Characterization of Solid Waste Leachate and Its Impact on Surface Water Quality: A Case Study at Rajbandh, Khulna, Bangladesh

Abstract

The present study was carried out to characterize leachate from waste dumping site and its impact on surrounding surface water quality at Rajbandh in Khulna. For this purpose, surface water samples (10) and leachate samples (5) were taken from the site during two season the monsoon season and post monsoon respectively. The samples were taken during the daytime from 9 a.m. to 1 p.m because at midday the temperature rises and the physico-chemical parameters of the water are modified. Some physico-chemical parameters such as pH, Electrical conductivity (EC), Total dissolved Solids (TDS), Dissolve Oxygen (DO), Chloride (Cl-), Magnesium (Mg2+), Calcium (Ca2+), Sodium (Na+), Potassium (K+), Biological Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), Iron (Fe2+), Phosphate (PO43-), Sulfate (SO42-), Nitrate (NO32-) were analyzed in the laboratory in accordance with standard laboratory procedure. As well as some heavy metals such as Cadmium, Chromium, Lead, Manganese, Iron and Zinc were also analyzed in the laboratory. It is observed that, the physicochemical characteristics of surface water and leachate samples vary among the parameters in two seasons throughout the study period. The concentration of TDS and EC were found to be high in leachate compare to surface water samples that might be caused due to the existence of high-level various anions and soluble salts with other inorganic components. In monsoon the TDS values ranged from 3227 ± 2357 for leachate and 737 ± 498 for surface water samples whereas in post-monsoon the variation followed by 4640 ± 1790 and 803 ± 232 for surface water and leachate respectively. In case of EC for leachate it varied from 3630 ± 1397 and 4900 ± 1734 for monsoon and post-monsoon seasons correspondingly but varied from 1473 ± 498 in monsoon and 1627 ± 473 in post-monsoon for surface water samples. The high concentration of BOD (3.91 ± 1.54 in monsoon and 6.25 ± 3.27 in post- monsoon) and COD (117.80 ± 58.31 in monsoon and 229.39 ± 166.55 in post-monsoon) value were found in surface water samples compared to leachate samples. In case of Cr for leachate it varied from 0.081 ± 0.029 and 0.070 ± 0.026 for monsoon and post-monsoon seasons correspondingly. As well as the concentration of Cd (0.023± 0.006 in monsoon and 0.087±0.068 in post monsoon) and Pb (0.35±0.109 in monsoon and 0.025±0.013 in post monsoon) varied greatly during both season. The concentration of heavy metals such as Pb, Zn, Cr and Mn in surface water samples was also greater than 0.001mg/l. Further for leachate COD was very strongly correlated with TDS and cadmium. Magnesium was significantly correlated with potassium. For surface water sample TDS was significantly correlated with EC and pH. Chloride was significantly correlated with Cd and pb was correlated with calcium. This study recommended that the authority should take proper steps for the management of waste as well as give emphasis on the leachate collection.