Heavy metal removal by sulfate‐reducing bacteria in recycled construction waste filter systems
Antje Stahl, Jonas Rudolph, Anne Rannefeld, Katrin Rübner, Harald Kurkowski, Wolfgang Eden, Zakaria Istanbuly, Nils Och, Frank Hlawatsch, Jan KueverAbstract
Calcium silicate masonry units (CS) and autoclaved aerated concrete (AAC) represent major fractions of construction waste in Germany, offering only limited recycling options. Current attempts suggest a reuse in urban water storage (sponge city concept) or stormwater filtration systems. Filter performance can be enhanced by applying specific bacteria, providing beneficial metabolic features. Sulfate‐reducing bacteria (SRB) promote heavy metal (HM) precipitation by the production of hydrogen sulfide (H 2 S), resulting in the formation of insoluble metal sulfides. This study investigated the potential of SRB to contribute to heavy metal removal in AAC and CS‐based filter systems, quantified by inductively coupled plasma optical emission spectrometry (ICP‐OES). pH‐adapted SRB cultures, supplemented with Cu, Pb, and Zn indicated the expected HM precipitation. In co‐incubations with AAC and CS, SRB showed metabolic activity demonstrated by H 2 S formation. However, also intrinsic material related effects on metal removal from the supernatant were observed, masking a potential biological effect under given conditions. Results indicate the potential of SRB‐supported AAC and CS filter systems but also highlight the need for further assessments, especially under field‐like conditions.