Effect of feeding time on the performance of a sequencing batch reactor treating a mixture of 4-CP and 2,4-DCP

Date

2007-06-01

Author

ŞAHİNKAYA, Erkan
Dilek, Filiz Bengü

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This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

This paper investigated the biodegradation kinetics of 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) separately in batch reactors and mixed in sequencing batch reactors (SBRs). Batch reactor experiments showed that both 4-CP and 2,4-DCP began to inhibit their own degradation at 53 and 25 mgl(-1), respectively, and that the Haldane equation gave a good fit to the experimental data because r(2) values were higher than 0.98. The maximum specific degradation rates (q(m)) were 130.3 and 112.4 mg g(-1) h for 4-CP and 2,4-DCP, respectively. The values of the half saturation (K-s) and self-inhibition constants (K-i) were 34.98 and 79.74 mgl(-1) for 4-CP, and 13.77 and 44.46 mgl(-1) for 2,4-DCP, respectively. The SBR was fed with a mixture of 220 mgl(-1) of 4-CP, 110 mgl(-1) of 2,4-DCP, and 300 mgl(-1) of peptone as biogenic substrate at varying feeding periods (0-8 h) to evaluate the effect of feeding time on the performance of the SBR. During SBR operation, in addition to self-inhibition, 4-CP degradation was strongly and competitively inhibited by 2,4-DCP. The inhibitory effects were particularly pronounced during short feeding periods because of higher chlorophenol peak concentrations in the reactor. The competitive inhibition constant (K-ii) of 2,4-DCP on 4-CP degradation was 0.17 mgl(-1) when the reactor was fed instantaneously (0 h feeding). During longer feedings, increased removal/loading rates led to lower chlorophenol peak concentrations at the end of feeding. Therefore, in multi-substrate systems feeding time plus reaction time should be determined based on both degradation kinetics and substrate interaction. During degradation, the meta cleavage of 4-chlorocatechol resulted in accumulation of a yellowish color because of the formation of 5-chloro-2-hydroxymuconic semialdehyde (CHMS), which was further metabolized. Isolation and enrichment of the chlorophenols-degrading culture suggested Pseudomonas sp. and Pseudomonas stutzeri to be the dominant species. (C) 2006 Elsevier Ltd. All rights reserved.

Subject Keywords

Environmental Engineering, Waste Management and Disposal, Management, Monitoring, Policy and Law, General Medicine

URI

https://hdl.handle.net/11511/35835

Collections

Department of Environmental Engineering, Article