Use of starch and potato peel waste for perchlorate bioreduction in water

The cost of carbon substrates for microbial reduction of perchlorate (ClO4 ) is central to the success and competitiveness of a sustainable bioremediation strategy for ClO4 . This study explored the potential application of starch in combination with an amylolytic bacterial consortia and potato peel waste for ClO4 bioreduction. We obtained a potent amylolytic bacterial consortium that consisted of a Citrobacter sp. S4, Streptomyces sp. S2, Flavobacterium sp. S6, Pseudoxanthomonas sp. S5, Streptomyces sp. S7, and an Aeromonas sp. S8 identified by 16S rDNA sequencing. ClO4 concentration substantially decreased in purified starch medium inoculated with the amylolytic bacterial consortium and Dechlorosoma sp. perclace. Potato peel waste supported ClO4 reduction by perclace with the rate of ClO4 reduction being dependent on the amount of potato peels. Over 90% ClO4 removal was achieved in 4 days in a single time point experiment with 2% (w/v) potato peels waste. ClO4 reduction in a non-sterile 0.5% potato peel media inoculated with perclace occurred with an initial concentration of 10.14F0.04 mg L 1 to 2.87F0.4 mg L 1 (71.7% reduction) within 5 days. ClO4 was not detected in the cultures in 6 days. In a non-sterile 0.5% potato media without perclace, ClO4 depletion occurred slowly from an initial value of 9.99F0.15 mg L 1 to 6.33F0.43 mg L 1 (36.63% reduction) in 5 days. Thereafter, ClO4 was rapidly degraded achieving 77.1% reduction in 7 days and not detected in 9 days. No susbstantial reduction of ClO4 was observed in the sterile potato peel media without perclace in 7 days. Redox potential of the potato peel cultures was favorable for ClO4 reduction, decreasing to as low as 294 mV in 24 h. Sugar levels remained very low in cultures effectively reducing ClO4 and was substantially higher in sterilized controls. Our results indicate that potato peel waste in combination with amylolytic microorganisms and Dechlorosoma sp. perclace can be economically used to achieve complete ClO4 removal from water.