Method for investigating and calculating water quantity and water quality of inlet water of rural domestic sewage treatment station

Abstract

The invention relates to the technical field of rural domestic sewage treatment, and discloses a method for investigating and calculating water quantity and water quality of inlet water of a rural domestic sewage treatment station. According to the method, on the basis of whether village and rural domestic sewage collection facilities are constructed or not and the basic domestic water consumption mode of villagers, data such as various types of water consumption, sewage discharge paths and sewage quality of typical peasant households are investigated on site, so that the sewage output, actually collected sewage quantity and receivable sewage quantity of the typical peasant households are calculated; the drainage scale and the water quality characteristics of the rural domestic sewage are accurately mastered through a water quantity and water quality model, the problem of large data difference in the existing rural domestic sewage investigation process is solved, the investigation cost is saved while the data accuracy and reliability are ensured, and the investigation efficiency is improved. And technical support is provided for effective treatment of rural domestic sewage according to local conditions.

Description

Technical Field

[0001] The invention relates to the technical field of rural domestic sewage treatment, and in particular to a method for investigating and calculating the amount and quality of influent to a rural domestic sewage treatment station. Background Art

[0002] For many years, the progress of rural water pollution prevention and control has lagged significantly behind that of industrial and urban water pollution prevention and control. The quality of rural living environment and water environment is generally poor, mainly manifested in the arbitrary discharge of domestic sewage, black and smelly water bodies and prominent eutrophication problems. my country currently has 2.5 million natural villages, a rural population of about 510 million, an annual rural domestic sewage discharge of more than 20 billion tons, and annual chemical oxygen demand, ammonia nitrogen, total nitrogen, and total phosphorus emissions of about 5 million tons, 250,000 tons, 450,000 tons, and 40,000 tons, respectively. However, as of 2023, the national rural domestic sewage treatment rate is only about 31%. It can be seen that from now on 20 to 30 years, the main market for sewage treatment in my country should be concentrated in rural areas, and there is huge space.

[0003] As for the rural domestic sewage treatment facilities that have been built, there is a widespread phenomenon of not being able to operate normally for a long time, or even being abandoned for a long time. A study conducted an investigation on rural sewage treatment facilities in Hangzhou, Zhejiang Province. The results showed that only 63.6% of the centralized rural domestic sewage treatment facilities could meet the normal operation standards. The main reasons for this were insufficient investigation before construction and insufficient operation and maintenance costs. Inaccurate water quantity and quality investigations were the primary reason why rural domestic sewage treatment facilities could not play their due role. This is mainly reflected in: (1) Unclear water quantity leads to excessive scale of treatment project design. The engineering design usually takes 100~150 L / person / day as the calculation of domestic sewage discharge according to the registered population and full caliber. In addition, the water use and drainage habits of each household in rural areas are different, resulting in the actual amount of sewage collected being far less than the sewage treatment capacity of the facility design, resulting in a waste of construction resources. (2) The designed influent water quality is too high, resulting in unstable facility operation. The sewage treatment project is designed according to the mixed concentration of black water and gray water. The designed influent COD concentration is usually 250-300 mg / L, which is quite different from the actual water quality, and the treatment facilities are difficult to operate stably in the long term. (3) The drainage path is unclear, resulting in the inability of the sewage pipe network to collect water. The preliminary investigation work was not carefully designed, and there were no household collection pipes, septic tank leakage, most of the washing water was directly discharged into the rainwater ditch, and the terrain survey was not detailed. There are problems such as the sewage collection pipe network not being able to collect sewage or collecting it incompletely. Therefore, in order to realize the reasonable construction of rural domestic sewage treatment facilities and give full play to their application effectiveness, it is particularly important to establish a scientific method for investigating and calculating the water quantity and quality of rural domestic sewage.

[0004] At present, there is no scientific and effective survey and calculation method for the quantification of the quantity and quality of rural domestic sewage in my country. Only Zhejiang Province has issued the "Guidelines for Calculation of Rural Domestic Sewage Quantity and Quality" (Zhejiang Provincial Department of Housing and Urban-Rural Development, May 2023). Although it also emphasizes that the design calculation of water quantity and water quality should be based on local survey data, it does not provide detailed explanations on how to conduct the survey. The design flow of domestic sewage is calculated using the population × per capita theoretical sewage generation quota, which is not the water volume result based on actual surveys of villages. This is often quite different from the actual sewage generation and the amount of water to be collected.

[0005] At present, no water quantity and quality survey and calculation method has been retrieved. There is only one device suitable for measuring the amount of rural domestic sewage (see the prior art with application number CN202323089743.4 for details). The device includes an RTU device body and a liquid level probe. By installing a small RTU device body in a specific sewage structure, the changes in liquid level data can be observed through the set liquid level probe and display screen, which makes it easier to grasp the rural domestic sewage discharge rules and actual water volume.

[0006] At present, there is no survey and calculation method for the quantity and quality of rural domestic sewage in my country, which leads to many problems in the design and operation of subsequent rural domestic sewage treatment facilities. Therefore, the present invention proposes a method for surveying and calculating the quantity and quality of rural domestic sewage to accurately grasp the quantity and quality characteristics of rural sewage. Summary of the invention

[0007] The purpose of the present invention is to provide a method for investigating and calculating the amount and quality of water entering a rural domestic sewage treatment station based on the above technical problems.

[0008] The technical solution of the present invention:

[0009] In order to achieve the above-mentioned object, the first aspect of the present invention provides a method for investigating and calculating the water quantity and water quality of influent to a rural domestic sewage treatment station, the method comprising the following steps: (1) Conduct a preliminary investigation on the drainage destination of sewage from farmers in the village to determine the type of drainage route, and determine the type of drainage mode in the village based on the type of drainage route. Select a typical farmer for each drainage mode, investigate and calculate the total water consumption of a single typical farmer, and calculate the total drainage volume of a typical farmer according to different water uses. Determine the amount of sewage to be collected based on the type of drainage route, and calculate the actual amount of sewage collected by a single typical farmer based on the collection rate of water collection facilities in the single typical farmer; (2) Based on the total water consumption and wastewater collection amount of typical surveyed farmers obtained in step (1), the model is used to estimate the wastewater collection amount and actual wastewater collection amount of each farmer. Meanwhile, other pollution sources in the village are investigated simultaneously to calculate the wastewater collection amount and actual wastewater collection amount of farmers in the whole village. (3) Based on the distribution of typical surveyed farmers, different points are selected within the village to test the quality of the village’s domestic sewage, and the water quality concentration that ultimately enters the rural sewage treatment facility is estimated based on the model.

[0010] Preferably, in step (1), the drainage path types are discharge into a septic tank, direct discharge into a sewage pipe, discharge through a soil infiltration stormwater ditch, overflow stormwater ditch, discharge into a stormwater ditch, a path used for nearby farmland irrigation, or a combination of several paths.

[0011] Further preferably, in step (1), the types of drainage modes include one or a combination of indoor sewage entering a septic tank, indoor sewage directly entering a village sewage pipe, outdoor sewage being recycled nearby, outdoor sewage infiltrating through courtyard soil, and outdoor sewage flowing through courtyard ditches.

[0012] Preferably, in step (1), the typical surveyed households are households with a permanent population of 3, 4 or 5 persons, which are selected according to the drainage pattern type in the whole village.

[0013] Preferably, in step (1), the total amount of sewage discharged by a single typical surveyed farmer is the sum of the amount of each type of sewage, and the calculation formula is as follows: ;

[0014] in, is the total amount of sewage discharged by a typical surveyed farmer, For toilet water consumption, The water consumption in the kitchen. is the amount of water used for indoor washing. It is the water consumption for yard washing, wherein the water consumption for yard washing includes natural infiltration or resource water and cross-flow water.

[0015] Preferably, in step (1), the calculation formula for the amount of sewage to be collected by a typical surveyed farmer is as follows:

[0016] ; Among them, Q y is the amount of sewage that should be collected by a typical surveyed farmer, Q w is the water consumption of toilet, Q c is the kitchen water consumption, Q x is the indoor washing water consumption, Q th is the cross flow volume.

[0017] According to a preferred embodiment, in step (2), the model includes the following contents:

[0018] S1: Data standardization: The daily water consumption data and sewage discharge data of typical surveyed farmers are standardized according to the following formula. At the same time, the sewage discharge data of typical surveyed farmers are divided by the permanent population of the whole village to obtain the daily sewage discharge per capita, and the maximum value of the daily sewage discharge per capita is determined, where the maximum value is recorded as Q max , the minimum value is recorded as Q min ;

[0019] , where the daily water consumption data is recorded as Q 用水量 , the sewage discharge data is recorded as Q 污水量 , Q is Q 用水量 or Q 污水量； is the data mean, is the data standard deviation; It is the standardized daily water consumption or sewage discharge;

[0020] S2: Construct a decision tree: Take the number of people in each typical surveyed farmer household as the root node, generate three child nodes of 3, 4, and 5 people, use the daily water consumption data and sewage discharge data of a single typical surveyed farmer household, and construct linear regression models for the three types of permanent residents in each child node to fit the relationship between the daily sewage discharge of the household and the total daily sewage discharge. The formula is as follows:

[0021] , where Q 预测水量 is the predicted value of daily sewage discharge of typical surveyed farmers; α is the sewage ratio coefficient, which indicates the impact of total water consumption on sewage discharge; β is the bias term, which is used to adjust the model baseline; is the total daily water consumption of a typical surveyed farmer;

[0022] S3: Parameter optimization: Select mean square error as the loss function, the formula is as follows, and use the gradient descent algorithm to optimize the model parameters α and β to minimize the loss function:

[0023] Among them, MSE is the mean square error; is the actual sewage volume of the ith household; is the sewage volume predicted by the model; N is the total number of samples;

[0024] S4: Model evaluation: Calculating R 2 , the formula is as follows: ; ; ;

[0025] in, is the residual sum of squares, which represents the sum of squared errors between the model prediction value and the actual value; is the total sum of squares, which represents the sum of squared errors between the actual value and its mean;

[0026] If R 2 >70%, and Q min <Q 预测水量 <Q max If it is not true, return to step S2 and readjust the model parameters until the model satisfies R 2 >70%, and Q min <Q 预测水量 <Q max ;

[0027] S5: Sewage volume prediction: Use the trained model to predict sewage discharge volume. The formula is as follows: , where Q 污水排放量 is the sewage discharge of farmers in the village; It is the total water consumption of farmers in the village.

[0028] Preferably, in step (2), the calculation formula for the amount of sewage to be collected by the whole village is: the amount of sewage to be collected by the whole village = the total amount of sewage to be collected by farmers in the village + the total amount of sewage to be collected by other pollution sources;

[0029] The calculation formula for the actual amount of sewage collected in the village is: the actual amount of sewage collected in the village = the total amount of sewage collected by farmers + the total amount of sewage collected by other pollution sources.

[0030] Further preferably, in step (3), the sampling points for the domestic sewage quality survey are arranged at the junctions of typical surveyed farmer's household pipes and sewage delivery branches, the junctions of other pollution source household pipes and sewage delivery branches, the junctions of sewage delivery branches and main pipes, and the junctions of downstream sewage delivery main pipes.

[0031] According to a particularly preferred embodiment, in step (3), the model includes the following contents:

[0032] T1: Collect the sewage discharge points of two typical surveyed farmers, measure the sewage quality of the sewage discharge points, and obtain the amount of pollutants through the following model. Calculate the total amount of pollutants of typical surveyed farmers according to the following formula, recorded as ω 典型调查农户 :

[0033] , where i represents the type of typical surveyed farmers, there are 2 types in total; j represents the population, there are 3 types in total, where "1" represents 3 people, "2" represents 4 people, and "3" represents 5 people; Cij is the sewage discharge concentration of the typical surveyed farmer with the i-th population j; Q ij is the sewage discharge of the typical surveyed farmer with the i-th type and population j;

[0034] T2: Measure the pollutant concentration C at the intersection of the sewage collection branch pipe and the sewage collection main pipe of a typical surveyed farmer 户-交点 , and the pollutant amount at the intersection of the typical surveyed farmer's sewage collection branch pipe and the sewage collection main pipe is calculated according to the following formula, recorded as ω 户-交点 : , where Q 户-交点 The sewage volume at the intersection of the sewage collection branch pipe and the sewage collection main pipe of a typical surveyed farmer;

[0035] T3: Calculate the total amount of pollutant consumption in the collection branch of the pollutant discharge of all households in the village according to the following formula, recorded as ω 全村户-支损 :

[0036] ,in, The total length of the sewage collection branch pipes of typical surveyed farmers, The total length of the branch pipes for collecting sewage from farmers in the village;

[0037] T4: Calculate the amount of pollutants at the sewage collection branch pipes of other pollution sources according to the following formula, denoted as ω 其他污染源 :

[0038] , where ω 其他污染源 is the total amount of wastewater discharged from other pollution sources, is the sewage discharge concentration of the i-th other pollution source, is the sewage discharge of the ith other pollution source;

[0039] T5: Measure pollutant concentration at the intersection of sewage collection branch pipes and sewage collection main pipes from other pollution sources , and calculate the pollutant amount at the intersection of the sewage collection branch pipe and the sewage collection main pipe from other pollution sources according to the following formula, recorded as ω 其他污染源-交点 : , where Q 其他污染源-交点 The amount of sewage at the intersection of the sewage collection branch pipe and the sewage collection main pipe of other pollution sources;

[0040] T6: Calculate the total amount of pollutant loss from the collection pipes of other pollution sources in the village according to the following formula, recorded as ω 其他污染源-支损 :

[0041] ,in, The total length of the sewage collection branch pipes of typical surveyed farmers, The total length of the branch pipes collecting sewage from other pollution sources in the village;

[0042] T7: Calculate the WWTP influent sewage volume Q according to the following formula WWTP :

[0043] According to the law of conservation of mass, the WWTP influent pollutant concentration C is obtained: WWTP The calculation model is: ,

[0044] Where Q WWTP It is the total amount of sewage discharged in the village.

[0045] Technical effects of the present invention:

[0046] The present invention is based on whether or not rural domestic sewage collection facilities are built in the village and the basic domestic water use methods of the villagers, and conducts on-site investigations on data such as various types of water consumption, sewage discharge paths and sewage quality of typical farmers, thereby calculating the sewage generation, actual sewage collection and expected sewage collection of typical farmers, and accurately grasping the drainage scale and water quality characteristics of rural domestic sewage through a water quantity and water quality model, thereby solving the problem of large data differences in the existing rural domestic sewage investigation process. The method of the present invention ensures data accuracy and reliability while saving investigation costs, thereby providing technical support for the effective management of rural domestic sewage according to local conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a diagram of the types of drainage patterns of the present invention;

[0048] Figure 2 It is a calculation diagram of various types of sewage volume of the present invention;

[0049] Figure 3 This is a process diagram for calculating the actual amount of various types of sewage collected in the present invention;

[0050] Figure 4 is a flow chart of step (2) of an embodiment of the present invention;

[0051] Figure 5 This is a layout diagram of sampling points for domestic sewage quality investigation according to the present invention. DETAILED DESCRIPTION

[0052] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0053] The present invention will be described in detail below by way of examples. In the following examples, unless otherwise specified, the raw materials are all commercially available.

[0054] In the following example, there are 250 households and 1,197 people in Zhenhai Village, Yazhou District, Sanya City, Hainan Province. The village is close to the sea and has sandy soil.

[0055] In the following examples, unless otherwise specified, the survey calculation methods for the total water consumption of each type of typical surveyed farmers (toilet water, kitchen water, indoor washing water, and courtyard washing water) are divided into the following situations:

[0056] a. Farmers only use well water or reservoir water. The total amount of water used for toilets in a single household is the sum of the amount of water used for defecation and urination. The total amount of water used for defecation per day = the number of defecations per day × the amount of water used for a single flush (C1), and the total amount of water used for urination per day = the number of urinations per day × the amount of water used for a single flush (C2). Among them, C1 and C2 are measured by the volume of a water scoop × the number of water scoops. The total amount of water used for washing in the house is calculated by the volume required for a single wash × the number of washes per month. The total amount of water used for kitchens and courtyard washing in a single household is calculated by the volume of buckets (tanks) × the number of water scoops.

[0057] b. Farmers use tap water and well water at the same time. According to the use of well water in a single household (such as kitchen water, courtyard washing water, etc.), the total well water consumption = bucket (tank) volume × number. The total toilet water consumption of a single household is the sum of the water consumption for defecation and urination. The total daily defecation and urination water consumption = the number of defecation and urination times per day × the single flushing volume (C3), where C3 is calculated using the single flushing volume of the flush toilet. The total indoor washing water consumption is calculated by the volume required for a single laundry × the number of laundry times per month. The total kitchen water consumption of a single household is calculated by the water consumption for cooking in the morning, noon and evening × the number of days. The remaining non-well water consumption is calculated as the monthly tap water consumption of a single household - toilet water consumption - indoor washing water consumption - kitchen water consumption.

[0058] c. Farmers only use tap water. The total amount of water used for toilets of a single household is the sum of the water used for defecation and urination. The total amount of water used for defecation and urination per day = the number of defecation and urination times per day × the amount of water used for a single flush (C3), where C3 is calculated using the amount of water used for a single flush of a flush toilet. The total amount of water used for indoor washing is calculated by the volume of laundry required per time × the number of laundry times per month. The total amount of water used for kitchens of a single household is calculated by the amount of water used for cooking in the morning, noon and evening × the number of days. The amount of water used for courtyard washing is calculated by the monthly amount of tap water used by a single household - the amount of water used for toilets - the amount of water used for indoor washing - the amount of water used for kitchens.

[0059] Example

[0060] This example is used to provide a method for investigating and calculating the water quantity and quality of the influent of a rural domestic sewage treatment station. The method includes the following steps: (1) A preliminary investigation was conducted on the destination of toilet water, kitchen water, indoor washing water, courtyard washing water and other sewage from farmers in Zhenhai Village, Yazhou District, Sanya City, Hainan Province to determine the types of drainage routes, and the types of drainage patterns in the village were determined based on the types of drainage routes. A typical farmer was selected for each drainage pattern, and the total water consumption of a single typical farmer was investigated in detail and calculated. The total drainage volume of the typical farmer was calculated according to different water uses, and the amount of sewage to be collected was determined based on the type of drainage route. Combined with the collection rate of water collection facilities such as septic tanks and household pipes in a single typical farmer, the actual amount of sewage collected by a single typical farmer was calculated.

[0061] The drainage path types are one or a combination of discharge into a septic tank, directly into a sewage pipe, through soil infiltration, overflow, discharge into a rainwater ditch, and nearby irrigation of farmland. In this embodiment, the indoor sewage of the village is all discharged into a septic tank, and there are four situations for outdoor washing water discharge: 81.6% of the households discharge into a septic tank, 8.4% of the households discharge directly into a sewage pipe, 6.8% of the households discharge through natural soil infiltration, and 3.2% of the households discharge into farmland;

[0062] The types of drainage modes include one or several combined drainage modes, including indoor sewage entering a septic tank, indoor sewage directly entering a village sewage pipe, outdoor sewage being recycled nearby, outdoor sewage infiltrating through courtyard soil, and outdoor sewage flowing through courtyard soil. Figure 1 As shown, in this embodiment, there are two types of drainage modes, "mode 1" and "mode 2". Specifically, there are 225 households with a total of 1,098 people that meet "mode 1", and there are 25 households with a total of 99 people that meet "mode 2".

[0063] The typical surveyed farmer is a family of 3, 4 or 5 selected according to the drainage mode type in the whole village. In this embodiment, the typical surveyed farmer uses tap water. In "Mode 1", a permanent population of 3 is selected as a typical surveyed farmer, and its total water consumption of various types of water is 7.5 tons / month. A permanent population of 4 is selected as a typical surveyed farmer, and its total water consumption of various types of water is 9.4 tons / month. A permanent population of 5 is selected as a typical surveyed farmer, and its total water consumption of various types of water is 11.6 tons / month. In "Mode 2", a permanent population of 3 is selected as a typical surveyed farmer, and its total water consumption of various types of water is 8.9 tons / month. A permanent population of 4 is selected as a typical surveyed farmer, and its total water consumption of various types of water is 13.4 tons / month. A permanent population of 5 is selected as a typical surveyed farmer, and its total water consumption of various types of water is 15.5 tons / month.

[0064] The total amount of sewage discharged by typical surveyed farmers is based on the toilet water consumption (Q w )、Kitchen water consumption (Q c )、Indoor washing water consumption (Q x)、Water consumption for yard washing (Q t ) is calculated, where the water consumption for courtyard washing (Q t ) includes natural infiltration or resource water (Q tz ) and cross flow volume (Q th ), the amount of each type of sewage is calculated as follows Figure 2 As shown in the figure, the total amount of sewage discharged by a typical surveyed farmer (Q z ) is the sum of all types of sewage, and the calculation formula is as follows: ;

[0065] The amount of sewage to be collected (Q y ) is the toilet water consumption of typical surveyed farmers (Q w )、Kitchen water consumption (Q c )、Indoor washing water consumption (Q x ), cross flow volume (Q th ), the calculation formula is as follows:

[0066] ;

[0067] Combined with the collection rate of water collection facilities such as septic tanks and household pipes in a typical surveyed farmer, if there is leakage in the water collection facility, the collection rate (η) is 0; if all the sewage in the water collection facility can be collected, the collection rate (η) is 100%. The actual amount of sewage collected by a typical surveyed farmer is calculated by the amount of each type of sewage and the collection rate of each water collection facility. The calculation process is as follows: Figure 3 shown.

[0068] According to the survey and calculation results, the water consumption of each type Q for the family of three selected in "Model 1" in this embodiment is obtained as follows: w , Q c , Q x and Q th The values ​​are 2.0 tons / month, 1.6 tons / month, 2.8 tons / month and 1.1 tons / month respectively, and the calculated amount of sewage to be collected is 6.7 tons / month; the water consumption of the selected family of 4 is Q w , Q c , Q x and Q th The values ​​are 2.7 tons / month, 2.3 tons / month, 3.8 tons / month and 0.6 tons / month respectively, and the calculated amount of sewage to be collected is 8.4 tons / month; the water consumption of the selected family of three is Q w , Q c , Q x and Q thThe values ​​are 3.2 tons / month, 2.8 tons / month, 4.1 tons / month and 1.5 tons / month respectively, and the calculated amount of sewage to be collected is 10.3 tons / month. w , Q c , Q x and Q th The values ​​are 2.4 tons / month, 2.0 tons / month, 3.4 tons / month and 1.1 tons / month respectively, and the calculated amount of sewage to be collected is 7.9 tons / month; the water consumption of the selected family of 4 is Q w , Q c , Q x and Q th The values ​​are 3.8 tons / month, 3.3 tons / month, 5.1 tons / month and 1.2 tons / month respectively, and the calculated amount of sewage to be collected is 11.6 tons / month; the water consumption of the selected family of three is Q w , Q c , Q x and Q th The values ​​are 4.1 tons / month, 3.2 tons / month, 7.2 tons / month and 1.0 ton / month respectively, and the calculated amount of sewage to be collected is 13.8 tons / month.

[0069] (2) Based on the total water consumption and the amount of sewage that should be collected of the typical surveyed farmers obtained in step (1), the model is used to estimate the amount of sewage that should be collected and the amount of sewage actually collected by each farmer. At the same time, other pollution sources in the village are investigated to calculate the amount of sewage that should be collected and the amount of sewage actually collected by farmers in the entire village.

[0070] The model is as follows: Figure 4 The specific contents are as follows:

[0071] S1: Data standardization: The daily water consumption data of typical surveyed farmers ( Q 用水量 ) and sewage discharge data ( Q 污水量 ) were standardized, and the sewage discharge data of typical surveyed farmers with 3 people were divided by the permanent population of the whole village to obtain the per capita daily sewage discharge, and the maximum value of the per capita daily sewage discharge was determined. Q max With minimum Q min ;

[0072] , where Q is the daily water consumption data ( Q 用水量 ) or sewage discharge data ( Q 污水量 ); is the data mean; is the data standard deviation; It is the standardized daily water consumption or sewage discharge;

[0073] S2: Construct a decision tree: Take the number of people in each typical survey household as the root node, generate three child nodes of 3, 4, and 5 people, and use the daily water consumption data of a single typical survey household ( Q 用水量 ) and sewage discharge data ( Q 污水量 ), in each sub-node, for the three types of permanent residents, linear regression models are constructed to fit the relationship between the daily sewage discharge of the residents and the total daily sewage discharge. The formula is as follows:

[0074] , where Q 预测水量 is the predicted value of daily sewage discharge of typical surveyed farmers; α is the sewage ratio coefficient, which indicates the impact of total water consumption on sewage discharge; β is the bias term, which is used to adjust the model baseline; is the total daily water consumption of a typical surveyed farmer;

[0075] S3: Parameter optimization: Select mean square error as the loss function (formula as follows), and use the gradient descent algorithm to optimize the model parameters α and β to minimize the loss function:

[0076] , where MSE is the mean square error; is the actual sewage volume of the ith household; is the sewage volume predicted by the model; N is the total number of samples;

[0077] S4: Model evaluation: Calculating R 2 , the formula is as follows: ; ; ;

[0078] in, is the residual sum of squares, which represents the sum of squared errors between the model prediction value and the actual value; is the total sum of squares, which represents the sum of squared errors between the actual value and its mean;

[0079] If R 2 >70%, and Q min <Q 预测水量 <Q max If it is not true, return to step S2 and readjust the model parameters until the model satisfies R 2 >70%, and Q min <Q 预测水量 <Q max ;

[0080] S5: Sewage volume prediction: Use the trained model to predict sewage discharge volume. The formula is as follows: , where Q 污水排放量 is the sewage discharge of farmers in the village; It is the total water consumption of farmers in the village.

[0081] In addition, other pollution sources include: the water volume survey of restaurants and homestays in the village is the same as that of single households, focusing on whether there is a grease trap, and the total sewage discharge, the amount of sewage to be collected, and the actual amount of sewage collected are calculated in the same way as single households;

[0082] The amount of water used by farmers raising livestock and poultry in the village needs to be investigated in terms of livestock and poultry breeding patterns, manure removal methods, and the destinations of sewage and manure discharge. The total amount of sewage discharged is the total amount of water used for breeding. The amount of sewage to be collected and the actual amount of sewage collected are calculated based on the drainage method and collection rate. The amount of water used for household agricultural and sideline product processing in the village needs to be investigated in terms of water consumption per unit product, annual output, and drainage method. The total amount of sewage discharged = water consumption per unit product × annual output. The amount of sewage to be collected and the actual amount of sewage collected are calculated based on the drainage method and collection rate.

[0083] In this embodiment, other pollution sources are: one school, whose tap water consumption is 180 tons / month, and the calculated amount of sewage to be collected is 140 tons / month; two hotels, whose tap water consumption is 56 tons / month in total, and the calculated amount of sewage to be collected is 49 tons / month; two homestays, whose tap water consumption is 116 tons / month in total, and the calculated amount of sewage to be collected is 108 tons / month.

[0084] The calculation formula for the amount of sewage that the whole village should collect is: The amount of sewage that the whole village should collect = the total amount of sewage that farmers in the village should collect + the total amount of sewage that other pollution sources should collect;

[0085] The calculation formula for the actual amount of sewage collected in the village is: the actual amount of sewage collected in the village = the total amount of sewage collected by farmers + the total amount of sewage collected by other pollution sources.

[0086] In this embodiment, the model calculates that the total amount of sewage to be collected by farmers in the village that meet "Model 1" is 2,713 tons / month, the total amount of sewage to be collected by farmers in the village that meet "Model 2" is 313 tons / month, and the total amount of sewage to be collected from other pollution sources is 297 tons / month. Therefore, the total amount of sewage to be collected in the whole village is 3,323 tons / month.

[0087] (3) Based on the typical distribution of surveyed farmers, different points are selected within the village to test the quality of the village’s domestic sewage, and the water quality concentration that ultimately enters the rural sewage treatment facility is estimated based on the model.

[0088] The sampling time for the domestic sewage quality survey is 8:00-10:00 in the morning, 11:30-13:30 at noon, and 19:30-21:30 at night. One water sample is taken from each sample and mixed to test the concentrations of pollutants such as SS, COD, ammonia nitrogen, TN, and TP in the kitchen water, washing water, septic tank supernatant, and agricultural sewage mixed water of typical surveyed farmers.

[0089] Among them, Figure 5 As shown in the figure, the sampling points for the domestic sewage quality survey are arranged at the junction of the typical survey farmer's household pipe and the sewage transmission branch pipe, the junction of other pollution source household pipes and sewage transmission branch pipes, the junction of the sewage transmission branch pipe and the main pipe, and the junction of the downstream sewage transmission main pipe.

[0090] The process of model calculation includes the following steps:

[0091] T1: Collect the sewage discharge points of two typical surveyed farmers, measure the sewage quality of the sewage discharge points, and obtain the amount of pollutants through the following model. Calculate the total amount of pollutants of typical surveyed farmers according to the following formula, recorded as ω 典型调查农户 :

[0092] , where i represents the type of typical surveyed farmers, there are 2 types in total; j represents the population, there are 3 types in total, where "1" represents 3 people, "2" represents 4 people, and "3" represents 5 people; C ij is the sewage discharge concentration of the typical surveyed farmer with the i-th population j; Q ij is the sewage discharge of the typical surveyed farmer with the i-th type and population j;

[0093] In this embodiment, according to the water quality survey results, the water quality monitoring results of the family of three selected in "Model 1" are SS 205 mg / L, COD 156 mg / L, ammonia nitrogen 3.88 mg / L, TN 14.9 mg / L, and TP 1.1 mg / L; the water quality monitoring results of the family of four selected in "Model 1" are SS 186 mg / L, COD 174 mg / L, ammonia nitrogen 2.68 mg / L, TN 13.7 mg / L, and TP 2.1 mg / L; the water quality monitoring results of the family of five selected in "Model 1" are SS 222 mg / L, COD 165 mg / L, ammonia nitrogen 5.88 mg / L, TN 24.5 mg / L, and TP 4.6 mg / L; the water quality monitoring results of the family of three selected in "Model 2" are SS 65 mg / L, COD 130 mg / L, ammonia nitrogen 1.6 mg / L, TN is 9.4 mg / L, TP is 0.35 mg / L; the water quality monitoring results of the family of 4 selected in "Model 2" are SS 86 mg / L, COD 134 mg / L, ammonia nitrogen 1.68 mg / L, TN 11.7 mg / L, TP 0.78 mg / L; the water quality monitoring results of the family of 5 selected in "Model 2" are SS 122 mg / L, COD 105 mg / L, ammonia nitrogen 2.38 mg / L, TN 11.5 mg / L, TP 0.6 mg / L;

[0094] In this embodiment, the sewage discharge of all 3-person households in the whole village in "Model 1" is 31.3 tons / day, the sewage discharge of all 4-person households is 46 tons / day, and the sewage discharge of all 5-person households is 20.8 tons / day; the sewage discharge of all 3-person households in the whole village in "Model 2" is 3.7 tons / day, the sewage discharge of all 4-person households is 5.65 tons / day, and the sewage discharge of all 5-person households is 2.6 tons / day; According to the above formula, ω 典型调查农户 As a result, SS was 20.63 kg / d, COD was 17.83 kg / d, ammonia nitrogen was 388.62 g / d, TN was 1736.96 g / d, and TP was 234.09 g / d;

[0095] T2: Measure the pollutant concentration C at the intersection of the sewage collection branch pipe and the sewage collection main pipe of a typical surveyed farmer 户-交点 , and the pollutant amount at the intersection of the typical surveyed farmer's sewage collection branch pipe and the sewage collection main pipe is calculated according to the following formula, recorded as ω 户-交点 : , where Q 户-交点 The sewage volume at the intersection of the sewage collection branch pipe and the sewage collection main pipe of a typical surveyed farmer;

[0096] In this embodiment, according to the water quality survey results, the pollutant concentrations at the intersection of the sewage collection branch pipe and the sewage collection main pipe of a typical surveyed farmer are SS 205 mg / L, COD 156 mg / L, ammonia nitrogen 3.88 mg / L, TN 14.9 mg / L, TP 1.1 mg / L; Q 户-交点 is 110.1 tons / day. According to the above formula, ω 户-交点 As a result, SS was 20.19 kg / d, COD was 17.15 kg / d, ammonia nitrogen was 344.61 g / d, TN was 1508.37 g / d, and TP was 206.99 g / d;

[0097] T3: Calculate the total amount of pollutant consumption in the collection branch of the pollutant discharge of all households in the village according to the following formula, recorded as ω 全村户-支损 :

[0098] ,in, The total length of the sewage collection branch pipes of typical surveyed farmers, The total length of the branch pipes for collecting sewage from farmers in the village;

[0099] In this embodiment, according to the field survey results, the total length of the sewage collection branch pipe of a typical farmer household is L 典型调查农户 6.7 km, L 全村农户 is 10.5 km, and according to the above formula, ω 全村农户-支损 As a result, SS was 689.55 g / d, COD was 1065.67 g / d, ammonia nitrogen was 68.97 g / d, TN was 358.23 g / d, and TP was 42.47 g / d;

[0100] T4: Calculate the amount of pollutants at the sewage collection branch pipes of other pollution sources according to the following formula, denoted as ω 其他污染源 :

[0101] , where ω 其他污染源 is the total amount of wastewater discharged from other pollution sources, is the sewage discharge concentration of the i-th other pollution source, is the sewage discharge of the ith other pollution source;

[0102] The water quality monitoring results of other pollution sources are as follows: the school monitoring results are SS 345 mg / L, COD 302 mg / L, ammonia nitrogen 14.4 mg / L, TN 4.7 mg / L, TP 1.2 mg / L; the hotel monitoring results are SS 256 mg / L, COD 213 mg / L, ammonia nitrogen 13.5 mg / L, TN 6.8 mg / L, TP 5.6 mg / L; the homestay monitoring results are SS 275 mg / L, COD 230 mg / L, ammonia nitrogen 15.5 mg / L, TN 8.7 mg / L, TP 4.8 mg / L;

[0103] In this example, the school sewage discharge is 6.4 tons / day, the restaurant sewage discharge is 2.5 tons / day, and the homestay sewage discharge is 4.5 tons / day. According to the above formula, ω 典型调查农户 As a result, SS was 4.09 kg / d, COD was 3.50 kg / d, ammonia nitrogen was 196.94 g / d, TN was 102.98 g / d, and TP was 43.28 g / d;

[0104] T5: Measure the pollutant concentration C at the intersection of the sewage collection branch pipe and the sewage collection main pipe of other pollution sources 其他污染源-交点 , and calculate the pollutant amount at the intersection of the sewage collection branch pipe and the sewage collection main pipe from other pollution sources according to the following formula, recorded as ω 其他污染源-交点 : , where Q 其他污染源-交点 The amount of sewage at the intersection of the sewage collection branch pipe and the sewage collection main pipe of other pollution sources;

[0105] In this embodiment, according to the water quality survey results, the pollutant concentrations at the intersection of the sewage collection branch pipe and the sewage collection main pipe of other pollution sources are SS 292.5 mg / L, COD 257.6 mg / L, ammonia nitrogen 12.3 mg / L, TN 7.0 mg / L, TP 2.9 mg / L; Q 其他污染源-交点 is 13.4 tons / day. According to the above formula, ω 其他污染源-交点 As a result, SS was 3.92 kg / d, COD was 3.45 kg / d, ammonia nitrogen was 164.82 g / d, TN was 93.8 g / d, and TP was 38.86 g / d;

[0106] T6: Calculate the total amount of pollutant loss from the collection pipes of other pollution sources in the village according to the following formula, recorded as ω 其他污染源-支损 :

[0107] ,in, The total length of the sewage collection branch pipes of typical surveyed farmers, The total length of the branch pipes collecting sewage from other pollution sources in the village;

[0108] In this embodiment, according to the field survey results, the total length of the sewage collection branch pipe of a typical farmer household is L 其他污染源 3.3 km, L 全村农户 is 7.1 km, and according to the above formula, ω 其他污染源-支损 As a result, SS was 365.75 g / d, COD was 107.58 g / d, ammonia nitrogen was 69.11 g / d, TN was 19.75 g / d, and TP was 9.51 g / d;

[0109] T7: Calculate the WWTP influent sewage volume Q according to the following formula WWTP :

[0110] According to the law of conservation of mass, the WWTP influent pollutant concentration C is obtained: WWTP The calculation model is:

[0111] , where Q WWTP is the total sewage discharge of the whole village (typical surveyed farmers + other pollution sources), C ij is the sewage discharge concentration of the typical surveyed farmer with the i-th population j; Q ij is the sewage discharge of the typical surveyed farmer with the i-th population j, ω 全村户-支损 Collect the total amount of pollutant consumption from the branch pipes for the pollutant discharge of all households in the village. is the sewage discharge concentration of the i-th other pollution source, is the sewage discharge of the i-th other pollution source, ω 其他污染源-支损 Collect the total amount of pollutant loss from branch pipes for pollutant discharge from other pollution sources in the village;

[0112] In this embodiment, the calculated result of T1-T6 is substituted into the above formula to obtain the influent pollutant concentration C WWTP The results were: SS was 186.68 mg / L, COD was 163.21 mg / L, ammonia nitrogen was 3.60 mg / L, TN was 11.84 mg / L, and TP was 1.83 mg / L.

[0113] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for investigating and calculating the quantity and quality of water entering a rural domestic sewage treatment station, characterized in that: The method comprises the following steps: (1) Conduct a preliminary investigation on the drainage destination of sewage from farmers in the village to determine the type of drainage route, and determine the type of drainage pattern in the village based on the type of drainage route. Select a typical farmer for each drainage pattern, investigate and calculate the total water consumption of a single typical farmer, and calculate the total drainage volume of a typical farmer according to different water uses. Determine the amount of sewage to be collected based on the type of drainage route, and calculate the actual amount of sewage collected by a single typical farmer based on the collection rate of water collection facilities in the single typical farmer; (2) Based on the total water consumption and wastewater collection amount of typical surveyed farmers obtained in step (1), the model is used to estimate the wastewater collection amount and actual wastewater collection amount of each farmer. Meanwhile, other pollution sources in the village are investigated simultaneously to calculate the wastewater collection amount and actual wastewater collection amount of farmers in the whole village. (3) Based on the distribution of typical surveyed farmers, different points are selected within the village to test the quality of the village’s domestic sewage, and the water quality concentration that ultimately enters the rural sewage treatment facility is estimated based on the model.

2. The method according to claim 1, wherein: In step (1), the drainage path types are one or a combination of discharge into a septic tank, discharge directly into a sewage pipe, discharge through a soil infiltration rainwater ditch, overflow rainwater ditch, discharge into a rainwater ditch, and discharge for nearby farmland irrigation; And / or, in step (1), the types of drainage modes include one or a combination of indoor sewage into a septic tank, indoor sewage directly into a village sewage pipe, outdoor sewage nearby resource utilization, outdoor sewage infiltration through courtyard soil, and outdoor sewage cross-flow through courtyard ditches; And / or, in step (1), the typical surveyed households are households with a permanent population of 3, 4 or 5 persons, selected according to the drainage pattern type in the whole village.

3. The method according to claim 1 or 2, wherein: In step (1), the total amount of sewage discharged by a typical surveyed farmer is the sum of all types of sewage, calculated as follows: ； in, is the total amount of sewage discharged by a typical surveyed farmer, For toilet water consumption, The water consumption in the kitchen. is the amount of water used for indoor washing. The water consumption for yard washing includes natural infiltration or resource recovery water and cross-flow water; And / or, in step (1), the calculation formula for the amount of sewage that should be collected by a typical surveyed farmer is as follows: ;in, The amount of sewage that should be collected by typical surveyed farmers is: For toilet water consumption, The water consumption in the kitchen. is the amount of water used for indoor washing. is the cross flow volume.

4. The method according to claim 1 or 2, wherein: In step (2), the model includes the following: S1: Data standardization: The daily water consumption data and sewage discharge data of typical surveyed farmers are standardized according to the following formula. At the same time, the sewage discharge data of typical surveyed farmers are divided by the permanent population of the whole village to obtain the daily sewage discharge per capita, and the maximum value of the daily sewage discharge per capita is determined, where the maximum value is recorded as , the minimum value is recorded as ; , where the daily water consumption data is recorded as Q 用水量 , the sewage discharge data is recorded as Q 污水量 , Q is Q 用水量 or Q 污水量； is the data mean, is the data standard deviation; It is the standardized daily water consumption or sewage discharge; S2: Construct a decision tree: Take the number of people in each typical surveyed farmer household as the root node, generate three child nodes of 3, 4, and 5 people, use the daily water consumption data and sewage discharge data of a single typical surveyed farmer household, and construct linear regression models for the three types of permanent residents in each child node to fit the relationship between the daily sewage discharge of the household and the total daily sewage discharge. The formula is as follows: , where Q 预测水量 is the predicted value of daily sewage discharge of typical surveyed farmers; α is the sewage ratio coefficient, which indicates the impact of total water consumption on sewage discharge; is the total daily water consumption of typical surveyed farmers; β is the bias term, which is used to adjust the model baseline; S3: Parameter optimization: Select mean square error as the loss function, the formula is as follows, and use the gradient descent algorithm to optimize the model parameters α and β to minimize the loss function: , where MSE is the mean square error; is the actual sewage volume of the ith household; is the sewage predicted by the model; N is the total number of samples; S4: Model evaluation: Calculating R 2 , the formula is as follows: ； ； ； in, is the residual sum of squares, which represents the sum of squared errors between the model prediction value and the actual value; is the total sum of squares, which represents the sum of squared errors between the actual value and its mean; If R 2 >70%, and Q min <Q 预测水量 <Q max If it is not true, return to step S2 and readjust the model parameters until the model satisfies R 2 >70%, and Q min <Q 预测水量 <Q max ; S5: Sewage volume prediction: Use the trained model to predict sewage discharge volume. The formula is as follows: , where Q 污水排放量 is the sewage discharge of farmers in the village; It is the total water consumption of farmers in the village.

5. The method according to claim 1 or 2, wherein: In step (2), the calculation formula for the amount of sewage that the whole village should collect is: the amount of sewage that the whole village should collect = the total amount of sewage that farmers in the village should collect + the total amount of sewage that other pollution sources should collect; The calculation formula for the actual amount of sewage collected in the village is: the actual amount of sewage collected in the village = the total amount of sewage collected by farmers + the total amount of sewage collected by other pollution sources.

6. The method according to claim 1 or 2, wherein: In step (3), the sampling points for the domestic sewage quality survey are arranged at the junctions of typical surveyed farmer's household pipes and sewage transmission branch pipes, the junctions of other pollution source household pipes and sewage transmission branch pipes, the junctions of sewage transmission branch pipes and main pipes, and the junctions of downstream sewage transmission main pipes.

7. The method according to claim 1 or 2, wherein: In step (3), the model includes the following: T1: Collect the sewage discharge points of two typical surveyed farmers, measure the sewage quality of the sewage discharge points, and obtain the amount of pollutants through the following model. Calculate the total amount of pollutants of typical surveyed farmers according to the following formula, recorded as ω 典型调查农户 : , where i represents the type of typical surveyed farmers, there are 2 types in total; j represents the population, there are 3 types in total, where "1" represents 3 people, "2" represents 4 people, and "3" represents 5 people; C ij is the sewage discharge concentration of the typical surveyed farmer with the i-th population j; Q ij is the sewage discharge of the typical surveyed farmer with the i-th type and population j; T2: Measure the pollutant concentration C at the intersection of the sewage collection branch pipe and the sewage collection main pipe of a typical surveyed farmer 户-交点 , and the pollutant amount at the intersection of the typical surveyed farmer's sewage collection branch pipe and the sewage collection main pipe is calculated according to the following formula, recorded as ω 户-交点 : , where Q 户-交点 The sewage volume at the intersection of the sewage collection branch pipe and the sewage collection main pipe of a typical surveyed farmer; T3: Calculate the total amount of pollutant consumption in the collection branch of the pollutant discharge of all households in the village according to the following formula, recorded as ω 全村户-支损 : ,in, The total length of the sewage collection branch pipes of typical surveyed farmers, The total length of the branch pipes for collecting sewage from farmers in the village; T4: Calculate the amount of pollutants at the sewage collection branch pipes of other pollution sources according to the following formula, denoted as ω 其他污染源 : , where ω 其他污染源 is the total amount of wastewater discharged from other pollution sources, is the sewage discharge concentration of the i-th other pollution source, is the sewage discharge of the ith other pollution source; T5: Measure the pollutant concentration C at the intersection of the sewage collection branch pipe and the sewage collection main pipe of other pollution sources 其他污染源-交点 , and calculate the pollutant amount at the intersection of the sewage collection branch pipe and the sewage collection main pipe from other pollution sources according to the following formula, recorded as ω 其他污染源-交点 : , where Q 其他污染源-交点 The amount of sewage at the intersection of the sewage collection branch pipe and the sewage collection main pipe of other pollution sources; T6: Calculate the total amount of pollutant loss from the collection pipes of other pollution sources in the village according to the following formula, recorded as ω 其他污染源-支损 : ,in, The total length of the sewage collection branch pipes of typical surveyed farmers, The total length of the branch pipes collecting sewage from other pollution sources in the village; T7: Calculate the WWTP influent sewage volume Q according to the following formula WWTP : According to the law of conservation of mass, the WWTP influent pollutant concentration C is obtained: WWTP The calculation model is: , where Q WWTP It is the total amount of sewage discharged in the village.

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