用电-多相催化技术处理油田废水

采用电－多相催化新技术对油田废水进行小试和中试研究。静态实验结果表明，与单独使用催化剂或电场相比，两者同时使用即电场和催化剂协同可以获得更高的CODCr去除率。并通过动态实验对电－多相装置中的催化剂种类和电极配置方式进行了选择。中试实验中，采用槽式反应器、SFS催化剂、多组电极、特定的电极排列方式进行电－多相催化处理，获得令人满意的CODCr去除结果。     

Electro-catalytic degradation of methylene blue wastewater assisted by Fe2O3-modified kaolin

The electrochemical oxidation of methylene blue (MB) wastewater assisted by Fe₂O₃-modified kaolin in a 200 mL electrolytic batch reactor with graphite plate as electrodes was investigated. The catalyst was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effects of pH, current density and introduction of NaCl on the efficiency of the electrochemical degradation process were also studied. It was found that Fe₂O₃-modified kaolin has higher catalytic activity in the electrochemical degradation of MB wastewater. 96.47% chemical oxygen demand (COD) removal was obtained in 40 min of electrochemical treatment of MB wastewater at pH 3, current density was equal to 69.23 mA cm⁻².     

Selective removal of copper ions from multi‐component aqueous solutions using modified silica impregnated with LIX 84

A silica support impregnated with 2‐hydroxy‐5‐nonylacetophenone oxime (LIX 84) was prepared after surface modification by ‐aminopropyltriethoxysilane. Fixed‐bed tests were conducted to investigate the capabilities of the prepared adsorbent with respect to the selective removal of copper ions from multi‐metal solutions. Break‐through curves were obtained using the modified silica for a solution containing Cu²⁺, Cd²⁺, Ni²⁺, Co²⁺ and Zn²⁺, as well as an industrial electronics wastewater sample. The copper adsorption capacities for the multi‐metal solution and the wastewater were 0.175 and 0.198 mmolg⁻¹, respectively under the conditions used in this study. The copper recovery ratios for the modified silica treated with the multi‐metal solution and the wastewater were 86 and 91%, respectively after treating with 0.1 moldm⁻³ HNO₃. The results show that the modified silica, prepared here, has potential value for the selective removal of copper ions from multi‐component aqueous solutions containing multi‐metals using a fixed‐bed reactor. © 2000 Society of Chemical Industry     

Treatment of wastewater from acrylonitrile‐butadiene‐styrene (ABS) resin manufacturing by biological activated carbon (BAC)

Background: The wastewater originating from the production of acrylonitrile‐butadiene‐styrene (ABS) resin is a toxic and refractory industrial wastewater. The purpose of this work is to investigate the characteristics of adsorption and biodegradation of biological activated carbon (BAC) for ABS resin wastewater. Results: More than 80% of chemical oxygen demand (COD), total organic carbon (TOC) and organic nitrogen (Org‐N) was removed after the 100th run in BAC with the help of bioregeneration, and the treatment efficiency of BAC was higher than that of adsorption and biodegradation alone. The initial Org‐N was mainly transformed into NH₄⁺‐N, and the transform efficiency reached 65% after the 100th run. After bioregeneration, the COD and TOC removal efficiencies of BAC reactor reached 88.97% and 86.26%, respectively. The BAC had different bioregeneration efficiencies of 94.41, 64.82, 61.05 and 40.04% for 3, 3‐imminodipropiononitrile, 3, 3‐oxydipropiononitrile, α, α‐dimethyl‐benzylalcohol and acetophenone, respectively, which mainly resulted from the different polarity of the compounds. Conclusion: BAC could protect microorganisms from shock loadings of toxic, refractory and complicated ABS resin wastewater. The mechanism of the organic pollutants removal by BAC consisted of three phases including adsorption, bioregeneration and stability. © 2012 Society of Chemical Industry     

Treatment of coking wastewater by a UBF‐BAF combined process

BACKGROUND: Coking wastewater is a major pollutant, produced in large quantities in many countries worldwide. This study investigates the performance of a combined system for treating coking wastewater. The system is based on an upflow blanket filter (UBF) with a biological aerated filter (BAF). Efficiency is assessed according to organic pollutants and nitrogen removal. RESULTS: It was found that hydraulic retention time (HRT) had a greater influence on the removal efficiency of NH₃‐N than chemical oxygen demand (COD). The BAF facilitated simultaneous carbonaceous removal and nitrification, depending on the reactor height. The system removed 81.5% of COD and 96.4% of NH₃‐N when the total HRT was 46.7 h (15.4 h for UBF and 31.3 h for BAF). Gas chromatography/mass spectrometry analysis indicated that the main components of the coking wastewater were phenols and nitrogenous heterocyclic compounds. Certain refractory compounds decomposed in the anaerobic section, resulting in the production of intermediates. Although most organics present in the influent were absent from the final effluent, a few residual contaminants could not be fully eliminated by the system. CONCLUSION: The experimental results show that the present system is feasible for the treatment of coking wastewater. Copyright © 2007 Society of Chemical Industry     

Effect of a chemical synthesis‐based pharmaceutical wastewater on performance,acetoclastic methanogenic activity and microbial population in an upflow anaerobic filter

The performance of an upflow anaerobic filter (UAF) treating a chemical synthesis‐based pharmaceutical wastewater was evaluated under various operating conditions. During start‐up, the UAF was initially fed by glucose till an organic loading rate (OLR) of approximately 7.5 kg COD m^?3 day^?1 with a hydraulic retention time of 2.3 days. A soluble COD removal efficiency of 98% was achieved before the addition of the wastewater. Initially, the filter inertia was acclimatized to the wastewater by sequential feeding of 10% (w/v), 30% (w/v) and 70% (w/v) of the pre‐aerated wastewater mixed with glucose followed by a 100% (w/v) pre‐aerated wastewater. During the operation, the COD removal efficiency and methane yield decreased to 75% and 0.30 m³ CH₄ kg^?1 COD_removed respectively. As the UAF became accustomed to the pre‐aerated wastewater, raw wastewater was fed in increasing ratios of 20% (w/v), 60% (w/v) and 80% (w/v) with the pre‐aerated wastewater as the remaining part. During this stage of the operation, a COD removal efficiency in a range of 77–86% was achieved and the methane yield decreased to 0.24 m³ CH₄ kg^?1 COD_removed. Finally, 100% (w/v) raw wastewater was fed and a COD removal efficiency of 65% was achieved with a methane yield of 0.20 m³ CH₄ kg^?1 COD_removed. At the end of the operation, acetoclastic methanogenic activity was only measured in the bottom section of the UAF, this showed a 90% reduction in comparison with activity of inoculation sludge. Microscopic examinations revealed that rod‐shaped methanogens remained as the dominant species whereas Methanosarcina‐like species and filaments were present only in insignificant numbers along the UAF. © 2002 Society of Chemical Industry     

A high‐efficient rotating disk photoelectrocatalytic (PEC) reactor with macro light harvesting pyramid‐surface electrode

A series of pyramid‐surface TiO₂/Ti electrodes were proposed, fabricated, and used in a rotating disk photoelectrocatalytic (PEC) reactor to treat rhodamine B (RB) solution. Compared with conventional planar electrode, pyramid‐surface electrode exhibited much lower light reflectivity, larger photocurrent, and better treatment efficiency. For samples containing 20 to 150 mg L^?1 RB, 100– 98% color removal, and 87–30% COD removal were obtained in 150 min using 1/3 (h/w) pyramid‐surface electrode, much higher than 98–77% and 48–9% obtained by a conventional planer electrode. The excellent treatment performance attributed to two major reasons: (a) enhanced light harvest resulted from multiple reflections of irradiation light on the pyramid‐surface, and (b) enlarged electrode surface area enabling the electrode to carry more TiO₂ catalyst and pollutants for treatment. Experimental results also showed that the pyramid‐surface electrode consumed less power and exhibited superior performance when treating high concentration wastewater. © 2011 American Institute of Chemical Engineers AIChE J, 58: 2448–2455, 2012     

A microbial fuel cell–electro‐oxidation system for coking wastewater treatment and bioelectricity generation

BACKGROUND: Coking wastewater is generated from coal coking, coal gas purification, and by‐product recovery processes. Increased interest is being focused on finding more sustainably effective and energy‐efficient methods for treating this wastewater. In this work, a system termed microbial fuel cell‐electro‐oxidation (MFC‐EO) was developed for simultaneous coking wastewater treatment and bioelectricity generation. RESULTS: Raw coking wastewater was first treated using MFCs. Power production, removal of total chemical oxygen demand (TCOD) and total nitrogen (TN) reached 538 ± 9 mW m^?2, 52 ± 1% and 50 ± 1%, respectively. Wastewater strength and phosphate addition were evaluated for the enhancement of power production and treatment efficiency. At the EO stage, the effect of current density and chloride concentration on pollutant abatement, current efficiency (CE_EO) and energy consumption (EC_EO) were investigated. The overall removal of TCOD and TN was 82 ± 1% and 68 ± 1%, respectively using the MFC‐EO process. CONCLUSIONS: A MFC‐EO process was developed for the first time for simultaneous bioelectricity generation and coking wastewater treatment. This study attempted to combine MFCs with a conventional EO process for coking wastewater treatment. Further strategies need to be investigated to optimize reactor configuration using low‐cost and highly efficient electrode materials. Copyright © 2009 Society of Chemical Industry     

Degradation of 1‐amino‐4‐bromoanthraquinone‐2‐sulfonic acid using combined airlift bioreactor and TiO2‐photocatalytic ozonation

BACKGROUND: Traditional treatment systems failed to achieve efficient degradation of anthraquinone dye intermediates at high loading. Thus, an airlift internal loop reactor (AILR) in combination with the TiO₂‐photocatalytic ozonation (TiO₂/UV/O₃) process was investigated for the degradaton of 1‐amino‐ 4‐bromoanthraquinone‐2‐ sulfonic acid (ABAS). RESULTS: The AILR using Sphingomonas xenophaga as inoculum and granular activated carbon (GAC) as biocarrier, could run steadily for 4 months at 1000 mg L^?1 of the influent ABAS. The efficiencies of ABAS decolorization and chemical oxygen demand (COD) removal in AILR reached about 90% and 50% in 12 h, respectively. However, when the influent ABAS concentration was further increased, a yellow intermediate with maximum absorbance at 447 nm appeared in AILR, resulting in the decrease of the decolorization and COD removal efficiencies. Advanced treatment of AILR effluent indicated that TiO₂/UV/O₃ process more significantly improved the mineralization rate of ABAS bio‐decolorization products with over 90% TOC removal efficiency, compared with O₃, TiO₂/UV and UV/O₃ processes. Furthermore, the release efficiencies of Br^? and SO₄^2? could reach 84.5% and 80.2% during TiO₂/UV/O₃ treatment, respectively, when 91.5% TOC removal was achieved in 2 h. CONCLUSION: The combination of AILR and TiO₂/UV/O₃ was an economic and efficient system for the treatment of ABAS wastewater. © 2012 Society of Chemical Industry     

Treatment of high‐fat‐containing dairy wastewater in a sequential UASBR system: influence of recycle

BACKGROUND: Raw cheese whey originating from white cheese production results in a strong and complex wastewater excessively rich in organic matter (chemical oxygen demand, COD = 28–65 g L^?1), fatty matter (14–24.5 g L^?1) and acidity (3.9–6.1 g L^?1). It was treated in a three‐stage configuration consisting of a pre‐acidification (PA) tank and sequential upflow anaerobic sludge bed reactors (UASBRs) at 2.8–7 g COD L^?1 day^?1 organic loading rates, during which the effects of effluent recycling at low rates and promoted SRB activity were investigated. Acidification, volatile fatty acids (VFA), COD and fatty matter removal and volatile solids were monitored throughout the system during the study. RESULTS: Recycling of the effluent promoted VFA and COD removal as well as pH stability in both stages of the UASBRs and the effluent where high alkalinity levels were recovered reducing alkali requirement to 0.05 g OH g^?1 COD_applied. Higher removal rates of 71–100 and 50–92% for VFA and COD were obtained by use of recycling. Fatty matter was removed at 63–89% throughout the study. Volatile solids build‐up was significant in the inlet zones of the UASBRs. CONCLUSIONS: The system produced efficient acidification in the PA tank, balanced pH levels and an effluent high in alkalinity and BOD/COD ratio. Efficient VFA removal and solids immobilization was obtained in both stages up to the highest loading rate. Recycling improved the system performance under high fatty matter loading conditions. A major advantage of the sequential system was that the second stage UASBR compensated for reduced performance in the first stage. Copyright © 2010 Society of Chemical Industry     

Degradation of cationic dye methylene blue by ozonation assisted with kaolin

An enhanced ozonation process, methylene blue (MB) wastewater treated by MnO₂/O₃ assisted with kaolin in a slurry reactor, at room temperature and atmospheric pressure, MB wastewater can be effectively purified, a chemical oxygen demand (COD) of 88.3% and a decoloration rate of 98.9% were obtained in 10 min at pH 11. Compared with MnO₂/O₃ catalytic ozonation (16.0% of decoloration and 33.3% of COD reduction), decoloration and COD reduction were markedly increased, indicating that kaolin can significantly improve the catalytic ozonation process. According to the experimental results, the hypothetical mechanism of degradation and the reaction kinetics were also proposed. COD reduction can be described by a second-order model and the reaction rate constant in the presence of kaolin was higher than that of absence of kaolin.     

Integration of continuous biological and chemical (ozone) treatment of domestic wastewater: 1. Biodegradation and post‐ozonation

The continuous treatment of domestic wastewater by an activated sludge process and by an integrated biological–chemical (ozone) oxidation process were studied in this work. Chemical oxygen demand (COD), biochemical oxygen demand (BOD), absorbance at 254 nm (UV₂₅₄) and nitrogenous compound content were the parameters followed in order to evaluate the performance of the two processes. Experimental data showed that both UV₂₅₄ and COD reductions are improved in the combined biological–chemical oxidation procedure. Thus, reductions of 59.1% and 37.2% corresponding to COD and UV₂₅₄, respectively were observed after the biological process (hydraulic retention time = 5 h; mixed liquor volatile suspended solids concentration = 3142 g m⁻³) compared with 71.0% and 78.4% obtained when a post‐ozonation step ( D _O3 = 41.7 g m⁻³) was included. During conventional activated sludge treatment, appropriate nitrification levels are only achieved with high hydraulic retention time and/or biomass concentration. Ozonation after the secondary treatment, however, allows improved nitrogen content reduction with total nitrite elimination. Post‐ozonation also leads to a higher biodegradability of the treated wastewater. Thus, the ultimate BOD/COD ratio goes from 0.16 after biological oxidation to 0.34 after post‐ozonation with 41.7 g O₃ m⁻³. © 1999 Society of Chemical Industry     

Electrochemical treatment of olive mill wastewater

Background Olive mill wastewater (OMW) constitutes a very strong agro‐industrial wastewater posing severe environmental threats in olive oil producing countries. The main objective of this study was to treat olive mill wastewater by electrochemical oxidation. The variables studied included the type and concentration of electrolyte solutions, voltage and time applied. Results: The electrolyte type and concentration significantly affected the degradation efficiency of the electrochemical oxidation. Optimal conditions for NaCl concentration were 3% (w/v) and 16 V. At these conditions chemical oxygen demand (COD) removal reached 70.8% after 8 h of electrochemical treatment, while color and turbidity were completely removed after short periods of treatment. However, bio‐assays indicated that the ecotoxicity of the treated wastewater remained unchanged, possibly due to the formation of chlorinated by‐products. Na₂SO₄ did not demonstrate sufficient efficiency. The simultaneous use of FeCl₃ and NaCl contributed to electro‐coagulation of OMW. After settlement, two separate phases were formed: the supernatant phase and the settled solids. Under optimal conditions (2% Na₂SO₄ + 1% FeCl₃; 24 V), the removal efficiency of COD reached 85.5% at the supernatant phase. Conclusion: NaCl was an effective electrolyte for OMW treatment. The electro‐coagulation process was also a successful process, but as in the case of NaCl the remaining acute toxicity of treated OMW was high. Copyright © 2007 Society of Chemical Industry     

Preparation of O‐carboxymethyl‐N‐trimethyl chitosan chloride and flocculation of the wastewater in sugar refinery

A novel water soluble amphiphilic O‐ carboxymethyl‐N‐trimethyl Chitosan chloride (CMTMC) was synthesized. The structure of this material was characterized by Fourier transform infrared (FTIR) spectroscopy, ¹³C nuclear magnetic resonance (¹³C‐NMR) spectroscopy and X‐ray diffraction (XRD) techniques. The results showed that CMTMC had been successfully prepared. To determine the flocculation performance of the synthesized amphiphilic polymer, a comparison was made among Chitosan (CS), N‐trimethyl chitosan chloride (TMC), O‐carboxymethyl chitosan (CMC), and CMTMC on the turbidity and COD removal efficiency of 1% (v/v) wastewater in sugar refinery suspensions at pH 5.0, 7.0 and 9.0 at a dosage range of 0–8 mg/L. The results showed that the water soluble amphiphilic polymer CMTMC, which contains longer polymer anion and polymer cation, had the best performance not only in turbidity removal but also in COD removal on sugar refinery wastewater. The using of CMTMC as a flocculant to treat wastewater in sugar refinery was actually more effective than CS, CMC, and TMC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Advanced oxidation of cork‐processing wastewater using Fenton's reagent: kinetics and stoichiometry

This work evaluates Fenton oxidation for the removal of organic matter (COD) from cork‐processing wastewater. The experimental variables studied were the dosages of iron salts and hydrogen peroxide. The COD removal ranged from 17% to 79%, depending on the reagent dose, and the stoichiometric reaction coefficient varied from 0.08 to 0.43 g COD (g H₂O₂)^?1 (which implies an efficiency in the use of hydrogen peroxide varying from 17% to 92%). In a study of the process kinetics, based on the initial rates method, the COD elimination rate was maximum when the molar ratio [H₂O₂]_o:[Fe²⁺]_o was equal to 10. Under these experimental conditions, the initial oxidation rate was 50.5 mg COD dm^?3 s^?1 with a rate of consumption of hydrogen peroxide of 140 mg H₂O₂ dm^?3 s^?1, implying an efficiency in the use of the hydrogen peroxide at the initial time of 77%. The total amount of organic matter removed by Fenton oxidation was increased by spreading the H₂O₂ and ferrous salt reagent over several fractions by 15% for two‐fractions and by 21% for three‐fractions. Copyright © 2004 Society of Chemical Industry     

Electrochemical oxidation of tannery wastewater

Tannery wastewater was treated by an electrochemical oxidation method using Ti/Pt, Ti/PbO₂ and Ti/MnO₂ anodes and a Ti cathode in a two‐electrode stirred batch reactor. The changes in colour concentration, chemical oxygen demand (COD), ammonia (NH₄⁺), sulfide and total chromium have been determined as a function of treatment time and applied current density. Gas chromatography–mass spectrometry (GC–MS) analysis, performed on the wastewater samples before and after treatment, as well as on foam samples, is reported. Anode efficiency, rate constants and energy consumption were estimated and discussed. The efficiency of Ti/Pt was 0.802 kgCOD h^?1 A^?1m^?2 and 0.270 kgNH₄⁺ h^?1 A^?1m^?2, and the energy consumption was 5.77 kWh kg^?1 COD and 16.63 kWh kg^?1 of NH₄⁺. The order of efficiency of anodes was found to be Ti/Pt ? Ti/PbO₂ > Ti/MnO₂. The results indicate that the electro‐oxidation method could be used for effective oxidation of tannery wastewater and a final effluent with substantially reduced pollution load can be obtained. © 2001 Society of Chemical Industry     

Biological treatment of saline wastewaters from marine‐products processing factories by a fixed‐bed reactor

Wastewaters generated by a factory processing marine products are characterized by high concentrations of organic compounds and salt constituents (>30 g dm^?3). Biological treatment of these saline wastewaters in conventional systems usually results in low chemical oxygen demand (COD) removal efficiency, because of the plasmolysis of the organisms. In order to overcome this problem a specific flora was adapted to the wastewater from the fish‐processing industry by a gradual increase in salt concentrations. Biological treatment of this effluent was then studied in a continuous fixed biofilm reactor. Experiments were conducted at different organic loading rates (OLR), varying from 250 to 1000 mg COD dm^?3 day^?1. Under low OLR (250 mg COD dm^?3 day^?1), COD and total organic carbon (TOC) removal efficiencies were 92.5 and 95.4%, respectively. Thereafter, fluctuations in COD and TOC were observed during the experiment, provoked by the progressive increase of OLR and the nature of the wastewater introduced. High COD (87%) and TOC (99%) removal efficiencies were obtained at 1000 mg COD dm^?3 day^?1. © 2002 Society of Chemical Industry     

Effect of pre‐treatments based on UV photocatalysis and photo‐oxidation on toluene biofiltration performance

BACKGROUND: The integration of UV photocatalysis and biofiltration seems to be a promising combination of technologies for the removal of hydrophobic and poorly biodegradable air pollutants. The influence of pre‐treatments based on UV_{254 nm} photocatalysis and photo‐oxidation on the biofiltration of toluene as a target compound was evaluated in a controlled long‐term experimental study using different system configurations: a standalone biofilter, a combined UV photocatalytic reactor‐biofilter, and a combined UV photo‐oxidation reactor (without catalyst)‐biofilter. RESULTS: Under the operational conditions used (residence time of 2.7 s and toluene concentrations 600–1200 mg C m^?3), relatively low removal efficiencies (6–3%) were reached in the photocatalytic reactor and no degradation of toluene was found when the photo‐oxidation reactor was operated without catalyst. A noticeable improvement in the performance of the biofilter combined with a photocatalytic reactor was observed, and the elimination capacity of the biological process increased by more than 12 g C h^?1 m^?3 at the inlet loads studied of 50–100 g C h^?1 m^?3. No positive effect on toluene removal was observed for the combination of UV photoreactor and biofilter. CONCLUSIONS: Biofilter pre‐treatment based on UV_{254 nm} photocatalysis showed promising results for the removal of hydrophobic and recalcitrant air pollutants, providing synergistic improvement in the removal of toluene. Copyright © 2011 Society of Chemical Industry     

Treatment of the refinery wastewater in a gas–liquid–solid three‐phase flow airlift loop bioreactor

Aerobic treatment of refinery wastewater was carried out in a 200 dm³ gas–liquid–solid three‐phase flow airlift loop bioreactor, in which a biological membrane replaced the activated sludge. The influences of temperature, pH, gas–liquid ratio and hydraulic residence time on the reductions in chemical oxygen demand (COD) and NH₄‐N were investigated and discussed. The optimum operation conditions were obtained as temperature of 25–35 °C, pH value of 7.0–8.0, gas–liquid ratio of 50 and hydraulic residence time of 4 h. The radial and axial positions had little influence on the local profiles of COD and NH₄‐N. Under the optimum operating conditions, the effluent COD and NH₄‐N were less than 100 mg dm^?3 and 15 mg dm^?3 respectively for more than 40 days, satisfying the national primary discharge standard of China (GB 8978‐1996). Copyright © 2005 Society of Chemical Industry     

Advanced ozone treatment of heavy oil refining wastewater by activated carbon supported iron oxide

The catalytic ozonation of heavy oil refining wastewater (HORW) was investigated over activated carbon supported iron oxides (FAC) catalysts using activated carbon (AC) as the reference. The catalyst was characterized by chemical analysis, XRD, N₂ adsorption–desorption and SEM. A significant increase in COD removal efficiency was observed in FAC + ozone compared with AC + ozone due to more hydroxyl radicals, identified by tert-butyl alcohol (TBA). The composition analysis of organic pollutant in HORW by FT-ICR MS discovered organic pollutants chain scission and oxidation process during the treatment. A great improvement of biodegradability for treated HORW had been obtained. The investigation uncovered the catalytic potential of FAC catalysts for ozonation of HORW.