Impact of Tannery Wastewater Treatment Plant Effluent on Phytoplankton Community of Receiving Stream Heading to Indian-Sundarbans

Abstract

Common Effluent Treatment Plant (CETP) of eastern India leather complex have crucial ecological importance for its close proximity to Indian Sundarbans. Phytoplankton composition in relation to physico-chemical parameters was monitored over 1 year period on direct CETP effluent receiving stream. This stream meets with the Bidyadhari River which flows through the coastal parts of West Bengal and meets with the Bay of Bengal. 3 distinct zones (Upstream, Effluent, and Downstream) were chosen to assess the impact of CETP effluent on receiving stream. Chlorophyceae, Cyanobacteria, Bacillariophyceae, and Euglenophyceae were shown to be dominant in phytoplankton studies. Canonical Correspondence Analysis showed Euglenophyceae was related to most polluted Effluent whereas Bacillariophyceae was closer to least polluted Upstream. Patterns of both Simpson’s diversity index and Simpson’s dominance index clearly indicated alteration in phytoplankton community in the Downstream after mixing of CETP effluent. In contrast to downstream, where pollution was more prevalent (COD 40 mg/dm³) and species diversity was lower (Simpson’s diversity index 6), upstream had lower pollution levels (12 mg/dm³) and more species diversity (15). Discriminant Analysis also supported the above-mentioned fact. The eutrophic condition in the downstream zone is indicated by higher species dominance values (Simpson’s dominance index 0.15) and rich nutrient loads.