Involvement and interaction of microbial communities in the transformation and stabilization of chromium during the composting of tannery effluent treated biomass of Vallisneria spiralis L.

Tannery effluent treated with aquatic macrophyte Vallisneria spiralis L. for 14 d showed significant improvement in physico-chemical properties and reduction in Cr concentration. Accumulation of Cr was found maximum in roots (358 microg g(-1)dw) as compared to shoot (62 microg g(-1)dw) of the plant. A laboratory scale composter was designed with the objectives to investigate the physico-chemical changes and role of microbes in stabilization and transformation of Cr in the composting material. Results revealed that the composting process was quick within 7-21 d as indicated by peak time for various physico-chemical parameters and drop in C/N ratio up to acceptable limit. The profile of microbial communities indicated that population of anaerobic, aerobic and nitrifying bacteria increased quickly at the initial phase, and reached a peak level of 4.2 x 10(6), 9.78 x 10(8) and 9.32 x 10(9) CFU g(-1), respectively at 21 d; while population of actinomycetes and fungi was found maximum i.e. 3.29 x 10(7) and 9.7 x 10(6) CFU g(-1), respectively, after 35 d of composting. Overall bacterial population dominated over the actinomycetes and fungi during the composting process. Cr((VI)) was transformed to Cr((III)) due to the microbial activity during the process. Sequential extraction of Cr fractionation showed its stabilization via changing into organic matter-bound and residual fractions during the composting.

Screening and identification of early warning algal species for metal contamination in fresh water bodies polluted from point and non-point sources.

The water bodies of Lucknow, Unnao and Kanpur (U.P.), India polluted through various point and non point sources were found to be either eutrophic or oligotrophic in nature. These water bodies supported a great number of algal diversity, which varied seasonally depending upon the physico-chemical properties of water. Further, the water bodies polluted through non point sources supports diverse algal species, while the water bodies polluted through point sources supports growth of tolerant blue green algae. High biomass producing algal species growing in these water bodies have accumulated significant amount of metals in their tissues. Maximum amount of Fe was found accumulated by species of Oedogonium sp. II (20,523.00 microg g(-1) dw) and Spirogyra sp. I (4,520.00 microg g(-1) dw), while maximum Chromium (Cr) was found accumulated in Phormedium bohneri (2,109.00 microg g(-1) dw) followed by Oscillatoria nigra (1,957.88 microg g(-1) dw) and Oedogonium sp. I (156.00 microg g(-1) dw) and Ni in Ulothrix sp. (495.00 microg g(-1) dw). Results showed that some of these forms growing in polluted environment and accumulating high amounts of toxic metals may be used as bioindicator species, however, their performance in metal contaminated water under different ecological niche is to be ascertained.

Isolation and characterization of chromate resistant bacteria from tannery effluent.

The tannery effluent emanating from Common Effluent Treatment Plant (CETP), Unnao (U.P, India) was found toxic in nature, having high BOD, COD, TDS and Cr content (5.88 mg l(-1)), which supported growth of chromate tolerant bacteria. Several chromate tolerant bacteria have been isolated from these effluent and maximum tolerant four strains (NBRIP-1, NBRIP-2, NBRIP-3 and NBRIP-4) were characterized in this study. These strains showed multiple metal and antibiotic resistances. Growth of these strains was reduced at higher Cr concentration with extention of lag phase. Chromium accumlulation by these isolates may have a great potential in recovery and detoxification of Cr from tannery effluent.