The effects of some inhibitory components on biological activated carbon processes

Some experimental results have already reported on a biological activated c arbon (BAC) process to show its effectiveness of the treatment of a kind of wastewater collected from plating industries, in which refractory organic pollutants and small amounts of heavy metal ions existed after physical-che mical treatment. However, the removal behavior of the organic pollutants in the BAC treatment under the existence of inhibitors, such as heavy metal i ons, was not made clear, Therefore, some laboratory-scale experiments were performed using some types of model wastewater. The organic substances chos en as the target pollutants were typical commercial reagents used in platin g industries. The influence of some inhibitory factors. such as concentrati ons of heavy metal ions, pH and salt concentrations on the removal of organ ic substances in the BAC treatment was examined. As a result, it was found that the activated carbon adsorption decreased the inhibition of coexisting heavy metal ions, while the ratio of the inhibition was not reduced by use of activated carbon when salt concentrations or pH values were varied, In addition, different levels of inhibition ratio appeared as different organi c substances were treated and it was Found thar less biodegradable organic substances tended to be affected by heavy metal ions acting as inhibitors. A proposed index, (BOD/COD)/(q/q(0)), could express some relationships with the magnitude of inhibition and with the removal efficiency of the organic pollutants under the conditions that the heavy metal ions coexist. Also, t he possibility of this approach for examinations to evaluate various kinds of treatments was suggested. (C) 1999 Elsevier Science Ltd. All rights rese rved.