Assessment of Physico-Chemical Parameters Along with the Concentration of Heavy Metals in the Effluents Released from Different Industries in Kathmandu Valley

Industrial effluents are one of the major sources of environmental pollution. The major objective of the study was to assess the physico-chemical parameters and concentration of heavy metals in industrial effluents of industries in Kathmandu Valley. Physico-chemical parameters like temperature, pH, electrical conductivity, turbidity, total dissolved salts, total suspended solids, hardness, calcium, magnesium, alkalinity, chloride, and nitrate were analyzed. Likewise, the concentration of heavy metals like arsenic (As), cadmium (Cd), iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), nickel (Ni), and lead (Pb) was also determined. On average, total suspended solids, calcium hardness, and nitrate were found above the permissible limits whereas the rest of the Physico-chemical parameters were found within the permissible limits. Regarding heavy metals, the total mean concentration of all the samples was observed in the following sequence: Fe > As > Zn > Mn > Pb > Cu > Ni > Cd. The levels of heavy metals particularly Fe, Pb, Zn, and As were found to exceed the national and international standard limits. The Pearson correlation analysis showed significant correlations ( p < 0.01 and p < 0.05) between most of the metals in the samples of effluents. The result suggested that effluents discharged from various industries are of potential threat to surface and groundwater sources as well as to human health. Thus, the construction of wastewater treatment plants is recommended in every industry for reuse purposes or discharging into the environment. Moreover, strict environmental laws must be created among the industries concerning the potential hazard of industrial effluents to the environment.