sewage

1. R.M.Bhardwaj,
Scientist ‘C’
Central Pollution Control Board,
Parivesh Bhawan, East Arjun Nagar,
Delhi-110032 (INDIA)
rmbdelhi@yahoo.co.in, scrmb.cpcb@nic.in
Questionnaire survey and data acquisition
on
Status of Wastewater Management in India

2. Increase in Urban Population
26 26 28 33
44
62
78
107
156
218
285
0
50
100
150
200
250
300
POPULATION,
million
1901 1921 1941 1961 1981 2001
Y E A R

3. Steps followed for Questionnaire survey on Water
Supply, Wastewater Generation, Collection,
Treatment in Urban Centres in India and
limitations of study
Step 1
• List 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/data
• Dispatch 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 issues
• Personal experience of Scientists/Engineers on specific
urban centers
• Data 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.

8. generation
Trend of Water Supply, Wastewater Generation and
Treatment in Class-I Cities
142 603
8638
7007
2756
212
1023
15191
12145
2485
299
1281
20607
16662
4037
423
1870
29782
23826
6955
0
5000
10000
15000
20000
25000
30000
35000
Number Popn (100,000) Water supply (mld) Wastewater(mld) Treatment(mld)
1978-79
1989-90
1994-95
2003-04

9. Trend of Water Supply, Wastewater Generation and Treatment in Class-
II Towns
190 128
1533
1226
67
241 207
1622
1280
27
345
236
1936
1650
62
498
375
3035
2428
89
0
500
1000
1500
2000
2500
3000
3500
Number Popn (lakh) Water supply Wastewater Treatment
1978-79
1989-90
1994-95
2003-04
generation

10. Data on Water Supply
• Source 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 précised
• Source of unorganised water supply
• Proposed plan for augmentation of water Supply
(source/Volume) and target year of commissioning
• In 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
Discussion on Questionnaire and Data
Collection Exercise

11. Data on Treatment of Raw Water for municipal
supply
• Type of treatment-Conventional/only Chlorination/
Raw water Supply
• Number and name of Treatment Plant(Govt.owned or
under BOOT)
• Design Capacity of each Plant
• Actual 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 adopted
• Continuous/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 account
• Specific 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 agency
• Level of treatment plant-Primary/Secondary/Tertiary
• Treatment 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 process
• Actual 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.