Influence of the activated sludge system configuration on heavy metal toxicity reduction

Abstract

The effect of configuration of activated sludge systems on heavy metal toxicity was investigated. Two bench-scale completely mixed activated sludge systems were operated identically in order to determine the toxic effects of Cr(VI), Zn(II) and industrial wastewater on the activated sludge biomass. One system was operated with an aerobic selector and the other without. Batch experiments based on OECD 209 (Organisation for Economic Cooperation and Development) were performed using a respirometer to find out potential toxicity reduction effect of an aerobic selector. The IC 50 (concentration of a chemical that exhibits 50% respiration inhibition) values of Cr(VI), Zn(II) and industrial wastewater in the activated sludge were determined. Results indicated that the heavy metals and industrial wastewater caused less inhibitory effect on the selector activated sludge system in comparison to the conventional activated sludge system. Cr(VI) was found to exert higher inhibition on both systems.

Acute and Chronic Toxicity of Acid Mine Drainage to the Activated Sludge Process

“…Tests were performed during the start-up period, and 8 and 20 days after AMD loading began strength synthetic AMD containing high concentrations of six metals, including Cu and Zn, which are known to exert toxic effects on activated sludge. For example, from previous studies, EC 50 values for Cd, Cu, and Zn range from 15 to 60 mg L -1 (Alkan et al 2008;Kelly et al 2004;Gutiérrez et al 2002;Sher et al 2000). However, EC 50 values in the current study ranged from 19 to 52% AMD.…”

“…the treatability of AMD by activated sludge. The activated sludge process is widely used to treat municipal and industrial wastewaters, many of which contain metals that can potentially inhibit microbial activity and growth (Alkan et al 2008;Pai et al 2009) and aerobic and anaerobic processes that are critical for plant performance (e.g. removal of organic matter, suspended solids, and nutrients; Chua et al 1999;Ong et al 2003Ong et al , 2004You et al 2009).…”

Pre‐treatment of Industrial Wastewater Polluted with Lead Using Adsorbents and Ultrafiltration or Microfiltration Membranes

“…However, the accumulation of lead inside the biological reactor may inhibit the biological activity of microorganisms and therefore direct biological treatment may be problematic (Hammes et al, 2003;Patidar and Tare, 2004). The level of inhibition depends on several factors such as the pH value, metal concentration, mixed liquor suspended solids (MLSS) concentration, solubility of the inhibitor, the presence and concentration of other heavy metals or other active or phenomenally inert substances (Juliastuti et al, 2003;Alkan et al, 2008). Consequently, industrial wastewater having high metal concentrations requires suitable pre-treatment in order to enhance the subsequent biological wastewater treatment.…”

Co-Treatment of Acid Mine Drainage With Municipal Wastewater Using the Activated Sludge Process: Preliminary Treatability Studies

“…Successful co-treatment depends on the capacity of the AS process to withstand significant loadings of acidity, heavy metals, and sulphate, whilst maintaining high biological wastewater treatment efficiency. Metals can exert toxic effects on the AS microorganisms that lead to inhibition of microbial activity and growth (Alkan et al, 2008;Pai et al, 2009), thus inhibiting aerobic and anaerobic processes that are critical for plant performance (e.g. removal of BOD, COD, suspended solids, and nutrients) (Chua et al, 1999;Ong et al, 2003;Ong et al, 2004;Xie and Nakamura, 2002;You et al, 2009).…”