Limiting factors of heavy metals removal during anaerobic biological pretreatment of municipal solid waste landfill leachate

An anaerobic biofilm reactor was used to pretreat a typical municipal solid waste landfill leachate. It challenging remove Fe, Pb, and Ni meet the discharge-to-sewer standards at hydraulic retention time (HRT) typically in previous studies. This work further systematically studied factors that limited metal removal. The HRT removal because required sulfides precipitation more than 3.5 times of HRT. Sulfide availability only slightly since adding sulfate above stoichiometric requirement improved by 5–11%. Via experiments combined with modeling, it found bisulfide dominant complex Fe removal, but humic acids-metal Pb Ni. When total dissolved sulfide concentration is <18 mg/L, substances are limiting three metals bisulfide. On other hand, when >250 substances.