Evaluating the removal of organic fraction of commingled chemical industrial wastewater by activated sludge process augmented with powdered activated carbon

Abstract

Three different technologies, namely, individual activated sludge (AS) biodegradation, powdered activated carbon (PAC) absorption, and a combination of absorption and biodegradation (PAC–AS), were applied to treat commingled chemical industrial wastewater from a chemical industrial park in Tianjin, China. Experimental results showed that chemical oxygen demand and total organic carbon of organic matters in the PAC–AS system were reduced by 64.4% and 68.1% respectively. These results suggested the considerable additive effects of both AS degradation and PAC adsorption. Organic matter fractionation was employed to reveal the removal characteristics of organic compounds during treatment. AS degradation preferred to remove the compounds in hydrophilic and transphilic neutral fractions, whereas PAC absorption removed the compounds in hydrophobic fractions. Further chemical identification analysis showed that hydrophobic fraction mainly contained carboxylic acids, esters, and aromatic structures. Hydrophilic and transphilic neutral fractions contained phenol compounds. Most aromatic acids-like compounds were identified in transphilic acid (TPI-A) fraction. Esters in hydrophobic neutral fraction and phenols in hydrophobic acid fraction were easily removed by biodegradation and adsorption during treatment. However, aromatic acids-like compounds, which were dominant compounds in TPI-A fraction, were difficult to biodegradation and adsorption.