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Abstract
Experiments were set-up to study the removal efficiency of lead from wastewater (as in the battery wastewater range, i.e. from 5 to 20mg Pb+2fL). Three types of reactor systems were employed in the present study; viz., (i) Activated sludge (AS), (ii) Activated sludge and granular activated carbon (GAC), and (iii) Granular activated carbon under different lead shock loads (5, 10, 15, and 20 mgPb+2fL). Lead toxic effect on biomass was also investigated.
The AS + GAC system gave the highest % COD removal and % Lead metal removal compared with the other two systems (AS System and GAC System). The effluent lead concentration from the AS+GAC system, provided the best results since they were the closest to the limits imposed by the regulations.
The main objective of the present work is to investigate the effect of lead (Pb +2) as a toxic material to wastewater biological treatment by using activated sludge with granular activated carbon. Increasing the lead shock loads resulted in (i) decreasing the maximum specific growth rate (~’H), (ii) decreasing the efficiency of COD removal, and (iii) increasing the lead toxicity for the AS system and the AS + GAC system.
The presence of lead (pb +1) in sewage that needed to be treated by using the activated sludge process produced different effects on the microbial growth. The toxic effect depends on the characteristics and concentration of the metal. However, at low concentrations of lead, relatively high toxic effects on microorganisms - in the activated sludge - were not observed.
Both of the adsorption isotherms, the ”Freundlich equation”, and the ”Langmuir equation” adequately represented the adsorption of lead (pb+2) from wastewater by the GAC (Aqua Sorb TM 1000) .