Abstract
Selenate removal from a water body is being vigorously debated owing to severe health impact, but inhibitions of coexisting anions have been reported. To suggest a viable treatment option, this study investigates the effect of nitrate and perchlorate on selenate reduction in a laboratory-scale sequencing batch reactor. The experimental design tests how competing electron acceptors (NO3− and ClO4−) and electron donor (acetate) limitations affect selenate reduction in the reactor. Results show that the reactor achieves almost complete selenate reduction within the initial concentration ranges of 0.1–1 mM by enriching selenate-reducing bacteria with appropriate temperature (30 °C) and acclimation period (50 days). We monitored simultaneous selenate and nitrate reduction in the reactor without specific inhibition due to a difference in microbial growth strategy related to electron donor status. Lack of perchlorate-reducing bacteria makes perchlorate addition (0.2 mM) not to be closely associated with dissimilative perchlorate reduction. These results provide information that can help us to understand the effect of competing electron acceptors on selenate reduction and the kinetics of potential parallel reactions in the reactor.
Highlights
IntroductionSelenium (Se) is an essential micronutrient but can cause adverse health effects (e.g. hair loss, fingernail loss, numbness in fingers or toes, and circulatory problems) with long-term and heavy exposure [1,2]
Selenium (Se) is an essential micronutrient but can cause adverse health effects with long-term and heavy exposure [1,2]
sequencing batch reactor (SBR) at 30 ◦ C selenate was reduced to below detection level after nine days. This result indicates that 30 ◦ C, higher than room temperature, is more appropriate for the growth of selenate-reducing bacteria, which is consistent with previous literature [14,20,21]
Summary
Selenium (Se) is an essential micronutrient but can cause adverse health effects (e.g. hair loss, fingernail loss, numbness in fingers or toes, and circulatory problems) with long-term and heavy exposure [1,2]. The United States Environmental Protection Agency permits the maximum concentration limit (MCL) of total Se as 50 μg/L and the regulations of national primary drinking water as 5 μg/L [2]. Most Se primarily exists either selenate (SeO4 2− ) or selenite (SeO3 2− ). Both oxyanions are toxic to living organisms various treatment technologies have been investigated to remove Se from water [7]. Physicochemical technologies effectively separate Se from the water supplied for domestic and industrial use, eventual post-treatments for the byproducts are required and technical limitations are still existing [8].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
