Comparative Study and Possible Phycoremediation of Effluent of JK Pulp and Paper Mill and Select Heavy Metals on Cyanobacteria

Abstract

Pulp and Paper Mill effluent contains toxic heavy metals like Hg, Cd and Pb. These effluent are deadly toxic to the aquatic organisms as these effluents are discharged into River Nagavalli without biological treatment. The main objective of the present study was to assess the Paper mill effluent: its impact on blue green algae (BGA) and whether BGA can be used for detoxification of the effluent waste water. The contaminated river water contained significant amount of heavy metals. An attempt was made to study the impact of heavy metals like Hg, Cd and Pb present in effluent on BGA/cyanobacterium under laboratory controlled conditions and a strategy was planned to study these heavy metals in combination as mixture. All the heavy metals tested showed stimulation and better growth at sub-lethal concentrations (MAC value) but at higher concentrations heavy metals were deadly toxic. The heavy metals when combined produced higher toxicity. No stimulation in the exposed alga was observed in heavy metal combinations. The algae could remove heavy metals from the effluent of the paper mill. The paper mill effluent though highly toxic but showed better behavior at sub-lethal concentrations towards the cyanobacterium. From the observed data it is evident that Westiellopsis was more tolerant than other BGA tested. This alga has potency to grow under stressful conditions and can be safely used for phycoremediation of paper mill effluent after dilution of the effluent. Along with the tested BGA other aquatic macrophytes in combination can be tried for total biological treatment of paper mill effluent before being discharged into the environment.