A novel eco-friendly recycling of food waste for preparing biofilm-attached biochar to remove Cd2+ and Pb2+ in wastewater

Abstract The development of green and sustainable cleaning technologies to properly reuse food waste and remove heavy metals in wastewater can avoid secondary damage to the environment. Our study proposes an innovative way to prepare an efficient adsorbent by growing biofilm bacteria in food waste and attaching them to biochar also prepared from food waste. Modification of the biochar by bacterial biofilm reduced the specific surface area but increased the average pore and the adsorption performance of Cd2+ and Pb2+. Electrostatic adsorption and the complexation by oxygen-containing functional groups were the main adsorption mechanisms of biofilm-attached biochar, and it was also easily recyclable by re-growth of the biofilm cultured by food waste. In wastewater containing both Cd2+ and Pb2+, the two have competitive adsorption sites on biofilm-attached biochar, but more functional groups participate in removing Cd2+. This study proposes a new idea to reuse food waste and prepare bio-modified biochar adsorbents and provides a strategy to remove Cd2+ and Pb2+ in wastewater by applying biofilm-attached biochar.