Liquid Waste Management @ Amrita
June 11, 2011
Dept of Social Work, Amritapuri
On the second afternoon of the International Conference on Society, Technology and Sustainable Development, Dr. M. Aravindakshan, Coordinator, Center for Environmental Studies at Amrita’s Coimbatore campus delivered an invited lecture on sustainable waste management, elaborating on his experience with liquid waste management at the campus.
Given below are excerpts from his talk.
At our campus in Coimbatore, we do not get much rainfall either from the South-West or the North-East monsoons, because we are located in the rain-shadow area of the Western Ghats. Average annual rainfall is only 60 cm. So, the area is virtually a desert.
But in this desert, we have been able to create an oasis. During the past twelve years, we have planted hundreds of thousands of trees. We received a certificate of appreciation from the United Nations Environmental Program for participating in the one-million tree planting program.
Water was needed to grow all these trees. Since water was scarce, we relied on careful and sustainable water use practices since the early days. In our campus, we have both liquid waste management as well as solid waste management. My talk, this time, is confined to mainly liquid waste management.
As you know, water is very precious for all. Demand for fresh water is increasing due to growing population. Rapid industrialization and urbanization has led to pollution of water bodies. More water is being used and wasted too.
What is wastewater?
That water which is adversely affected in quality due to human activity and contains urine, faeces, food materials, oil, dissolved soap, chemicals and other contaminants is waste water. In 2010, over 25 billion litres of untreated wastewater flowed into India’s rivers and coastal waters every day. Existing treatment capacity is only able to treat less than 30% of the wastewater generated.
Sustainable wastewater treatment involves processing wastewater, ridding it of all contaminants, so that it can be used again. It also helps prevent pollution of our water bodies.
Wastewater is typically treated using physical, chemical and biological means. Sedimentation is the most common physical method used in most parts in India. Chlorination, ozonization and other such methods constitute chemical wastewater treatment. Biological methods such as bioremediation involve the use of microorganism metabolism to remove pollutants.
At our Coimbatore campus, we treat wastewater through bioremediation. Over the past eleven years, 5 Effluent Treatment Plants (ETP) have been set up. Around 95% of used water reaches one or the other ETP through a network of sewage pipes. From family quarters, guest house, ashram, ladies hostel, estate office, boys’ hostel, messes, etc., 10-12 lakh liters of water every day reaches the various ETPs. This is not a small amount. If all this water was wasted, our campus would have remained a desert. Now, it is an oasis in a desert.
We do not use any chemicals for wastewater treatment. Our campus is a chemical-free zone. We use Effective Microbes (EM) technology, developed in 1982 by Dr. Tero, University of Ryukyus, Japan. One kilogram of jaggery is dissolved in nineteen liters of water, then filtered, and added to one liter of EM1 solution. After being in a closed container for 5-7 days, EM2 solution is ready. Four kilograms of zeolite are added to this, mixed thoroughly until the material holds together, and then made into balls, approximately 100g in weight. Each ball is covered with a green banana or teak leaf and allowed to ferment over 4 to 5 days, until EM Bokashi is ready for use.
One ball of EM Bokashi is added to every 50,000 liters of accumulated wastewater. Because EM Bokashi is so effective, there is no foul smell in the water. Because of these effective microbes, our sludge content is also very minimal. From the collection tank, wastewater is pumped to aeration tank. The water is further filtered, resulting in treated water that is of good quality for all practical purposes.
We mainly use this water for gardening. We have planted over one lakh trees in the campus. Our gardens extend over 10 acres of land. We are still planting to this day. This is possible only because of the recycled wastewater. Our campus is spectacularly clean and green and I am proud to say that it is considered as one of the best campuses in India and maybe even the world.