Transformation of di-n-butyl phthalate in an anaerobic/anoxic/oxic leachate treatment process

Transformation of di- n -butyl phthalate (DBP) was investigated in anaerobic/anoxic/oxic (A/A/O) leachate treatment processes. Good removal was achieved under A/A/O conditions. Although the DBP removal was affected by the initial DBP concentration, the overall DBP removal efficiencies for this system were high (> 94%). Only traces of DBP remained in the effluent. The results of mass balance calculations indicated that approximately 33.7–50.7% of the DBP was degraded by the activated sludge, 48.9–64.9% accumulated in the system, and 0.4–1.4% was contained in the final effluent. This confirms that biodegradation and adsorption to activated sludge are both major mechanisms for DBP removal from leachate. The results of correlations between the DBP removal efficiencies and leachate contaminants indicated that the total nitrogen (TN) and total phosphorus (TP) may be key factors influencing the biodegradation of DBP. Half of the DBP in the system adsorbs on the activated sludge. This differs from previous studies in which DBP was mostly biodegraded. DBP is not completely removed when it adsorbs onto sludge. Therefore, methods for decreasing DBP adsorption and increasing the biodegradation efficiencies of the leachate treatment processes should be investigated in future.