A two-stage design enhanced biodegradation of high concentrations of a C16-alkyl quaternary ammonium compound in oxygen-based membrane biofilm reactors.

Quaternary ammonia compounds (QAC), such as hexadecyltrimethyl-ammonium (CTAB), are widely used as disinfectants and in personal-care products. Their use as disinfectants grew during the SARS-CoV-2 (COVID-19) pandemic, leading to increased loads to wastewater treatment systems and the environment. Though low concentrations of CTAB are biodegradable, high concentrations are toxic to bacteria.

Simultaneous biodegradation kinetics of 1,4-dioxane and ethane.

Biodegradation of 1,4-Dioxane at environmentally relevant concentrations usually requires the addition of a primary electron-donor substrate to sustain biomass growth. Ethane is a promising substrate, since it is available as a degradation product of 1,4-Dioxane's common co-contaminants. This study reports kinetic parameters for ethane biodegradation and co-oxidations of ethane and 1,4-Dioxane.

Identifying biodegradation pathways of cetrimonium bromide (CTAB) using metagenome, metatranscriptome, and metabolome tri-omics integration.

Traditional research on biodegradation of emerging organic pollutants involves slow and labor-intensive experimentation. Currently, fast-developing metagenome, metatranscriptome, and metabolome technologies promise to expedite mechanistic research on biodegradation of emerging organic pollutants. Integrating the metagenome, metatranscriptome, and metabolome (i.

Phenotypic and Transcriptional Responses of Biofilms to UV-C Irradiation via Side-Emitting Optical Fibers: Implications for Biofouling Control.

Biofilms give rise to a range of issues, spanning from harboring pathogens to accelerating microbial-induced corrosion in pressurized water systems. Introducing germicidal UV-C (200-280 nm) irradiation from light-emitting diodes (LEDs) into flexible side-emitting optical fibers (SEOFs) presents a novel light delivery method to inhibit the accumulation of biofilms on surfaces found in small-diameter tubing or other intricate geometries. This work used surfaces fully submerged in flowing water that contained , an opportunistic pathogen commonly found in water system biofilms.

Co-metabolic biodegradation of chlorinated ethene in an oxygen- and ethane-based membrane biofilm reactor.

Groundwater contamination by chlorinated ethenes is an urgent concern worldwide. One approach for detoxifying chlorinated ethenes is aerobic co-metabilims using ethane (CH) as the primary substrate. This study evaluated long-term continuous biodegradation of three chlorinated alkenes in a membrane biofilm reactor (MBfR) that delivered CH and O via gas-transfer membranes.

The structure of biodegradable surfactants shaped the microbial community, antimicrobial resistance, and potential for horizontal gene transfer.

While most household surfactants are biodegradable in aerobic conditions, their biodegradability may obscure their environmental risks. The presence of surfactants in a biological treatment process can lead to the proliferation of antimicrobial-resistance genes (ARG) in the biomass. Surfactants can be cationic, anionic, or zwitterionic, and these different classes may have different effects on the proliferation ARG.

A synergistic platform enables co-oxidation of halogenated organic pollutants without input of organic primary substrate.

While co-oxidation is widely used to biodegrade halogenated organic pollutants (HOPs), a considerable amount of organic primary substrate is required. Adding organic primary substrates increases the operating cost and also leads to extra carbon dioxide release. In this study, we evaluated a two-stage Reduction and Oxidation Synergistic Platform (ROSP), which integrated catalytic reductive dehalogenation with biological co-oxidation for HOPs removal.

Coremoval of Energetics and Oxyanions via the In Situ Coupling of Catalytic and Enzymatic Destructions: A Solution to Ammunition Wastewater Treatment.

Ammunition wastewater contains toxic nitrated explosives like RDX and oxyanions like nitrate and perchlorate. Its treatment is challenged by low efficiency due to contaminant recalcitrance and high cost due to multiple processes needed for separately removing different contaminant types. This paper reports a H-based low-energy strategy featuring the treatment of explosives via catalytic denitration followed by microbial mineralization coupled with oxyanion reduction.

Reductive Dehalogenation of Herbicides Catalyzed by PdNPs in a H-Based Membrane Catalyst-Film Reactor.

More food production required to feed humans will require intensive use of herbicides to protect against weeds. The widespread application and persistence of herbicides pose environmental risks for nontarget species. Elemental-palladium nanoparticles (PdNPs) are known to catalyze reductive dehalogenation of halogenated organic pollutants.

Hydrodehalogenation of Trichlorofluoromethane over Biogenic Palladium Nanoparticles in Ambient Conditions.

Among a number of persistent chlorofluorocarbons (CFCs, or freons), the emissions of trichlorofluoromethane (CFCl, CFC-11) have been increasing since 2002. Zero-valent-Pd (Pd) catalysts are known to hydrodehalogenate CFCs; however, most studies rely on cost-inefficient and eco-unfriendly chemical synthesis of PdNPs and harsh reaction conditions. In this study, we synthesized Pd nanoparticles (PdNPs) using biomass as the support and evaluated hydrodehalogenation of CFC-11 catalyzed by the biogenic PdNPs.

Wastewater treatment for ships experiencing large temperature changes： the activated sludge/membrane-biofilm reactor.

A particular challenge to treatment systems for ship wastewater comes from low and variable temperatures. We evaluated the temperature response (35-15 °C) of a novel biological treatment system involving activated sludge followed by a membrane-biofilm reactor: the activated sludge/membrane-biofilm reactor (AS-ABfMemR). In this study, a pilot-scale AS-ABfMemR achieved over 96% chemical oxygen demand (COD) and 94% total nitrogen (TN) removal from a ship wastewater (550-960 mgCOD·L and 52-77 mgTN·L) with a continuous operation with a hydraulic retention time of 12 h at 25 °C.

Palladium (Pd) Loading-Controlled Catalytic Activity and Selectivity for Chlorophenol Hydrodechlorination and Hydrosaturation.

Reductive catalysis by zero-valent palladium nanoparticles (PdNPs) has emerged as an efficient strategy for promoting the detoxification of chlorophenols (CPs) hydrogenation. Most studies achieved hydrodechlorination of CP to phenol for detoxification, but it requires considerably high energy input and harsh conditions to further hydrosaturate phenol to cyclohexanone (CHN) as the most desired product for resource recovery. This study documented 4-CP hydrodechlorination and hydrosaturation catalyzed by PdNPs deposited on H-transfer membranes in the H-based membrane catalyst-film reactor, which yielded up to 99% CHN selectivity under ambient conditions.

Hydrodefluorination of Perfluorooctanoic Acid in the H-Based Membrane Catalyst-Film Reactor with Platinum Group Metal Nanoparticles: Pathways and Optimal Conditions.

PFAAs (perfluorinated alkyl acids) have become a concern because of their widespread pollution and persistence. A previous study introduced a novel approach for removing and hydrodefluorinating perfluorooctanoic acid (PFOA) using palladium nanoparticles (PdNPs) in situ synthesized on H-gas-transfer membranes. This work focuses on the products, pathways, and optimal catalyst conditions.

Reductive destruction of multiple nitrated energetics over palladium nanoparticles in the H-based membrane catalyst-film reactor (MCfR).

Nitrated energetics are widespread contaminants due to their improper disposal from ammunition facilities. Different classes of nitrated energetics commonly co-exist in ammunition wastewater, but co-removal of the classes has hardly been documented. In this study, we evaluated the catalytic destruction of three types of energetics using palladium (Pd) nano-catalysts deposited on H-transfer membranes in membrane catalyst-film reactors (MCfRs).

Adsorption and Reductive Defluorination of Perfluorooctanoic Acid over Palladium Nanoparticles.

Per- and polyfluoroalkyl substances (PFASs) comprise a group of widespread and recalcitrant contaminants that are attracting increasing concern due to their persistence and adverse health effects. This study evaluated removal of one of the most prevalent PFAS, perfluorooctanoic acid (PFOA), in H-based membrane catalyst-film reactors (H-MCfRs) coated with palladium nanoparticles (PdNPs). Batch tests documented that PdNPs catalyzed hydrodefluorination of PFOA to partially fluorinated and nonfluorinated octanoic acids; the first-order rate constant for PFOA removal was 0.

H-Based Membrane Catalyst-Film Reactor (H-MCfR) Loaded with Palladium for Removing Oxidized Contaminants in Water.

Scalable applications of precious-metal catalysts for water treatment face obstacles in H-transfer efficiency and catalyst stability during continuous operation. Here, we introduce a H-based membrane catalyst-film reactor (H-MCfR), which enables in situ reduction and immobilization of a film of heterogeneous Pd catalysts that are stably anchored on the exterior of a nonporous H-transfer membrane under ambient conditions. In situ immobilization had >95% yield of Pd in controllable forms, from isolated single atoms to moderately agglomerated nanoparticles (averaging 3-4 nm).

A Synergistic Platform for Continuous Co-removal of 1,1,1-Trichloroethane, Trichloroethene, and 1,4-Dioxane via Catalytic Dechlorination Followed by Biodegradation.

Groundwater co-contaminated with 1,4-dioxane, 1,1,1-trichloroethane (TCA), and trichloroethene (TCE) is among the most urgent environmental concerns of the U.S. Department of Defense (DoD), U.

-Chlorophenol (4-CP) Removal by a Palladium-Coated Biofilm: Coupling Catalytic Dechlorination and Microbial Mineralization via Denitrification.

Rapid dechlorination and full mineralization of para-chlorophenol (4-CP), a toxic contaminant, are unfulfilled goals in water treatment. Means to achieve both goals stem from the novel concept of coupling catalysis by palladium nanoparticles (PdNPs) with biodegradation in a biofilm. Here, we demonstrate that a synergistic version of the hydrogen (H)-based membrane biofilm reactor (MBfR) enabled simultaneous removals of 4-CP and cocontaminating nitrate.

Stable dechlorination of Trichloroacetic Acid (TCAA) to acetic acid catalyzed by palladium nanoparticles deposited on H-transfer membranes.

Trichloroacetic acid (TCAA) is a common disinfection byproduct (DBP) produced during chlorine disinfection. With the outbreak of the Coronavirus Disease 2019 (COVID-19) pandemic, the use of chlorine disinfection has increased, raising the already substantial risks of DBP exposure. While a number of methods are able to remove TCAA, their application for continuous treatment is limited due to their complexity and expensive or hazardous inputs.

Increased expression of antibiotic-resistance genes in biofilm communities upon exposure to cetyltrimethylammonium bromide (CTAB) and other stress conditions.

Quaternary ammonium compounds (QAC, e.g., cetyltrimethylammonium bromide, (CTAB)) are widely used as surfactants and disinfectants.

Long-Term Continuous Co-reduction of 1,1,1-Trichloroethane and Trichloroethene over Palladium Nanoparticles Spontaneously Deposited on H-Transfer Membranes.

1,1,1-Trichloroethane (1,1,1-TCA) and trichloroethene (TCE) are common recalcitrant contaminants that coexist in groundwater. H-induced reduction over precious-metal catalysts has proven advantageous, but its application to long-term continuous treatment has been limited due to poor H-transfer efficiency and catalyst loss. Furthermore, catalytic reductions of aqueous 1,1,1-TCA alone or concomitant with TCE catalytic co-reductions are unstudied.

The Nature and Oxidative Reactivity of Urban Magnetic Nanoparticle Dust Provide New Insights into Potential Neurotoxicity Studies.

The recent discovery of magnetic nanoparticles (NPs) in human brain tissue has raised concerns regarding their source and neurotoxicity. As previous studies have suggested that magnetite in urban dust may be the source, we collected urban magnetic dust and thoroughly characterized the nature of ambient urban magnetic dust particles prior to investigating their neurotoxic potential. In addition to magnetite, magnetic dust contained an abundance (∼40%) of elemental iron (Fe).

Accurate O delivery enabled benzene biodegradation through aerobic activation followed by denitrification-coupled mineralization.

Although benzene can be biodegraded when dissolved oxygen is sufficient, delivering oxygen is energy intensive and can lead to air stripping the benzene. Anaerobes can biodegrade benzene by using electron acceptors other than O , and this may reduce costs and exposure risks; the drawback is a remarkably slower growth rate. We evaluated a two-step strategy that involved O -dependent benzene activation and cleavage followed by intermediate oxidation coupled to NO respiration.

Evolution of the microbial community of the biofilm in a methane-based membrane biofilm reactor reducing multiple electron acceptors.

Previous work documented complete perchlorate reduction in a membrane biofilm reactor (MBfR) using methane as the sole electron donor and carbon source. This work explores how the biofilm's microbial community evolved as the biofilm stage-wise reduced different combinations of perchlorate, nitrate, and nitrite. The initial inoculum, carrying out anaerobic methane oxidation coupled to denitrification (ANMO-D), was dominated by uncultured Anaerolineaceae and Ferruginibacter sp.

Autotrophic antimonate bio-reduction using hydrogen as the electron donor.

Antimony (Sb), a toxic metalloid, is soluble as antimonate (Sb(V)). While bio-reduction of Sb(V) is an effective Sb-removal approach, its bio-reduction has been coupled to oxidation of only organic electron donors. In this study, we demonstrate, for the first time, the feasibility of autotrophic microbial Sb(V) reduction using hydrogen gas (H2) as the electron donor without extra organic carbon source.