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Investigates the effect of adsorption on the biodegradation of nitrilotriacetate (NTA) by Chelatobacter heintzii. Solution degradation of NTA; Desorption of NTA from gibbsite; Desorption-degradation of NTA at pH and pH 6; Desorption-degradation of NTA with equal molar copper (Co) at pH 7; Location of the Co.

Focuses on the disposal of nitrilotriacetic acid (NTA) in soil and subsurface environments. Influence of aqueous geochemistry on NTA degradation; Materials and methods used.

Discusses use of bioreclamation of organochlorine-contaminated soil and groundwater. Description of organohalogens; Limitations of bioremediation of petroleum hydrocarbons; Limited oxygen concentration in presence of extra biodegradable organic carbon; Potential for anaerobic treatment of organic contaminants; Improvements in technology brought about by increasing field experience.

Electrical energy consumption per order ( E EO ) is an important figure-of-merit for the selection and optimization of ultraviolet (UV)-based advanced oxidation processes (UV-AOPs). However, E EO applications are limited by the lack of an accurate and facilitative evaluation method because E EO presents reactor property dependence. In this study, we developed an E EO prediction method for multiscale UV-AOP reactors for micropollutant removal in water. The method utilized the reaction rate constants determined in a reference reactor (e.g., mini-fluidic photoreaction system), complemented by a scale-up method that clarified the dependence of E EO on reactor properties. The predicted results of various UV-AOPs were verified experimentally in four bench/pilot-scale reactors in laboratory and a full-scale flow-through reactor (FFR) in field using sulfamethazine as a model micropollutant. For example, E EO values of 0.105 and 0.058 kWh m -3 order -1 were predicted in the FFR at H 2 O 2 doses of 5 and 10 mg L -1 , respectively, which generally agreed with verification results. Additionally, the developed method could assist the identification of appropriate reactors in the laboratory for E EO measurements, providing a valuable supplement for the E EO prediction in practice. The developed method presents acceptable accuracy, convenience, and low cost, which would significantly facilitate E EO evaluations for practical UV-AOP applications.

Kinetic comparisons of micropollutant degradation by ultraviolet (UV) based advanced oxidation processes among various radiation sources are an important issue, yet this is still a challenge at present. This study investigated comparatively the kinetics of sulfamethazine (SMN) degradation by the UV/H 2 O 2 process among three representative radiation sources, including low-pressure mercury UV (LPUV, monochromatic), medium-pressure mercury UV (MPUV, polychromatic), and vacuum UV(VUV)/UV (dual wavelengths causing different reaction mechanisms) lamps. Experiments were conducted with a newly developed mini-fluidic MPUV photoreaction system and a previously developed mini-fluidic VUV/UV photoreaction system. Measured and modeled results both indicate that the photon fluence-based SMN degradation rate constant ( k p ' ) followed a descending order of VUV/UV/H 2 O 2 > MPUV/H 2 O 2 (200-300 nm) > LPUV/H 2 O 2 , and the k p ' of the MPUV lamp was dependent on the wavelength range selected for photon fluence calculation. Analysis of potential errors revealed that a shorter effective path-length could have a lower error, and the maximum errors for the MPUV/H 2 O 2 and LPUV/H 2 O 2 processes in this study were 7.7% and 18.2%, respectively. This study has developed a new method for kinetic comparisons of micropollutant degradation by UV-AOPs among various radiation sources at bench-scale, which provides useful reference to practical applications.

A vacuum-ultraviolet/ultraviolet (VUV/UV) mercury lamp was found to be a highly efficient radiation source for UV-based advanced oxidation processes (AOPs). If this lamp could enhance the UV/H 2 O 2 process, it would be very attractive. Hence, we have investigated sulfamethazine (SMN) degradation by the VUV/UV/H 2 O 2 process based on a bench-scale mini-fluidic VUV/UV photoreaction system (MVPS), a pilot reactor, and a model analysis. At high [SMN] 0 in the MVPS, the apparent SMN degradation rate constant ( k' app ) increased with increasing H 2 O 2 dose, while at low [SMN] 0 , k' app decreased with increasing H 2 O 2 dose; this behavior was unexpected. Meanwhile, at low [SMN] 0 in a pilot reactor, H 2 O 2 induced just a slight enhancement in the VUV/UV/H 2 O process. A numerical simulation of the process suggested that for an integrated AOP (i.e., VUV/UV/H 2 O 2 ) consisting of various component AOPs, H 2 O 2 could inhibit the component AOPs with HO* that did not originate from H 2 O 2 (e.g., VUV photolysis of water). The apparent H 2 O 2 role in the integrated AOPs was dependent on the contribution comparison between component AOPs that involved HO* that did or did not originate from H 2 O 2 . These results revealed important information regarding the application of the VUV/UV/H 2 O 2 process in water treatment.

The vacuum-ultraviolet/ultraviolet/chlorine (VUV/UV/chlorine) process, with a VUV/UV mercury lamp used as the light source, was found to be a highly efficient advanced oxidation process (AOP) in a previous study. Hence, its application feasibility for trace organic pollutant removal from drinking water becomes attractive. In this work, a bench-scale mini-fluidic VUV/UV photoreaction system was used to determine the degradation kinetics of sulfamethazine (SMN), a model sulfonamide antibiotic frequently detected with trace levels in aquatic environments. Results indicated that SMN (0.1 mg L -1 ) could be degraded rapidly by VUV/UV/chlorine, and a synergism was observed between the VUV/UV and UV/chlorine processes. Photon-fluence based rate constants of SMN degradation were determined to be 6.76 × 10 3 and 8.51 × 10 3 m 2 einstein -1 at chlorine doses of 0.05 and 0.5 mg L -1 , respectively. The presence of natural organic matter in real waters significantly inhibited SMN degradation. In addition, pilot tests were conducted to explore the practical performance of the VUV/UV/chlorine process, thereby allowing electrical energy per order to be calculated for cost evaluation. The effect of flow pattern on photoreactor efficiency was also analyzed by computational fluid dynamics simulations. Both bench- and pilot-scale tests have demonstrated that the VUV/UV/chlorine process, as a new AOP, has potential applications to trace organic pollutant removal in small-scale water treatment.

The performance of a medium-pressure (MP) mercury lamp photoreactor is strongly influenced by the spatial photon fluence rate (PFR) distributions which are wavelength-dependent. To address this issue, PFR distributions in an MP lamp photoreactor were measured using a 360-degree response microfluorescent silica detector (MFSD). To accurately express the optical behavior in an MP photoreactor, PFR, MFSD response PFR (PFR MFSD ), and effective germicidal PFR (PFR GER ) were defined and compared. The measured axial and radial PFR MFSD values agreed well with the corresponding results from a simulation model (UVCalc). The PFR and PFR GER were obtained from the measured PFR MFSD by using correction factors calculated by the UVCalc. Under identical UV transmittance (254 nm) conditions (75% and 85%), the weighted average PFR GER values were 13.3-18.7% lower than the corresponding PFR values, indicating that PFR GER , rather than PFR should be used in MP photoreactor design to meet disinfection standards. Based on measured lamp output, medium absorption spectrum, MFSD response, and microbial DNA response spectrum, the detailed relationships between the PFR, PFR MFSD , and PFR GER were elucidated. This work proposes a new method for the accurate description of wavelength-dependent PFR distributions in MP photoreactors, thus providing an important tool for the optimal design of these systems.

Vacuum ultraviolet (VUV) and ultraviolet (UV)/chlorine processes are regarded as two of many advanced oxidation processes (AOPs). Because of the similar cost of VUV/UV and UV lamps, a combination of VUV and UV/chlorine (i.e., VUV/UV/chlorine) may enhance the removal of organic pollutants in water but without any additional power input. In this paper, a mini-fluidic VUV/UV photoreaction system (MVPS) was developed for bench-scale experiments, which could emit both VUV (185 nm) and UV (254 nm) or solely UV beams with a nearly identical UV photon fluence. The photon fluence rates of UV and VUV output by the MVPS were determined to be 8.88 × 10(-4) and 4.93 × 10(-5) einstein m(-2) s(-1), respectively. The VUV/UV/chlorine process exhibited a strong enhancement concerning the degradation of methylene blue (MB, a model organic pollutant) as compared to the total performance of the VUV/UV and UV/chlorine processes, although the photon fluence of the VUV only accounted for 5.6% of that of the UV. An acidic pH favored MB degradation by the VUV/UV/chlorine process. The synergistic mechanism of the VUV/UV/chlorine process was mainly ascribed to the effective use of (•)OH for pollutant removal through formation of longer-lived secondary radicals (e.g., (•)OCl). This study demonstrates that the new VUV/UV/chlorine process, as an enhanced AOP, can be applied as a highly effective and energy-saving technology for small-scale water and wastewater treatment.

Surface-engineered amphiphilic polymer-coated silicon nanoparticles (SiNPs) were employed as photocatalysts to capture and degrade a model organic contaminant (methanol) in water. This study represents the first time SiNPs have been employed in the initiation of advanced oxidation processes that are commonly used to degrade organic constituents in industrial wastewaters. The quantum yield of photocatalytic methanol oxidation and the corresponding yield factor for the generation of active OH radicals are reported. The size and surface defect dependent photocatalytic activity of SiNPs was investigated. The yield factors (η) decreased with increasing particle size and reached impressive values that exceeded that of equivalent TiO2 nanoparticle systems by 3-4 times and are comparable to the robust UV/Cl2 and UV/H2O2 systems. The higher photocatalytic efficiency of SiNPs is attributed to the combined effects of quantum confinement, effective band gap, and surface states, among which surface states play a dominant role. SiNPs provide a potentially tunable, biologically inert, and robust nanoparticle system for photocatalytic oxidation of wastewater contaminants.

The solar UV/chlorine process has emerged as a novel advanced oxidation process for industrial and municipal wastewaters. Currently, its practical application to oil sands process-affected water (OSPW) remediation has been studied to treat fresh OSPW retained in large tailings ponds, which can cause significant adverse environmental impacts on ground and surface waters in Northern Alberta, Canada. Degradation of naphthenic acids (NAs) and fluorophore organic compounds in OSPW was investigated. In a laboratory-scale UV/chlorine treatment, the NAs degradation was clearly structure-dependent and hydroxyl radical-based. In terms of the NAs degradation rate, the raw OSPW (pH ∼ 8.3) rates were higher than those at an alkaline condition (pH = 10). Under actual sunlight, direct solar photolysis partially degraded fluorophore organic compounds, as indicated by the qualitative synchronous fluorescence spectra (SFS) of the OSPW, but did not impact NAs degradation. The solar/chlorine process effectively removed NAs (75-84% removal) and fluorophore organic compounds in OSPW in the presence of 200 or 300 mg L(-1) OCl(-). The acute toxicity of OSPW toward Vibrio fischeri was reduced after the solar/chlorine treatment. However, the OSPW toxicity toward goldfish primary kidney macrophages after solar/chlorine treatment showed no obvious toxicity reduction versus that of untreated OSPW, which warrants further study for process optimization.

The fluence rate (FR) distribution in an ultraviolet (UV) reactor was determined experimentally in situ by use of a novel 360° micro fluorescent silica detector (MFSD). The UV response of the MFSD was systematically characterized, and the results indicated that this detector responded only to UV in the range from 210 to 280 nm. The nonlinearity was found to be less than 1% as the FR varied from 0.083 to 2110 μW/cm2. The luminescent signal increased by 0.11% for every degree increase in temperature in the studied range of 0-55 °C. FR distribution tests were performed in different media (air or water) with the water transmittance at either 95% or 85% determined in a 1-cm path length. The FR distribution of the near-lamp region (e.g., radius<50 mm) was well determined with the nearest distance to the sleeve being less than 3 mm. Comparisons were made between the experimental data and the calculations by use of the UVCalc model. This work demonstrates that the MFSD is a novel technique that can provide in situ and real-time measurements of the FR distribution in a UV reactor.