Biological perchlorate reduction in packed bed reactors using elemental sulfur.
Sulfur-utilizing perchlorate (ClO4-)-reducing bacteria were enriched from a denitrifying wastewater seed with elemental sulfur (S0) as an electron donor. The enrichment was composed of a diverse microbial community, with the majority identified as members of the phylum Proteobacteria. Cultures were inoculated into bench-scale packed bed reactors (PBR) with S0 and crushed oyster shell packing media. High ClO4-concentrations (5-8 mg/L) were reduced to < 0.5 mg/L at an empty bed contact time (EBCT) of 13 h. Low C1O4- concentrations (60-120 microg/L), more typical of contaminated groundwater sites, were reduced to < 4 microg/L at an EBCT of 7.5 h. PBR performance decreased when effluent recirculation was applied or when smaller S0 particle sizes were used, indicating that mass transfer of ClO4- to the attached biofilm was not the limiting mechanism in this process, and that biofilm acclimation and growth were key factors in overall reactor performance. The presence of nitrate (6.5 mg N/L) inhibited ClO4- reduction. The microbial community composition was found to change with ClO4- availability from a majority of Beta-Proteobacteria near the influent end of the reactor to primarily sulfur-oxidizing bacteria near the effluent end of the reactor.
Sahu
Ashish K
AK
Aquateam-Norwegian Water Technology Centre A/S, Oslo, Norway.
Conneely
Teresa
T
Nüsslein
Klaus R
KR
Ergas
Sarina J
SJ
D001419:Bacteria / Q000378:metabolism*; D019149:Bioreactors; D004785:Environmental Pollutants / Q000737:chemistry / Q000378:metabolism; D017744:Medical Waste Disposal; D010084:Oxidation-Reduction; D010472:Perchlorates / Q000737:chemistry / Q000378:metabolism*; D013455:Sulfur / Q000737:chemistry*
D004785:Environmental Pollutants; D017744:Medical Waste Disposal; D010472:Perchlorates; D013455:Sulfur; C494474:perchlorate