Valorization of bio-waste for the removal of aluminum from industrial wastewater

Abstract

In recent years, aluminum has been appearing increasingly in the aquatic environment in various ways as a result of human activities. One sustainable method of remediating this is by recycling the waste materials that are used to remove heavy metals from wastewater. The objective of the present work is to develop an environmentally friendly method to remove any aluminum that is present in industrial wastewater. It involves the use of Spent Mushroom Substrate (SMS) from Agaricus Bisporus as an adsorbent. The disposal of SMS creates serious problems in Agaricus Bisporus cultivation. These are both environmental and economic. One solution is to use the SMS as bioremediating agent to remove the heavy metals from the industrial waters. This will make use of a readily available agricultural waste as a valuable resource, as well as decrease the consumption of both chemicals and energy during the removal of heavy metals from wastewater. The upscale feasibility experiments that were conducted in bioreactors have shown that the SMS achieved efficiencies of more than 95% in removing aluminum from wastewater with 2.66 kg of SMS at a hydraulic retention time of 16 days. Output concentrations of less than 1 ppm of aluminum were achieved in most of the bioreactors. In some cases, an aluminum concentration of zero was reached. The experiments revealed the pH of the optimum biosorption to be between 5.9 and 6.5. The best configuration to obtain the highest aluminum removal efficiency was a simple bioreactor that contained SMS without peat. The removal of aluminum remained active for at least 10 weeks in a continuous daily flow of 1 L/day. Its low environmental impact, simplicity and cost effectiveness indicate that the proposed method is well₋suited to the treatment of industrial wastewaters by the use of SMS and, in particular, to the elimination of such metal ions as aluminum.