Application of Chitosan-Based Filtration Technique for Removal of Heavy Metals from Surface Water

Abstract

Surface water pollution in the surrounding rivers of Dhaka city has been threatening to the supply of potable water to the city dwellers. The major pollution parameters are pH, Turbidity, TDS, EC and Heavy metal concentration which indicates physical and chemical pollution in the river water. During the dry season pollution level in Buriganga River exceeds the surface water standard and it becomes unsuitable for drinking purpose. The objective of the present study was to reduce the level of physico-chemical parameters and heavy metal concentration in surface water by Chitosan adsorbent. Chitosan was prepared in laboratory. The tests were carried out with two different filter where Chitosan-sand and Charcoal-sand were used as adsorbent (filter material). pH was found in river water ranging from 7.8 to 8.0, after chitosan treatment it was reduced and ranged from 7.1 to 7.8. No significant change occurred in charcoal treatment. Highest Turbidity, TDS and EC in river water was found 116 NTU, 192 mg/l and 372 µs/cm respectively and it was reduced by Chitosan with an average efficiency of 94.01 % , 85.33 %., 84.91 %. In the case of Charcoal treatment, the average efficiency was only 23.55 %, 11.41 % and 12.26 % for Turbidity, TDS and EC respectively. Heavy metal Pb, Cr, Zn, and Ni was found in river water ranging from 8.9368 to 10.900 ppm, 70.320 to 73.576 ppm, 16.595 to 19.231 ppm and 6.003 to 6.8730 ppm respectively. This level was significantly reduced by Chitosan with an average efficiency of 99.76 %, 99.89 %, 99.89 % and 99.87% respectively. For Charcoal treatment this efficiency was too low. Using Chitosan for household water treatment process and for water treatment in remote areas or sudden flood areas where chemical treatment is not available, might be considered as an excellent option for water purification.