Clean rivers and groundwater are essential to safeguard natural resources, ecosystems and human health. Fresh water sources are the lifeblood of planet Earth for the survival of human beings.
In Delhi due to the paucity of resources and technologies, the sewage and municipal wastes are not properly collected and treated. About 3,268 million litres (MLD) of wastewater including industrial effluents against the treatment capacity of 2,756. MLD is discharged into the Yamuna River by the 16 major unlined drains of Delhi but only 2083 MLD is treated.
Thus, a considerable amount of untreated and partially treated sewage is discharged regularly into the Yamuna River regularly making it polluted turning it into a big drain. Also, most of the drains in Delhi are unlined and there is possibility of leachability of the chemicals even to the groundwater. Moreover, solid wastes like sludge, garbage, plastics, glass materials, metallic canes, fibers, waste papers, street sweepings, fuel residues, domestic wastes, etc. are usually disposed of indiscriminately to the sites of the unlined drains leading to contamination of soil and water.
In our project from Ministry of Earth Science on “Study of contamination of earth (soil and groundwater) through leaching of sewage waste from heavily loaded unlined drains in Delhi”, we have studied leachability in 9 out of 16 major drains of Delhi. We have found high levels of BOD, COD, total hardness, Calcium hardness, total dissolve solids, Turbidity, Electrical conductivity, nitrate and Nitrite in the drain leachate which indicates soil profiles are saturated within drain contamination. Contaminants leach down in the form of dissolved ions or salts of of calcium, phosphates, nitrates, sodium, potassium, chloride, carbonates, sulphates, nutrients, organic matter, etc.
The contamination level is so high that even the physical parameter like odour, colour, and suspended particles are in unacceptable limit. Even the surrounding atmosphere of drains has very foul smell with toxic gases released making it unhealthy for the residents and passers-by. The public staying near drains have even reported with health issues and deterioration of their AC linings, faucets, etc.
Soil zone is so much saturated that microbes easily pass out from earth crust to the groundwater bodies as observed in the leachate of the lysimetric studies as well as in groundwater samples. Therefore one should have a clear understanding of Persistence, degradation and Leaching of chemicals like Polyromantic hydrocarbons (PAH’s), Polychlorinated biphenyls (PCB’s), Pesticides, heavy metals, other toxic residues and of pathogenic microbes.
Such high levels of contaminants in the groundwater pose a great health risk to consumers. Delhi Jal Board can supply only 830 MGD against the daily requirement of 1,100 MGD. Therefore, people in Delhi depend on groundwater resources for drinking as well as domestic purposes.
Recommendations and Vision
Reduction in groundwater pollution because of unlined drains, the concrete lining of all the unlined drains is highly recommended and also the efficiency of the sewage and solid waste treatment plants must be increased. Sewage discharged should be treated before releasing into unlined drains.
The solution lies in the “decentralisation of STP plants” to treat sewage waste before release in the unlined drains. The drains must be used only for rainwater harvesting. Decentralisation of STP plants can be accomplished by joint efforts of residents under the campaign of “Take care of your own waste”.
Resident’s Welfare Association must take action with government, NGO’s and corporates contribution to fulfil social responsibility of treating the sewage waste by installation of collective STP plants. Contribution from every house may be taken to install STP plant over main sewer. Treated water may be diverted to utilise for gardening in parks, compost may be distributed to the residents for kitchen, garden and may be used in parks as well. Some nations have implemented these practices.
Energy efficient STP plants may be designed which run on their own bio-fuel generation so that they can work continuously. Once the sewage waste is treated not only groundwater is saved from contamination from leaching but Yamuna River will also be saved from sewage waste pollution. Once sewage waste pouring is stopped, Yamuna will clean itself sweeping the waste water away with the next flush of fresh water from its source mountains.
Similarly, Effluent treatment plants in industries must be enforced strictly with “Zero discharge policy” to save water resources from toxic chemicals.
Above model can be replicated in other states as well after successful implementation of pilot project in Delhi.
The vision can be achieved with proper policy formation and further enforcement with the support of all stakeholders.
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