Removal of 1,4-dioxane from industrial wastewaters: routes of decomposition under different operational conditions to determine the ozone oxidation capacity.

This paper denotes the importance of operational parameters for the feasibility of ozone (O3) oxidation for the treatment of wastewaters containing 1,4-dioxane. Results show that O3 process, which has formerly been considered insufficient as a sole treatment for such wastewaters, could be a viable treatment for the degradation of 1,4-dioxane at the adequate operation conditions. The treatment of both synthetic solution of 1,4-dioxane and industrial wastewaters, containing 1,4-dioxane and 2-methyl-1,3-dioxolane (MDO), showed that about 90% of chemical oxygen demand can be removed and almost a total removal of 1,4-dioxane and MDO is reached by O3 at optimal process conditions. Data from on-line Fourier transform infrared spectroscopy provides a good insight to its different decomposition routes that eventually determine the viability of degrading this toxic and hazardous compound from industrial waters. The degradation at pH>9 occurs faster through the formation of ethylene glycol as a primary intermediate; whereas the decomposition in acidic conditions (pH<5.7) consists in the formation and slower degradation of ethylene glycol diformate

1,4 dioxane removal from groundwater using point-of-entry water treatment techniques

This feasibility study investigated the removal of an emerging organic contaminant, 1,4 dioxane, from groundwater using point-of-entry (POE) treatment techniques in response to its discovery in some small New Hampshire groundwater-based private drinking water systems. The New Hampshire Department of Environmental Services (NHDES) is evaluating future treatment options for dioxane contamination of these small, groundwater-based private systems. Treatment technologies assessed for dioxane removal included: air stripping, carbon adsorption, direct UV photolysis, and UV-peroxide (H2O2) oxidation. Criteria used to assess the suitability of these technologies for POE application included: dioxane removal efficiency, capital and operations and maintenance (O & M) cost, ease of use, and safety. Initial tests indicated that air stripping and direct photolysis were not feasible treatment options for a maximum contaminant level (MCL) of 3 mug/L dioxane. Carbon adsorption and UV-Peroxide oxidation were both found to treat dioxane to ≤ 3 mug/L (96% and 82% removal, respectively). This study determined that carbon adsorption using a coconut-based carbon is the most feasible dioxane treatment option for a POE system based on cost evaluations and treatment experience

Bacterial biofilm attachment to sustainable carriers as a clean-up strategy for wastewater treatment: A review

Wastewater treatment using biofilm technology with sustainable carriers contributes towards the circular bioeconomy. The use of renewable biological materials and wastes as novel biofilm supports promotes material valorisation and reusability, decreasing the depletion of natural resources and the generation of waste and emissions. This manuscript presents a comprehensive review of the sustainable bacterial biofilm carriers used in biological wastewater rehabilitation. They include organic and inorganic materials from natural sources such as clays, volcanic rocks, stones, bamboo and luffa fibers and waste-based materials as wood husk, coconut husk, corncob, waste tire rubber, cigarette filter rods, textile wastes, among others. The material characteristics and application performance as sustainable bacterial biofilm carrier to remove several toxic pollutants and nutrients typically found in domestic or industrial effluents, in batch experiments and biofilm reactors were analyzed. Cell attachment and biofilm formation mechanisms are discussed. Processing approaches and surface modifications of the referred materials are presented. The review emphasizes the economic and environmental benefits of sustainable carriers compared to traditional ones. This survey is in tune with the need to explore materials that are included within the principles of circular economy, allowing the application of a more environment friendly and cost-effective water treatment.info:eu-repo/semantics/publishedVersio

Modification of TiO2 with hBN: high temperature anatase phase stabilisation and photocatalytic degradation of 1,4-dioxane /

This paper examines the modification of anatase TiO2 with hexagonal boron nitride (hBN) and the impact this coupling has on the temperature of the anatase to rutile phase transition and photocatalytic activity. All samples were 100% anatase when calcined up to 500 °C. At 600 °C, all BN-modified samples contain mixed rutile and anatase phases, with 8% and 16% BN–TiO2 showing the highest anatase contents of 64.4% and 65.5% respectively. The control sample converted fully to rutile at 600 °C while the BN modified sample converted to rutile only at 650 °C. In addition to TiO2 phase composition, XRD also showed the presence of bulk boron nitride peaks, with the peak at 26° indicating the graphite-like hBN structure. Density functional theory calculations of hBN-rings adsorbed at the anatase (101) surface show strong binding at the interface; new interfacial bonds are formed with key interfacial features being formation of B–O–Ti and N–Ti bonds. Models of extended hBN sheets at the anatase (101) surface show that formation of B–O and N–Ti bonds along the edge of the hBN sheet anchor it to the anatase surface. 16% BN–TiO2 at 500 °C showed a significant increase in the photocatalytic degradation of 1,4-dioxane when compared with pure anatase TiO2 at 500 °C. This arises from the effect of hBN on anatase. The computed density of states (DOS) plots show that interfacing anatase with BN results in a red shift in the TiO2 energy gap; N-p states extend the valence band maximum (VBM) to higher energies. This facilitates transitions from high lying N-p states to the Ti-d conduction band. A simple photoexcited state model shows separation of electrons and holes onto TiO2 and BN, respectively, which promotes the photocatalytic activity.ye

Development of novel adsorbents for the removal of emerging contaminants from water

Emerging contaminants (ECs) such as estrogen hormones, perfluoro compounds (PFCs), bisphenol-A (BPA), and 1,4-dioxane have been detected in natural water at many places. The existing conventional wastewater treatment systems are not designed for the removal of these contaminants. This critical issue leads to the need for the development of advanced and effective technologies.β-cyclodextrin (β-CD) is a glucose-based molecule which has high affinity for different organic contaminants by the formation of host/guest inclusion complexes. In this research, water soluble β-CD was reacted with certain crosslinking agents and copolymers to form water insoluble β-CD and to coat β-CD onto silica particles. The development of such novel hybrid adsorbents provides high binding capacity with organic contaminants along with high mechanical strength. Three different approaches were used to develop adsorbents by using two crosslinking agents (epichlorohydrin (EPI) and hexamethylene diisocyanate (HMDI), two copolymers (glycidoxypropyl trimethoxysilane and aminopropyl triethoxysilane) and three solvents (NaOH, dimethyl formamide (DMF), and dimethyl sulfoxide (DMSO). The developed adsorbents were tested for the removal of ECs of interest (estrogens, PFCs, 1,4-dioxane, and BPA) under batch and column conditions from Milli-Q water. The adsorbent prepared by reacting β-CD with HMDI as crosslinking agent with the molar ratio of 1:8 showed best results in removing the target compounds. The adsorbent showed more than 95% removal of 17β-estradiol (in single component) and more than 90% of most of the estrogens (in multicomponent), more than 99% of PFOA, and a maximum of 90% removal in case of BPA. However, the developed adsorbent did not show any removal in case of 1,4-dioxane. The developed adsorbent showed a good regeneration capacity in removing PFOA over three successive cycles. The characterization of the adsorbents using FTIR, TGA, and TEM confirmed the coating of β-CD onto silica particles. The removal of ECs of interest was dependent on the nature of both adsorbents and adsorbates. The nature of adsorbent such as type of crossling agent, molar ratio between β-CD and crosslinking agents affect the removal of the contaminants. Similarly, the nature of adsorbates such as size, shape, and presence of functional groups affect the removal efficiency.Civil Engineerin

Low Level Quantification of 1,4-Dioxane and Investigation of 1,4-Dioxane Co-Metabolism by Mycobacterium sp. 1A.

1,4-Dioxane (dioxane) is a probable human carcinogen and is often found comingled with chlorinated aliphatic hydrocarbon (CAH) contamination since dioxane is used as a stabilizer in CAH solutions. Dioxane is miscible in water, has a low K[subscript ow], low H[subscript cc], and is highly recalcitrant in the environment. The presence and potential transformation of dioxane at CAH sites undergoing remediation has been difficult to ascertain due to the difficulty of analysis. Typical analyses performed for CAH's, such as direct liquid injection onto a gas chromatograph equipped with a flame ionization detector, are ineffective at detecting dioxane. Methods have been developed to analyze low levels of dioxane, but they require extraction techniques involving the use of harmful solvents and expensive consumables. A method of analyzing environmentally relevant concentrations of 1,4-dioxane in the sub-μg/L range by heated purge-and-trap coupled with gas chromatography mass spectrometry is presented. This method demonstrates a method detection limit of 0.13 μg/L which is below the EPA risk assessment concentration of 0.35 μg/L. Detection at this level has allowed for the characterization of the 1,4-dioxane degradation capabilities of an Actinomycete culture, Mycobacterium sp. 1A (1A). Culture 1A was found to degrade dioxane at rates two to four times faster in the absence of propane than in the presence of propane. Although propane did inhibit dioxane transformation, dioxane was still observed to be completely transformed in the presence of propane. Culture 1A was able to utilize propane or 2-propanol for growth and concurrently transform 100 μg/L of dioxane in mineral salts growth media (MSM) and in amended and non-amended site groundwater. Although culture 1A grew efficiently on 2-propanol, it exhibited lower rates of dioxane transformation than cells grown on propane

COMBINED OZONE AND ULTRASOUND PROCESS FOR THE DESTRUCTION OF 1,4-DIOXANE IN CONTINUOUS FLOW REACTOR

Clean water is essential to life. Growth in world population, changing diets, and a warming climate are driving an increase in the demand for water. Better management of water resources will help prevent scarcity, but in order to fully meet the future demand for safe, clean drinking water, new water treatment technologies are needed. This dissertation investigates a technology which is not well understood; the combination of ozone and ultrasound as potentially an efficient technology. Since nearly all previously published studies of combined ozone/ultrasound utilized batch reactors, a continuous flow reactor was constructed for this research. 1,4-Dioxane, henceforth referred to as dioxane, was chosen to evaluate the effectiveness of the combined ozone/ultrasound process. Dioxane is commonly detected in surface and groundwater and is a suspected human carcinogen. A recalcitrant contaminant, it resists direct oxidation by chlorine, oxygen, ozone, and biological treatment. It is miscible in water and doesn't sorb readily to organic matter, so it spreads rapidly in groundwater contamination plumes. It also resists air stripping and filtration, including reverse osmosis. For these reasons, dioxane makes an excellent candidate to measure the effectiveness of advanced oxidation processes, such as combined ozone/ultrasound. The treatment of dioxane by advanced oxidation processes has been studied extensively in the past. However, only one study has been published using combined ozone/ultrasound, and it was done in a batch reactor operating at a high ultrasonic frequency. The reactor built for this study also permitted reactor pressurization effects to be studied in a manner that has not been reported before for the combined ozone/ultrasound process. In this study, the combination of ozone and ultrasound was found to cause synergistic removal of dioxane from drinking water; the removal achieved by the combination significantly exceeded the sum of the removal achieved by ozone and ultrasound separately. In fact, the combination of ozone and ultrasound was found to remove more than double the dioxane that would be removed by doing both treatment processes separately. Ultrasound (20 kHz) was ineffective in removing dioxane alone, achieving less than 20% removal. At 16 mg/L, ozone alone was found to achieve removal of up to 86% after a 16 minute treatment time, but appears sensitive to matrix effects, especially pH. When ultrasound was combined with just 1.2 mg/L of aqueous ozone, over 90% removal occurred after a 16 minute treatment. Removal of dioxane was found to be driven not by ozone itself, but by radicals, suggesting that the decomposition of ozone is responsible for the generation of radical species and subsequent removal of dioxane. Ultrasound was found to increase the decomposition of ozone and appeared to be driving increased mass transfer of ozone into the aqueous phase. Modest reactor pressure appears to aid dioxane removal, but further increases in pressure did not appear to further enhance removal. An empirical model was constructed using a form similar to the Chick & Watson model for disinfection. Given inputs of initial aqueous ozone concentration, initial dioxane concentration, treatment time, and ultrasonic power, the model is able to predict effluent concentrations of dioxane with a relative root mean squared error of less than 5%. Additionally, RCT and mass balance analyses were performed, and both analysis techniques suggested that the removal of dioxane is dependent on the consumption of aqueous ozone. Spiked drinking water is representative of water that has undergone conventional treatment but requires a polishing step, and the combined ozone/ultrasound has shown promise as a polishing technology. Owing to its recalcitrance, prevalence, and mobility, dioxane represents a real and challenging groundwater contaminant, and combined ozone/ultrasound has shown promise as a groundwater treatment option. Additionally, the process is capable of dioxane removal in a pH range of 4-10. This pH independence, coupled with its ability to degrade recalcitrant contaminants, suggests that combined ozone/ultrasound holds promise as an industrial wastewater treatment option, too. The removal achieved by both ozone and combined ozone/ultrasound was an order of magnitude greater than what has been reported in previously published reports. However, a comparison of cost effectiveness relative to other advanced oxidation processes remains an area for future study. Finally, the combined ozone/ultrasound process holds promise as a drinking water treatment option in remote areas, since it requires only electricity. As a promising technology for polishing water for reuse, treating contaminated groundwater, treating industrial wastewater, and potentially improving access to safe drinking water in remote areas, combined ozone/ultrasound could aid in meeting global water demand in the future.Civil Engineerin

The 21st Annual International Conference on Soils, Sediments and Water

Conference at a Glance Monday, October 17, 2005 Workshops (Workshops #1 and #2: 10:00am - 5:00pm; Workshop #3: 1:00 - 5:00pm; Workshop #4: 1:00 - 3:00pm, Workshop #5: 2:00 - 5:00pm) 1) Theory and Use of Field Portable X-ray Fluorescence for Soil Analysis 2) In-Situ Chemical Oxidation Workshop 3) The Role of Anaerobic Biodegradation Processes in Passive and Enhanced Monitored Natural Attenuation Programs 4) Application of Classic and Emerging Techniques in Environmental Forensics 5) Environmental Fate of Hydrocarbons in Soils and Groundwater Tuesday, October 18, 2005 Platform Presentations 8:30am – Noon Session 1: Environmental Biotechnology Session 2: Ecological Restoration and Natural Treatment Systems Session 3: Pesticides (10:30am – Noon) Session 4: Heavy Metals 1:30 – 5:30pm Session 1: Arsenic Session 2: Bioremediation Session 3: Bioremediation Strategies for Contaminated Soils and Sediments Session 4: Ozone Poster Session 4:00 – 6:00pm, Exhibit Area, First Floor, Campus Center Social 4:30-6:00pm, Exhibit Area, First Floor, Campus Center Workshops 7:00 - 10:00pm 6) Applied Environmental Forensics Workshop 7) Massachusetts Contingency Plan Method 2 Risk Characterizations Wednesday, October 19, 2005 Platform Presentations 8:30am – Noon Session 1: Perchlorate: Emerging Issues and Innovative Remedial Approaches Session 2: Soil Geochemical Background on a Continental Scale Session 3a: Environmental Fate Session 3b: Risk Assessment Session 4: Environmental Stewardship and Proactive Management at Small Arms Ranges 1:30 – 5:30pm Session 1: Ecoterrorism: Research Issues Session 2: Environmental Forensics Session 3a: Legal/Regulatory Session 3b: MTBE Session 4: Bioremediation of Acid Mine Drainage Wastes Poster Session 4:00 – 6:00pm Exhibit Area, First Floor, Campus Center Social 4:30-6:00pm, Exhibit Area, First Floor, Campus Center Workshops 7:00 - 10:00pm 8) In-Situ Thermal Remediation 9) Perchlorate: The Path to Regulatory Standards Setting and Future Assessment & Cleanup Implications 10) NIMS (National Incident Management System) and the Environment Thursday, October 20, 2005 Platform Presentations 8:30am – Noon Session 1: Evolving Strategies for Dealing with Contaminated Sediments Session 2: Pay-for-Performance Remediation Technologies - Methods & Case Studies of Science & Economics Session 3: Phytoremediation Session 4: Site Assessment 1:30 – 5:30pm Session 1: Remediation Session 2: Chemical Oxidation Session 3a: Analysis Session 3b: Indoor Ai