Textile industries release huge amount of effluents to aquatic systems, which contain toxic and hazardous pollutants degrading the environment. A laboratory scale study was conducted to characterize physicochemical parameters of local textile industrial effluents and evaluate their impact on aquatic macrophytes and algae. Total suspended solids (TSS) and total dissolved solid (TDS) was found 100 to 336 mg/L and 1856 to 4356 mg/L, respectively. The recorded pH was 9.6 to 11.2 and temperature 40.5 to 43°C. Dissolved oxygen (DO), biological oxygen demand (BOD) and chemical oxygen demand (COD) was recorded 0.11 to 0.5, 151.24 to 299.1 and 652.8 to 2304 mg/L, respectively. Electrical conductivity (EC) was monitored 2210 to 6020 μs/cm; salinity was found 1.1 to 3.3 ‰, and color 1890.75 to 5625 PCU. Zinc (Zn), cadmium (Cd), copper (Cu) were 0.0838 to 0.596, 0.0 to 0.0006, 0.018 to 0.1727 ppm, respectively. Except heavy metals concentrations all of the physicochemical parameters were found beyond the standard limit set by department of Environment (DoE). Textile industrial effluents showed the toxic effects on aquatic macrophytes and algae, as aquatic macrophytes could hardly survive 2 days on textile effluents and noticeable reduction of algal concentration was found when grown on textile effluents. Key words: Textile effluents; Toxic effects; Physicochemical parameter; Aquatic macrophytes; Algae DOI: 10.3329/bjsir.v45i1.5187 Bangladesh J. Sci. Ind. Res. 45(1), 79-84, 2010

Constructed wetlands are treatment systems that use natural processes involving wetland vegetation, soils, and their associated microbial assemblages to improve water quality. These systems can be used commercially for efficient biological treatment of wastewater, and it will also act as a better eco-friendly method when compared with other conventional treatment methods. A constructed wetland pilot scale unit was constructed in the SRM University campus which was allowed to treat wastewater from the sewage treatment plant III. The pilot scale unit was designed based on EPA and CPCB guidelines. The dimension of the constructed wetland was 250 9 150 9 80 cm with a slope of 0.01 (1 %). The design is as per Darcy's law. The wetland unit has a cross section of 3.75 m 2 and has been designed with hydraulic loading of 0.8 m 3 /(m 2 /day) and recommended flow of 3 m 3 /day. The retention time provided for the unit was 24, 48, 72, 96, and 120 h. Phragmites australis also known as common reed was the wetland plant species planted in the unit. Six field trials were carried out during the project and with average removal efficiencies of 75.99 % for BOD, 76.16 % for COD, 57.34 % for TDS, 62.08 % for Nitrate, 58.03 % for Phosphate, 57.83 % for Potassium.

Effluents samples collected from post discharge of equalization tanks of local compositetextile mills of Saver were treated with aquatic macrophytes, algae and their combination. Theywere found to be effective for the reduction of chemical oxygen demand (COD) and pH. Sixty nineper cent of COD was reduced with the combination treatment of Nostoc, Eichhornia crassipes andPistia stratiotes. With the combination treatment of Nostoc and E. crassipes reduced 65 per centCOD in glass containers. pH was reduced from 11.2 to 8.6. Between earthen and glass containers,glass container was found to be more effective.Key words: Industrial effluents; COD; pH; Aquatic macrophytes; AlgaeDOI: 10.3329/jbas.v34i1.5487Journal of Bangladesh Academy of Sciences, Vol.34, No.1, 9-14, 2010

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