Degradation pathway, toxicity and kinetics of 2,4,6-trichlorophenol with different co-substrate by aerobic granules in SBR

The present study deals with cultivation of 2,4,6-trichlorophenol (TCP) degrading aerobic granules in two SBR systems based on glucose and acetate as co-substrate. Biodegradation of TCP containing wastewater starting from 10 to 360 mg L−1 with more than 90% efficiency was achieved. Sludge volume index decreases as the operation proceeds to stabilize at 35 and 30 mL g−1 while MLVSS increases from 4 to 6.5 and 6.2 g L−1 for R1 (with glucose as co-substrate) and R2 (with sodium acetate as co-substrate), respectively. FTIR, GC and GC/MS spectral studies shows that the biodegradation occurred via chlorocatechol pathway and the cleavage may be at ortho-position. Haldane model for inhibitory substrate was applied to the system and it was observed that glucose fed granules have a high specific degradation rate and efficiency than acetate fed granules. Genotoxicity studies shows that effluent coming from SBRs was non-toxic.

► Biodegradation of TCP (10–360 mg L−1) containing wastewater was achieved in SBR. ► Spectral studies show that the biodegradation occurred via chlorocatechol pathway and modified ortho-cleavage. ► TCP Biodegradation kinetics followed the Haldane model for inhibitory substrate. ► Genotoxicity studies shows that effluent coming from SBRs was non-toxic. ► In our opinion, the present technique offers an attractive alternative to remove the TCP containing wastewater by aerobic granules in SBR.