State of wastewater treatment in India

A government report on Urban and Industrial Water Supply and Sanitation for the Twelfth Five - Year Plan (2012-2017) highlights the following points about wastewater in India:

• Urban and industrial India will have huge implications on the use of water and discharge of waste• Cities worry about water, but not the waste this water will generate• The challenge of sewage collection and treatment has not received adequate attention• No Indian city is in a position to boast of a complete sewerage system, which can keep up with the sanitation and pollution challenge• The capital intensity of the current waste system results in the fact that cities can only provide for a few and not for all• If sewage systems are not comprehensive – spread across the city to collect, convey and intercept waste of all – then pollution will not be under control

The above observations made in the report go on to show that not all is well as far as sewage treatment in India is concerned.

Factors that hinder wastewater treatment

The government report says, "The cost of a wastewater treatment plant depends on two key factors -- the quality of raw influent and the quality of the receiving medium." It adds that most cities in India do not have facilities to treat human excreta or chemical industrial waste.

Furthermore, these plants are technologically backward and were built at times when the nature of waste was biological and not chemical. With time, the quantity and characteristic of wastewater discharge has drastically changed. In their current state, most wastewater treatment plants are obsolete and are in need of newer technology and capacity expansion.An important factor that hinders wastewater treatment is unavailability of land for building new plants. Land is in short supply in urban India and also a very expensive commodity. As a result, cities and towns are finding it difficult to manage and treat the huge quantities of waste generated on a daily basis.

Construction and maintenance costs are major deterrents too. According to the government report, in the mid-1990s, when the first-generation sewage treatment plants were built, they cost Rs 20 lakh to Rs 30 lakh per MLD (million litres per day).

Today, the same plants cost close to Rs 1 crore per MLD to build. India's deficit of sewage treatment would require huge investment, if only greenfield options are considered. Retrofitting -- A viable option

'Retrofit' or upgradation of existing wastewater treatment plants can solve problems of increased capacity as well as need for improved quality. Retrofitting can be defined as addition of new technology or features to older systems.

Retrofitting is less capital-intensive than building a new plant, optimizes the working of the existing plant while also increasing its lifespan. Membrane technology plays a vital role in retrofits. Low-pressure ultrafiltration membranes that can be fitted downstream of aeration systems of existing plants offer multiple benefits of capacity expansion and improved effluent quality.

Few advantages of retrofitting with membrane technology include:• Improved productivity of wastewater treatment plants• Reduction in per unit operating costs • Significant improvement in quality that can make effluent reusable in non-potable applications.

Treatment plants that used to discharge effluent could be upgraded and treated effluent could serve as a revenue generator.

Examples of retrofits in India can be seen in the industrial sector, where plants have seen increase in capacity by > 80% and improvement in effluent standards to reuse levels. This has been archieved with minimal investment in land and civil works. Such practices need to be translated in the Municipal segment as well, thus reducing the investment burden for new plants.

References:

http://planningcommission.nic.in/aboutus/committee/wrkgrp12/wr/wg_indu_sani.pdf

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