are formulated, including adjusting the intensity of cell wall disruption, adjusting the PAM type, increasing the flocculant dosage, and calibrating the dehydration equipment. Whether to adjust the drying treatment parameters is determined based on the results of the cell wall disruption assessment.
2. The sludge reduction and drying method for wastewater treatment according to claim 1, characterized in that, Based on the determination result that the unit energy consumption is greater than the unit energy consumption distribution range, the current dehydration resistance state is determined to be an energy consumption warning state. The unit energy consumption distribution range is determined based on historical energy consumption data.
3. The sludge reduction and drying method for wastewater treatment according to claim 1, characterized in that, In response to the energy consumption warning state, determining the change in the turbidity of the dehydrated filtrate and the unit energy consumption includes: Obtain the turbidity of the dehydrated filtrate and the unit energy consumption within the monitoring period corresponding to the energy consumption early warning status; The turbidity change trend of the dehydrated filtrate and the energy consumption change trend of the unit energy consumption are determined respectively, and the time range of turbidity change and the time range of energy consumption change are determined. The overlapping time range is determined based on the turbidity change time range and the energy consumption change time range, so as to determine the overlapping time ratio; In response to the turbidity change trend being consistent with the energy consumption change trend and the overlap time ratio being not less than the reference ratio, it is determined that the synchronous change condition is met and the change state is determined to be a synchronous change state. The change states include synchronous change states and asynchronous change states.
4. The sludge reduction and drying method for wastewater treatment according to claim 1, characterized in that, The initial determination of the cell wall breaking state based on the aforementioned changes includes: In response to the synchronous change state, the initial judgment of the cell wall breaking state is that the cell wall breaking state is excessive. In response to the asynchronous state of the change, if the initial judgment is that the cell wall breaking state is not an over-breaking state, then the soluble chemical oxygen demand and capillary water absorption time of the sludge before mechanical dewatering are obtained.
5. The sludge reduction and drying method for wastewater treatment according to claim 1, characterized in that, In response to the normal energy consumption state, the cell wall breaking state is determined to be the normal cell wall breaking state.
6. The sludge reduction and drying method for wastewater treatment according to claim 4, characterized in that, A secondary determination of the cell wall disruption state is performed based on the soluble chemical oxygen demand and the capillary water absorption time, including: In response to the capillary water absorption time not exceeding the preset upper limit of water absorption time, the cell wall breakage state is determined to be the normal cell wall breakage state. In response to the capillary water absorption time exceeding a preset upper limit, the cell wall disruption state is determined based on the soluble chemical oxygen demand, wherein: In response to the soluble chemical oxygen demand being lower than the preset lower limit of oxygen demand, the cell wall breaking state is determined to be an insufficient cell wall breaking state. In response to the soluble chemical oxygen demand exceeding the preset upper limit of oxygen demand, the cell wall disruption state is determined to be an over-disruption state.
7. The sludge reduction and drying method for wastewater treatment according to claim 4, characterized in that, The process of obtaining the soluble chemical oxygen demand and the capillary water absorption time includes: The soluble chemical oxygen demand and capillary water absorption time of the sludge before mechanical dewatering were tested a preset number of times, and the corresponding test results were obtained. The average value is calculated based on the test results of each soluble chemical oxygen demand (COD) test and recorded as the soluble COD. The average value is calculated based on the results of each capillary water absorption time test and recorded as the capillary water absorption time.
8. The sludge reduction and drying method for wastewater treatment according to claim 1, characterized in that, Based on the determination of the cell wall disruption state, formulate pre-dehydration adjustment measures, including: In response to the excessive cell wall disruption, pre-dehydration adjustment measures were implemented to reduce the intensified cell wall disruption intensity and increase the flocculant dosage. In response to insufficient cell wall disruption, pre-dehydration adjustment measures were formulated to enhance cell wall disruption intensity and adjust the PAM type. In response to the normal state of cell wall disruption, the adjustment measures before dehydration were to observe the dehydration equipment and calibrate the measuring instruments.
9. The sludge reduction and drying method for wastewater treatment according to claim 1, characterized in that, Based on the results of the cell wall disruption assessment, determine whether to adjust the drying treatment parameters, including: In response to over-disruption and under-disruption, the drying feed rate is reduced and the drying temperature is increased or the residence time is extended.
10. The sludge reduction and drying method for wastewater treatment according to claim 1, characterized in that, Determining whether to adjust drying parameters based on the results of the cell wall disruption assessment also includes: In response to the normal state of cell wall disruption, maintain the current drying parameters.