DJB commissions state-of-the-art WWTP at Chilla

DJB commissions state-of-the-art WWTP at Chilla

The Delhi Jal Board, in its effort to provide better sewage treatment facility to the city, has commissioned a state-of-the-art Waste Water Treatment Plant (WWTP) at Chilla. The technology used in the plant, the Improvised Sequential Batch Reactors (ISBR) technology, is more economical and delivers better output as compared to other technologies.

The Dual Membrane Dome and generation of Hydropower are two important and unique characteristics of the ISBR technology and is first-of-its-kind in the world. The patent for the technology is pending.

This WWTP is located at Chilla in East Delhi, which is a densely populated area. The use of the ISBR Technology makes it possible to set up allows the plant in a small area. Hence, DJB has constructed this 9 MGD plant on a very small foot print, i.e., about 40% of the size of a conventional plant, along the Shahdara Drain no. 1 on a DBO (Design-Build-Operate) basis.

Earlier, the sewage was treated using techniques such as (1) Activated Sludge Process i.e. ASP (2) Up-flow Anaerobic Sludge Blanket i.e. UASB (3) Sequentional Batch Reactor i.e. SBR. Typically, WWTPs based on conventional ASP require large areas and the WWTPs using the UASB technique require large areas and do not deliver consistent performance, while SBR based WWTPs consume very high electric power. Other factors such as the intermittent supply of electricity also deter the smooth functioning of WWTPs. As a result of this, the treated effluent of poor quality flows into the River.

It is expected that with the introduction of the ISBR technology the sewage will be treated with better efficiency and more economically. The technology uses both anaerobic and aerobic processes to treat sewage. The Combi-treat unit generates biogas by treating the sewage anaerobically, which then reduces the organic load to be handled by further treatment in the ISBR basins.

The biogas that is generated is stored under flat-roofed Combi-treat unit which ensures proper sealing of the reactor to avoid any leakage through it, which is generally observed at dome like digesters. The Membrane Dome pushes out the gas but remains unharmed due to the corrosive gases within the digester which is not possible with conventional metal-roofed digesters. The ISBR provides aerobic treatment and has improvements over the SBR sewage treatment technology that enables it to create a suitable condition for the generation of hydropower while maintaining the outlet quality at par with the SBR technology. It is pertinent to note that this is the only technology in the world which can generate hydropower through sewage even on a flat terrain. In addition, power is also produced from methane and biogas which keeps the environment clean and healthy. The power generation within the plant will reduce dependency on power grids, as well.

The Combitreat-ISBR requires minimal land area and the plant premises are very hygienic and are, therefore, suitable for densely populated areas such as Delhi. When it comes to the outlet parameters, Combi-treat-ISBR is the frontrunner. It consistently delivers BOD < 10mg/l, TSS < 10mg/l, high nitrate and phosphorus removal.

After witnessing the 3 year performance of the first WWTP based on this technology of 30 MLD capacity at Pune, Delhi Jal Board scrutinized the Technology through independent experts from IIT Kanpur. Based on the findings of IIT Kanpur experts, DJB decided to employ the use of ISBR technology for its 9 MGD capacity WWTP at Chilla.

Currently, the plant is undergoing trial runs and is under the process stabilization phase. Since the treated effluent will be of good quality, an improvement in the water quality of the River is also expected once the treated sewage is released into it.With the use of this technology and the resultant energy efficiency of the plant, DJB expects a positive impact on its financial status as well.