ABSTRACT
Wastewaters contaminated by both selenium and ammonium need to be treated prior to discharge into natural water bodies, but there are no studies on the simultaneous removal of selenium and ammonium. A sequencing batch reactor (SBR) was inoculated with activated sludge and operated for 90days. The highest ammonium removal efficiency achieved was 98%, while the total nitrogen removal was 75%. Nearly a complete chemical oxygen demand removal efficiency was attained after 16days of operation, whereas complete selenate removal was achieved only after 66days. The highest total Se removal efficiency was 97%. Batch experiments showed that the total Se in the aqueous phase decreased by 21% with increasing initial ammonium concentration from 50 to 100mgL-1. This study showed that SBR can remove both selenate and ammonium via, respectively, bioreduction and partial nitrification-denitrification and thus offer possibilities for treating selenium and ammonium contaminated effluents.
Subject(s)
Ammonium Compounds/isolation & purification , Batch Cell Culture Techniques/methods , Bioreactors/microbiology , Selenic Acid/isolation & purification , Sewage/microbiology , Biodegradation, Environmental , Biological Oxygen Demand Analysis , Nitrates/isolation & purification , Nitrites/isolation & purification , Nitrogen/isolation & purification , Selenium/isolation & purification , Time FactorsABSTRACT
A peptide hydrogel with an antimicrobial activity is developed as a bandage contact lens. The antimicrobial activity is enhanced with the addition of the biomolecules penicillin G or poly-ε-lysine and is positive against Staphylococcus aureus and Escherichia coli. The lens is also noncytotoxic toward a human corneal epithelial cell line and as a consequence is of great potential as a drug-eluting bandage lens replacing conventional corneal ulcer treatment.
Subject(s)
Anti-Bacterial Agents , Escherichia coli/growth & development , Hydrogels , Penicillin G , Polylysine , Staphylococcus aureus/growth & development , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Contact Lenses , Cornea/microbiology , Epithelial Cells/microbiology , Humans , Hydrogels/chemistry , Hydrogels/pharmacology , Penicillin G/chemistry , Penicillin G/pharmacology , Polylysine/chemistry , Polylysine/pharmacologyABSTRACT
This study investigated bioreduction of selenite by anaerobic granular sludge in the presence of heavy metals and analyzed the fate of the bioreduced selenium and the heavy metals. Selenite bioreduction was not significantly inhibited in the presence of Pb(II) and Zn(II). More than 92% of 79 mg/L selenite was removed by bioreduction even in the presence of 150 mg/L of Pb(II) or 400mg/L of Zn(II). In contrast, only 65-48% selenite was bioreduced in the presence of 150-400 mg/L Cd(II). Formation of elemental selenium or selenide varied with heavy metal type and concentration. Notably, the majority of the bioreduced selenium (70-90% in the presence of Pb and Zn, 50-70% in the presence of Cd) and heavy metals (80-90% of Pb and Zn, 60-80% of Cd) were associated with the granular sludge. The results have implications in the treatment of selenium wastewaters and biogenesis of metal selenides.
