Demand for water posed by growing population, urbanization and industrialization coupled with poor rainfall has ultimately led to water scarcity in many areas of India. Older generations still remember that until 50 years ago, Ettimadai and surrounding areas were cultivated with sugar cane, bananas and plenty of vegetables. They were irrigated by the water from the open wells.
Unscrupulous exploitation of ground water and large-scale cultivation of coconut under flood irrigation brought down the water to deeper levels. Today most of the open wells are dried up and the water table of bore wells are 400-600 feet or more deep down.
The changing crop pattern affected the environment and the changed environment affected agriculture. Present day agriculture is heavily dependent upon irrigation and the scanty rainfall received is insufficient, especially for crops like coconut.
Water conservation and management has become the most crucial environmental issue of the village and surrounding areas. Therefore, besides effluent water treatment, the campus has adopted additional water conservation and water harvesting measures to recharge the underground water resources and conserve soil moisture.
As a result of all these water conservation measures adopted by the University, the campus experiences no soil erosion or water loss. In Ettimadai village ground water recharge is seen in ravines and wells.
The water received is fully conserved through the following measures:-
Recharging the underground water, conserving soil moisture
Rainwater collection from buildings into large and small pits allows the water to percolate down and recharge subsurface water sources. Drip, sprinkler and mist irrigation systems have been laid out to economize water use. The entire coconut farm is irrigated by recycled water through drip irrigation, which serves as a model for coconut farming.
Soil erosion and water loss is prevented by construction of bunds and planting soil binding plants and trees on the bunds. The land is also divided into plots. Water harvesting from the terraces of the buildings is done and the harvested water is collected in the several pits constructed on the campus.
As a water crisis exists on the one hand, on the other, effluents from domestic and industrial operations pollute the available fresh water resources of the land.
This situation inevitably created a need for effective wastewater utilization and wastewater management. A number of biological and chemical technologies have emerged for effluent treatment before discharging into a water body. The cost effectiveness also plays an important role in deciding the technology for effluent treatment.
Initially the institute started the effluent treatment with activated sludge treatment, which involved using cow dung, diammonium phosphate and urea during the process. Later on, a more eco-friendly bio-remediation treatment method was adopted using Effective Microbes (EM) technology.
It is a unique method where no chemicals are used in the entire treatment process. Using EM for wastewater treatment is one of the rapidly emerging technologies, first developed in Japan and now currently used in many parts of the world. The effluent water is recycled and utilized for irrigating farms and gardens.
The recycled water is free from heavy metals, infectious microbes and other contaminants. Plant growth is enhanced by the use of this recycled water, probably due to the growth- promoting factors that the water contains.
The cost efficiency of EM technology compared with activated sludge process is significant. The total cost of activated sludge process treatment for 100 000 liters is Rs. 26 whereas the same volume treated with EM technology only costs Rs. 3.
Effluent Treatment Plant at Amrita Deemed University
A quantity of six lakhs liters of waste water is generated from the hostels, residences, and canteens every day. However, the consumption pattern varies according to student strength in the hostels. There are two ETPs for treatment of this wastewater at the campus which utilizes Effective Microbes (EM) technology.
Such an elaborate bio-remediation plant, one which adopts no chemical treatment, is probably, the only one of its kind in India. The water is injected back into the soil through irrigation.
The process of effluent water treatment is carried out in the following units:
Effluents from hostels, residences, kitchen, canteens and other places are collected in a collection tank (capacity 350m3) and about 4 to 5 balls of EM Bokashi are added into the collection tank for every 2,50,000 liters. A removable grid screen traps stones, plastic and other solid wastes; daily solid waste removal is done manually.
Effluent is pumped from the collection tank to the aeration tank (350m3). A mechanical aerator (15HP) is used to dissolve atmospheric oxygen into the effluent. A retention time of 24 – 32 hours is given for aeration and the microbes to act on the wastewater.
After aeration, the EM-treated effluent is allowed to settle in a settling tank (120m3) to remove suspended solids. The settled sludge is removed periodically by mechanical pump and used for coconut farming.
The treated water is then transferred to the filter, which is made up of gravel, cyclose and sand layers of varying thickness. After filtration, clear treated water is pumped into storage tanks.