Integration of microbial reductive dehalogenation with persulfate activation and oxidation (Bio-RD-PAO) for complete attenuation of organohalides

Abstract

Due to the toxicity of bioaccumulative organohalides to human beings and ecosystems, a variety of biotic and abiotic remediation methods have been developed to remove organohalides from contaminated environments. Bioremediation employing organohalide-respiring bacteria (OHRB)-mediated microbial reductive dehalogenation (Bio-RD) represents a cost-effective and environmentally friendly approach to attenuate highly-halogenated organohalides, specifically organohalides in soil, sediment and other anoxic environments. Nonetheless, many factors severely restrict the implications of OHRB-based bioremediation, including incomplete dehalogenation, low abundance of OHRB and consequent low dechlorination activity. Recently, the development of in situ chemical oxidation (ISCO) based on sulfate radicals (SO 4 ·− ) via the persulfate activation and oxidation (PAO) process has attracted tremendous research interest for the remediation of lowly-halogenated organohalides due to its following advantages, e.g., complete attenuation, high reactivity and no selectivity to organohalides. Therefore, integration of OHRB-mediated Bio-RD and subsequent PAO (Bio-RD-PAO) may provide a promising solution to the remediation of organohalides. In this review, we first provide an overview of current progress in Bio-RD and PAO and compare their limitations and advantages. We then critically discuss the integration of Bio-RD and PAO (Bio-RD-PAO) for complete attenuation of organohalides and its prospects for future remediation applications. Overall, Bio-RD-PAO opens up opportunities for complete attenuation and consequent effective in situ remediation of persistent organohalide pollution.

Phosphorus Removal and Storage Polymer Synthesis by Tetrasphaera-Related Bacteria with Different Carbon Sources

“…Biological phosphorus removal is more cost-effective and sustainable than chemical phosphorus removal in wastewater treatment. , Polyphosphate-accumulating organisms (PAOs) use polyphosphate (poly-P) as an energy source under carbon-rich anaerobic (feast) condition and convert carbon sources into biomacromolecules such as polyhydroxyalkanoates (PHA). Under the subsequent carbon-deficient aerobic (famine) condition, phosphate is accumulated as poly-P. − Organic carbon source is a key factor influencing P release and uptake activities. , The classical PAO model was established with Candidatus Accumulibacter, where volatile fatty acids (VFAs) served as carbon sources. , Fermentative PAOs such as Tetrasphaera were studied more recently, which can hydrolyze complex substrates including amino acids and sugars and are not limited to the circulating glycogen and PHA to gain energy for growth. − In many wastewater treatment plants (WWTPs), Tetrasphaera (1.3–11.9%) can be more abundant than Ca . Accumulibacter (0–2.9%), indicating their potentially overlooked roles in phosphorus removal …”

“…6,7 The classical PAO model was established with Candidatus Accumulibacter, where volatile fatty acids (VFAs) served as carbon sources. 8,9 Fermentative PAOs such as Tetrasphaera were studied more recently, which can hydrolyze complex substrates including amino acids and sugars and are not limited to the circulating glycogen and PHA to gain energy for growth. 10−12 In many wastewater treatment plants (WWTPs), Tetrasphaera (1.3−11.9%) can be more abundant than Ca.…”