Meat & bone meal (MBM) incineration ash for phosphate removal from wastewater and afterward phosphorus recovery

Abstract

Abstract Meat & bone meal ash (MBMA), the bottom ash collected from a UK industrial-scale incinerator in a power plant with meat & bone meal (MBM) as the mono-energy source, was characterised in terms of its elemental and crystalline compositions. MBMA has high phosphorus concentration (13.48% P, or 31.31% P2O5) and low hazardous element content. The phosphorus present in it, which mainly in the form of hydroxyapatite (HAP), would only release at initial acid leaching pH lower than 2.7 at solid: liquid ratio of 1:1 (wt.). Then MBMA was used for P removal from synthetic phosphate wastewater in batch adsorption experiments. The removal of P can be completed over a wide range of initial pH within an hour with removal capacity ∼115 mg g−1 being achieved. The main P removal mechanisms can be explained by HAP precipitation because of the MBMA seeding effect. After the wastewater treatment process, P content of the ash was increased from 13.48% to 16.18% (or 37.06% P2O5), and the acid consumption for P recovery from the ash after wastewater treatment was reduced by 20% compared with the original MBMA. The acid consumption under optimized conditions was as low as ∼3 mM H+/mM P. The application of MBMA for P-containing wastewater treatment not only offered the benefit of wastewater remediation, but it also contributed greatly to the feasibility of using MBMA for P recovery.