Survey of 2,3,7,8-Tetrachlorodibenzo-p-dioxin Biodegradation In Anaerobic Sequencing Batch Reactor

2,3,7,8-tetrachlorinedibenzo-p-dioxin (TCDD) is known as the most toxic compound. Because of high toxicity, high stability and resistance in the environment it is of high importance. Thus, the purpose of this study was to survey the biodegradation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in an anaerobic sequencing batch reactor (ASBR). This study was conducted using an anaerobic sequencing batch reactor (ASBR) which was made from glass with the volume of 3 liters. Main substrate and the auxiliary substrate were TCDD and methanol, respectively. The operation of the reactor consisted of 4 stages of feeding, reaction, settling, and discharge. COD tests on the input substrate and output effluent samples of the reactor were implemented based on the standard methods. TCDD analysis was conducted on the samples by gas chromatography equipped by an ECD detector, and biogas was measured by gas meters. Best performance of the ASBR achieved 99.4% COD removal, 97.5% TCDD removal and 2.32 L/d biogas production, which occurred in the inorganic loading of 2.5 g COD/L.d and TCDD loading of 100 ng/L.d. Evidence indicated that during the increasing of the loading in the first stages of the study pH loss amount was about 1 unit, however, after a long operation the pH of the reactor reached 7.2, which is the indication of stable performance of the anaerobic reactor. It is concluded that TCDD biodegradation by reactor used in this study is possible in the maximum organic loading of about 2.5 g COD/L.d with injection amount of 200 ng/l TCDD.