Analysis of remediation potential of whole bacterial cells on wastewater decolourisation and detoxification.

Textile effluent is one of the major sources of land and water pollution due to the presence of dyes in addition to other contaminants. The lands receiving these toxic effluents have become deprived of a number of species of natural flora. Competency of indigenous bacterial strains to degrade the dyestuffs present in textile wastewater was evaluated. Decolourization by the bacterial strains was found to be 36%, 66% and 89% for B. cereus , B. thurningienis and B. licheniformis , respectively. The comparative analysis showed that COD reduced to 80% by B. cereus , 82% by B. thuringiensis and 93% by B. licheniformis whereas BOD reduced to 61% by B. cereus , 65% by B. thuringiensis and 69% by B. licheniformis. TS, TDS, TVS and TSS contents reduced to 34%, 89%, 21%, 9% by B. cereus , 36%, 98%, 30%, 41% by B. thuringiensis and 43%, 99%, 43% and 49% by B. licheniformis. Seed germination and growth of Triticum eastivum was used as an indicator to study the phytotoxic effects of textile mill effluents. Plants grown with treated effluent showed maximum growth of plumule and radical and such properties may be helpful to develop alternatives for the management of dyeing wastewater. Maximum tolerance index and minimum relative toxicity and percentage phytotoxicity was found with bioremidiated textile industrial effluent. This study showed the effectiveness of biological pretreatment involving appropriate microorganisms. Bioremediation, no doubt, is an inexpensive and environment friendly approach for eradication of toxic effects caused by dyes and ultimately the conservation of natural flora. Studies have shown toxic effects of textile discharges on plant growth and seed germination. Unfortunately knowing the facts about their serious environmental and health threats, the untreated mill waste water is allowed to flow in crop fields, river and drinking water. In this study, the bioassay used for mill effluent toxicity was established on assessing the changes in shoot and root elongation of Triticum aestivum using as a test plant. Significant reduction in shoot and root length was observed when plant grown in the presence of untreated effluent as compared to bioremidiated effluent and control after 7 days. Image 1 • Three Bacillus strains effectively decolorized the textile effluent by adsorption. • Bacilli highly reduced biological and chemical oxygen demand of effluent. • Total solid contents of effluent removed radically with all three Bacillus strains. • Plants grown with biological treated effluent showed maximum growth of plumule and radical. • Minimum percentage phytotoxicity was found with bioremediated industrial effluent. [ABSTRACT FROM AUTHOR]