Bioethics in India: Proceedings of the International Bioethics Workshop in Madras: Biomanagement of Biogeoresources, 16-19 Jan. 1997, University of Madras; Editors: Jayapaul Azariah, Hilda Azariah, & Darryl R.J. Macer, Copyright Eubios Ethics Institute 1997.

98. Production of Farm Vermi-Compost using Treated Tannery Effluent Water

Lavanya P.G. & J. Venkatakrishnan
Agricultural Res.Station , Virinjipuram , N.A.A.Dist. 632104


Tamil Nadu is a state having much share in the industrial economy of India. The tannery industry as a major share cropper of the foreign exchange earner, has in the recent past become a highly controversial subject because of the scope with which it is viewed in the midst of environmentalists. Though it is developing our economy on a whole, it will be highly unethical when we don't look upon its merits and demerits

North Arcot Ambedkar district is one of the important districts of Tamil Nadu where more than 1000 tanneries both of big and small scale are concentrated. It will look highly unethical when we say that these industries are concentrated in the major Muslim inhabited area because Muslims have the practice of cow-slaughter, from the time immemorial. This has led to the rise of secondary processing industries like hides and skin industry and slowly to the leather processing industry as a whole.

The tannery industry has been in existence in the N.A.A. District., for the past 100 years. This would reveal the level of contamination in the Palar river belt. Nearly million gallons of effluent has been discharged per day in the Palar river basin. During early days leather processing was done through vegetable tanning. In the recent past of 25 years chemical tanning has been in vogue and this has ultimately damaged the whole environment, as well the ecological balance remaining upset.

In this perspective, the farming practices has also become redundant and this has been realized in animal husbandry too. So the question of cattle population rise has also become highly major due to the influence of Pollutants mainly Cr dumped into the soil. It is also noteworthy to say that the cattle fed with Sugar-cane tops have become sterile due to the effect of Tannery Pollutants. So this has led to the reduction in the cattle Population and the generation of cattle manure and its further application to the field rendering sustainable agriculture practically impracticable.

With this background it was decided to produce compost on a profitable as well on a larger scale utilising the existing resources in a polluted environment.

Materials and Methods

The Agricultural Research Station, Virinjipuram, Vellore functioning under Tamil Nadu Agricultural University has conducted research on the production of Farm Vermi- compost using treated Tannery effluent water. The chemical properties of the effluent are as follows: (Parameters: Value) pH 7.96; Conductivity 0.71; Total Suspended Solids 80 (mg/l); Total Dissolved Solids 5190; Chlorides 1833; SO4= 466; Oils & Grease 2; BOD 5 day at 20 C 12; Sulphides (as S) BDL; COD 124; NH4-N 26.6; Phenolic Compounds BDL (as Phenols ); Cr 6+ BDL; Total Cr (as Cr) BDL; % Na 80; Boron BDL; Kjel.-N (as N) BDL PO4= -

Pits of Dimension 6'X 6'X 6' were dug for the production of farm Vermicompost . The bottom-most layer was lined with pebbles and cobbles for 1 foot , to facilitate adequate drainability and the overlying layer for 1 foot was lined with coarse sand above which a layer of one foot of fine sand was laid which served as the Verm-bed. This layer was sprinkled with treated tannery effluent water over which 200 worms of the species (Octocheatona serrata) commonly found in Red soils was collected from the local Palar river bed and incorporated . All efforts were undertaken to keep the bed moist till 3 days to provide the worms a better adopted environment. Above the verm-bed were incorporated Farm wastes viz., Paddy straw , Cumbu straw, Sorghum straw, Maize Straw, Orchard wastes like Guava , Mango Leaf wastes and Pappaya stem Wastes, Coconut rind , Green gram, Black gram seed wastes , Banana and Sugarcane trash each of one foot were incorporated layer by layer and each layer was sprinkled with 20 litres of treated tannery effluent . Over each layer of waste a small layer of fine sand was sprinkled uniformly to simulate the soil atmosphere. It was also felt that sprinkling of cow dung may enhance growth rate for which a litre of cow dung solution was also sprinkled over each layer. The manure pit was turned periodically once in three days to facilitate faster decomposition .This practice was continued until the manure pit reached its height and the manure was harvested after a maturity period of 4 months. A control was also laid to serve as a check. Temperature of the decomposing pit was monitored periodically. The nutrient content of the manure was assessed after the harvest (Table 2).The multiplication rate of the worms were detected by the Grid as well as Quartering Technique.

Results and Discussion

The results revealed that the manure obtained a friable nature after 4 months. It was also observed that the Tannery effluent irrigated manure exhibited darker colour compared to the control. It was observed that during the initial stages of decomposition the temperature was lower, whereas during the final stages, the temperature shot up revealing the higher microbial load activity. (Table 1). A temperature differential was also observed between well water and treated effluent water which showed higher level compared to the former.

It was also observed that the secondary predators like ants became a menace due to its high drainability and moisture exchange equilibrium . This anomaly was taken care by sprinkling BHC 2 % dust around the pit.

It was also noted that the worm multiplication rate was 10 times of that of the initial count and the average size of the worm was about 10 mm and the worms of Tannery effluent irrigated pit showed darker colour indicating the uptake of some organic matter along with heavy metals. It was also observed that the Verm compost production was economically remunerative due to its low cost of production of 350 Rs. per tonne. So from a pit of 6"x6'x6' dimension one can generate 10 tonnes Which in turn can be applied to 4 ha as the vermicompost manure recommendation to any crop is 2.5 tons ha-1 as to that of FYM or any other manure which accounts for 12.5 tons ha-1. So there is a saving of nearly 6000 Rs. from a manure pit of 6'x6'x6' dimension.

Table 1: Effect Of Tannery Effluent On Temperature (degrees C) Of Verm-Pit

Well Water Tannery water

Initial Final Initial Final

29.5 31.5 32.0 38.5

27.5 30.0 33.0 39.0

26.5 29.5 31.0 38.0

28.5 31.0 29.5 37.5

25.5 28.0 28.5 37.0

24.5 27.5 32.0 38.5

26.5 29.5 33.5 39.5

25.5 28.0 31.5 38.2

24.0 27.0 32.5 39.0

24.5 27.5 31.5 38.0

The results also revealed that the Cr concentration of the manure was less (0.05 ppm ) (Other minerals: N - 2.5 %; K - 3.5 %; P - 1.8 %; Ca - 0.8 %; Ec - 0.23 dS m-1; Cr - 0.05 ppm; Fe - 0.07 ppm; Mn - 0.05 ppm; Zn - 0.03 ppm; Cu - 0.01 ppm), as the earth worm can store the heavy metals in the gut. Further the Bio-resource can secrete acids of biological and biochemical value which can immobilize the Cr by reducing the Cr (vi) to Cr (iii), which is of low solubility and less carcinogenic.

Hence it is recommended to the farming community that in a polluted environment where purity of soil and water becomes bleak, it is advisable to use a Bio-geo resource friendly earthworm which can sustain the environmental health as well pay much dividends to the farming community, as well reduce their fertilizer bill. Further this technique gives the scope of making an organism more energy efficient as well prevent their state of extinction.

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