IWRA Proceedings

AbstractSeveral industrial wastewater streams may contain heavy metals such as Cd, Cr, Cu, Pb, Zn, etc. including the waste liquids generated by metal finishing or the mineral processing industries. The toxic metals must be effectively treated/removed from the wastewaters. If the wastewaters were discharged directly into natural waters, it will constitute a great risk for the aquatic ecosystem, whilst the direct discharge into the sewerage system may affect negatively the subsequent biological wastewater treatment. In recent years, the removal of heavy metal from sewage, industrial and miningwaste effluents has been widely studied. Their presence in streams and lakes has been responsible for several types of health problems in animals, plants and human beings. Among the many methods available to reduce heavy metal concentration from wastewater, the most common ones are chemical precipitation, ion-exchange, and reverse osmosis. Most of these methods suffer from some drawbacks such as high capital and operational costs, incomplete metal removal, low selectivity, high energy requirements. The aim of the present paper is to study the efficiency of a new process for wastewater treatment by adsorption onto inert solid biomaterials (ISBM) using the batch equilibration technique. These inert solid biomaterials are ground dried plants obtained from Carpobrotus edulis plant. The results show that the inert solid biomaterials present a good retention of heavy metals and phosphate ions from real wastewater. This retention increased with increasing of contact time. The removal percentage of heavy metals from industrial wastewater by Carpobrotus edulis was 94 % for Cd, 91 % for Cu, 99 % for Pb and 98% for Zn. The maximum adsorption capacity was depending on the type of ions (atomic weight, ionic radius and electronegativity). The results indicate that the chemical oxygen demand (COD) values decrease after contact with ISBM. The results obtained are compared with those obtained from -i) distilled water and -ii) from laboratory solutions with various concentrations. These results indicate that the inert solid biomaterials could be used for removal of heavy metals and pollutant minerals from wastewater.