3 Steps followed for Questionnaire survey on Water Supply, Wastewater Generation, Collection, Treatment in Urban Centres in India and limitations of studyStep 1List out candidate Cities/Towns for data collection-various classes categorised by Census Deptt.(Calcutta case)Information is available for city specific rather than outer growth/urban agglomeration.civic agencies does not keep record for non municipal areas.Information is difficult to obtain for development region/authority area as the census is held once in a decade.Growth rate figures are used for estimation wherever information gaps are observed.
4 Step 2 Identification of Civic Agency & Dispatch of Questionnaire Multiple agencies are involved in providing civic services and the administrative set up varies from State to State. The civic agency may be Municipality/ Corporation/ State Water Board/ Public Health Engineering Deptt or Private Agencies.There may be gaps in information/dataDispatch of Questionnaire for Data Acquisition to one and all possible sources, followed by reminders periodically. Persuasion and follow up through concerned Ministries of State Govt. and Union Ministries. Ultimate option-use of Statutory power.Personal visit to urban centres for Questionnaire survey and to verify contents wherever doubt arise.
5 Step 3 Data receipt, entry,Checking, Validation and Processing Data received from Civic agencies is entered in dbase/ Excel format.Replies received from multiple agencies for the same city needs careful integration.Data checking to find errors in reporting of population figures, units on volume of water supply/ wastewater generation, per capita figures, checks on the ratio of water supply v/s wastewater generation, level of % wastewater collection, treatment capacity, type of treatment process and mode of disposal(irrigation, recipient water body etc.)Checking, if data is within the limits of national norms, if the data is within the expected ranges for a parameter, if data are physically or scientifically possible(general checks),if the correlation of parameters(some conditional checks) does exist.
6 Step 3(Contd.)Data verification/validation by using maps/atlas, topo sheets, past records for each city, water mission reports on per capita level of water supply for different classes of urban centers in the country and various studies carried out by the organisation on environmental issuesPersonal experience of Scientists/Engineers on specific urban centersData processed to prepare National,State wise and river basin wise tables on class I cities and Class II towns covering a number of parameters i.e population, volume of water supply in a city,per capita water supply,source of water supply, % of population covered with water supply, wastewater generation, sewered population, wastewater collection, treatment and place of disposal.
7 Step 3 (Contd)Another study on performance evaluation of sewage treatment plants(STPs) is carried out to assess the efficiency of units and compliance level for discharge of pollutants such as pH,Suspended Solids, Chemical Oxygen Demand and Biochemical Oxygen Demand in the treated wastewater, apart from a number of other parameters.The performance of the STPs is inconsistent due to a number of reasons and frequent monitoring is not possible.
10 Discussion on Questionnaire and Data Collection Exercise Data on Water SupplySource of Organised Water Supply and Volume (mld/mgd)-River / Canal /Lake / Subsurface/Sea-need caution on the unit/source/multiple source% of population covered-information not précisedSource of unorganised water supplyProposed plan for augmentation of water Supply (source/Volume) and target year of commissioningIn case of multiple supplying agencies-verification of figures/ sources/ jurisdiction is difficult, estimation based on pumping hours are made-Case of NCT of Delhi-DDA/CPWD/Private builders
11 Data on Treatment of Raw Water for municipal supply Type of treatment-Conventional/only Chlorination/ Raw water SupplyNumber and name of Treatment Plant(Govt.owned or under BOOT)Design Capacity of each PlantActual Volume of Water Treated (not metered only pumping capacity and period of pumping is available)Disposal of back wash water(Volume/Place) and does alum recovery process adoptedContinuous/Intermittent Supply
12 Generation of Wastewater Volume of Wastewater Generation (mld/mgd) –Municipal Domestic/Industrial-information provided is based on engineering estimates i.e 80% of water supply-industrial figures are based on production that is under reported.Volume of Wastewater reaching pump houses through sewers (mld/mgd)- calculated figures are based on pumping hours.Pumping capacity reduce considerably by ageing of pumps.% of population covered by sewers-information is estimated zone wise.Volume of wastewater flowing in open drains (old city areas/unplanned growth) is difficult to accountSpecific studies undertaken indicates wastewater generation is more than the water supply figures- unaccounted water-bore wells by individuals due to inadequate supply from civic agency.Official figures of water supply in Delhi is 640 mgd whereas measured flow of drains is 727 mgd. Possibility of effluent from subsurface does not arise in case of Delhi because the water table is quite deep and going down further due to over abstraction.
13 Waste water Collection Volume of Wastewater Collected through sewerage system(mld/mgd) –Municipal Domestic/ Industrial-estimated figures-Total generated volume is not collected due to settlement/choking of sewers and disruption of pumping due to power shortages.Volume of Wastewater collected through open drains/storm water drains and pumped for irrigation or pumped for treatment (mld/mgd)-objective of data is to prioritise efforts for sewerage.Is there separate sewers for domestic and industrial wastewater-only planned industrial estates have separate sewers% of wastewater collected-figures are not available with civic agencies.Attempt made to estimate in Delhi during the performance assessment of sewage treatment plants indicates that only about 42% wastewater is collected through sewers rest is flowing in open drains.Figures varies widely from city to city.
14 Sewage (Wastewater) Treatment Installed Treatment Capacity (mld/mgd)Number and name of Sewage Treatment Plant (Govt.owned or under BOOT), specify agencyLevel of treatment plant-Primary/Secondary/TertiaryTreatment Technology and Design Capacity of each Plant (mld/mgd)-Primary/Secondary/Tertiary. Activated Sludge Process/Trickling Filter/Upflow Anaerobic Sludge Blanket/Other Anaerobic (Bio Filter) process, Oxidation pond,any other processActual inflow of Wastewater in each Sewage Treatment Plant (mld/mgd)Actual volume of wastewater (Sewage) Treated (mld/mgd).Experience of Delhi indicates that despite having sewage treatment capacity of 2300mld only about 1400 mld is treated upto secondary level through ASP.
15 Performance Evaluation of Sewage Treatment Plants Sewage treatment plants evaluated based on composite sampling of each treatment unit to assess the efficacy of system and compliance to prescribed standards.Intermittent Power Supply is one of the main constraint in activated bio mass treatment systems that reduces the performances to a great extent.It is observed that non energy intensive technologies such as Oxidation Pond/Facultative Pond are performing relatively better than mechanised systems.Reduction percentages vary from parameter to parameter.
16 Harmonisation with International Questionnaires and availability of data Methodology adopted in India is quite similar to International pattern however there are number of issues needs to addressed for data gaps in respect of developing economies.Population is growing at fast pace and process of infrastructure development is a dynamic in developing economies.Frequent updating of information is not possible as being followed in EU.Records are not computerised, Data variation are evident.Statistics on water/wastewater management is not compiled,collated and published by civic agencies and State Govt.Hence methods for gross estimates are required to be designed .Infrastructure development for municipal water supplies is priority, in contrast to wastewater collection and treatment.Hence data is broadly lacking for the letter part.Data related to treatment of wastewater and their performance may be a difficult proposition.
17 Thanks to UNSD for giving me this opportunity to share findings.
Your consent to our cookies if you continue to use this website.