Effluent treatment using effective micro organism in Amrita campus
Scarcity of drinking water has become a major problem in most places. The saying by Ismail Serageldin, former World Bank vice president, "The next world war will be over water", may soon become a reality. Waste water treatment by utilising effective micororganism as demonstrated by organisations such as Amrita Vishwa Vidyapeetham can be a solution to some of the water shortage problems
Introduction
Demand for water posed by growing population, urbanization and industrialization coupled with poor rainfall has ultimately led to water scarcity in many areas in India. As the water crisis exists on one hand, on the other hand effluents from the domestic and industrial operations pollute the available fresh water resources of the land. This situation inevitably has created a need for effective wastewater utilization and wastewater management. A number of biological and chemical technologies have emerged for effluent treatment before being discharged into a water body. Some technologies which adopt the recycling and reuse of wastewater are gaining more focus. The cost effectiveness also plays an important role in deciding for adoption of appropriate technology for effluent treatment.
Considering the current water crisis and other environmental problems that arise due to discharge of effluents, Amrita Vishwa Vidyapeetham, Coimbatore has adopted a biological method for waste water treatment. The institute initially started the effluent treatment with activated sludge treatment, which involved the use of cow-dung, diammonium phosphate and urea in the process. Later, a more ecofriendly biological treatment method using the Effective Microbes (EM) technology was adopted. In the EM wastewater treatment, no chemicals are used in the entire treatment cycle. The effluent treatment plant (ETP) in Amrita campus uses EM and has been supplying clean water for irrigation for the last four years.
Effective Microorganisms (EM)
Effective Microorganism is used for sustainable environment management. It uses beneficial and effective microorganisms. The technology was developed in the University of Ryukyus, Okinawa, Japan in 1982 by Dr. Teruo Higa. Today more than 29 countries are using EM successfully.
EM is a versatile product that uses micro-organisms found in all ecosystems. It respects nature and does not contain genetically engineered microbes. These microorganisms are collected from the natural environment from within the country and therefore are indigenous. EM contains selected species of microorganisms such as predominant populations of lactic acid bacteria, yeast, photosynthetic bacteria, smaller quantities of actinomycetes, fermenting fungi and other types of microorganisms. All of these are mutually compatible with one another and coexist in liquid culture. The principle of EM is the conversion of a degraded ecosystem full of harmful microbes, to one that is productive and contains useful microorganisms.
EM can be used in diverse areas of applications such as agriculture, poultry, animal husbandry, aquaculture, solid and liquid waste management, environment cleanliness and hygiene and related activities.
The microbes perform the function of breaking down the sewage influent. These microbes live in the sludge of treatment plants and holding tanks. They digest the solids and breakdown various compounds. Some wastewater treatment systems are exceptionally efficient, others perform effectively soon after start up, but later stop performing as well. To understand how and why some wastewater treatment systems work well and others don’t there is the need to understand the function of microbes. As microbes are living organisms, they require certain nutrients and environments to survive, multiply and perform. In any wastewater treatment system there is a vast array of microbes present, i.e. aerobic, anaerobic and facultative, each performing specific functions in their respective parts of the system. Each species has a tolerance of ecological minimums and maximums with regard to various conditions; pH, temperature, dissolved oxygen levels and nutrient levels. All microbes require optimal conditions in order to proliferate and infuse the system with sufficient numbers of microbes to maximize the efficiency of the wastewater treatment plant.
EM is a liquid concentrate produced from cultivation of over 80 strains of mixture of aerobic and anaerobic microorganisms. It mainly consists of lactic acid bacteria, photosynthetic bacteria, yeast, and ray fungi (see Table 1). This concentrated EM (EM1) solution is available from the manufacturer (Maple Orgtech) in India.
Use of EM at the Campus
The Amrita Vishwa Vidyapeetham Campus uses EM technology for effluent treatment in recycling of sewage effluent, food waste treatment in transforming waste into organic compost and cleaning of bathrooms. EM1 is activated by the following procedure into extended EM and for the actual effluent treatment another preparation called EM Bokashi is prepared.
Preparation of EM Bokashi
One kg of jaggery is dissolved in 19 liters of water and filtered and 1 liter of EM1 is added to the jaggery water. The solution is kept in a closed container in a cool place away from direct sunlight for 5 days. This solution is called extended EM. or EM 2. Four Kg of Zeolite (Sodium aluminium silicate) is taken in a container and extended EM is added in drops. It is mixed thoroughly until the material holds together, after which it is made into a ball of approx. 100g each. Each ball is covered with green leaf (banana or teak) and kept in closed polythene bags and again in closed plastic container for 4-5 days to allow fermentation. After fermentation, these balls are called EM Bokashi. Bokashi is a Japanese word meaning "fermented".
Effluent Treatment Plant at Amrita Deemed University
Amrita Institutions at Ettimadai campus in Coimbatore Dist. of TN consumes on an average 5 lakhs liters of water a day. The process of effluent treatment is carried out in the following units
Collection Tank
The effluents from hostels, residences, kitchen, canteen and other places are collected in collection tank. To remove stones, plastics and other solid wastes a grid removal screen is provided where the solid waste removal is done manually and daily. There are three ETPs for treatment of wastewater, which utilizes Effective Microbes (EM) technology. Effluents from the sources mentioned above are collected in a collection tank (capacity 350m3). About 4 to 5 balls of EM Bokashi are added into the collection tank for every 2,50,000 liters.
Aeration tank
From the collection tank, effluent is pumped to the aeration tank (350m3). Mechanical aerator (15HP) is used in aeration tank to dissolve atmospheric oxygen into the effluent. A retention time of 24-32 hours is given for the aeration and the microbes to act on the wastewater.
Settling tank
After aeration, the EM treated effluent is allowed to settle in a settling tank (120m3) to remove the 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, cylose and sand layers of varying thickness. After filtration, clear treated water is pumped into storage tanks. The water requirement for agriculture and garden plants in the campus are fully met by this water. The flow chart of ETP is given in Fig.1. The test results of effluent treatment using EM are presented in Table 2. The performance figures are compared with values of raw effluent as well as with standards of Pollution Control Board (PCB).
Economics of EM Technology
EM Technology does not involve any chemicals unlike in the conventional effluent treatment system and therefore ecofriendly. EM is economical compared to other chemical and biological treatment. The cost efficiency and comparison with activated sludge treatment is shown in Table 3. Moreover aeration time can be reduced by 25% compared to activated sludge treatment. There is also considerable reduction in sludge generation. No foul odor occurs in the treatment process.
Factors affecting efficiency of EM treatment
Since the effluent treatment process is dependent on the action of microbes, any factor that will affect the microbial population will result in the low efficiency of the system. It was observed that the type of food used in the residences and canteen has considerable influence in this regard. When large quantities of onion and beetroot were served as food the efficiency of effluent treatment was reduced. This interesting observation points out the need for further research on bioremediation process utilizing EM for effluent treatment.
Acknowledgement
The assistance given by Sri. K. Kathiravan, Research Associate, in analyzing the effluent samples is acknowledged.
Courtesy: P.C. Gopinathan,
M. Aravindakshan and V. Radhamani Pillai, Center for Environmental Studies, Amrita Vishwa Vidyapeetham, Coimbatore-641105