STP Maintenance : Sewage Treatment Plant in Apartment Complexes: New Nitrogen Standards

– This Article has been authored by Dr. Ananth Seshadri Kodavasal. Dr. Kodavasal has more than 30 years of experience as an environmental Engineer and is a looked upon as a foremost authority on Sewage Treatment Plants.

This Commentary is a rejoinder to a recent Notification from the Karnataka State Pollution Control Board revising standards for quality of treated sewage.  More specifically the KSPCB has introduced NH4-N (Ammonia Nitrogen) and Total Nitrogen and set limits of 5 mg/L and 10 mg/L respectively for these parameters in treated domestic sewage.  The new standards are made applicable to all Sewage Treat Plant’s (STP’s) including those in Residential Apartment Complexes, Commercial Complexes and the Large STP’s of Urban Local Bodies (ULB) such as City Municipal Corporation, Town Municipal Corporation etc. in Karnataka.

The KSPCB  takes refuge under the plea that the Notification has been issued following a Direction from the Central Pollution Control Board – Delhi ( CPCB ) dt. 21-08-2015 to enforce these new Rules.

Here is the link to the Notification from KSPCB

Let me explain why I feel both agencies, and the KSPCB in particular have missed the Wood for the trees and why this is a Knee Jerk reaction similar to several others which we have now come to expect from such “Expert” bodies constituted by the Government.

  1. From a reading of the brief narration given of the CPCB Direction, it is clear that the Rules must be made applicable to Large STP’s of ULB’s and not to distributed , decentralized small, mini and micro STP’s in Residential Apartment Complexes.
  1. Has the KSPCB got any expert technical opinion or has it conducted any public consultation before applying the Rules across the board to all STP’s?
  1. Has the KSPCB done even a cursory study on the technical and practical feasibility of enforcing these Rules in the Micro and Mini STP’s ?
  1. Has the KSPCB explored other alternative technologies, methods and means of reducing Nitrogen pollution in the lakes and water bodies? Is Nitrogen control in the STP at great cost, expenditure of energy and chemicals the only solution?

The Answers to all these questions can only be a resounding NO.

However, to comply by the recent notification from KSPCB, here are a few tips for Management Committee’s and Resident Welfare Associations to try out modifying their present STP systems within constraints of cost and space.

1. There are various ways of handling Nitrogen and it will be STP specific.  But all of them will have to be based on Biological Nutrient Removal (BNR) techniques. Basically it will involve adding an anoxic stage (In the absence of Oxygen, but with mixing) either at the head or at the end of the Current STP’s, depending on space availability and other factors.  Depending on the route selected also, energy and chemical addition requirements will vary.

2. Not many vendors/ plumbing consultants/ architects are familiar with BNR techniques and their application ( indeed I do believe they do not even understand basic biological techniques for  BOD, COD, TSS removal). It is best that Apartments seek expert help in this matter.

There is still hope however that if a large number of aggrieved citizens make a representation to the KSPCB, the Nitrogen limit may be reviewed and STPs’ in apartment complexes may be exempted from this requirement.

Here is an alternative method  to beneficially harvest Nitrogen in sewage and make money instead of pouring money down the STP drain.

Water Hyacinth - Sewage Treatment Plant

About 25 years ago, I was summoned by Sri. Srihari Khoday, the liquor Baron of the day in  Karnataka to study  treatment plants in their breweries and distilleries.  When the main discussions concluded, as an aside, Mr. Khoday asked me for my opinion on the technical feasibility of harvesting Water Hyacinth ( Eichhornia Crassipes) on a commercial scale from lakes in Bangalore, more particularly Bellandur ( Yes – Bellandur was polluted even in those days).  Water Hyacinth takes up huge quantities of Nitrogen and phosphorus for growth and becomes biomass which then can be anaerobically digested to generate Methane and energy therefrom and supply power to nearby industries. The largest consumer in the vicinity was Hindustan Aeronautics Limited ( HAL).  Twenty five years ago, this struck me as a revolutionary idea, and out of the box thinking of a visionary businessman with great commercial acumen.

Srihari Khoday’s idea could not find the wings to take off.  I have myself proposed very economical, practical and executable solutions to resuscitating defunct STP’s in Bangalore to all the authorities in the Government directly concerned.  Needless to say, they have fallen only on deaf ears.

This is however not for practice in individual apartment complexes, but on a large commercial scale in Lakes and water bodies which receive  sewage from such complexes.  In such an event one can design a scientific Hyacinth farming and harvesting protocol such that the lake biota is not unduly stressed by this activity.

Leave us your comment below if you feel aggrieved by the recent Nitrogen Regulations from KSPCB.

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