Lidia Dąbrowska, Agata Rosińska
The aim of the presented research was to analyse the pollution of the Warta River (Poland) with coplanar PCBs (77, 126 and 169) and heavy metals (Ni, Cd, Pb). Aluminum sulfate and pre-hydrolyzed polyaluminum chloride (PAX-XL10, PAX-XL60, PAX-XL69, PAX-XL1905) were used as coagulants, and the following parameters were analysed in water samples from the Warta River: turbidity, colour, TOC and concentrations of PCBs and heavy metals (Ni, Cd, Pb). Composition of water was modified in order to obtain concentrations of each heavy metal of ca. 0.3 mg/L with implementation of particular amounts of cadmium-, lead nitrate (Cd(NO3)2·4H2O, Pb(NO3)2) and nickel chloride (NiCl2·6H2O). In order to obtain concentration of 300 ng/L in case of each congener, a standard mixture PCB MIX3, which consisted of indicator congeners, was added to water. After application of PAX-XL1905, polyaluminum chloride with the highest alkalinity, the best results (among the investigated coagulants) for chosen contaminants removal were obtained; 92% decrease of turbidity and 63% TOC concentration was acquired. In case of heavy metals, best effects were obtained for lead and cadmium removal using PAX-XL1905. Concentration of these metals was reduced from 0.3 mg/L to 0.07 and 0.12 mg/L, respectively. Good results of lead removal were also obtained with use of the other coagulants: PAX-XL60 and aluminum sulfate; its concentrations were decreased to following values: 0.09, and 0.12 mg/L, respectively. When PAX-XL1905 was applied, the residual aluminum concentration in purified water was below 0.05 mg/L, whereas, when aluminum sulfate was used the concentration was below 0.3 mg/L. The highest removal rates for indicator PCBs were obtained with use of aluminum sulfate. Total concentration of PCBs was reduced by 65%. Removal efficiency for particular congeners amounted from 54% (PCB 77) to 72% (PCB 126).
usuwanie PCB; proces koagulacji
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