Key points are not available for this paper at this time.
In this study, we investigated the effects of sodium chloride (concentrations ranging from 0to60g∕L) on the performance of sequencing batch reactors (SBRs) using a microbial culture developed from a domestic sewage treatment plant. The lab-scale SBRs were fed with synthetic wastewater (acetate as the organic substrate) containing either sodium chloride solution or seawater to ensure consistency in feed composition. It was found that sodium chloride concentrations of up to 10g∕L stimulated substrate removal. The organic removal efficiency decreased from 96%, when no sodium chloride was added, to 86% when 60g∕L of sodium chloride was introduced into the influent wastewater. Effluent turbidity increased significantly when the sodium chloride concentration in the wastewater was equal to or above 30g∕L even though the sludge volume index (SVI) decreased. The increase in effluent turbidity could be caused by the release of nondissolved cellular components due to plasmolysis of microorganisms as observed by scanning electron microscopy. Experiments involving seawater (with 20g∕L total dissolved solids) showed that organic removal efficiency improved from 87 to 95% while effluent turbidity and SVI values were lowered when the loading rate parameter (Li) was lowered from 0.6to0.3mg total chemical oxygen demand (mg VSS day). Optical microscopy and scanning electron microscopy indicated morphological changes in the microbial population. From this study, it was concluded that microbial culture from domestic wastewater facilities could be acclimated in a SBR to treat wastewater containing sodium chloride concentrations of up to 60g∕L.
Ng et al. (Mon,) studied this question.