Perchlorate removal by the autotrophic bacteria using hydrogen as an electron donor in MBR

Abstract

Since the discovery of perchlorate in the ground water and surface water, there has been increasing concern in human health effect resulting from chronic exposure to perchlorate. In fact, it revealed that perchlorate leads to damage thyroid hormone activity and infant cerebral development. Most perchlorate come from synthetic ones which have been explicitly manufactured as developing aerospace industry and military science. However, perchlorate removal is very difficult because it is highly soluble, mobile and stable in water. In the literature review, we discussed possible technologies including physical, chemical, biological and biochemical reduction. Recent developments were also covered. We took a biological treatment applying the autotrophic bacteria using hydrogen as an electron donor to secure water against perchlorate or apply to the industrial wastewater containing a high level of perchlorate. The reactor for perchlorate treatment was manufactured based on a MBR process. We studied acclimation strategy, nitrate inhibition against perchlorate removal and microbial community change during perchlorate or nitrate removal period. First, two different acclimation types were performed to know how perchlorate affects the non-adapted bacteria during the acclimation period. One was a fed-batch operation having acute toxicity and another was a continuous operation having chronic toxicity. The acclimation period during the fed-batch operation (14 days) was almost half that during the continuous operation (31 days). We also confirmed that the bacteria in the fed-batch operation had a higher activity than the bacteria in the continuous operation through comparison of maximum substrate utilization rate ($q_{max}$); the fed batch one (2.92 mg $ClO_4^-$/mg DW-d) was much higher than the $q_{max}$ of continuous one(0.27 mg $ClO_4^-$/mg DW-d). We increased perchlorate loading rate (PLR) of the continuous operation by 300 mg $ClO_4^-$ /L/d from 50 mg $ClO_4^-$ /L/d t...