Surindra Suthar

Nitrate contamination in groundwater of some rural areas of Rajasthan, India.

Efforts were made to evaluate the level of nitrate in some agro-economy based rural habitations of northern Rajasthan, India. A total of 64 groundwater samples from 21 different villages/sub-villages of district Sri Ganganagar, India were collected and analyzed for nitrate (as NO(3)(-)), sulphate (as SO(4)(2-)) and few other parameters. NO(3)(-) level in groundwater was 7.10-82.0 mg l(-1) for individual samples. But average NO(3)(-) for total samples was 60.6+/-33.6 (SD) mg l(-1), which indicates the non-suitability of groundwater for drinking purposes, if BIS permissible limit (22.6 mg l(-1)) is considered as reference level. SO(4)(2-) ranged form 28.6 to 660.3 mg l(-1) in this area. The regression analysis indicates the difference sources for NO(3)(-) and SO(4)(2-) contamination in different regions rather than a common source. The point and non-point sources of NO(3)(-) and SO(4)(2-) in groundwater of this region may be N-fertilizer, sewerage, animal waste, organic manure, geology of sub-surface soil layers, pit latrines, etc. Results thus indicated that groundwater of this part of the State is severely polluted due to anthropogenic activities. The continuous consumption of such water may pose serious health hazardous in local residents.

Feasibility of vermicomposting in biostabilization of sludge from a distillery industry

The feasibility of vermicomposting technology to stabilize the distillery industry sludge mixed with a bulking agent (cow dung) in different proportions viz. 20% (T1), 40% (T2), 60% (T3) and 80% (T4), was tested using composting earthworm Perionyx excavatus for 90 days. The vermitreated sludge was evaluated for different physico-chemical parameters and all vermibeds expressed a significant decrease in pH (10.5-19.5%) organic C contents (12.8-27.2%), and an increase in total N (128.8-151.9%), available P (19.5-78.3%) as well as exchangeable K (95.4-182.5%), Ca (45.9-115.6%), and Mg contents (13.2-58.6%). Data suggested that inoculated earthworms could maximize the decomposition and mineralization rate, if sludge is used with appropriate bulking material for earthworm feed. Vermicomposting also caused significant reduction in total concentration of metals: Zn (15.1-39.6%), Fe (5.2-29.8%), Mn (2.6-36.5%) and Cu (8.6-39.6%) in sludge. Bioconcentration factors (BCFs) for metals in different treatments were also calculated and the greater values of BCFs indicate the capability of earthworms to accumulate a considerable amount of metals in their tissues from substrate. The reproduction biology of P. excavatus in different treatments was also monitoring during experimentation and they showed the maximum rate of biomass gain, growth (mg weight worm(-1) week(-1)) and cocoon production rate in T2, while least values of these parameters were in T4 treatment. The feasibility of earthworms to mitigate the metal toxicity and to enhance the nutrient profile in sludge might be useful in sustainable land restoration practices at low-input basis.

Vermistabilization of municipal sewage sludge amended with sugarcane trash using epigeic Eisenia fetida (Oligochaeta).

Efforts have been made in this study to stabilize the sewage sludge mixed with sugarcane trash in four different proportions: 20% (T(1)); 40% (T(2)); 60% (T(3)) and 80% (T(4)), under laboratory conditions using epigeic earthworm (Oligochaeta) Eisenia fetida. The composting potential of worm was also evaluated in 100% sewage sludge treatment (T(5)). The changes in chemical properties of substrate was measured at the end. The vermicomposted material showed decrease in organic C (4.8-12.7%) and exchangeable K (3.2-15.3%) content, whereas increase in total N (5.9-25.1%) and available P (1.2-10.9%), exchangeable Ca (2.3-10.9%) and exchangeable Mg (4.5-14.0%) contents. Vermicomposting process caused considerable reduction in concentration of diethylene-triaminepentaacetic acid (DTPA) extractable metals: Cu (4.98-30.5%), Fe (5.08-12.64%), Mn (3.31-18.0%), Zn (2.52-15.90%) and Pb (2.38-20.0%). E. fetida showed the better growth performances in first three treatments (T(1)-T(3)) possibly due to higher content of organic matter (supplied by bulking agent, i.e. sugarcane trash). The earthworm mortality was higher in vermibeds those contained more sludge proportions. Study revealed that vermicomposting might be an efficient technology to convert negligible municipal sewage sludge into value-added products. The feasibility of earthworms to mitigate the metal toxicity and to enhance the nutrient profile might be useful to convert noxious sludge into useful products, at low-input basis.

Bioconcentrations of metals (Fe, Cu, Zn, Pb) in earthworms (Eisenia fetida), inoculated in municipal sewage sludge: do earthworms pose a possible risk of terrestrial food chain contamination?

Efforts have been made to evaluate the possible risks of metal bioaccumulation in composting earthworms during vermicomposting of hazardous wastes, e.g., sewage sludge. The sewage sludge was diluted by mixing cow dung in different proportions, and vermicomposted sludge as well as inoculated earthworms were analyzed for metal (Fe, Cu, Zn, Pb) contents. The sludge processed by worms showed a significant reduction in concentration of metals, Cu (29.4–51.6%), Fe (13.1–19.9%), Zn (15.2–25.8%), and Pb (4.6–46.9%), at the end. A considerable concentration of metals, total Cu (16.7–27.6 mg kg−1), total Fe (42.9–89.8 mg kg−1), total Zn (5.85–75.0 mg kg−1), and total Pb (1.79–12.4 mg kg−1), in composting earthworms was also recorded. The greater values of bioconcentration factors for metals suggested the possible risk of entering contaminants in higher food chains; since, earthworms are near to the terrestrial food chain, they can potentially mediate metal transfer from soil to a range of predators, including birds. Therefore, feasibility of vermitechnology in hazardous waste recycling needs close attention in respect to possible risk of environmental contamination.

Potential of domestic biogas digester slurry in vermitechnology

This work illustrates the potential of domestic biogas digester slurry in vermicompost production. To achieve the objectives biogas plant slurry (BGS) was mixed with crop residues (CR) in different ratios to produce seven different feed mixtures for earthworm Eisenia fetida. After 15weeks vermicomposted material was analyzed for different chemical parameters. In all waste mixtures, a decrease in pH, organic C and C:N ratio, but increase total N, available P and exchangeable K was recorded. C:N ratio of end material (vermicompost) was within the agronomic acceptable limit (<20). The reproduction biology of E. fetida in different waste mixture was also monitored and they showed excellent biomass gain as well as cocoon production in all waste mixtures. The results clearly suggested that vermitechnology could be a potential technology to convert byproducts of domestic biogas plant slurry into some value-added products.

Contaminated drinking water and rural health perspectives in Rajasthan, India: an overview of recent case studies

Access to safe drinking water is an important issue of health and development at national, regional, and local levels. The concept of safe drinking water assumes greater significance in countries like India where the majority of the population lives in villages with bare infrastructures and poor sanitation facilities. This review presents an overview of drinking water quality in rural habitations of northern Rajasthan, India. Although fluoride is an endemic problem to the groundwater of this region, recently, other anthropogenic chemicals has also been reported in the local groundwater. Recent case studies indicate that about 95% of sites of this region contain a higher fluoride level in groundwater than the maximum permissible limit as decided by the Bureau of Indian Standards. Nitrate (as NO

Potential of Allolobophora parva (Oligochaeta) in vermicomposting

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Vermicomposting of vegetable-market solid waste using Eisenia fetida: impact of bulking material on earthworm growth and decomposition rate.

contamination has appeared as another anthropogenic threat to some intensively cultivable rural habitations of this region. Biological contamination has appeared as another issue of unsafe drinking water resources in rural areas of the state. Recent studies have claimed a wide variety of pathogenic bacteria including members of the family Enterobacteriaceae in local drinking water resources. Overall, the quality of drinking water in this area is not up to the safe level, and much work is still required to establish a safe drinking water supply program in this area.

Earthworms as bioindicator of metals (Zn, Fe, Mn, Cu, Pb and Cd) in soils: Is metal bioaccumulation affected by their ecological category?

The aim of this study was to assess the potential of Allolobophora parva Eisen as a candidate for vermicomposting practices. Five organic waste mixtures: cow dung (CD), biogas plant slurry (BGS), cow dung+vegetable waste (CD+VW), BGS+VW and VW+Soil were vermicomposted using A. parva. Vermicomposting showed a decrease in pH, organic C and C:N ratio, but increase total N, available P and exchangeable K at the end. C:N ratio of end material (vermicompost) was within the agronomic acceptable limit (<20). The high level of NPK in worm-processed material indicates the candidature of this species for waste management operations. The earthworm also showed an excellent growth in different wastes. Results thus indicate that A. parva appeared a potential tool for conversion of organic wastes into value added products for sustainable land restoration practices.