Posts Tagged ‘sewage’


On the sludge management and reuse potential in Bangalore

May 12, 2014

One of the many critical factors affecting productivity in Indian soils is the absence of nutrients such as Nitrogen, Potassium and Phosphates. Even Carbon is in short supply as well as micro-nutrients such as Zinc and Boron.  AA substantial part of our artificial fertilizers is imported and we run up quite a huge bill. Fertilizer prices too are shooting up leading to an imbalance in their application. It has been reported for example that Urea which is relatively cheaper is over applied on soils causing more harm than good.

Cut to urban cities. Sewage treatment plants are coming up in large numbers. The Bangalore Water Supply and Sewerage Board –the utility responsible for sanitation and sewage, will eventually be setting up 25 sewage treatment plants treating nearly 1100 Million Litres Per day of sewage. These plants will mostly be secondary and tertiary treatment plants. Each million litre of sewage generates nearly a Tonne of sludge. Imagine 1100 Tonnes of sludge will be generated in the city of Bangalore alone. This is 120 truckloads of sludge.

There are smaller sewage treatment plants dotting the landscape in apartments and layouts too. These too generate smaller quantities of sludge. Overall this represents a management challenge of large proportions.

Research:  Currently at the GKVK-University of Agricultural Sciences – research work is going on to understand the nutrient value of this sludge. A Ph D student is pursuing her Doctorate and is experimenting on field trials using the sludge as manure. The initial test results show very good amounts of Potassium and Phosphates in the sludge.



Separately sludge is also being picked up from Ecosan toilets. These are source separating composting toilets which segregate urine and solids. The solids are covered with ash after every use and desiccated before application as a fertilizer on soils. Farmers of Kamasamudram and H.D.Kote have such toilets in their homes and are very happy with the fertilizer they get. In fact this compost is priced at Rs 10 a kg.


Sludge sells for upto Rs 10 a kg.

Similarly the landscape of rural India is dotted with pit toilets, more than 130 million of them at the last count. These too accumulate solid sludge and need to be emptied using mechanical systems. They are also found to be rich in Phosphates and Potassium.

All these various forms of sludge will be taken, tested applied on fields and crop productivity tested under expert supervision.

When research and application come together in a spirit of cooperation, it is possible to find solutions for India’s vast water, food and sanitation problems. At the base, this is a nutrient cycle at play. How we scientifically understand and manage it will show us the path to solutions. If every gram of sludge generated in our Sewage Treatment Plants become useful as manure it will partially solve India’s fertilizer needs and eliminate pollution. It will also increase productivity and richness of our soils as well as enhance the livelihood opportunities of farmers.

Recognizing and converting waste to a resource will help thousand of apartments and layouts, small and medium towns and even metropolis to manage their sewage efficiently for reuse and recycling. This would be water wisdom.


Honey-suckers in Dubai

December 24, 2012

Apparently the whole of Dubai runs on Honey-suckers as this video from a blog shows



Reusing wastewater – treatment systems

November 25, 2010


This waste could be a resource

A look at some emerging technologies for wastewater treatment by S. Vishwanath

Try them out: (Top) Soil biotechnology system in Mumbai; (below) let waste-water have its uses

Managing waste-water as a resource has become the new paradigm, what with water resources being seriously competed for and the general difficulty of accessing water. Added to this scarcity value of water are the tougher laws on the environment and for pollution control.

Some of the interesting new technologies include DEWATS or decentralised wastewater treatment systems and SBT or Soil Bio-technology.

The DEWATS system looks at treating wastewater from a small 1000 litres to 1000 cubic metres per day. This system can handle wastewater from homes, apartments, institutions and even small and medium industries.

It is a four-step process which involves sedimentation, up-flow anaerobic digestion, aerobic treatment in horizontal planted gravel filters and, finally, aerobic treatment in a polishing pond.

The website says that more than 350 DEWATS systems have been implemented all across South Asia. The one at the Arvind Eye Hospital in Pondicherry has been an outstanding model.

Ideal combination

The SBT treatment or the Soil Bio-Technology system has been developed by Professor Shankar from IIT-Mumbai. The system also uses what is called a combination of organic and inorganic matter in a soil layer with bacteria and earthworms as a mode of treatment.

A three million litres per day treatment plant is running in Mumbai for some time and the results have been extremely positive. In Bangalore, two experimental plants of smaller scale have been running and have shown excellent preliminary results.

Both DEWATS and SBT use nature as their source of treatment. Bacteria and soil-based creatures do their job sometimes in an anaerobic condition as with part of the DEWATS and sometimes in aerobic conditions as in SBT.

Both require low energy, if at all, and there are no moving parts, thus reducing maintenance issues and cost. Both can be integrated into landscapes and the treated wastewater used for productive irrigation applications as well as for non-potable uses such as toilet flushing.

Zero discharge

The systems help in ensuring ‘zero discharge’ for the building where they are used.

More information on DEWATS is available on the website which is the Centre for Dewats Dissemination Society in India.

It organises regular training programmes too.

Information on for SBT from Prof H.S.Shankar should be available on the e-mail

China has seen a boom in wastewater treatment systems over the last five years. Similarly India too will see a boom in the business. Solutions for wastewater treatment will necessarily have to adapt to Indian conditions and work on reducing maintenance cost and manpower requirement.

The nutrients recovered from the waste-water treatment need to be used productively for soil enhancement rather than to pollute water bodies.

One of the biggest threats to the environment resulting in contamination of both surface water and ground water has been domestic sewage. Treating this will protect the environment and fresh water supplies, thus enhancing sustainable water availability. This is the path to water wisdom.