Effect of high salinity on yeast activated sludge reactor operation

Yeast activated sludge was developed and operated at salinities of 0, 15, 30, 45, and 60 g/l NaCl. The kinetics of the various sludges degrading a wastewater with glycerol as the carbon source were determined. Inhibition due to salinity was analyzed and it was found that the limiting concentration of NaCl is 120 g/l. Salinity affects the maximum growth rate of the sludge. Reactors were exposed to shock salinity changes. Salt shocks affected maximum growth rate of the reactors but treatment was still effective. The effect of pH adjustment was investigated and it was determined that hourly adjustments of pH led to the most effective treatment outcomes. Finally, DNA of the reactors was investigated. Although Scheffersomyces spartinae (Debaryomycetaceae family) was clearly more suited to the high salinity environment than other yeast species, even at high salinity the number of species was diverse. This suggests the potential to use a number of yeast species for high salinity wastewater treatment.