Selecting sanitation solutions
Image: WSUP
Overview of presentation
• Background
• Sewerage systems
• Septage management
• Options analysis
• Discussion
Background
Safe collection, treatment & dispoal –Goal of NUSP100 % of human excreta and liquid wastes from all sanitation facilities must be disposed-off safely.
This will be achieved by:
• Ensuring that all human wastes are collected, treated and disposed off safely;
• Promoting proper disposal and treatment of sludge from on-site installations (septic tanks, pit latrines, etc.);
• Promoting proper functioning of network-based sewerage systems and ensuring connections of households to them;
• Encourage recycle and reuse of treated waste water for non-potable applications, wherever possible.
Service Chain to Meet Sanitation Needs for Different Customers
Water
closetSewer network
Treatment
plantReuse
/disposal
TreatmentReuse/
disposalTransportEmptyingContainment
Centralised system
On-site systems
Decentralised system
Water
closetSewer network
Treatment
plantReuse
/disposal
Latrine/Septic tanks etc
Vacuum truck or simpleremptying and transport
Simplified or conventional network
Reuse
6100%88%
WC tosewer
On-site facility
Septic tanks, covered pits,
VIPs etc.
Open defecation (including open pits)
Unsafelyemptied
or discharged
33%
19%
TreatmentReuse/
disposalTransportCollectionContainment
Source: Census 2011
Not treatedbut unknown where it goes
Urban sanitation situation?
Urban India – 1 Lakhs Plus
41%9%
Not treated
to standard
14%
Treated
50%
41%
17% Leakage
17%9%
81%Receiving
WatersLocal area and beyond, via
drains
Sewer coverage No of Cities % of population<10 % 191 16.45%
10 - 30% 158 20.10%30 - 60% 75 24.22%
>60% 78 39.23%
Sanitation Service Delivery World-Wide
Figure from Boston Consulting Group, 2013
Sewerage systems
Status of STPs and sewage treatment
9
Class I cities Class II cities Total (MLD)
Wastewater generated (mld) 35558 2697 38255
Wastewater Treated (mld) 11554 234 11788Potential for additional treatment (mld) 24004 2463 26467
Untreated effluent (%) 68% 91% 69%
CSE (2014) report on Ganga Basin says
that sewage generation is
underestimated and hence the
treatment capacity needed is much
higher
Source: The river, its pollution and what we can do to clean it – A CSE Breifing Paper, 2014)
Status of STPs and sewage treatment
11
Inadequate treatment performance:
• Evaluation of 152 STPs reveals that:
• 30 non operational
• 9 under construction
• 114 operational, of which 49 do not meet discharge standards
• Only 43% of total STPs meet discharge norms
Under construction6%
Not operating STPs19%
Not meeting BOD Standard
32%
Meeting BOD standards
43%
PERFORAMNCE ASSESSMENT OF 152 STPS BY CPCB
Options for cost recovery
• Normally determined by the funding agency,
• User charges in cities studied ranges from Rs. 75 – 115/month for households and between Rs 150 – 230/month for commercial establishments.
• Can contribute to 50 – 200% of O&M cost
User fee
• A portion of the property tax is apportioned to water and drainage
• In TN for example:
• ~22% of PT allocated to water and drainage
• ~5.5% of PT generally earmarked for sewerage system.
Property tax
•Deposits can help to reduce the debt service burden (10 – 30%) and hence the user charge (Rs. 50/HH)
Public deposits
•~80% of energy needs of STP can be met from sludge based power generation. ~40 – 50% of O&M costs are on account of the energy needs. Results in overall reduction of the O&M Costs .
Energy recovery:
•Can meet almost 100% of plants O&M needs
•Examples from various ULBs regarding sale of treated wastewater
Sale of treated
wastewater
12
Septage management
Septage characteristics
S. No. Characteristics Value (mg/l)
1. Total Solids 12,000 – 35,000
2. Total suspended solids 45 – 73% of TS(0.5 – 2.5%)
3. BOD 840 – 2,600
4. COD 1,200 – 10,000
Source: http://www.eawag.ch/forschung/sandec/publikationen/ewm/dl/fsm_2.pdf
Why empty septic tanks?
Source: USAID, 2010
The septage management cycle
Options analysis
18100%88%
WC tosewer
On-site facility
Septic tanks, covered pits,
VIPs etc.
Open defecation (including open pits)
Unsafelyemptied
or discharged
26%20%
TreatmentReuse/
disposalTransportCollectionContainment
Source: Census 2011
Not treatedbut unknown where it goes
Tiruchirapalli
36%10%
Not treated
to standard
6%
Treated
54%
36%
Leakage
27%10%
80%Receiving
WatersLocal area and beyond, via
drains
27%
Coverage by piped sewer Number of Wards Share of city population
<5% 8 17%
5-10% 9 18%
10-20% 20 33%
20-30% 14 19%
> 30% 9 14%
Total 60
19100%88%
WC tosewer
On-site facility
Septic tanks, covered pits,
VIPs etc.
Open defecation (including open pits)
Unsafelyemptied
or discharged
16% 12%
TreatmentReuse/
disposalTransportCollectionContainment
Source: Census 2011
Not treatedbut unknown where it goes
Kumbakonam
55%13%
Treated
32%
55%
Leakage
16%13%
88%Receiving
WatersLocal area and beyond, via
drains
4%
16%
Coverage by piped sewer Number of Wards Share of city population
<5% 7 16%
5-10% 10 23%
10-20% 11 24%
20-30% 2 5%
>30% 15 32%
Total 45
Factors influencing treatment options
*- Average of HPEC Estimates and actual cost incurred for several Sewer systems implemented in Tamil Nadu under World
Bank Project
# - System serving 100 - 1000 households. Data provided by CDD, Bangalore
Boston Consulting Group 2013
Selection of options: Urban
The highest cost option of centralized sewerage has economic payback of two times
Data source: WSP 2012
Urban China
Courtesy of WSP
Comparison sewer-based sanitation and fecal sludgemanagement in Dakar, Senegal
X 28
Dodane et al, 2012
Comparison of treatment options
Details Network* On-site Decentralized#
Capex Rs/HH 25000 - 30000 5000 – 10,000 13500 - 32500
Opex Rs/HH 1600 1000 145 - 630
*- Average of HPEC Estimates and actual cost incurred for several Sewer systems implemented in Tamil Nadu under World
Bank Project
# - System serving 100 - 1000 households. Data provided by CDD, Bangalore
WSP 2015
Thanks