Potential for reuse of waste water and treated sludge is not being exploited to the full in Jaipur

sanitation1Excerpts from the study, “Wastewater Management in Jaipur: A City Level Sanitation Study”, published* by the National Institute of Urban Affairs, Delhi

The Jaipur City Development Master Plan 2025 was adopted and notified in 2011 (JDA, 2011). The plan estimated the wastewater generation in 2025 to be 783 MLD. The plan divided the city into four zones and proposed the treatment of the waste water in a series of STPs located in these separate zones for a total interim treatment capacity of 317 MLD. The treated water from the eastern part was to be released towards the Bandi River. The treated water from the western and south western parts was to be released towards the Chandlai dam. The treated water from the northern and north eastern part was to be pumped and released into the Dhund River. The treated water from the central part was to be channelled through the Dravyavati River towards the Dhund River.

The Dravyavati Riverfront Development Project consists of the construction of 5 STPs at intervals of 9 kms along the 47 kms of the length of the river within the city area as follows –  Bassi Sitarampura: 20 MLD; Devri: 15 MLD; Sanganer: 100 MLD; Bambala: 25 MLD; Goner: 10 MLD/ Along with this 81 kilometers of sewers are to be laid to carry all the sewage that was being earlier released untreated into the river to the STPs.

The project has been undertaken by a private consortium which is to recover the capital and O&M expenditure of the project by developing commercial and residential real estate on the land overlooking the river front. A process was also started to ring fence the water supply and sewerage functions of the city under a separate Jaipur Water Supply and Sewerage Board in 2017 as per the recommendations of the JNNURM. Currently, the water supply is being done mainly by the Public Health Engineering Department (PHED) with some amount being done by Jaipur Municipal Corporation (JMC) and Jaipur Development Authority (JDA).

The construction of sewers and STPs is done by the JDA mainly and also the JMC to some extent and in the last few years by the Rajasthan Urban Infrastructure Development Project (RUIDP) and the Rajasthan Urban Drinking Water, Sewerage and Infrastructure 22 Sanitation Capacity Building Platform Corporation (RUDSICO). The sewers are maintained by the JMC while the Sewage Treatment Plants (STPs) are maintained by the JMC mostly and some by the JDA. This multiple institutional governance of the water supply and sewerage services results in inefficiencies in both operational and financial terms and that is why it was provided under JNNURM that these services should be ring fenced under a separate institution which will undertake the construction and O&M of all facilities, arrange the funds for these and also collect user charges. However, even though a draft Jaipur Water Supply and Sewerage Board Bill (GoR, 2018) has been drafted, it has not been enacted yet.

Sewage Treatment

The most crucial aspect of centralised sanitation systems are the sewage treatment plants (STP). Even if there is an extensive sewerage system, as there is in Jaipur, which conveys the sewage to the STPs, unless there is adequate sewage treatment capacity, the sewage will be released untreated into the environment as is happening in most parts of the country.

The total STP installed capacity at present is 442 MLD which is not only much more than the current design wastewater load of about 330 MLD but enough to meet the projected growth for the next ten years. However, installed capacity by itself is not enough as proper operation and maintenance of STPs is required for them to be able to treat the sewage flowing in so that the effluent that is released or reused meets the standards set by the Central Pollution Control Board (CPCB). Therefore, it is necessary to review the functioning of the STPs in Jaipur.

The biggest STP in Jaipur is the one at Delawas which has an installed capacity of 125 MLD which uses the activated sludge process of treatment. The specific characteristics of this STP are as given in Table 3 below. This STP, by using the activated sludge process, reduces the cost of chemical dosing because it uses the bacteria in part of the sludge to pretreat the sewage inflow. Also it digests the sludge to produce biogas, mainly methane, which is then scrubbed and cleaned and burnt to generate energy which is used in running the aeration pumps.

The typical monthly cost of O&M for activated sludge process STPs for treating the waste water as per the relevant standards is about Rs15,00,000 per MLD per year and the energy required is 200 Kwh per million litres (Majumdar, 2004). Thus, the STP requires for its operation 91,25,000 Kwhs of electricity of which 35,04,000 kwhs are generated from the gasification of sludge. Consequently, assuming a rate of Rs 7 per Kwh of electricity there is a saving of Rs 17.5 Lakhs per month on the electricity cost.

However, in winter when the retention times are high and in the monsoons when the sludge content of the wastewater is lower, the gas production is much less and so is the electricity generation. However, according to the CPCB evaluation report mentioned earlier, the STP is not operating to full capacity and it is also not treating the water to the prescribed standards before releasing it into the Dravyavati River. As much as 30 percent of the incoming sewage is being bypassed and some of the water quality parameters of the treated effluent being released into the Dravyavati River are not as per standards. The treated effluent is also not being chlorinated before release and as a consequence there is a higher than permissible level of faecal coliform in it. A later evaluation report by the Rajasthan State Pollution Control Board found the Biological Oxygen Demand (BOD) of the treated water in the Delwas STP to be as high as 79 mg/l and 99 mg/l in the two units which is very high (ToI, 2016).

Thus, even by the CPCB standards for effluents, the Biological Oxygen Demand (BOD) ,Chemical Oxygen Demand (COD) and Total Suspended Solids (TSS) levels and so the polluted nature of the effluents is high and due to lack of chlorination the disease potential is also high. When compared to the much stricter standards required for surface water as per IS 2296, the inadequately treated water being released into the Dravyavati and Bandi Rivers are a serious health hazard. Apart from these STPs there is a newer one constructed by the JDA of 30 MLD at Ralawta with ASP as treatment process which had a BOD value less than 30 mg/l but higher than 10 mg/l in 2016.

Apart from Delawas, the sludge from all the other STPs is not being disposed of properly and constitutes a health hazard as it is being dumped arbitrarily in open areas near the STPs. Even in the Delawas STP there is not much effort to sell the manure slurry that is being produced after digestion of the sludge to produce biogas. The newly implemented Dravyavati Riverfront project too suffers from the same problem of inadequate treatment of the wastewater that is coming into its five STPs.

The waste water used to drain into the Dravyavati through a number of drains opening into it earlier but now the water is directed to the STPs and released from there in a concentrated manner. The residents near the STPs have been protesting about the stench from the released water (ToI, 2018). The water looks turbid even after it has travelled a few kilometers downstream from the STPs.

Thus, even though there is adequate sewage treatment capacity in Jaipur it is not being properly utilised at present resulting in polluted water being released into the rivers by the STPs. This operational inefficiency also means that the potential for reuse of the waste water and the treated sludge is not being exploited to the full leading to loss of revenue. A detailed financial analysis follows that reveals the lack of financial resources that plagues the sanitation sector in Jaipur.

*Content for the report is developed by Rahul Banerjee. Click HERE to read the full report

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