Multi-angle comprehensive evaluation system and method for domestic sewage treatment process

Abstract

The invention relates to a multi-angle comprehensive evaluation system and method for a domestic sewage treatment process, and the system comprises a technical evaluation module, an economic evaluation module, an environment evaluation module, a comprehensive evaluation module and an analysis module, and constructs a technical efficiency evaluation index TEA according to an effluent stability index and the stability of technical operation; taking the weighted sum of the macroscopic cost evaluation index, the cost evaluation indexes of different types and the cost evaluation indexes of different stages as an economic evaluation index EA; the comprehensive environmental evaluation index CEA is equal to CEAS + CEAG-delta CEAW; the results of the technical evaluation module, the economic evaluation module and the environment evaluation module are obtained, and a weighted summation result is used as a comprehensive evaluation result CE; relative advantages and disadvantages of the domestic sewage treatment process are integrally evaluated through CE, and technical, economic or environmental improvement measures can be taken according to relative sizes of output results of the technical evaluation module, the economic evaluation module and the environmental evaluation module. According to the method, the actual operation state of the technology can be presented more accurately, and the evaluation accuracy is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment technology evaluation, and in particular to a multi-angle comprehensive comparison evaluation system and method for domestic sewage treatment processes. Background Art

[0002] Wastewater pollution affects human health, environmental safety and economic stability, thus causing serious global environmental challenges. As a typical type of wastewater, domestic wastewater accounts for the largest share of global wastewater flow. Domestic wastewater is an important source of pollution in rural water environment, including kitchen wastewater, toilet wastewater and washing wastewater. Common domestic wastewater treatment technologies include activated sludge process using sequencing batch reactor, oxidation ditch, anaerobic-anoxic reactor, anaerobic-anoxic-anoxic (A 2 O) reactors and membrane bioreactors, as well as the construction of wetlands and moving bed biofilm reactors. In addition, several advanced domestic treatment technologies have been proposed, including membrane bioreactors (MBR), moving bed biofilm reactors (MBBR), several combined processes (such as A 2 O-MBR, pre-denitrification-anaerobic-anoxic-anoxic + moving bed biofilm reactor (A 3 O-MBBR)).

[0003] Related studies have evaluated the rural domestic sewage treatment process to select the best treatment technology. In terms of technical efficiency evaluation, the current evaluation of relevant technologies mostly adopts a multi-criteria decision-making method, lacking analysis from the micro and macro perspectives of sewage quality and equipment operation. The economic evaluation method is mainly based on life cycle cost evaluation, and the environmental evaluation method is also based on life cycle evaluation. Although the comprehensive evaluation method from the environmental and economic perspectives has been established, the technical evaluation is mainly aimed at removal efficiency, and there is still a lack of analysis from the perspectives of macro equipment operation and micro effluent water quality. Therefore, it is urgent to establish a set of comprehensive evaluation methods and systems from multiple perspectives of technology, economy and environment to evaluate its sustainability and promote the development of rural domestic sewage treatment technology. Summary of the invention

[0004] In view of the problems existing in the prior art, the purpose of the present invention is to provide a multi-angle comprehensive evaluation system and method for domestic sewage treatment processes, so as to reduce the cost of domestic sewage treatment and reduce pollution while improving technical performance, and to evaluate the materials, energy, waste, process, economy and other aspects of rural domestic sewage treatment technologies. It is also possible to conduct comparative analysis on different links of different treatment technologies (such as pretreatment, biochemical treatment, sludge treatment), and to provide a comprehensive evaluation system from the technical, economic and environmental perspectives.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] In the first aspect, the present invention provides a comprehensive comparative evaluation system for each link of domestic sewage treatment process from multiple angles, including a technical evaluation module, an economic evaluation module, an environmental evaluation module, a comprehensive evaluation module and an analysis module.

[0007] The technical evaluation module is based on the water stability index TST EQ The technical efficiency evaluation index TEA is constructed based on the stability S of technical operation to evaluate the technical effect of domestic sewage treatment process.

[0008] TEA=∑S'×W1+∑TST' EQ ×W2;

[0009] In the formula, the superscript ' represents the corresponding normalized value; W1 and W2 are weight coefficients, and their sum is 1;

[0010] The economic evaluation module uses the weighted sum of macro cost evaluation indicators, different types of cost evaluation indicators and different stages of cost evaluation indicators as the economic evaluation indicator EA, where the macro cost evaluation indicator is the sewage treatment plant's charge to the company CIM, the total cost C TO , Profit C PF and operating cost C OC The sum of different types of cost assessment indicators is the auxiliary cost C a 、Energy cost C e and material cost C w The cost evaluation index at different stages is the operating cost of the pretreatment part of the wastewater treatment technology C E , Operation cost of biochemical treatment part C B , Operation cost of sludge treatment part C S sum;

[0011] The environmental assessment module includes industrial emission indicators CEA for wastewater, waste gas and solid waste in domestic sewage treatment processes W , CEA G , CEA S , then the comprehensive environmental assessment index CEA = CEA S +CEA G -ΔCEA W ;

[0012] Where ΔCEA W It represents the difference between the industrial emission index of the same pollution factor in the inlet and outlet water. The industrial emission index of wastewater, waste gas and solid waste is determined by the weight of the pollution factor among all pollutants, W. x The cumulative sum of industrial emission indicators with the corresponding pollution factor x;

[0013] For pollutants in wastewater and exhaust gas, In wastewater, In the exhaust gas, For pollutants in solid waste, W x According to the hazardous solid waste, general solid waste, and domestic solid waste, the values ​​are 0.5, 0.4, and 0.1 respectively;

[0014] Comprehensive evaluation module, obtains the results of technical evaluation module, economic evaluation module and environmental evaluation module, and takes the weighted sum of the three as the comprehensive evaluation result CE;

[0015] The analysis module uses CE to evaluate the relative advantages and disadvantages of domestic sewage treatment processes as a whole, and can take technical, economic or environmental improvement measures based on the relative size of the output results of the technical evaluation module, economic evaluation module and environmental evaluation module.

[0016] Furthermore, the water stability index TST EQ The calculation process is:

[0017] The effluent stability index is calculated according to the following formula based on the maximum, minimum, average concentration and weight of effluent pollution:

[0018]

[0019] In the formula, TST EQ is the water stability index; ST EQ,i is the effluent stability index of the i-th pollutant, i is an integer ranging from 1 to j, representing COD, TN, TP, NH4 + -N, where j = 4; C max COD / TN / TP / NH4 within a certain measurement period + - Maximum value of N concentration, in mg / L; C at For effluent COD / TN / TP / NH4 + -N average value, unit: mg / L; C min COD / TN / TP / NH4 within a certain measurement period + -N minimum value, unit: mg / L; W i The weight value of the i-th pollutant;

[0020] Stability of technical operation S:

[0021]

[0022] Where t is the average downtime caused by technical failure; T is the annual design operating time.

[0023] In a second aspect, the present invention provides a multi-angle comprehensive comparative evaluation method for each link of a domestic sewage treatment process, the method comprising:

[0024] Water stability index TST EQ and the stability of technical operation S to construct the technical efficiency evaluation index TEA, where:

[0025] TEA=∑S'×W1+∑TST' EQ ×W2;

[0026] Among them, the superscript ' represents the corresponding normalized value; W1 and W2 are weight coefficients, and the sum is 1;

[0027] The weighted sum of macro cost evaluation indicators, different types of cost evaluation indicators and different stages of cost evaluation indicators is used as the economic evaluation indicator EA;

[0028] CEA is an industrial emission index for wastewater, waste gas and solid waste in domestic sewage treatment processes. W , CEA G , CEA S , construct comprehensive environmental evaluation index CEA=CEA S +CEA G -ΔCEA W ; where ΔCEA W CEA, an industrial emission index representing the same pollutant in and out of water W difference;

[0029] The result of weighted sum of technical efficiency evaluation index TEA, economic evaluation index EA and comprehensive environmental evaluation index CEA is taken as the comprehensive evaluation result CE;

[0030] Use CE to evaluate the relative advantages and disadvantages of domestic sewage treatment processes as a whole.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention constructs a multi-angle comprehensive evaluation system for domestic sewage treatment technology, covering three key dimensions of technology, economy and environment, and can comprehensively evaluate the performance and sustainability of different domestic sewage treatment technologies: in terms of technical efficiency evaluation, it cuts in from the perspective of macro and micro technology, studies water quality stability by using multiple parameters such as effluent pollutants at the micro level, and introduces parameters such as equipment operation time at the macro level to measure operation stability, breaking through the limitations of previous technical evaluations and more accurately presenting the actual operation status of the technology. In the economic evaluation link, it comprehensively considers multiple aspects such as investment cost, operation cost, sludge treatment cost, profit and various additional costs, and gives a precise calculation formula, which is different from the traditional life cycle cost evaluation, helps to accurately estimate the cost-effectiveness of different technologies, and can provide a more accurate basis for investment decisions. In the environmental evaluation, a comprehensive environmental evaluation index is introduced, which is different from the traditional life cycle environmental evaluation, takes into account the effects of wastewater, waste gas and solid waste on the environment in all aspects, considers the impact of wastewater, waste gas and solid waste on the environment, and can more comprehensively evaluate the impact of technology on the environment, changing the shortcomings of the previous single-angle evaluation, and the environmentally friendly evaluation helps to promote the development of green and sustainable sewage treatment technology.

[0033] The evaluation system of the present invention also has a wide range of application prospects. It can not only be used to evaluate the performance of existing technologies, but also provide guidance for the research and development of new technologies. At the same time, the evaluation system can also be adjusted and optimized according to the actual operating conditions of different industries, so as to conduct a comprehensive evaluation of other fields.

[0034] The present invention takes into account the annual design operating time of the equipment, the average downtime caused by equipment failure, etc. from the perspective of macro equipment operation, and proposes the stability of technical operation and the water storage stability index to construct a technical efficiency evaluation index, which can more accurately present the actual operating status of the technology and improve the accuracy of the evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0036] Figure 1 A framework diagram of the technical, economic and environmental aspects of the present invention;

[0037] Figure 2 Comparison chart of evaluation results using different evaluation indicators for different processes: (a) effluent water quality stability index; (b) technical operation stability; (c) technical efficiency evaluation index; (d) macro cost evaluation index; (e) different types of cost evaluation indicators; (f) different parts of cost evaluation indicators;

[0038] Figure 3Comparison chart of evaluation results of different environmental evaluation indicators: (a) industrial wastewater emission indicators; (b) industrial waste gas emission indicators; (c) industrial solid waste emission indicators; (d) comprehensive environmental evaluation indicators;

[0039] Figure 4 Schematic diagram of the comprehensive evaluation results CE of the four processes. DETAILED DESCRIPTION

[0040] The present invention is further explained below in conjunction with the embodiments and drawings, but this is not intended to limit the scope of protection of the present application.

[0041] The multi-angle comprehensive comparison and evaluation system for each link of the domestic sewage treatment process of the present invention includes a technical evaluation module, an economic evaluation module, an environmental evaluation module, a comprehensive evaluation module and an analysis module, and constructs a comprehensive evaluation system for different links of different domestic sewage treatment technologies. It can evaluate and calculate the materials, energy, waste, process stability, economy and other aspects of the treatment technology. The specific contents are as follows:

[0042] S1, Technical Efficiency Assessment (TEA)

[0043] From the perspective of macro and micro technology, the technical efficiency evaluation index TEA is constructed based on the equipment operation parameters and effluent water quality parameters. The specific contents are as follows:

[0044]

[0045] TEA=∑S'×W1+∑TST' EQ ×W2

[0046] Where X' is S and TST EQ Normalized value of; X is S and TST EQ The actual value of X max and X min It is S and TST EQ The maximum and minimum values ​​of W are equally important and are distributed proportionally, with a total sum of 1. x is the weight of all indicators, W1 is 0.5, W2 is 0.5.

[0047] S11, Stability of sewage quality:

[0048] In the micro-technical evaluation, the maximum value, minimum value, average concentration and weight of effluent pollution are introduced to study the stability of effluent water quality:

[0049]

[0050] In the formula, TST EQ is the water stability index; ST EQ,iis the effluent stability index of different pollutants; i is different pollutants; j is the number of different pollutants; C max COD / TN / TP / NH4 within a certain measurement period + - Maximum value of N concentration (mg / L); C at For effluent COD / TN / TP / NH4 + -N average value (mg / L); C min COD / TN / TP / NH4 within a certain measurement period + -N is the minimum value (mg / L); Wi is the weight coefficient, which can be obtained by calculation according to the standard GB / T40201-2021.

[0051] S12, Stability of technical operation:

[0052] In the macro-technical evaluation, parameters such as the average downtime caused by technical failures and the annual designed operating time are introduced to calculate the stability of technical operation:

[0053]

[0054] Where t is the average downtime caused by technical failure; T is the annual design operating time.

[0055] S2, Economic Evaluation (EA)

[0056] The parameters considered in the economic evaluation method include investment cost, operating cost, sludge treatment cost, profit, material cost (such as various chemicals PAM, PAC, etc.), energy cost (such as electricity), waste treatment cost (such as wastewater, sludge), auxiliary cost (such as labor cost, equipment depreciation cost) and cost of each stage. The specific contents are as follows:

[0057]

[0058] In the formula, CIM is the fee charged by the sewage treatment plant to the company (year); Q is the cost of treating 1 ton of wastewater; i is the number of days; and L is the amount of wastewater treated per day.

[0059] C IV =C C +C E

[0060]

[0061] In the formula, C IV One-time investment cost for factory construction; C V is the annual investment cost; t is the service life of the sewage treatment plant; C C is the capital cost; C E For equipment cost.

[0062] C TO =C V +C OC +C ST

[0063] In the formula, C TO is the total cost; C OC is the operating cost; C ST Cost of sludge treatment;

[0064] C OC =C a +C e +C w +C m

[0065]

[0066] C w =∑m w ×C 0,w

[0067] In the formula, C a Auxiliary costs (such as labor costs, equipment depreciation costs); C e is the energy cost (such as electricity); C w is the water consumption cost (water, steam); C m is the material cost (chemicals); m e is power; P is equipment power (kWh); t1: is equipment operation time (hours); m w is the water volume; n is the number of equipment; C 0,e is the unit price of electricity; C 0,w The unit price of water.

[0068] C ST =C t +C IL

[0069] In the formula, C t is the transportation cost; C IL for incineration and landfill costs.

[0070] C PF =CIM-C TO

[0071] In the formula, C PF For profit.

[0072]

[0073] Where t0 is the investment payback period.

[0074] C=m×C0

[0075] In the formula, C is the single item (material / water / energy / additional) cost; m is the quality of unit material / water / energy / additional cost; C0 is the market unit price of unit material / water / energy / additional cost.

[0076] C OC =C E +C B +C S

[0077]

[0078]

[0079] In the formula, C E It is the pretreatment part of wastewater treatment technology; C B For the biochemical treatment part; C S For the sludge treatment part.

[0080] S3, Comprehensive Environmental Assessment (CEA)

[0081] The comprehensive environmental assessment applies to the entire industrial process, including the environmental impact of wastewater, waste gas and solid waste, and conducts a comprehensive assessment. The specific contents are as follows:

[0082] S31, Impact of pollutants in wastewater on the environment:

[0083]

[0084] S32, Impact of pollutants in exhaust gas on the environment:

[0085]

[0086] S33, Impact of pollutants in solid waste on the environment:

[0087]

[0088] CEA=CEA S +CEA G -ΔCEA W

[0089] In the formula, CEA W , CEA G , CEA S and CEA x are the CEA of industrial emission indicators of wastewater, waste gas, solid waste and waste x respectively; ΔCEA W It indicates the difference between the industrial emission index of the same pollution factor in the inlet and outlet water, which refers to the CEA of the inlet water. W Value and CEA of effluent WThe difference between the values ​​is because both the inlet and outlet of the wastewater contain pollutants, so a special measurement index is established to distinguish it from waste gas and solid waste; x is the type of pollutant in the wastewater / solid waste (such as COD, TN, TP, NH3-N, sludge), and y represents the type of waste (such as wastewater, waste gas). in and C out is the influent and effluent concentration of pollutant x in waste y; R x is the correlation ratio of waste x; is the emission standard of pollutant x; S max,x,y is the maximum concentration of pollutant x in waste y; W x is the weight of the pollution factor x among all pollutants. For pollutant x, m in,x,y and m out,x,y Represent the amount of waste y in the inlet and outlet respectively.

[0090] Finally, in the comprehensive evaluation, the results of technical efficiency, economy, and comprehensive environment evaluation are equally important, and the weights are set at 0.33 respectively, CE = TEA × W1 + EA × W2 + CEA × W3;

[0091] Use CE to evaluate the relative advantages and disadvantages of domestic sewage treatment processes as a whole.

[0092] Example 1

[0093] This example selects a large sewage treatment plant in Baiyangdian, Hebei Province as the evaluation object, and selects two typical wastewater treatment technologies and their improved technologies (A 2 O-MBR、MA 2 O-MBR, A 3 O-MBBR、MA 3 O-MBBR) is divided into three parts (i.e. pretreatment, biological treatment and sludge treatment) to conduct a comprehensive comparative evaluation from multiple perspectives of technology, economy and environment. The specific contents are as follows:

[0094] S1, water stability index TST EQ The technical efficiency evaluation index TEA is constructed based on the stability S of technical operation:

[0095]

[0096] TEA=∑S'×W1+∑TST' EQ ×W2

[0097] Where X' is S and TST EQ Normalized value of; X is S and TST EQ The actual value of X max and X min It is S and TST EQThe maximum and minimum values ​​of have equal weights and are distributed proportionally, with a total of 1. W represents the weight coefficient, where W1 is 0.5 and W2 is 0.5.

[0098] S11, Stability of sewage quality:

[0099] In the micro-technical evaluation, the maximum value, minimum value, average concentration and weight of effluent pollution are introduced to calculate the effluent stability index:

[0100]

[0101] In the formula, TST EQ is the water stability index; ST EQ,i is the effluent stability index of the i-th pollutant; i is an integer ranging from 1 to j, representing COD, TN, TP, NH4 + -N, where j = 4; C max COD / TN / TP / NH4 within a certain measurement period + - Maximum value of N concentration (mg / L); C at For effluent COD / TN / TP / NH4 + -N average value (mg / L); C min COD / TN / TP / NH4 within a certain measurement period + -Minimum value of N (mg / L); W i is the weight value of the i-th pollutant, which can be obtained by calculation according to the standard GB / T40201-2021.

[0102] The results of effluent water quality stability index of four wastewater treatment technologies are as follows Figure 2 As shown in Figure (a), MA 3 The O-MBBR process showed better stability under typical operating conditions and wastewater variation conditions, TST EQ The values ​​of ' are 1.28E-01, 9.88E-02, 9.18E-02, and 8.93E-02, respectively. 2 O-MBR and MA 2 Compared with O-MBR process, MA 3 The O-MBBR process has lower operating costs and simpler operating conditions for treating Baiyangdian rural domestic sewage. The appropriate sludge return ratio (150%) can improve the denitrification capacity of the anaerobic and anoxic zones, which is beneficial to MA 3O-MBBR technology removes total nitrogen. The water inlet mode in the optimization stage can distribute the inlet water to the anoxic tank and the anaerobic tank in different proportions, increase the carbon source, and improve the efficiency of nitrogen and phosphorus removal. At the same time, the filler of the MBBR pool also has an important influence on the stability of the effluent. After optimizing the operating conditions, a large number of microorganisms and organic matter will be adsorbed on the surface of the MBBR pool and inside the filler, forming a more compact biofilm, making the system more stable. Therefore, MA 3 Effect of O-MBBR process on COD and NH4 + -N and total nitrogen have the best removal rate and optimal effluent stability.

[0103] S12, Stability of technical operation:

[0104] In the macro-technical evaluation, parameters such as the average downtime caused by technical failures and the annual design operating time are introduced to calculate the stability S of technical operation:

[0105]

[0106] Where t is the average downtime caused by technical failure; T is the annual design operating time.

[0107] The stability calculation results of the technical operation of the four wastewater treatment technologies are as follows: Figure 2 As shown in Figure (b), the results are sorted as follows: 3 O-MBBR>MA 3 O-MBBR=A 2 O-MBR>MA 2 O-MBR, the calculated values ​​of S' are 0.81, 0.79, 0.79, and 0.71 respectively. 2 Compared with O-MBR and fixed biomass system, A 3 O-MBR has higher cost, less sludge volume and higher efficiency. 3 O-MBR is more suitable for the construction and renovation of existing water treatment plants. At the same time, the application of A in high-load wastewater 3 O-MB BR can effectively gather functional bacteria and reduce the floor space. In addition, the filler in the MBBR pool does not need to be replaced, reducing the number of equipment failures. 2 O-MBR has poor technical operational stability, which may be due to the fact that the process requires a lot of equipment (such as pumps and blowers). The system is also prone to accidents (such as equipment failure and human error). Changes in operating conditions will also lead to an increase in the required equipment and failure rate, which will have a negative impact on its ability to treat wastewater. Moreover, it is difficult to immediately restore the performance of the biological treatment process after the process is repaired or replaced. The concentration of suspended solids will directly affect the membrane and cause it to clog. The accumulation of dirt and the growth of microorganisms on the membrane surface will also affect the membrane, causing it to clog and shorten its service life.

[0108] Finally, according to TEA = ∑S'×W1+∑TST' EQ ×W2 Multiply the normalized value by the weight to obtain the technical efficiency evaluation index TEA for each treatment technology, such as Figure 2 As shown in Figure (c), A 2 O-MBR、MA 2 O-MBR, A 3 O-MBBR、MA 3 The technical efficiency evaluation values ​​of O-MBBR were 3.97E-01, 4.31E-01, 5.07E-01 and 5.12E-01 respectively. According to the TEA evaluation results, the best treatment technology is MA 3 O-MBBR, followed by A 3 O-MBBR, this is because MA 3 The O-MBBR process has a long service life, is easy to maintain, and has excellent nitrogen and phosphorus removal performance. 3 O-MBBR occupies less space, has fewer backwashing times, has less impact on sludge bulking, and has high technical operation stability. 2 The O-MBR process involves multiple treatment stages and complex operating conditions. In particular, the membrane is susceptible to contamination and requires regular cleaning and replacement. 3 O-MBBR is more suitable for rural domestic sewage treatment with higher technical stability.

[0109] S2, Economic Evaluation (EA)

[0110] The parameters considered in the economic evaluation method include investment cost C V , operating cost C OC ; Sludge treatment cost and profit C PF , Material cost C m (such as various chemicals), energy costs (such as C e , C w ), waste treatment costs (such as wastewater, sludge), auxiliary costs C a (such as labor costs, equipment depreciation costs) and the costs of each part, the specific contents are as follows:

[0111]

[0112] In the formula, CIM is the fee charged by the sewage treatment plant to the company (year); Q is the cost of treating 1 ton of wastewater; i is the number of days; L is the amount of wastewater treated per day;

[0113] C IV =C C +C E

[0114]

[0115] In the formula, C IV One-time investment cost for factory construction; C V is the annual investment cost; t is the service life of the sewage treatment plant; C C is the capital cost; C E For equipment cost;

[0116] C TO =C V +C OC +C ST

[0117] In the formula, C TO is the total cost; C OC is the operating cost; C ST Cost of sludge treatment;

[0118] C OC =C a +C e +C w +C m

[0119]

[0120] C w =∑m w ×C 0,w

[0121] In the formula, C a Auxiliary costs (such as labor costs, equipment depreciation costs); C e is the energy cost (such as electricity); C w is the water consumption cost (water, steam); C m is the material cost (chemicals); m e is power; P is equipment power (kWh); t1: is equipment operation time (hours); m w is the water volume; n is the number of equipment; C 0,e is the unit price of electricity; C 0,w is the unit price of water;

[0122] C ST =C t +C IL

[0123] In the formula, C t is the transportation cost; C IL for incineration and landfill costs;

[0124] C PF =CIM-C TO

[0125] In the formula, C PF for profit;

[0126]

[0127] In the formula, t0 is the investment payback period;

[0128] C=m×C0

[0129] Where, C is the single item (material / water / energy / additional) cost; m is the mass of unit material / water / energy / additional cost; C0 is the market price of unit material / water / energy / additional cost;

[0130] C OC =C E +C B +C S

[0131]

[0132] In the formula, C E It is the pretreatment part of wastewater treatment technology; C B For the biochemical treatment part; C S For the sludge treatment part;

[0133] The economic evaluation results are as follows Figure 2 As shown in (d), (e), and (f), it includes macro cost assessment, different types of cost assessment, and cost assessment at different stages. Figure 2 As shown in Figure (d), the macro cost can be divided into four parts (i.e., the wastewater treatment plant’s charge to the company CIM, the total cost C TO , Profit C PF and operating cost C OC The CIM values ​​of the four wastewater treatment technologies are the same, mainly because the same charging standard is used for enterprises, that is, charging per ton of wastewater. The relative total costs are as follows: A 2 O-MBR>MA 2 O-MBR>A 3 O-MBBR>MA 3 O-MBBR, which is directly related to the complexity of the treatment process. 2 O-MBR and MA 2 O-MBR has the highest operating cost, mainly due to the high power consumption of the root blower. 3 O-MBBR consists of three tanks (i.e., anaerobic tank, anoxic tank and aerobic tank), while A 2 O-MBR consists of two tanks (i.e. anoxic tank and aerobic tank). 2The O-MBR process requires more energy and two air pumps to maintain the membrane driving pressure to ensure the normal operation and filtration of the membrane. 2 O-MBR and MA 2 Compared with O-MBR, A 3 O-MBBR and MA 3 O-MBBR has lower costs. Higher profits can bring better economic benefits to the corresponding industries. Due to the lower total cost, MA 3 The profit obtained by O-MBBR in the sewage treatment process is higher than that of other technologies.

[0134] The cost types are further evaluated. The main types of costs can be divided into auxiliary costs, a 、Energy cost C e and material cost C w The results of comparing different types of costs show that auxiliary costs and energy costs account for a high proportion. Energy costs are mainly electricity consumption and labor, auxiliary costs are mainly equipment depreciation costs, and material costs are mainly from chemicals. Due to the absence of root blowers and MBR production pumps, MA 3 O-MBBR technology has the lowest power consumption, which is 68.95kWh / d. Figure 2 The evaluation results of different types of cost estimation evaluation indicators in Figure (e) are: 2 O-MBR>MA 2 O-MBR>A 3 O-MBBR>MA 3 O-MBBR.

[0135] Further comparison of the cost evaluation of the four technologies at different stages is as follows: Figure 2 As shown in Figure (f), the biological treatment part C B The cost of sludge treatment is the highest, followed by S and preprocessing part C E For stage I (pretreatment stage), based on the unique water inlet method, MA 3 The total cost of O-MBBR is lower, while the total cost of stage II (biological treatment) is higher because the reaction is mainly concentrated in the biological treatment stage, which requires a lot of equipment. 3 O-MBBR technology uses biofiller instead of biofilm, reducing the cost and replacement cost of the membrane. 3 O-MBBR technology in A 3 O-MBBR technology changes the operating conditions and has a lower total cost.

[0136] S3, Comprehensive Environmental Assessment (CEA)

[0137] The comprehensive environmental assessment applies to the entire industrial process, including the environmental impact of wastewater, waste gas and solid waste, and conducts a comprehensive assessment. The specific contents are as follows:

[0138] S31, Impact of pollutants in wastewater on the environment:

[0139]

[0140]

[0141] The results of △CEAw are as follows Figure 3 As shown in Figure (a), MA 3 O-MBBR has the smallest environmental impact on wastewater, followed by MA 2 O-MBR, A again 2 O-MBR, and finally A 3 O-MBR. COD, NH4 + -N, TP, TN and other major pollutants have a greater impact on the environment, among which COD has the greatest impact on the environment, while TN has a smaller impact on the environment.

[0142] S32, Impact of pollutants in exhaust gas on the environment:

[0143]

[0144] Environmental impacts of gaseous pollutants Figure 3 As shown in Figure (b), A 3 O-MBBR has the greatest environmental impact, followed by A 2 O-MBR、MA 3 O-MBBR and MA 2 O-MBR process. 2 Compared with O-MBR, A 3 O-MBBR has a pre-denitrification zone, which produces nitrogen dioxide and a small amount of nitrous oxide through denitrification. During the oxidation stage, due to the high oxygen content, some microorganisms may be converted into substances that produce nitrous oxide and methane, resulting in the production of nitrous oxide and methane. However, it should be noted that the actual operation will be affected by many factors such as influent quality and reactor operating conditions.

[0145] S33, Impact of pollutants in solid waste on the environment:

[0146]

[0147] CEA=CEA S +CEA G -ΔCEA W

[0148] In the formula, CEA W , CEA G , CEA S and CEA x are the CEA of industrial emission indicators for wastewater, waste gas, solid waste and waste x, respectively. x is the type of pollutant in wastewater / solid waste (such as COD, TN, TP, NH3-N, sludge), and y is the type of waste (such as wastewater, waste gas). in and C out is the influent and effluent concentration of pollutant x in waste y; R x is the correlation ratio of waste x; is the emission standard of pollutant x; S max,x,y is the maximum concentration of pollutant x in waste y; W x is the weight of the pollution factor x among all pollutants. For pollutant x, m in,x,y and m out,x,y Represent the amount of waste y in the inlet and outlet respectively.

[0149] The impact of pollutants in the solid waste of these four processes on the environment is as follows Figure 3 As shown in (c), A 2 O-MBR>MA 2 O-MBR>A 3 O-MBBR>MA 3 O-MBBR. M-A3O-MBBR produces the least solid waste (sludge) and has the least impact on the environment.

[0150] In conclusion, the comprehensive environmental assessment index CEA is negatively correlated with environmental impact. Among the four wastewater treatment technologies, Figure 3 As shown in (d), MA 3 O-MBBR has the highest comprehensive environmental impact, followed by MA 2 O-MBR, then A 2 O-MBR, A 3 O-MBBR has the lowest comprehensive environmental impact. 3 O-MBBR technology is a relatively environmentally friendly rural sewage treatment process and should be more widely promoted and studied.

[0151] Finally, in the comprehensive evaluation, the results of technical efficiency, economy, and comprehensive environment are equally important, and the weight of each is set at 0.33. The specific contents are as follows:

[0152] CE=TEA×W1+EA×W2+CEA×W3

[0153] Among them, W1, W2, and W3 are the weight coefficients of the corresponding indicators, and the sum is 1;

[0154] The comprehensive evaluation results of the four technologies, which comprehensively consider their economic, environmental and technical aspects, are as follows: Figure 4 , where MA 3 The comprehensive evaluation result of O-MB BR technology is the best, which is -2.57E-01, followed by MA 2 O-MBR is -2.58E-01, A 2 O-MBR is -2.96E-01, A 3 O-MBBR is -3.30E-01. Technical efficiency evaluation is positively correlated with the comprehensive environmental impact index. The more stable the technology, the greater the comprehensive environmental impact index, the smaller the impact on the environment, and the higher the profit. According to the comprehensive environmental evaluation indicators, the economic evaluation can be optimized by improving the stability of the technology to achieve efficiency improvement. Therefore, the comprehensive environmental evaluation results of the technology can confirm effective pollution control strategies, such as optimizing the treatment process parameters in wastewater treatment, such as adjusting the sludge return ratio and the water inlet mode to enhance the denitrification and phosphorus removal capabilities and stabilize the effluent water quality; in waste gas treatment, control the reaction conditions, according to the waste gas production link of the sewage treatment process, accurately control conditions such as oxygen content, and inhibit the generation of harmful gases; in solid waste treatment, choose technology that produces less sludge, optimize conditions during process operation to reduce sludge generation; reasonably dispose of sludge, such as sludge incineration and purification of waste gas, avoid secondary pollution, and improve removal efficiency.

[0155] Any matters not described in the present invention are applicable to the prior art.

Claims

1. A comprehensive comparison and evaluation system for each link of domestic sewage treatment process from multiple angles, characterized in that: It includes technical evaluation module, economic evaluation module, environmental evaluation module, comprehensive evaluation module and analysis module. The technical evaluation module is based on the water stability index TST EQ The technical efficiency evaluation index TEA is constructed based on the stability S of technical operation to evaluate the technical effect of domestic sewage treatment process. TEA=∑S’×W1+∑TST’ EQ ×W2; In the formula, the superscript ' represents the corresponding normalized value; W1 and W2 are weight coefficients, and their sum is 1; The economic evaluation module uses the weighted sum of macro cost evaluation indicators, different types of cost evaluation indicators and different stages of cost evaluation indicators as the economic evaluation indicator EA, where the macro cost evaluation indicator is the sewage treatment plant's charge to the company CIM, the total cost C TO , Profit C PF and operating cost C OC The sum of different types of cost assessment indicators is the auxiliary cost C a 、Energy cost C e and material cost C w The cost evaluation index at different stages is the operating cost of the pretreatment part of the wastewater treatment technology C E , Operation cost of biochemical treatment part C B , Operation cost of sludge treatment part C S sum; The environmental assessment module includes industrial emission indicators CEA for wastewater, waste gas and solid waste in domestic sewage treatment processes W , CEA G , CEA S , then the comprehensive environmental assessment index CEA = CEA S +CEA G -ΔCEA W ; Where ΔCEA W It represents the difference between the industrial emission index of the same pollution factor in the inlet and outlet water. The industrial emission index of wastewater, waste gas and solid waste is determined by the weight of the pollution factor among all pollutants, W. x The cumulative sum of industrial emission indicators with the corresponding pollution factor x; For pollutants in wastewater and exhaust gas, In wastewater, In the exhaust gas, For pollutants in solid waste, W x According to the hazardous solid waste, general solid waste, and domestic solid waste, the values ​​are 0.5, 0.4, and 0.1 respectively; Comprehensive evaluation module, obtains the results of technical evaluation module, economic evaluation module and environmental evaluation module, and takes the weighted sum of the three as the comprehensive evaluation result CE; The analysis module uses CE to evaluate the relative advantages and disadvantages of domestic sewage treatment processes as a whole, and can take technical, economic or environmental improvement measures based on the relative size of the output results of the technical evaluation module, economic evaluation module and environmental evaluation module.

2. The system according to claim 1, characterized in that Water stability index TST EQ The calculation process is: The effluent stability index is calculated according to the following formula based on the maximum, minimum, average concentration and weight of effluent pollution: In the formula, TST EQ is the water outlet stability index; ST EQ,i is the effluent stability index of the i-th pollutant, i is an integer ranging from 1 to j, representing COD, TN, TP, NH4 + -N, where j = 4; C max COD / TN / TP / NH4 within a certain measurement period + - Maximum value of N concentration, in mg / L; C at For effluent COD / TN / TP / NH4 + -N average value, unit: mg / L; C min COD / TN / TP / NH4 within a certain measurement period + -Minimum value of N, in mg / L; W i The weight value of the i-th pollutant; Stability of technical operation S: Where t is the average downtime caused by technical failure; T is the annual design operating time.

3. A multi-angle comprehensive comparative evaluation method for each link of domestic sewage treatment process, characterized in that: The method comprises: Water stability index TST EQ and the stability of technical operation S to construct the technical efficiency evaluation index TEA, where: TEA=∑S’×W1+∑TST’ EQ ×W2; Among them, the superscript ' represents the corresponding normalized value; W1 and W2 are weight coefficients, and the sum is 1; The weighted sum of macro cost evaluation indicators, different types of cost evaluation indicators and different stages of cost evaluation indicators is used as the economic evaluation indicator EA; CEA is an industrial emission index for wastewater, waste gas and solid waste in domestic sewage treatment processes. W , CEA G , CEA S , construct comprehensive environmental evaluation index CEA=CEA S +CEA G -ΔCEA W ; where ΔCEA W CEA, an industrial emission index representing the same pollutant in and out of water W difference; The result of weighted sum of technical efficiency evaluation index TEA, economic evaluation index EA and comprehensive environmental evaluation index CEA is taken as the comprehensive evaluation result CE; Use CE to evaluate the relative advantages and disadvantages of domestic sewage treatment processes as a whole.

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