Electrical Energy Per Order Research Articles

Application of the UV-C photo-assisted peroxymonosulfate oxidation for the mineralization of dimethyl phthalate in aqueous solutions

In this study, the degradation of dimethyl phthalate (DMP), taken as model compound for phthalate esters, by the photo-assisted peroxymonosulfate (PMS) process was investigated. The high oxidation potential of hydroxyl and sulfate radicals generated by the activation of PMS under UV-C light irradiation was used to completely oxidize aqueous DMP solutions. Experiments were conducted at varying initial pH values (3.0, 6.0, and 9.0) and PMS concentrations (0-60 mM) to evaluate the effect of different reaction conditions on DMP treatment performance with the PMS/UV-C process. It was observed that lowering the initial reaction pH slightly improved the degradation rate of DMP. On the contrary, TOC abatements were slightly enhanced with increasing initial reaction pH. An adequate (optimum) PMS concentration of 40 mM resulted in the fastest and highest DMP degradation rates and efficiencies, respectively. At an initial concentration of 100 mg L(-1), more than 95% DMP removal was obtained after only 20 min under PMS/UV-C treatment conditions. For the proposed adequate PMS concentration (40 mM) the lowest electrical energy per order (EE/O) value was calculated as 2.9 kW h m(-3) order(-1).

Ultraviolet Light-Emitting Diodes and Peroxydisulfate for Degradation of Basic Red 46 from Contaminated Water

Abstract In this article, a novel batch reactor of ultraviolet (UV) light-emitting diodes (LEDs) and peroxydisulfate has been studied for the degradation of Basic Red 46 (BR46) as a model organic pollutant in water. Almost no dye degradation was achieved with UV LED alone, whereas 43% of destruction was obtained in the presence of peroxydisulfate. More than 90% of the dye content was eliminated using UV LED and peroxydisulfate simultaneously in 30 min. Effects of different parameters such as UV LED irradiation, peroxydisulfate concentration, dye concentration, pH, and current on the removal of BR46 were investigated. Satisfactory degradation of BR46 was observed for tested pH range of 2–9.8, with peak at pH 6.43. Electrical energy per order (EEO) for degradation values of BR46 using both UV LEDs and traditional UV lamps in different concentrations of peroxydisulfate were calculated. Our results show that using LEDs reduces EEO significantly. On increasing the current from 360 to 2,000 mA, the decolorizati...

Impact of IX-UF Pretreatment on the Feasibility of UV/H2O2 Treatment for Degradation of NDMA and 1,4-Dioxane

PWN considers ion exchange and ultrafiltration (IX-UF) for replacing the existing CSF pretreatment at the Andijk water treatment plant. Advanced oxidation (UV/H2O2) in combination with granular activated carbon filtration (GAC) as a non selective barrier against organic micro pollutants is operational since 2004. Effects of an improved pretreatment on the UV/ H2O2 in terms of direct photolysis, OH-radical oxidation and energy consumption are presented in this paper. NDMA and 1,4-dioxane are selected to show the impact of pretreatment on UV photolysis and hydroxyl radical oxidation, respectively. Key water quality parameters are DOC and nitrate for scavenging and competition for UV light. Compared to CSF, the electrical energy per order (EEO) for IX-UF treated water was reduced with about 50%.

Ozonation of estrogenic chemicals in biologically treated sewage

The present study shows that ozonation of effluents from municipal wastewater treatment plants (WWTPs) is likely to be a future treatment solution to remove estrogens and xeno-estrogens. The required ozone dose and electrical energy for producing the ozone were determined in two WWTP effluents for removal of 17 estrogenic chemicals. The estrogenic compounds included parabens, industrial phenols, sunscreen chemicals, and steroid estrogens. The obtained values of Electrical Energy per Order (EEOs) for the treatment of the estrogens were in the range 0.14-1.1 kWh/m(3) corresponding to 1.7-14 g O3/m(3). It is furthermore suggested that UV-absorbance is a useful parameter for online control of the ozone dose in a full scale application since the absorbance of the WWTP effluents and the remaining concentration of the estrogens and xeno-estrogens correlated well with the applied ozone dose.

Integrated Photocatalytic Filtration Array for Indoor Air Quality Control

Photocatalytic and filtration technologies were integrated to develop a hybrid system capable of removing and oxidizing organic pollutants from an air stream. A fluidized bed aerosol generator (FBAG) was adapted to prepare TiO(2)-loaded ventilation filters for the photodegradation of gas phase ethanol. Compared to a manually loaded filter, the ethanol photodegradation rate constant for the FBAG coated filter increased by 361%. Additionally, the presence of the photogenerated intermediate product, acetaldehyde, was reduced and the time for mineralization to CO(2) was accelerated. These improvements were attributed to the FBAG system providing a more uniform distribution of TiO(2) particles across the filter surface leading to greater accessibility by the UV light. A dual-UV-lamp system, as opposed to a single-lamp system, enhanced photocatalytic filter performance demonstrating the importance of high light irradiance and light distribution across the filter surface. Substituting the blacklight blue lamps with a UV-light-emitting-diode (UV-LED) array led to further improvement as well as suppressed the electrical energy per order (EE/O) by a factor of 6. These improvements derived from the more uniform distribution of light irradiance as well as the higher efficiency of UV-LEDs in converting electrical energy to photons.

Optimization of UV‐promoted peroxydisulphate oxidation of C.I. Basic Blue 3 using response surface methodology

In this paper photooxidative decolorization of C.I. Basic Blue 3 (BB3), by a UV/peroxydisulphate process is reported. Response surface methodology (RSM) was employed to investigate the effects of different operational parameters on the photooxidative decolorization efficiency. The variables investigated were the reaction time, initial dye concentration, initial S2O8 2− concentration and the distance of the solution from the UV lamp. Central composite design (CCD) was used for the optimization of the UV/peroxydisulphate process. Photooxidative decolorization efficiency was enhanced by the addition of an optimum amount of peroxydisulphate. An increase in UV light intensity increased the photooxidative decolorization efficiency. A decrease in photooxidative decolorization efficiency with increasing initial BB3 concentration was observed. Predicted values of photooxidative decolorization efficiency were found to be in good agreement with experimental values (R 2 = 99.06% and Adj‐R 2 = 98.24%), which indicated the suitability of the CCD model employed and the success of CCD in optimizing the conditions of the UV/peroxydisulphate process. The results of optimization predicted by the model showed that maximum decolorization efficiency (>98%) was achieved at the optimum conditions: reaction time 11 min, initial dye concentration 10 mg/L, initial peroxydisulphate concentration 1.5 mmol/L and distance of UV lamp from the solution 6 cm. The figure‐of‐merit electrical energy per order (EEo) was employed to estimate the electrical energy consumption.

UV/peroxydisulfate oxidation of C. I. Basic Blue 3: Modeling of key factors by artificial neural network

The present work deals with the photooxidative decolorization of C.I. Basic Blue 3 (BB3), in the presence of potassium peroxydisulfate (K2S2O8) irradiated by a 30W UV-C lamp in a batch reactor. Results showed that photooxidative decolorization rate was affected by the operational parameters such as the reaction time, UV light intensity and initial concentrations of peroxydisulfate and BB3. Photooxidative decolorization efficiency was enhanced by the addition of proper amount of peroxydisulfate. The increase of UV light intensity increased the photooxidative decolorization rate. This increase is due to the enhanced production of sulfate and hydroxyl radicals. The decrease in photooxidative decolorization rate with increasing initial BB3 concentration has been observed. It could be stated that the complete removal of color, could be achieved in a relatively short time, about 20min. The figure-of-merit electrical energy per order (EEo) was employed to estimate the electrical energy consumption and related treatment costs. An artificial neural network model was developed to predict the photooxidative decolorization efficiency. The findings indicated that ANN provided reasonable predictive performance (R2=0.9877) while the influence of each parameter on the variable studied was assessed, reaction time being the most significant factor, followed by initial concentration of the dye.

Photocatalytic removal of C.I. Basic Red 46 on immobilized TiO2 nanoparticles: Artificial neural network modelling

C.I. Basic Red 46, commonly used as a textile dye, was photocatalytically removed using supported TiO2 nanoparticles irradiated by a 30 W UV‐C lamp in a batch reactor. The investigated photocatalyst was industrial Degussa P25 (crystallite mean size 21 nm) immobilized on glass beads by a heat attachment method. The catalyst was characterized by XRD, SEM, TEM and BET techniques. The process of the dye decolorization in the presence of TiO2 nanoparticles was experimentally studied through changing the initial dye concentration, UV light intensity and initial pH. The influence of inorganic anions such as chloride, sulphate, bicarbonate, carbonate and phosphate on the photocatalytic decolorization of BR46 was investigated. The decolorization of BR46 follows the pseudo‐first‐order kinetic according to the Langmuir–Hinshelwood model (k 1 = 0.273 mg L−1min−1, 2 = 0.313 (mg L−1)−1). The efficiency parameters such as apparent quantum yield and electrical energy per order (EEO) were estimated. An artificial neural network model (ANN) was developed to predict the photocatalytic decolorization of BR46 solution. The findings indicated that the ANN provided reasonable predictive performance (R2 = 0.96). The influence of each parameter on the variable studied was assessed: initial concentration of the dye being the most significant factor, followed by the initial pH and reaction time.

Evaluation of electrical energy per order (EEO) with kinetic modeling on the removal of Malachite Green by US/UV/H2O2 process

The kinetics of decolorization of Malachite Green (MG) as a model cationic dye from textile industry, by US/UV/H2O2 process, was investigated with nonlinear regression analysis. The experimental results indicated that the decolorization kinetics of MG in this process fit well by pseudo-first order kinetics. With nonlinear regression analysis a model was developed for pseudo-first order constant (kap) as a function of operational parameters such as initial concentrations of H2O2 (25–600 mg l− 1) and MG (1.82–9.87 mg l− 1), temperature (294–307 K) and power density (0.049–0.16 W ml− 1) as following: kap=283exp(−9000/RT)(0.0205+(1.76×10−3[H2O2]o1+4.86×10−4[H2O2]o+9.5×10−6[H2O2]o2)[MG]−0.668(P/V)0.313. For electrical energy cost evaluation, the figure-of-merit electrical energy per order (EEO) was estimated from experimental and theoretical data. The results show that EEO is very sensitive to the mentioned operational parameters.

An evaluation of a pilot-scale nonthermal plasma advanced oxidation process for trace organic compound degradation

This study evaluated a pilot-scale nonthermal plasma (NTP) advanced oxidation process (AOP) for the degradation of trace organic compounds such as pharmaceuticals and potential endocrine disrupting compounds (EDCs). The degradation of seven indicator compounds was monitored in tertiary-treated wastewater and spiked surface water to evaluate the effects of differing water qualities on process efficiency. The tests were also conducted in batch and single-pass modes to examine contaminant degradation rates and the remediation capabilities of the technology, respectively. Values for electrical energy per order (EEO) of magnitude degradation ranged from <0.3 kWh/m 3-log for easily degraded compounds (e.g., carbamazepine) in surface water to 14 kWh/m 3-log for more recalcitrant compounds (e.g., meprobamate) in wastewater. Changes in the bulk organic matter based on UV 254 absorbance and excitation-emission matrices (EEM) were also monitored and correlated to contaminant degradation. These results indicate that NTP may be a viable alternative to more common AOPs due to its comparable energy requirements for contaminant degradation and its ability to operate without any additional feed chemicals.

H2O2/UV-Coxidation of potential endocrine disrupting compounds: a case study with dimethyl phthalate

This paper discusses the feasibility of the ultraviolet radiation-hydrogen peroxide (H(2)O(2)/UV-C) process as an advanced oxidation process (AOP) in the treatment of endocrine disrupting compounds (EDC). Dimethyl phthalate (DMP) was chosen as the model compound owing to its classification as an EDC. Experiments have been conducted at various pH values (3.5, 6.0 and 9.0) and initial H(2)O(2) concentrations (0-60 mM) in a batch reactor equipped with a low-pressure mercury UV-C lamp in order to evaluate the optimal operation conditions of the H(2)O(2)/UV-C process. The most effective pH value for the degradation of DMP by H(2)O(2)/UV-C treatment was found as 6.0. DMP abatement increased with increasing H(2)O(2) concentrations from 5 to 30 mM. Further increase in initial H(2)O(2) concentration, however, reduced both the rate and extent of DMP removal as well as chemical oxygen demand (COD) and total organic carbon (TOC) removals. A simple kinetic model was proposed for DMP, COD and TOC abatements confirmed pseudo-first-order reaction. The electrical energy per order (EE/O) values for DMP oxidation and TOC mineralization were calculated as 3.3 and 19 kWh m(-3) order(-1) respectively for the optimum treatment conditions (H(2)O(2,o) = 30 mM, pH(o) = 6.0, DMP(o)= 100 mg L(-1)). Inhibition of oxygen uptake rate by activated sludge (ISO 8192) was evaluated as a tool for assessing the acute toxicity of untreated and H(2)O(2)/UV-C treated DMP. According to the results obtained in this work, the use of the H(2)O(2)/UV-C process is recommended to achieve a complete DMP oxidation and high mineralization degree of aqueous solution of DMP.

Evaluation of a photocatalytic reactor membrane pilot system for the removal of pharmaceuticals and endocrine disrupting compounds from water

A photocatalytic reactor membrane pilot system, employing UV/TiO 2 photocatalysis, was evaluated for its ability to remove thirty-two pharmaceuticals, endocrine disrupting compounds, and estrogenic activity from water. Concentrations of all compounds decreased following treatment, and removal followed pseudo-first-order kinetics as a function of the amount of treatment. Twenty-nine of the targeted compounds in addition to total estrogenic activity were greater than 70% removed while only three compounds were less than 50% removed following the highest level of treatment (4.24 kW h/m 3). No estrogenically active transformation products were formed during treatment. Additionally, the unit was operated in photolytic mode (UV only) and photolytic plus H 2O 2 mode (UV/H 2O 2) to determine the relative amount of energy required. Based on the electrical energy per order (EEO), the unit achieved the greatest efficiency when operated in photolytic plus H 2O 2 mode for the conditions tested.

Application of central composite design for the optimization of photo-destruction of a textile dye using UV/S2O8 2- process

Application of central composite design for the optimization of photo-destruction of a textile dye using UV/S2O8 2- process The photooxidative destruction of C. I. Basic Red 46 (BR46) by UV/S2O8 2- process is presented. Central Composite Design (CCD) was employed to optimize the effects of operational parameters on the photooxidative destruction efficiency. The variables investigated were the initial dye and S2O8 2- concentrations, reaction time and distance of the solution from UV lamp. The predicted values of the photodestruction efficiency were found to be in good agreement with the experimental values (R2 = 0.9810, Adjusted R2 = 0.9643). The results of the optimization predicted by the model showed that the maximum decolorization efficiency (&gt;98%) was achieved at the optimum conditions of the reaction time 10 min, initial dye concentration 10 mg/l, initial peroxydisulfate concentration 1.5 mmol/l and distance of UV lamp from the solution 6 cm. The figure-of-merit electrical energy per order (EEo) was employed to estimate the electrical energy consumption and related treatment costs.

Evaluating UV/H 2O 2 processes for methyl tert-butyl ether and tertiary butyl alcohol removal: Effect of pretreatment options and light sources

In this paper, we evaluate the efficiency of UV/H 2O 2 process to remove methyl tert-butyl ether (MtBE) and tertiary butyl alcohol (tBA) from a drinking water source. Kinetic models were used to evaluate the removal efficiency of the UV/H 2O 2 technologies with different pretreatment options and light sources. Two commercial UV light sources, i.e. low pressure, high intensity lamps and medium pressure, high intensity lamps, were evaluated. The following pretreatment alternatives were evaluated: (1) ion exchange softening with seawater regeneration (NaIX); (2) Pellet Softening; (3) weak acid ion exchange (WAIX); and (4) high pH lime softening followed by reverse osmosis (RO). The presence or absence of a dealkalization step prior to the UV/H 2O 2 Advanced Oxidation Process (AOP) was also evaluated for each pretreatment possibility. Pretreatment has a significant impact on the performance of UV/H 2O 2 process. The NaIX with dealkalization was shown to be the most cost effective. The electrical energy per order (EEO) values for MtBE and tBA using low pressure high output UV lamps (LPUV) and 10 mg/L H 2O 2 are 0.77 and 3.0 kWh/kgal-order, or 0.20 and 0.79 kWh/m 3-order, respectively. For medium pressure UV high output lamps (MPUV), EEO values for MtBE and tBA are 4.6 and 15 kWh/kgal-order, or 1.2 and 4.0 kWh/m 3-order, for the same H 2O 2 dosage.

Photooxidative removal of the herbicide Acid Blue 9 in the presence of hydrogen peroxide: modeling of the reaction for evaluation of electrical energy per order (EEO)

The present work deals with photooxidative removal of the herbicide, Acid Blue 9 (AB9), in water in the presence of hydrogen peroxide (H2O2) under UV light illumination (30 W). The influence of the basic operational parameters such as amount of H2O2, irradiation time and initial concentration of AB9 on the photodegradation efficiency of the herbicide was investigated. The degradation rate of AB9 was not appreciably high when the photolysis was carried out in the absence of H2O2 and it was negligible in the absence of UV light. The photooxidative removal of the herbicide was found to follow pseudo-first-order kinetic, and hence the figure-of-merit electrical energy per order (EEo) was considered appropriate for estimating the electrical energy efficiency. A mathematical relation between the apparent reaction rate constant and H2O2 used was applied for prediction of the electricity consumption in the photooxidative removal of AB9. The results indicated that this kinetic model, based on the initial rates of degradation, provided good prediction of the EEo values for a variety of conditions. The results also indicated that the UV/H2O2 process was appropriate as the effective treatment method for removal of AB9 from the contaminated wastewater.

UV/H 2O 2 treatment of Rhodamine B in aqueous solution: Influence of operational parameters and kinetic modeling

The decolorization and degradation of Rhodamine B (RB) were investigated using UV radiation in the presence of H 2O 2 in a batch photoreactor at different light intensities. H 2O 2 and UV light have a negligible effect when they were used on their own. Removal efficiency of RB was sensitive to the operational parameters such as initial concentrations of H 2O 2 and RB, initial pH and light intensity. The results indicated that efficiency of process decreased with addition of inorganic ions and alcohols to the dye solution as hydroxyl radical scavengers. The semilogarithmic graphs of the concentrations of RB versus time were linear, suggesting pseudo-first order reaction for decolorization and degradation processes. A simple kinetic model is proposed which confirms pseudo-first-order reaction. The electrical energy per order (EE/O) values for decolorization and degradation of RB solution were calculated. Results shows that applying an optimum hydrogen peroxide concentration can reduce the EE/O.

The photo-oxidative destruction of C.I. Basic Yellow 2 using UV/S2O8 2− process in an annular photoreactor

The photo-oxidative decolorization of C. I. Basic Yellow 2 (BY2), was investigated using UV radiation in the presence of peroxydisulfate (S2O8 2−) in an annular photoreactor at different conditions. S2O8 2− and UV-light showed negligible effect when they were used independently. Removal efficiency of BY2 was sensitive to the operational parameters such as initial concentrations of S2O8 2−, BY2 and pH. The conversion ratios of BY2 at the volumetric flow rates of 330, 500 and 650 mLmin− 1 were 84%, 78%, 69% in 1 h, respectively. The results showed that in the presence of S2O8 2−, the photooxidation quantum yield obtained higher than direct photolysis quantum yield, suggesting that photodecay of BY2 was dominated by photooxidation. The electrical energy per order (EE/O) values for decolorization of BY2 solution was calculated. Results show that applying an optimum peroxydisulfate concentration can reduce the EE/O.

Photolysis and advanced oxidation treatment of estrogenic chemicals in tap water and treated sewage

The removal efficiency by photolysis and advanced oxidation (AOP) of some estrogeniccompounds was investigated in tap water and biologically treated sewage. The compoundsinvestigated included parabens, industrial phenols, sunscreen chemicals and steroid estrogens.Treatment experiments were performed using a UV lamp optimized for photochemicaltreatment in a flow through set-up. The effect of different concentrations of H2O2 anddifference between tap water and treated sewage was investigated for all compounds.The treatment effectiveness is evaluated based on the Electrical Energy per Order (EEO) (unitkWh/111e3), which is defined as the electrical energy consumed per unit volume of water treatedrequired for 90 % removal of the investigated compound.It was found that the removal efficiency was better in tap water than in wastewater which isdue to the shadow effect from the inorganic and organic substance in the wastewater. Further,it was found that the removal of all the compounds was dependent of the UV dose for bothtreatment methods. The energy required for 90% removal of the compounds was between 28kWh/111e3 ± 2.9 (butylparaben) and 1.2 kWh/ 111e3 (estrone) for the UY treatment. The AOPresults in a more unifom1 value of EEO, which is between 8. 7 kWh/m3 (bisphenol A andbenzophenone-7) and 1.8 kWh/m3 ( I 7a-ethynyl estradiol).The removal at different concentration of H2O2 was investigated and it was found thatremoval effectiveness increased with concentration until 60 mg/L, but decreased at I 00 mg/L,which may be caused by H2O2 scavenging the HO'-radicals.

Photolysis and advanced oxidation treatment of pharmaceuticals in tap water and treated sewage

The aim of this study was to investigate the removal efficiency of six phannaceuticals byphoto-degradation and the advanced oxidation process (AOP), UV/H2O2. The sixphannaceuticals were the four NSAIDs ibuprofen, diclofenac, naproxen and ketoprofen, thepharmacological active metabolite of the lipid lowering agent, clofibrin, clofibric acid, and theanticonvulsant and mood stabilizing drug, carbamazepine.Treatment experiments were perfom1ed using a UV lamp optimized for photochemicaltreatment in a flow through set-up. For the AOP experiments 60 mg/L H2O2 was added to thewater before treatment. The treatment effectiveness is evaluated based on the ElectricalEnergy per Order (EEO) (unit kWh!m\ which is defined as the electrical energy consumedper unit volume of water treated required for 90% removal of the investigated compound.It was found that four of the six phannaceuticals were completely removed in tap water byboth UV treatment and the AOP. The exceptions were ibuprofen and carbamazepine, whichexhibited a relationship between UV dose and removal. The electrical energy per order, EEOwas detennined to 8.2 kWh/ml (UV) and 3. 7 kWh/ml (UV /H2O2 ) for ibuprofen.In the wastewater effluent the removal by UV irradiation was almost complete for ketoprofen,while the other compounds show dependency of flow rate/UV dose. Ibuprofen was thecompound that needed the highest UV dose to remove 90% (EEO = 33.4 kWh/ml) wherenaproxen and clofibric acid required 9.6 kWh/ml and 5.5 kWh/ml, respectively. Ketoprofenand diclofenac needed considerable less energy than clofibric acid. Ibuprofen and naproxen isbiodegradable and will be removed in biologically treated wastewater. Therefore, the relevantestimate of the needed treatment is the energy use for removal of clofibric acid which required5.5 kWh/ml for 90% removal.

Effect of inorganic oxidants in photodecolourization of an azo dye

Aqueous solutions of the dye Acid Orange 7 were decolourized in the presence of ultraviolet irradiation (UV) and photocatalyst, TiO 2. Decolourization rate was increased in the presence of UV/TiO 2 compared to UV alone. Addition of hydrogen peroxide, H 2O 2, in concentrations ranging from 8.82 × 10 −3 to 7.1 × 10 −2 M to the solution containing pollutant and TiO 2 (0.5 g l −1) resulted in increased rates of decolourization. The rate of dye decolourization using periodate, NaIO 4, (4.76 × 10 −5 to 1 × 10 −3 M) at TiO 2 concentration of 0.5 g l −1 under UV illumination was higher than that for UV/TiO 2/H 2O 2 and increases with periodate concentration. The rate of decolourization of Acid Orange 7 was found to follow first-order kinetics. Reaction rate orders with respect to the oxidant species were 0.51 and 0.8, respectively for H 2O 2 and NaIO 4. Kinetic parameters of the photodecolourization process such as apparent rate constant ( k app) and initial reaction rate ( R initial) and efficiency parameters such as apparent quantum yield ( Q app) and electrical energy per order (EE/O) were estimated and compared for UV/TiO 2, UV/TiO 2/H 2O 2 and UV/TiO 2/IO 4 − catalytic systems.