Only 15% sewage treated in Mumbai

NEW DELHI: Sewage tops the areas of concern in the South Asia Seas (SAS) region, said a recent UN report on marine environment. “Rising tide of sewage threatens world’s oceans, endangering human health, wildlife,” said the report.

The other priority issues for the SAS region were identified as: Litter - solid waste (industrial and municipal); agricultural chemicals; oil hydrocarbons; sediment; and physical alteration and destruction of habitats.

The report states that human settlements with large populations and numerous small and medium-scale industries, large industries, as well as power plants situated along the coasts of the SAS region are the hotspots for marine environment.

They include areas near the mouths of rivers along which are situated numerous cities such as Mumbai, Kolkata, Dhaka, Chennai, and Karachi, as well as industries with inadequate waste management. Sewage is of particular concern in these hotspots.

The combination of discharges of raw sewage and untreated industrial waste has caused low to serious degradation of the coastal and marine environments at several locations in the region. Except in a few urban areas, the sewage treatment facilities are inadequate, the reported treatment capacity in Mumbai being just 15 per cent. Karachi is worse off with just six per cent.

The sewage load in the SAS region has progressively increased during the past decade in the absence of adequate expansion of treatment systems. In a separate estimate 7,000 million l/day of sewage are generated in the coastal areas of all the South Asian countries.

In most instances, sewage does not only contain human waste but also various environmentally harmful household compounds.

This problem is exacerbated by the common practice of discharging untreated or inadequately treated industrial wastewater into the domestic wastewater stream. The situation at Ankleshwar, Gujarat, is illustrative: the liquid wastes are simply dumped into storm sewers, canals, and ditches.

As a result, most sewers contain a variety of toxic and non-biodegradable substances, making their treatment less effective and more costly. Some of the effluents go directly to the Amlakhari River, which passes through villages that use the water from this river. Six effluent outlets carry the waste, both treated and untreated, through the open countryside to the mouth of the Narmada.

The inadequate number of sewage treatment plants in operation, combined with the poor operating conditions of the existing plants and the practices of discharging mostly untreated wastewater are likely to have an adverse impact on the quality of coastal waters, says the report.

As a consequence of steadily growing coastal populations in most of the countries, the amount of poorly treated or untreated sewage wastewater being discharged into coastal waters is increasing. During the next decade, several of the biggest cities in the SAS Region, including Mumbai, Kolkata, Dakha, Chennai, and Karachi will rank among the largest in the world. This has serious implications for the health of the region’s coastal and marine environments.