Biological Treatment of Textile Wastewater and Its Re-Use in Irrigation: Encouraging Water Efficiency and Sustainable Development

Abstract

The present study focused on the isolation of potential bacteria from contaminated soil of textile industries and subsequent employment of those organisms in treatment of textile waste-water. Wastewater was treated by novel isolates and the biologically treated wastewater was used for the irrigation (phytotoxicity evaluation) of two important edible crop plants (Brassica nigra and Cyamopsis tetragonolobus). For this, plants were grouped as I, II, III and IV that received the tap water, raw effluent, chemically treated and biologically treated wastewater respectively. 46 bacterial isolates were obtained and optimization of parameters revealed that one strain, namely UBL-27 (Comamonas sp. UBL 27) decolorized the wastewater to a max. of 80% in static (anoxic) condition at pH 8 in 24 hours at 32oC. There was a remarkable performance in the germination percentage under biologically-treated wastewater to about 83.6% when compared to that of Control Group producing 92.9%. In contrast to this, the germination % was significantly too low (p≤0.05) in the other cases with the raw wastewater and chemically treated wastewater. The wastewater had marked effect on the growth of the Brassica nigra, the height of the plant was higher in the biologically treated effluent (11.2 ± 0.4 cm) and control group (12.1±0.2) than Group II (8.9±.17 cm) and Group III (9±0.2 cm). Weight of the plant was 1.95±0.35 g and 1.68±0.47 g in Group I and Group IV. It was significantly lower in case of Group II and Group III. In Cyamopsis tetragonolobus, heights of the plant among the four groups at the end of 80 days were 102.3±3.4, 52±7.6, 45.3±4.9 and 92.8±5 cm respectively. Similarly, no. of leaves/plant among the four groups was 49.2±3.2, 26.8±4.5, 32±2.4 and 47±4.5. Total yield of the plant under the experimental area for Group I was 3.15±0.09 kg while that of the Group IV was 2.92±0.09 kg. The yield was significantly lower in the Group II and III such as 1.67±0.17 kg and 2.06±0.22 kg respectively. To consolidate, the raw effluent has decreased the yield by more than 45% (p≤0.05) while that of the chemically treated group by more than 30%. Though, biologically treated wastewater may not be absolutely fit for drinking purposes or for recycling in dyeing processes, it is proved from this, that the eco-friendly alternative can be used for the irrigation purposes beside abatement of water and soil pollution.