Water Management

Rain water harvesting

Rain water harvesting is defined as the process of collecting and storing rain for later productive use. Given our quest for water, it is but logical to look at the rains as primary source of water, as one of the major resource for a city like Delhi. Laws and notifications, directives and executive diktats are often being issued, that require us to capture water to the extent possible and harvest it for either replenishing the dwindling ground water level or to use it during the months when its availability is less.

Rooftop water harvesting offers an affordable means of accessing good quality water at the point of consumption, where the control of the water supply lies at the user level. Rooftop Rainwater can be stored for long periods in tanks without deterioration of quality as it is purest form of water.

DMRC has installed rain water harvesting structures at elevated stations, viaducts, depots and staff colonies. This installation shall continue in ongoing phase-III. As an illustration, a schematic diagram of capturing rain water harvesting from viaducts, till the collection chamber is shown in Figure A. Figure B depicts the recharge of ground water through filter media to the ground.

Rain Water Harvesting Structures at Shastri Park Depot

DMRC has provided 89 new rain water harvesting pits at 30 locations having a total capacity of 2596 cum in the last year (FY 2016-17). The increased capacity of rain water harvesting in the year is 30.16 % against the target of 10%. Currently DMRC has 553 rain water harvesting pits at 114 locations which have a total capacity of 11,203 cum. In the current FY 2017-18, DMRC has planned to install 5 new RWH pits having capacity of 50 cum.

Waste Water Treatment

Provision of ETPs, STPs and bio-digesters in DMRC
Waste water treatment is an important initiative to be taken for the betterment of the society and for future generations. Treating waste water and reusing the treated water is an important part of water conservation effort. Waste water treatment is a process, wherein the contaminants are removed from waste water to produce effluent suitable for reuse or discharge in waste water drain.

An Effluent Treatment Plant treats the waste water to remove any toxic and non toxic materials or chemicals from the waste water. A Sewage Treatment Plant (domestic waste water treatment) removes contaminants from waste water and household sewage. The treated water from ETP/STP if it meets the standards, can be reused or else to be discharged into drains.

Given the nature of activities associated with the organization, DMRC understood its impact upon water resources right from beginning and to conserve this precious resource ETPs and STPs were installed at depots, colonies and also at a few metro stations.

The treated water is being used for horticulture and toilet flushing to the maximum extent possible. Currently the excess treated water from ETP/STP, after meeting the potential for reuse, is being sent into drains. Since the treated water is much cleaner, it helps to bring down the pollution load of drains by dilution.

Total capacity of ETPs and STPs installed in DMRC is 761 cum and 2,054 cum from which 748 kilolitre treated water is being reused per day.

DMRC has taken a new step towards recycling of waste water by installing bio-digester tank. In bio-digester tank, a consortium of anaerobic bacteria has been formulated and adopted to work at temperature as low as 5 ยบ C. This is the component which acts as inoculum (seed material) to the bio-digester and converts the organic waste into methane and carbon dioxide. The anaerobic process inactivates the pathogens responsible for water borne diseases. Bio-digester serves as reaction vessel for bio-methanation and provides the anaerobic conditions and required temperature for the bacteria. The optimum temp is maintained by microbial heat, insulation of the reactor and solar heating at places wherever required.

Bio-digester tanks were constructed at 9 metro stations from which 185 kilolitre treated water is being used per day.

Thus, currently around 933 KL of treated water from ETP, STP and bio-digesters is being used per day various purposes.