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Frequent outbreaks of harmful algal blooms (HABs) have brought adverse impacts on human health, economic viability, and recreational activities in many communities in the United States. Cyanobacteria (or blue‐green algae) blooms are the most common type of HABs in surface water. Current bactericides for controlling the blooms are disadvantageous due to the recycling difficulty. In this study, an innovative magnetic nanomaterial―γFe2O3/TiO2 nanoparticle—was used to inactivate toxic cyanobacteria species found in a lake in Southern Illinois that frequently experienced HABs. Cyanotoxin genes of mcy, nda, cyr, and sxt were used for targeting microcystin‐, nodularin‐, cylindrospermopsin‐, and saxitoxin‐producing cyanobacteria, respectively, by quantitative polymerase chain reaction (PCR) method. It was found that the concentration of chlorophyll a presents a strong correlation (R2 = 0.6024) with the gene copy obtained from 16S rRNA targeted for all cyanobacteria, but not with that from individual toxigenic cyanobacteria. The inactivation efficiencies of the nanomaterials under visible light were as high as 5‐log and 1‐log for cyanobacteria species containing mcyE/ndaF and sxtA genes, respectively, an improvement over the treatment under darkness. These nanomaterials can be recycled by their magnetic properties for reuse. Communities susceptible to HAB outbreaks are expected to benefit from the developed method for mitigating the blooms. Practitioner points Lab‐made γFe2O3/TiO2 nanoparticles can be used to inactivate microcystin/nodularin‐ and saxitoxin‐producing cyanobacteria species. qPCR method can be used for targeting toxic cyanobacteria; Chl a cannot be used as a standalone indicator for HABs. Better inactivation efficiency under visible light indicated possible application of the technology under sunlight for HAB mitigation from surface water.

A two-chambered microbial fuel cell (MFC) was used for the first time for the remediation of an emerging contaminant-1,4-dioxane in its anode chamber. Groundwater historically detected 1,4-dioxane contamination was sampled from a Superfund site.Comparative study was carried out between metabolic (i.e., 1,4-dioxane as sole carbon source) and cometabolic (i.e., 1,4-dioxane and methanol as carbon sources) anodic degradations. It was found that cometabolic degradation increased 1,4-dioxane removal by 10%-52% after 7 days and increased maximum power production of the MFC by 18% to 88.9 mW/m 3 . Oxalic acid was detected as a main metabolic degradation product. Beside oxalic acid, acetic acid and isopropanol were also detected as main products for cometabolic degradation. The presence of a biofilm for 1,4-dioxane anodic degradation was observed by a scanning electron microscopy. Phyla of Bacteroidetes, Firmicutes, and Proteobacteria, as well as a variety of species, were identified for the first time-especially Rikenella sp. and Solitalea canadensis, whose relative abundances were the highest of 18.8% and 24.0% for metabolic and cometabolic degradation, respectively. This study provided an innovative and sustainable approach for 1,4-dioxane anodic biodegradation, which would be potentially utilized for remediation of groundwater contaminated by 1,4-dioxane. © 2019 Water Environment Federation • Practitioner points• Groundwater contaminated with 1,4-dioxane was remediated in the anode chamber of a two-chambered microbial fuel cell. • Cometabolic pathway increased 1,4-dioxane removal and power production of the MFC compared to metabolic pathway. • The presence of a biofilm for 1,4-dioxane anodic degradation was observed, and oxalic acid was a main degradation product. • This study would be potentially utilized for 1,4-dioxane-contaminated groundwater remediation with simultaneous energy production. • External voltage supply for bioelectrochemical remediation of groundwater would potentially be reduced when treating chlorinated hydrocarbons co-occurred with 1,4-dioxane.

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