Bioremediation of industrial effluent at source using aquatic macrophytes

Kerala State in India has 4.3% of the total number of small-scale industries in the country which is around 4,52,826 and this number is increasing per annum. Even though industrialization and urbanization are considered as the steppingstone to a country’s development, the effluents released into the water bodies may lead to unrepairable damage to the aquatic environment thereby affecting livelihood of coastal people. The present investigation was done in Cochin inshore waters (9° 59’ 12. 56” N and 76° 16’ 20. 74” E) polluted due to effluent discharge into the canal water connecting to the sea through the lake. The chemical parameters showed wide variation in ammonia content in effluent water which was found to be very high with a value of 4.05 mg/l compared to the normal estuarine water (0.14 mg/l) and was 96% higher in effluent water. Similarly, the phosphate and silicate content of the effluent water was about 84.3 and 87.6% higher than the normal estuarine water. The presence of heavy metals like zinc as well as copper was also observed in the effluent. Experiment conducted in the laboratory using aquatic plants like Eichhornia crassipes, Pistia stratiotes and mangrove such as Rhizophoramucronata and Bruguiera gymnorrhiza for 5 days showed increase in DO and BOD level with decreasing TSS and nutrients. The absorption of ammonium ion was quite low, ranging from 4.0 -10.5%, but toxicity of ammonia was observed to affect the aquatic plant and mangrove used for treatment. The biosorption study was carried out for the removal of heavy metals from the effluent by passing through a column packed with seaweed powder of Sargassum wightti and Kappaphycus alvarezii. Sargassum could accumulate zinc 17.6 (mg/kg) and copper (1.96 mg/kg) whereas Kappaphycus could accumulate 76.1 (mg/kg) of zinc and 16.64 (mg/kg) of copper in different effluent collected from outfall area leaving the elute below the detection level. The main aim of this study is to bring forth a new concept of eco-friendly processes to counter contamination of water bodies by phytoremediation using various aquatic plants and suggest the industries to implement this cost effective technology of effluent treatment. This will ensure reuse of freshwater and protect the fragile aquatic system from pollution besides mining the heavy metals from the seaweed through phytomining.