Assessment of biostimulation and bioaugmentation for removing chlorinated volatile organic compounds from groundwater at a former manufacture plant

Abstract

Site in a former chemical manufacture plant in China was found contaminated with high level of chlorinated volatile organic compounds (CVOCs). The major contaminants chloroform (CF), 1,2-dichloroethane (1,2-DCA) and vinyl chloride (VC) in groundwater were up to 4.49 × 10, 2.76 × 10 and 4.35 × 10 μg/L, respectively. Ethene and methane were at concentrations up to 2219.80 and 165.85 μg/L, respectively. To test the hypothesis that the CVOCs in groundwater at this site could be removed via biodegradation, biomarker analyses and microcosm studies were conducted. Dehalococcoides 16S rRNA gene and VC-reductase gene vcrA at densities up to 1.5 × 10 and 3.2 × 10 copies/L were detected in some of the groundwater samples, providing strong evidence that dechlorinating bacteria were present in the aquifer. Results from the microcosm studies showed that at moderate concentrations (CF about 4000 μg/L and 1,2-DCA about 100 μg/L), CF was recalcitrant under natural condition but was degraded under biostimulation and bioaugmentation, while 1,2-DCA was degraded under all the three conditions. At high concentration (CF about 1,000,000 μg/L and 1,2-DCA about 20,000 μg/L), CF was recalcitrant under all the three treatments and 1,2-DCA was only degraded under bioaugmentation, indicating that high concentrations of contaminants were inhibitory to the bacteria. Electron donors had influence on the degradation of contaminants. Of the four fatty acids (pyruvate, acetate, propionate and lactate) examined, all could stimulate the degradation of 1,2-DCA at both moderate and high concentrations, whereas only pyruvate and acetate could stimulate the degradation of CF at moderate concentration. In the microcosms, the observed first-order degradation rates of CF and 1,2-DCA were up to 0.12 and 0.11/day, respectively. Results from the present study provided scientific basis for remediating CVOCs contaminated groundwater at the site.

Impact of 6:2 fluorotelomer alcohol aerobic biotransformation on a sediment microbial community

“…For DNA extraction, 0.5 g sediment mixture was aseptically collected from the sample bottle after mixing well (volume ratio of sediment to river water was approximately 2:3) and extracted with FastDNA SPIN kit for soil (MPBIO, USA), according to the manufacturer's protocol. The quality and quantity of the DNA extract was determined by a SMA1000 UV spectrophotometer (Meriton, China) and confirmed by electrophoresis on a 1% agarose gel as previously described (Zhang et al, 2016a). The OD 260 /OD 280 ratio ranged from 1.63 to 1.96, and the DNA concentrations ranged from 79.7 to 186.4 μg/mL.…”

Impact of magnetite nanoparticles on the syntrophic dechlorination of 1,2-dichloroethane

“…A variety of techniques have been developed for the remediation of CAHs. In-situ biostimulation of these dechlorinating populations is one technology which is commonly used due to its low cost and high environmental sustainability, when compared to other technologies (Zhang et al, 2016). This is usually done via the injection of a fermentable electron donor in the subsurface contaminated environment, such as lactate.…”

Natural Magnetite Minerals Enhance 1,2-Dichloroethane Reductive Dechlorination

“…A typical strategy for 1,2-DCA remediation relies on in situ biostimulations of such dechlorinating microorganisms. As compared to other technologies, this approach benefits from generally lower costs and higher environmental sustainability [9]. It usually involves the injection of fermentable electron donors, such as acetate, lactate, citrate, glycerol, etc., directly into the subsurface of the contaminated site [10].…”