Development of evaluation criteria and techno-Economic criteria to ensure sustainable operation of urban wastewater treatment plant

iture funded by the Provincial/Municipal People's Committee through the Department of Finance and allocated to the Department of Construction. The wastewater fee is found in the water consumer’s invoices. Water supply revenue from such fee is annually paid to the municipal or provincial budget to redistribute to the drainage enterprises. 1.3.4.   Technology and technical issues a. Drainage and wastewater treatment technology Consistent criteria and implementation procedures have not been available to evaluate and select the drainage and wastewater treatment 8 technology for cities, industrial parks and hospitals. Feasible technologies such as: combination of concentrated and distributed wastewater collection and treatment, gradually upgrading the post- treatment water quality, ensuring the solvency of service users, etc., are not the top priorities of consultant and decision makers. b. Technical issues The above analysis unveiled that: Technical and financial conditions for study and launch of wastewater drainage and treatment technology, etc., are relatively restricted; it lacks the environmental pollution treatment solutions and technologies suitable with the regional and local conditions or at river basins as well as good response to the climate change and seawater rise in drainage and wastewater treatment activities is not found. 1.4.   Existing conditions on sustainable operation of the world’s WWTPs 1.4.1.   Existing conditions on sustainable operation of WWTPs in some countries in the world Root causes of WWTPs’ ineffective operation may include: Degradation of infrastructure, inactive pumping station, leakage pipeline and malfunction of wastewater treatment works. Many plants are also left (or not operated) due to insufficient O&M expenditure or technical capacity to fulfill the tasks, especially at local level and upon control by the restricted management systems. 1.4.2.   Overview about the financial management policies and mechanisms to ensure the WWTPs’ sustainable operation in the world It is not simple to strengthen the wastewater management and operation performance and some problems (such as water discharge management, financial aspects, etc.) must be completely handled. 1.4.3.   Existing conditions on evaluating the sustainable operation of the world’s WWTPs 1.4.3.1.   Evaluation of Greek WWTP’s sustainable operation The evaluation of WWTPs’ sustainable operation aims to set up the methods and apply such methods to evaluate 14 Greek-based WWTPs in the context that it not only involves in compliance but also specific aspects related to other issues such as environment, technique, economics and social affairs and then each plant's sustainability may be evaluated[44]. 9 With reference to the questions, the quality or quantity consultancy table given for each criterion is completed. Results of such criteria evaluation are used for subsequent standardization and valid as the reference standard in the WWTP system. 1.4.3.2.   Evaluation of wastewater treatment sustainability in Sweden In order to illustrate the sustainability of wastewater drainage and treatment system, three various scenarios are used with three comparative examples from three different countries: Sweden, South Africa and Mexico. Then it is evaluated by a comprehensive comparison methodology [72]. Upon comparison among Sweden, South Africa and Mexico, it is found that various systems are evaluated to have advantages and disadvantages in its respective settings. The evaluation results are also unveiled that the evaluation results are depended on the context of such three countries. Conclusions of Chapter 1: Intensive investments from various financial resources have been launched by Vietnamese Government in the fields of water drainage and environmental sanitation fields for the cities since many years. However, due to various reasons, including the technical reasons such as improper wastewater treatment technology, investment indicators of water drainage system are asynchronous and characterized by the non- guaranteed operation qualification, low wastewater connection percent, etc. Such factors make the invested wastewater treatment and drainage systems operate ineffectively. Adverse impacts of climate changes are increasingly clear for Vietnam and urban wastewater drainage and treatment is one of the activities to be seriously affected. Main factors to ensure a sustainable operation of an urban WWTP include treatment technology and proper operation and management. Such fitness must be evaluated in accordance with the criteria related to the technical, environmental, socio-economic factors. Therefore, such criteria must be analyzed, selected and quantified in combination with the consultation of experts and managers, etc., who are extensively experienced in the fields of wastewater drainage and treatment. The experience of countries in the world unveiled that evaluation of WWTP’s sustainability must have a panorama on considering the criteria in any various aspects such as economics, techniques, environment and socio-economics and the criteria significance must be 10 determined, corresponding to the various environment and economic viewpoints, etc. CHAPTER 2: SCIENTIFIC BASIS AND RESEARCH METHODOLOGY 2.1.   Scientific basis to develop the evaluation criteria and indicators, ensuring the sustainability of urban WWTPs 2.1.1.   General concept Concepts: Sustainability; criteria; indicators; techno-economic criteria, criteria set. 2.1.2.   Sustainable operations of concentrated urban Wastewater Treatment Plant (WWTP) 2.1.2.1.   Sustainability of urban WWTP A proper WWTP for sustainable development is supported by the proper investment and operation expenses. Its long-term operation is technically and legally guaranteed as well as its pollution treatment performance is highly appreciated and accepted by the community. 2.1.2.2.   Sustainability of urban concentrated WWTP in the context of climate changes The technical criteria’ adaptability with the climate change impacts is demonstrated by the selected wastewater treatment technology line which may prevent the salt water intrusion upon tide and heavy rains in the coastal cities. Works arranged in the WWTPs must process and well adapt with the BOD and salt contents in the wastewater and act against the high material oxidization, etc. WWTPs must be located at high terrain. Such plants must well operate in the high salt content conditions. WWTPs must be able to retain water for a long time. 2.1.3.   Evaluation criteria of urban WWTP’s sustainability Evaluation criteria of wastewater treatment technologies are proposed in Table 2.2 below: Table 2.2: List of evaluation criteria for urban WWTP’s sustainability No. Criteria group Criteria 1 Wastewater treatment capacity and efficiency The Plant’s actual capacity must ensure to cover project site Treatment must be qualified with the environmental standards for basic 11 contaminant indicators in domestic wastewater (SS, BOD, TN, TP, coliform, etc.) Treatment must be qualified with the environmental standards for some pollution criteria available in the production and service wastewater, etc., in the project site 2 O&M costs O&M costs are low Energy savings and efficiency and energy recovery of equipment and works are feasible Treatment costs are saved thanks to recovery and reuse of wastewater, waste sludge and biogas 3 Adaptability of wastewater technology with local context Selected wastewater treatment technology is suitable with the local natural conditions and load bearing capacity of receiving source The technology is advanced and suitable with the available science and technology conditions in the area 4 Stable operating conditions of works and equipment Operation of works and equipment is not complicated Equipment and its components are easily replaced Works operation is qualified with the environmental requirements 5 Adaptability with the adverse impacts of climate changes and input factor changes Treatment efficiency is ensured in the conditions that the wastewater is characterized by salt concentration and sudden high temperature Treatment efficiency is ensured in the conditions that the input wastewater is characterized by varied contents of SS, BOD and other pollution criteria It is possible to store water when the input wastewater flow rate is increased 12 for long time due to storm and rain. 6 Safety and environmental friendliness WWTPs are located far from the residential areas and sensitive ecosystem zone, making use of natural conditions to enhance the wastewater cleaning, restricting the bad odor and noise, etc. Cleaning conditions and working conditions in WWTPs are qualified with the standards promulgated by the Ministry of Health 2.1.4.   Techno-economic criteria to ensure the urban WWTP’s sustainability According to 6 selected criteria set and application of proper analytic methods, techno-economic criteria sets may be designed and developed to ensure the operation sustainability and stability of a WWTP. The proposed techno-economic criteria are shown in Table 2.3: Table 2.3: List of techno-economic criteria to ensure sustainable operation of WWTP No. Techno-economic criteria group Techno-economic criteria 1 Technology Wastewater capacity and mode 2 O&M Adaptability with local conditions Adaptability with climate changes Safety and environmental friendliness 3 Legislation and management Management mode on operation of WWTP operator Management Asset management 13 4 Finance Water drainage service charge Income of WWTPs Possibility of O&M cost savings Each of criteria group may be based on various criteria. The various criteria groups may share some indicators, creating an interwoven matrix demonstrated in Figure 2.4. 2.2.   Research methodology to design the techno-economic criteria and indicators 2.2.1.   Theoretical analysis and synthesis method This method aims to study various literatures on existing conditions of urban WWTPs and related jurisdictions. 2.2.2.   Field trip survey method The method aims to obtain the data on WWTPs to ensure the evaluation criteria sets and techno-economic indicators to ensure the sustainable development concentrated urban WWTPs, nationwide. 2.2.3.   Weighting method of criteria The Analytic Hierarchy Process (AHP) method has been applied to determine the weights of evaluation criteria to summarize the sustainable development of WWTPs as AHP is a technique to decide Urban WWTP’s sustainable operation Criteria group 1 Wastewater treatment capacity and efficiency Criteria group 2 O&M costs Criteria group 3 Adaptability of wastewater treatment technology with local conditions Criteria group 4 Stable operating conditions of works and equipment Criteria group 5 Safety and environmental friendliness Criteria group 6 Adaptability with adverse impacts of climate changes and input factor changes Technology Finance Legislation and management O&M Techno-economic criteria for urban WWTP’s sustainable operation Figure 2.4: Relation between criteria groups and techno-economic criteria groups 14 and arrange the evaluation criteria by significance. Thanks to that a most smart decision may be found. 2.2.4.   Expert consultation method In this study, the questionnaires are delivered to two expert groups, namely: -   Group 1: Science and technology official with qualification in water supply & drainage, environment engineering and technical infrastructure at universities, research institutions, etc. -   Group 2: Managers of enterprises involving in water supply & drainage, environment engineering, infrastructure engineering, etc. Expert consultation aims to evaluate the significance of indicator criteria to determine AHP weights for the criteria. Comparison score for significance of AHP-based criteria pairs is taken from average score of consultants: Each expert has determined the significance for criteria. Next, it is required to study and summarize the significance of each criterion and determine the weights. Evaluation criteria of wastewater treatment technology are often quantified by weights or scores from the consultancy data processing results shown in Appendix 3.4. 2.2.5.   Analytic Hierarchy Process (AHP) method Analytic Hierarchy Process (AHP) method is a method used to calculate the weights applied for multi-criteria decision making problems. Quantification comparison is initiated by using the comparison pairs of solutions in accordance with its relative efficiency against the applied criteria to select a proper solution. AHP was studied and developed in 1980s by Saaty [78]. Expert choice software facilitates to determine the weights for evaluation criteria of urban WWTP’s sustainability: Step 1: Create tree model (create from criteria group and supply the branches, i.e., criteria) Step 2: Enter the value to compare the significance of criteria groups demonstrated in Table 3.1 and Appendix 3.5. Step 3: Enter the value to compare the significance of criteria demonstrated in Table 3.3 Step 4: After data is processed by Expert Choice Software, the obtained results are weights, demonstrating the significance level of 15 the criteria groups and criteria (demonstrated in Table 3.4 and Appendix 3.6). Conclusions of Chapter 2 Chapter 2 has successfully setup the scientific basis, analyzed and selected the proper research methodologies. Requirements on urban WWTP’s sustainability must be set forth to design and develop the evaluation criteria as well as techno-economic indicators to ensure the plant’s good operation. The study applies the theoretical analysis and synthesis method, summarizes the literature review, determines the weights, and analyzes AHP and expert consultation method. Such methods mutually support each other and well adapt to determine the weights of criteria. Expert method uses the intelligence, exploit the evaluation viewpoint of high qualified experts to review and judge a problem, a scientific event, particularly sustainability in WWTPs’ operation to give out the advises which are well matched with the practice on such sustainability activities. The Analytic Hierarchy Process (AHP) method has been applied to determine the weights of evaluation criteria to summarize the sustainable development of WWTPs as AHP is a technique to decide and arrange the evaluation criteria by significance. Thanks to that a most smart decision may be found. 16 CHAPTER 3: DESIGN EVALUATION CRITERIA AND TECHNO-ECONOMIC CRITERIA TO ENSURE URBAN WWTP’SSUSTAINABLE OPERATION 3.1.   Design evaluation criteria for sustainable development of WWTPs Upon determination of evaluation criteria for WWTP’s sustainable operation, the consultation table has been designed in the form specified in Appendix 3.1: - Evaluate sustainable operation of WWTPs by 6 criteria groups. New WWTPs are recorded with sustainable operation if total score of 70-100 for 6 criteria groups is agreed by the experts: Total score of criteria in column “Max score value” and “Min score value” is 100 and 70, respectively. - The main findings from the MoC-level study “Investigation and proposal of factors to select the proper urban wastewater treatment technology for regions in Vietnam” launched by Ass.Prof.Dr Tran Duc Ha [9] unveiled that, Min value of 65 is technologically taken. In addition to the technology factors, other aspects such as economic efficiency, adaptability with climate changes, etc., have been considered hereof. The min score of sustainable WWTP is 70 in accordance with the expert consultation results. Such 70 score threshold is used as the minimum threshold to evaluate the sustainable WWTPs. Score of expert-based criteria is tabled in Table 3.4: Contents of this appendix demonstrate the mean of Max and Min scores, corresponding to each criterion. Within the contents hereof, the evaluation criteria for the urban WTTP’s sustainability is based on total score of criteria higher or equal to 70 scores (Min scores). Therefore, weights of Min score criteria of consultation table are determined. Calculations of AHP-based evaluation model are supported by Expert choice 11.0. Results are shown in Table 3.4 (table results are converted with weights multiplied with 100%): 17 Table 3.4 Weights of criteria (determined by Expert choice 11 Software) Criteria Weights among criteria group (%) Weight among criteria set (%) 1. Wastewater treatment capacity and efficient 100 33.7 The Plant’s actual capacity must ensure to cover project site 37.2 12.5 Treatment must be qualified with the environmental standards for basic contaminant indicators in domestic wastewater (SS, BOD, TN, TP, coliform, etc.) 39.4 13.3 Treatment must be qualified with the environmental standards for some pollution criteria available in the production and service wastewater, etc., in the project site 23.4 7.9 2 Appropriateness of wastewater treatment technology with local conditions 100 15.2 Selected wastewater treatment technology is suitable with the local natural conditions and load bearing capacity of receiving source 46.3 7.0 The technology is advanced and suitable with the available science and technology conditions in the area 28.0 4.3 Wastewater treatment technology must be well matched with the local management and operation capacity 25.7 3.9 3. O&M costs 100 20.9 O&M costs are low 53.2 11.1 Energy savings and efficiency and energy recovery of equipment and works are feasible 25.7 5.4 18 Treatment costs are saved thanks to recovery and reuse of wastewater, waste sludge and biogas 21.1 4.4 4. Stable operating conditions of works and equipment 100 12.5 Operation of works and equipment is not complicated 41.7 5.2 Equipment and its components are easily replaced 32.8 4.1 5. Adaptability with adverse impacts of climate changes and input factor changes 100 7.7 Treatment efficiency is ensured in the conditions that the wastewater is characterized by salt concentration and sudden high temperature 39.3 3.05 Treatment efficiency is ensured in the conditions that the input wastewater is characterized by varied contents of SS, BOD and other pollution criteria 39.3 3.05 It is possible to store water when the input wastewater flow rate is increased for long time due to storm and rain. 21.4 1.6 6. Safety and environmental friendliness 100 10 Wastewater treatment works do not cause bad odor, surrounding environmental pollution, noise, less incidents and wastewater leakage, reducing the soil, underground water source and surface water pollution risks of surroundings 49.8 5.0 WWTPs are located far from the residential areas and sensitive ecosystem zone, making use of natural conditions to enhance the wastewater cleaning, restricting the bad odor and noise, etc. 30.2 3.0 Cleaning conditions and working 20.0 2.0 19 conditions in WWTPs are qualified with the standards promulgated by the Ministry of Health Priority sequence of criteria group is determined as follows: Wastewater treatment capacity and efficiency>O&M costs>Suitability of wastewater treatment technology with the local conditions> Operating conditions of works and environment > Environmental friendliness and safety > Adaptability with adverse impacts of climate change and input factor changes. Two criteria groups of Wastewater Treatment Capacity and Efficiency and O&M Costs have the highest significance level of 33.7 and 20.9, respectively and this is completely suitable with the practice. Such two criteria groups are essential and necessary for the wastewater treatment plants. Concretely, the system must be properly and effectively functioned (Criteria group of Wastewater Treatment Capacity and Efficiency) and the system must be qualified with the economic criteria (O&M cost criteria group) such as investment expenditure, O&M costs, etc. 3.2.   Development of techno-economic criteria to ensure sustainable operation of urban wastewater treatment plant 3.2.1.   Technology criteria group For the technology criteria grop, the treatment efficiency criteria is the most important one. Moreover, in order to evaluate the best performance of WWTP’s technology, criteria on appropriateness of wastewater treatment technologies and local conditions, good adopt and adapt with climate changes as well as criteria on impacts of WWTPs on surrounding environment. 3.2.1.1.   Water discharge capacity and mode criteria Discharging mode is another basic factor related to calculation of water drainage network and wastewater works. Urban wastewater discharging mode is depended on water consumption mode and characterized by non-regulating water discharge coefficient Kch. Kch refers to the ratio of discharge flow rate of the highest water consumption hours of the highest water consumption day (qh,max) and 20 wastewater flow rate of average water consumption hours of average water consumption day (qh,tb). 3.2.1.2.   Wastewater Treatment Efficiency Criteria Wastewater treatment requirements (level): Treatment is qualified with level A of QCVN 40:2011/BTNMT or QCVN 14:2008/BTNMT. Currently, the wastewater pollution is mainly evaluated by 4 parameters as follows: SS; BOD5; TN, TP; Coliform According to QCVN 40-MT:2011/BTNMT: Consumers have domestic and urban wastewater volume greater than or equal to 1500 (one thousand and five hundred) cubic meter/day and night (m3/24h): Maximum allowable value of pollution parameters in domestic and urban wastewater upon discharge into the wastewater receiving source is calculated by following formula: Cmax = C x Kq x Kf 3.2.2.   O&M criteria group 3.2.2.1.   Suitability with the local conditions: Selected wastewater treatment technology must be well matched with the urban conditions such as natural characteristics (terrains, engineering geology, hydro-geology, climate and weather, etc.); socio-economic conditions (urban level, land use conditions and structure); urban development planning characteristics; the project’s financial capacity, etc. 3.2.2.2.   Adaptability with climate change In order to guarantee sustainable operation of urban WWTPs, the climate change-related criteria must be considered, namely: -   Treatment efficiency in the conditions that the wastewater is characterized by salt concentration and sudden high temperature. -   Treatment efficiency in the conditions that the input wastewater is found with contents of SS, BOD and other variable pollution criteria. -   Water storage capacity for a long time due to increase in storm, flood and works (regulating tanks, wastewater stabilizing reservoir, etc.) 3.2.2.3.   Environmental friendly safety 21 When efficiency of urban wastewater treatment production line is evaluated, it is required to take care about issues such as bad odor restriction and treatment capacity, generated waste sludge volume and sludge treatment method, etc. 3.2.3.   Regulation and management criteria group 3.2.3.1.  Criteria on WWTP operator management mechanism The enterprise form of WWTP operator is mainly single member liability limited company or Joint Stock Company operating under the Law on Enterprises and managing the water drainage assets and wastewater treatment in accordance with the contract signed with the Owner under the Decree No.: 80/2014/ND-CP. 3.2.3.2.   Management and operation organization Corresponding to each available wastewater treatment enterprise form of Single Member Liability Limited Company or Joint Stock Company, the management apparatus of wastewater treatment enterprises is generally structured in accordance with the aforesaid diagrams in Figure 3.1, Figure 3.3 and Figure 3.3. 3.2.3.3.   Asset Management According to the Decree No. 80/2014/ND-CP of the Government dated 6 August 2014 on water drainage and wastewater treatment, for urban water drainage system, the concentrated rural residential area is invested by the State budget. The water drainage unit selection is c