HEAVY METAL REMOVAL IN A COMBINED UASB-DFAF AND HUASB-DFAF SYSTEM REACTORS TREATING MUNICIPAL WASTEWATER

Abstract

Heavy metal pollution has nowadays becomes a serious environmental problem. Various methods for heavy metal removal from wastewater have been extensively studied in recent years. This study is carried out to investigate the removal of heavy metals (HMs) in a combined UASB-DFAF and HUASB-DFAF systems in treating municipal wastewater. The experiment was carried out as a lab scale model involving combinations of up-flow anaerobic sludge blanket as a primary treatment system, followed by down flow aerobic filter as a secondary treatment. Performance of UASB-DFAF is compared with HUASB-DFAF system to treat the heavy metals of Cd, Pb, Al, As, Zn, Mn and Fe. The removals of heavy metals were investigated in the UASB-DFAF and HUASB-DFAF against hydraulic retention time (HRT) of 23 hours, 15 hours and 11 hours. Influent COD concentration was fed into the reactors at a constant rate of 1000 mg/l. The influent is a mixture of modified domestic wastewater with glucose, peptone and meat extract. Effluent samples were collected from the reactors and were analyzed for concentration of heavy metals. Concentration of metals decreases from 0.17 to 0.04 µg/L with time for cadmium (Cd), from 10.4 to 0.88 µg L-1 for (Pb), from 36.64 to 7.12 µg L-1 for Zinc (Zn), from 2.93 to 1.56 µg L-1 for Arsenic (As), from 3077 to 650.57 µg L-1 for Ferum (Fe), from 61.53 to 13.01 µg L-1 for (Al) and increase from 349.28 to 453.03 µg L-1 for (Mn). All heavy metals analyses were conducted using ICP-MS and AAS.