Post-treatment impacts of a novel combined hydrogen peroxide (H2O2) oxidation and WOx/ZrO2 catalysis used for the removal of 1,4-dioxane and chlorinated volatile organic compound (CVOC) contaminants were investigated in soil and groundwater microbial community. This treatment train removed ~90% 1,4-dioxane regardless of initial concentrations of 1,4-dioxane and CVOCs. The Illumina Miseq platform and bioinformatics were used to study the changes to microbial community structure. This approach determined that dynamic shifts of microbiomes were associated with conditions specific to treatments as well as 1,4-dioxane and CVOCs mixtures. The biodiversity was observed to decrease only after oxidation under conditions that included high levels of 1,4-dioxane and CVOCs, but increased when 1,4-dioxane was present without CVOCs. WOx/ZrO2 catalysis reduced biodiversity across all conditions. Taxonomic classification demonstrated oxidative tolerance for members of the genera Massilia and Rhodococcus, while catalyst tolerance was observed for members of the genera Sphingomonas and Devosia. Linear discriminant analysis effect size was a useful statistical tool to highlight representative microbes, while the multidimensional analysis elucidated the separation of microbiomes under the low 1,4-dioxane-only condition from all other conditions containing CVOCs, as well as the differences of microbial population among original, post-oxidation, and post-catalysis states. The results of this study enhance our understanding of microbial community responses to a promising chemical treatment train, and the metagenomic analysis will help practitioners predict the microbial community status during the post-treatment period, which may have consequences for long-term management strategies that include additional biodegradation treatment or natural attenuation.
Ibuprofen (IBU) is widely used in the world as anti-inflammatory drug, which posed health risk to the environment. A bacterium capable of degrading IBU was isolated from activated sludge in a sewage treatment plant. According to its morphological, physiologic, and biochemical characteristics, as well as 16S rRNA sequence analysis, the strain was identified as Serratia marcescens BL1 (BL1). Degradation of IBU required the presence of primary substrate. After a five-day cultivation with yeast powder at 30°C and pH 7, the highest degradation (93.47%±2.37%) was achieved. The process of BL1 degrading IBU followed first-order reaction kinetics. The BL1 strain was applied to a small biological aerated filter (BAF) device to form a biofilm with activated sludge. IBU removal by the BAF was consistent with the results of static tests. The removal of IBU was 32.01% to 44.04% higher than for a BAF without BL1. The indigenous bacterial community was able to effectively remove CODMn (permanganate index) and ammonia nitrogen in the presence of BL1.
