A fu­tile ex­er­cise

At present, Delhi treats the same waste­water at mul­ti­ple plants be­cause treated wa­ter gets mixed with waste­water in drains

Down to Earth - - SANITATION -

Delhi sew­er­age net­work is di­vided into six zones. The Shah­dara drainage zone has three sewage treat­ment plants (STPs) at Sonia Vi­har, Ya­muna Vi­har and Kondli. The Ya­muna Vi­har STP draws waste­water for treat­ment from a nearby drain. After treat­ment, the ef­flu­ents are dis­charged back into the same drain down­stream of the in­take point (see map). As the drain trav­els to­wards the Ya­muna river, more un­treated waste is added to it. This hap­pens be­cause the Ya­muna Vi­har area is only par­tially sew­ered and the STP is op­er­at­ing at just 58 per cent of its 90 mil­lion litres of wa­ter per day (MLD)ca­pac­ity, ac­cord­ing to the Delhi Jal Board (DJB).

As a re­sult, another treat­ment plant at Kondli in­ter­cepts this waste­water and treats it all over again. This re-treated waste is once again di­verted into an open drain. This drain col­lects more waste­water from un­sew­ered colonies of Delhi and Noida be­fore it meets the river. The end re­sult is that the out­put of the two STPs is com­pletely negated. Kondli area is mostly sew­ered and has three treat­ment plants with a com­bined ca­pac­ity of 450 MLD (40.5 MLD of this is un­der con­struc­tion).

NEW PRO­POSAL

Un­der the Sew­er­age Master Plan for Delhi 2031, the DJB plans to di­vide the Shah­dara drainage zone into three smaller sub-drainage zones: Sonia Vi­har, Ya­muna Vi­har and Kondli. It also plans to set up a new treat­ment plant at Ya­muna Vi­har, which will have a ca­pac­ity of 112.5 MLD. DJB is in the process of mak­ing in­ter­cep­tor sew­ers that will check all waste­water sub-drains from mix­ing with the main Shah­dara link drain that car­ries treated wa­ter to the Ya­muna. Mean­while, the Wazirabad Trunk Sewer, laid un­der the Ya­muna Ac­tion Plan-II, will be used to bring most of the sewage to the Ya­muna Vi­har treat­ment plant.

BUT PROB­LEM PER­SISTS

The plan as­sumes that there will be no out­fall from the treat­ment plants into the drain, which is un­likely. The plan is over­am­bi­tious about the run­ning ca­pac­i­ties of the old and new treat­ment plants. It also does not ex­plain how the new plant at Ya­muna Vi­har will run at full ca­pac­ity or how the old plant will be up­graded to run at full ca­pac­ity. The plan also un­der­es­ti­mates the ac­tual waste­water gen­er­ated as it does not in­clude the dis­charge on ac­count of ground­wa­ter ex­tracted in the area.

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