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Dairy waste and a lush green campus - A journey
By:Anju Rani1, Pradeep K. Sharma2 Nishant Rai1, L.M.S Palni1
The Indian agricultural system is predominantly a mixed crop-livestock farming system, with the livestock segment supplementing farm incomes by providing employment, draught animals and manure (FYM). According to the Economic Survey (2015-16), India ranks first in the milk production, accounting for 18.5 % of world production, achieving an annual output of 146.3 million tons during 2014-15 as compared to 137.69 million tons during 2013-14 recording a growth of 6.26 %. Besides milk, livestock farming system provides cow dung and urine which need to be managed by economically viable, socially safe and environmentally sustainable methods. The Graphic Era University (GEU) has developed a model, adopting green technologies (Figure 1) for converting dairy waste (wastewater and cow dung) into (a) vermicompost, (b) clean and odorless water for irrigation, and utilizing both for the maintenance of huge lush green campus (Figure 2 D & E).
Figure 1: Two-pronged strategy used for dairy waste management at Graphic Era University
Figure 2:
A) Cow Shed, B) Constructed wetland unit for treatment of dairy waste water, C) Vermicompost unit,
D &E) University Green campus
Two cowsheds are maintained in the university premises of GEU (Fig 2 A), with more than adult 60 cows including both Indian and foreign breeds. One shed generates approximately 3000 L wastewater and 5-10 tonnes cow dung per day. Liquid waste and solid waste are treated independently through constructed wetland and vermicomposting, respectively.
Dairy wastewater (cow urine, washings and bathings; twice in a day) is directed to a constructed wetland (CW) unit for treatment. CWs simulate natural wetlands in which processes such as filtration, microbial degradation, nitrification and denitrification, etc. are allowed to proceed to remove pollutants from wastewater. Constructed wetland technology has been used for treatment of wastewater of varied origin (dairy, municipal sewage and domestic) and composition. Such a unit located in the campus (Fig 2 B) treats dairy wastewater in terms of organic matter, nitrogen, phosphate, suspended solids and pH, through P-adsorption, organic matter degradation and nitrification (by microbial film developed around gravel). All nitrogen forms are biochemically interconvertible and are removed by ammonification, nitrification and denitrification. Macrophytes such as Phragmites also contribute to waste water purification via the plant-uptake mechanism. In an ongoing constructed wetland treatment facility, treated wastewater showed marked positive effect on different parameters (DO, BOD, COD, TN, NH4-N, NO3-N, TSS & TP) in comparison to untreated wastewater (Table 1). Details of constructed wetland technology can be seen in a recent article by Sharma et al. (ENVIS Bulletin for Himalayan Ecology, Vol 23, 79-84, 2015 )
Table 1: Various parameters of dairy wastewater before and after treatment
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S. No.
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Parameters
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Influent concentration
mg/L-1
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Effluent concentration
mg/L-1
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1
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Dissolved Oxygen (DO)
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1.65
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6.79
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2
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Biochemical Oxygen Demand (BOD)
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619
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6.5
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3
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Chemical Oxygen Demand (COD)
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1019
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24
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4
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Total Nitrogen (TN)
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124
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43
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5
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Ammonium Nitrogen (NH4-N)
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74
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36.6
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6
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Nitrate(NO3-N)
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1.2
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3.7
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7
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Total Suspended Solids (TSS)
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450
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6
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8
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Total Phosphorus (TP)
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49.5
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2.5
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Further cow dung along with other degradable solid waste, i.e waste paper, horticultural (twigs, prunings) and kitchen waste (from hostels), etc. is taken to a vermicompost unit (Fig 2 C). Available bio-waste is heaped in the open and chopped, if necessary. In the vermicompost bed, biodegradable waste is kept in layers in the following order: (From top to bottom)-plant leaves/prunings, cow dung, plant leaves/prunings, kitchen waste, plant leaves/prunings. The depth, length and width of vermicompost beds are 1.5 feet and 2 feet, respectively. Water is sprinkled intermittently to maintain 60-70 % moisture content and the heap is turned upside down after every 15-30 days. Vermicompost is usually ready after 90 days. Currently, approximately 250 tonnes of vermicompost are produced annually through the composting unit which is then used in the university gardens across campus. This ensures recycling of the hostel, garden and dairy waste by converting it to useful biofertilizer.
In addition to waste management, vermicompost helps build up soil fertility and restore its vitality. Several studies have indicated the agronomic impacts of vermicompost such as improved seed germination, enhanced seedling growth and development, and increased plant productivity much more than what is possible by mere conversion of mineral nutrients into plant-available forms. The growth responses of plants from vermicompost appear more like hormone-induced activity associated with the high levels of nutrients, humic acid and humates in vermicompost rather than boosted by high levels of plant-available nutrients. Nutrient composition of vermicompost has been found (% values) to be: Organic carbon (9.8-13.4), nitrogen (0.51-1.61), phosphorus (0.19 - 1.02), potassium (0.15 - 0.73 ), calcium (1.18 - 7.61), magnesium (0.093 - 0.568), sodium (0.058 - 0.158), copper (0.0026 - 0.0048 ), iron (0.2050 - 1.3313) and manganese (0.0105 - 0.2038 )
1Department of Biotechnology, 2Department of Environmental Sciences, Graphic Era University, Clement Town, Dehradun-248002
E-mail: [email protected]
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