Selectively enriched mixed sulfate-reducing bacteria for acrylamide biodegradation

Acrylamide (AM) is a carcinogen and neurotoxicant, and its growing application in numerous industrial processes is contaminating the environment. In addition, the inhibitory effect of AM makes its biodegradation in the environment challenging. This study investigated AM degradation using a selectively enriched inoculum of mixed sulfate-reducing bacteria (SRB) isolated from a local wastewater treatment plant in Daegu, Korea. The use of SRB is promising for effectively treating several environmental pollutants, but the feasibility for biodegrading AM has not yet been reported. Experimental results showed that 73% AM (initial concentration: 7 mM) biodegradation was achieved in just 120 h, together with 42% and 96% TOC and sulfate removal, respectively. In addition, the SRB performance was not significantly affected by a threefold increase in the AM concentration; biodegradation performance dropped by only 12%. These results imply SRB immunity toward lethal contaminants and the viability of using SRB in different treatment processes. The kinetic results of batch studies enabled development of a pseudo-first-order kinetic model for AM biodegradation, TOC, and sulfate removal. In addition, although the sulfate removal efficiency was affected by a higher sulfate loading, it had little effect on AM and TOC removal. This study shows the potential of using SRB to effectively degrade recalcitrant pharmaceutical pollutants.