Activated carbon from sewage sludge and its application in a combined activated sludge-powdered activated carbon (AS-PAC) treatment

摘要

Surplus biological sludge from wastewater treatment operations was converted into activated carbon and then added to thernaerated vessel of an activated sludge process treating phenol and glucose. Sludge-based activated carbon was found to bernmesoporous in nature, with a good adsorption capacity for large molecular weight compounds, such as tannic acid andrnlimited removal efficiency for smaller molecules such as phenol. The addition of carbon, either sludge-based or commercial,rnenhanced phenol removal from 58% to 98.7% and from 87 to 93% the organic matter removal as measured by the ChemicalrnOxygen Demand (COD) when operated with feed concentrations of 100 mg phenol/l and 2500 mg COD/l. No differencesrnwere found between the activated sludge-activated carbon bench scale continuous reactors operating with either commercialrnor sludge-based activated carbon in spite of the higher adsorption capacity of the former. It is suggested that phenol removalrnby adsorption on activated carbon in the combined AS-PAC system may be impaired by the obstruction of pores due tornbacterial growth, the effect being more important for the commercial activated carbon with a narrower pore size distribution.