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.
To Bioethics in India book contents
To Eubios Ethics Institute books
To Eubios Ethics Institute home page