A study on the Pamba river pollution and its possible treatment strategies

Abstract

The Pamba river water is heavily polluted with suspended and dissolved solids, total and faecal coliforms and heavy metals besides high dissolved organic load. Chlorine has been the most widely used disinfectant for the purification of water systems throughout the world. Pamba river water with high amount of faecal coliforms and suspended solids was subjected to a chlorination dosage of 10 mg/l for 30 minutes contact time followed by dechlorination with sodium thiosulphate. The super chlorination resulted in the doubling of COD and BOD indicating the formation of more recalcitrant highly toxic chlorination derived byproducts. The newely formed compounds were extracted and were subjected to structural analysis by FT/IR, GC/MS and NMR. The data obtained indicated the presence of trihalomethanes and haloacetic acids as the toxic chlorination derived byproducts. Coagulation with alum and flocculation with the natural flocculant, Muringa seed powder were initially carried out for the removal of dissolved and suspended solids along with the removal of high amount of coliforms. The remaining coliforms were eliminated at low dose chlorination with out the formation of high amount of chlorination derived byproducts. These strategies were integrated into a newely designed multistage reactor system for the complete treatment of contaminated water. Filtration through nano silver filter was also included as the terminal stage treatment method.The present treatment strategy developed is very effective and can even be applied online at large scale as an alternate system to the existing water treatment methods newline