湿式氧化技术处理化工废水的研究

采用湿式氧化技术处理在生产磺胺间二甲氧嘧啶过程中产生的高浓度有机废水。在反应温度为250℃,初始ρ(COD)为4 575 mg/L,反应时间为2 h,pH值为7~8时,采用湿式双氧水氧化和催化湿式氧化,COD去除率分别为78.3%和92.0%,表明催化湿式氧化具有较好的COD去除效果。同时考察了催化湿式氧化中反应温度、反应时间、废水pH值对COD去除率的影响。     

A study on ruthenium-based catalysts for pharmaceutical wastewater treatment

Ruthenium-based catalysts were prepared by a saturation-dip method. Their catalytic activity was evaluated by a catalytic wet oxidation (CWO) process. The ruthenium-based catalysts were used to purify organic pharmaceutical wastewater with high concentration pyridine and pyridine derivatives that have high chemical oxygen demand (COD). In the CWO process, organic pharmaceutical wastewater was continuously pumped into fixed-bed reactors filled with Ru-based catalysts, while the organic components in wastewater were catalytically degraded by oxygen at high temperatures and pressures (temperature, 170-300 degrees C; pressure, 1.0-10 MPa). The experimental results showed that the prepared catalysts could effectively purify pharmaceutical wastewater with high concentration organic components, which are difficult to degrade biochemically, and that the removal rates of both COD and total nitrogen were over 99%.     

Recalcitrant COD degradation by an integrated system of ozonation and membrane bioreactor.

In order to treat wastewater to a low residual COD-concentration such as 125 mg/L, classical biological treatment is not sufficient for many types of industry. This research focused on the integrated treatment of the wastewater of the paper industry, with a membrane bioreactor (MBR) and an oxidation step. The optimal configuration was examined. Screening tests with different types of oxidation showed that ozonation after biological treatment could reduce the COD with 40% with an ozone dose of 0.4-0.8g O3/g COD. BOD/COD ratio could be increased up to 0.19. Neither combination of ozone with UV and/or hydrogen peroxide nor the process H2O2/UV or (photo-)Fenton reagents gave any improvement in COD reduction or BOD increase, unless the doses were very high. Based on these results, an integrated system MBR-ozonation was designed, with recirculation of MBR effluent over ozonation. This test showed that reduction of COD up to 125 mg/L immediately behind the MBR required a lot of ozone. A technically feasible solution was to discharge the water after an extra ozonation step, which resulted in a high total ozone dosage. The alternative, the consecutive treatment activated sludge-ozonation-activated sludge, did not give a better COD-removal with the same ozone dose as the integrated concept. The economic evaluation proves that the integrated chemical and biological treatment is expensive for the paper industry if a low discharge limit of COD has to be complied with.     

Effect of ozone, chlorine and hydrogen peroxide on the elimination of colour in treated textile wastewater by MBR.

In treating textile wastewater, the application of membrane bioreactor (MBR) technology showed high efficiency in COD and BOD5 removal. However, insufficient colour removal was achieved for possible reuse. The aim of the work presented in this paper was to test the performance of chemical advanced oxidation on the elimination of the colour downstream of an MBR. To improve the quality of the membrane bioreactor effluent three different oxidation treatments were tested at lab-scale: ozonation, chlorination and hydrogen peroxide oxidation. Colour, COD and BOD5 were controlled in order to assess the effectiveness of each process. For chlorination, even with 250 mg/L (active chlorine) only 80% colour removal (SACin = 14; SACout = 2.8) was achieved which is considered unsatisfactory. For hydrogen peroxide, the colour removal was even poorer; it was just 10% at a concentration of 250 mg/L. In contrast, good results were obtained by ozonation. By using only 38 mg/L within 20 minutes, it was possible to achieve the reuse recommendation with a satisfactory colour removal of 93% (SACin = 14; SACout = 0.98). The results showed that ozonation was the most promising method.     

催化湿式氧化高浓度SDBS废水的研究

以过渡金属氧化物CuO为主活性组分,通过复合第二活性组分Co3O4和掺入电子助剂CeO2的考察,研制出适用于催化湿式氧化处理高浓度十二烷基苯磺酸钠(SDBS)废水的复合催化剂。实验结果表明,新制备的复合催化剂有较好的催化活性。通过对反应温度、氧气分压和废水pH值等工艺条件的考察,得出催化湿式氧化处理高浓度SDBS废水适宜的工艺条件为:反应温度为280℃、氧气分压为3 MPa、pH值为8.2,在此条件下用自制的催化剂处理初始COD质量浓度为4 942.1 mg/L的SDBS废水,在120 min内,COD去除率达到88.1%,而在相同条件下未加催化剂的湿式氧化COD去除率只有30.7%。     

Ozone catalysed with solids as an advanced oxidation process for landfill leachate treatment.

Heterogeneous catalytic ozonation (HCO) of wastewater is gaining both research and industrial interests. It is proved to be an advanced oxidation process since it involves hydroxyl radicals as oxidation species. Few studies have been carried out to test HCO in the treatment of landfill leachates. This work has been carried out to test three types of catalysts: activated carbon (AC), expanded perlite (EP) and titanium dioxide (TiO2) combined with ozone at 80 g/m3 gas concentration for the treatment of a leachate generated by Jebel Chakir landfill site near Tunis-capital of Tunisia. The work has shown a reduction in COD of about 45% and an increase in biodegradability (BOD5/COD) from 0.1 to 0.34. A catalyst concentration of 0.7 g/L was found optimal for the treatment of the leachate.     

The efficacy of ozone as a pre- and post-treatment option for UASB-treated food processing wastewaters.

The efficiency of ozone as a pre- and post-treatment to UASB treatment was investigated, followed by a study into UASB reactor performance with ozonated wastewater as substrate. Combinations of pre- and/or post-ozonation with UASB treatment gave better results than ozonation or UASB alone and COD reductions of 53.0-98.9% were achieved for treatment of canning and winery wastewaters. A UASB reactor was fed with pre-ozonated cannery wastewater for over 70 d. COD removal improved from between 58.8 and 64.4% to between 85.3 and 91.8% after pre-ozonated substrate feed commenced. Subsequent increases in organic loading rate (OLR) from 2.4 to 3.4 kgCOD m(-3) x d(-1) did not affect reactor performance. By including a final post-ozonation treatment to this UASB effluent a total COD reduction of 99.2% was achieved.     

Performance evaluation of physicochemical processes for biologically pre-treated livestock wastewater.

The use of a combination of biological and physicochemical methods is a promising technique to reduce highly concentrated pollutants in livestock wastewater: firstly, biodegradable organic matters, nitrogen and a part of phosphorus should be removed in a biological treatment process and then residual non-biodegradable organic matters, color and phosphorus be eliminated by physicochemical methods. In this study, therefore, the integrations of chemical coagulation, activated carbon adsorption, Fenton oxidation and ozonation were evaluated to provide an appropriate post-treatment process for biologically pre-treated livestock wastewater. With applying a single method such as coagulation and Fenton oxidation, a yellowish brown color and COD still remained. According to the experimental result, the quality of treated wastewater including color was enough to be discharged after chemical coagulation followed by ozonation or Fenton oxidation process. Among these, ozonation was the most effective technology for decolorization. Neither simple biological nor physicochemical process provides an adequate treatability for the sufficient depletion of organics and decolorization when treating livestock wastewater. Considering only the removal efficiency, the integration of Fenton oxidation and ozonation would be an efficient alternative as a post-treatment.     

深度处理维生素制药废水的中试研究

维生素制药废水经过初步生化处理后,出水水质无法满足要求,具有难降解、COD和氨氮浓度高的特点,针对这些特点,本文采用"强化复合曝气水解酸化→高效厌氧复合反应→流离生物接触氧化"连续工艺深度处理维生素制药废水,研究其可行性。处理规模为7.2 m3/d的中型试验结果表明:强化复合曝气水解酸化能使进水B/C值由0.33提高到0.48,提高下一步生化反应的处理效率,当进水CODCr的浓度为150～641 mg/L,氨氮浓度为6～115 mg/L时,平均去除率分别达到84.28%、93.8%,出水COD浓度小于50mg/L,氨氮浓度小于5 mg/L,出水水质能够达到《城镇污水处理厂污染物排放标准》GB18918-2002中的一级A指标,该连续工艺深度处理此类废水具有可行性和稳定性。     

Advanced oxidation of bleached eucalypt kraft pulp mill effluent.

In this study a poorly biodegradable (BOD/COD = 0.3) industrial alkaline ECF bleaching filtrate was treated using different advanced oxidation processes to evaluate their use in combined chemical-biological treatment aimed at increasing recalcitrant COD removal and improving final effluent quality. Oxidative treatments included ozonation combined with hydrogen peroxide (2, 5, 10, 20 mmol L(-1) O3/0.7, 2, 5, 10 mmol L(-1) H2O2) and photocatalysis with hydrogen peroxide (UV/2, 4 and 8 mmolL(-1) H2O2) and with TiO2 (UV/TiO2/0.7 and 4 mmol L(-1) H2O2). The O3/H2O2 process increased effluent biodegradability by up to 68% as a result of increasing BOD and decreasing COD. Increasing the O3 dose had a greater effect on biodegradability improvement and lignin and colour removal efficiencies than increasing the H2O2 dose. A combined oxidant dose of 5 mmol L(-1) O3 and 2 mmol L(-1) H2O2 resulted in 75% lignin removal, 40% colour removal and 6% carbohydrate loss without mineralizing the organic carbon. The photocatalytic processes led to a decrease in effluent biodegradability through combined decrease in BOD and increase in COD and did not result in efficient lignin or colour removal. Photocatalytic oxidation was apparently inhibited by the high chloride and COD levels in the alkaline filtrate, and may be more efficient in recalcitrant COD removal if performed after biological.     

Phenol wastewater remediation: advanced oxidation processes coupled to a biological treatment.

Nowadays, there are increasingly stringent regulations requiring more and more treatment of industrial effluents to generate product waters which could be easily reused or disposed of to the environment without any harmful effects. Therefore, different advanced oxidation processes were investigated as suitable precursors for the biological treatment of industrial effluents containing phenol. Wet air oxidation and Fenton process were tested batch wise, while catalytic wet air oxidation and H2O2-promoted catalytic wet air oxidation processes were studied in a trickle bed reactor, the last two using over activated carbon as catalyst. Effluent characterisation was made by means of substrate conversion (using high liquid performance chromatography), chemical oxygen demand and total organic carbon. Biodegradation parameters (i.e. maximum oxygen uptake rate and oxygen consumption) were obtained from respirometric tests using activated sludge from an urban biological wastewater treatment plant (WWTP). The main goal was to find the proper conditions in terms of biodegradability enhancement, so that these phenolic effluents could be successfully treated in an urban biological WWTP. Results show promising research ways for the development of efficient coupled processes for the treatment of wastewater containing toxic or biologically non-degradable compounds.     

Reuse of a dyehouse effluent after being treated with the combined catalytic wet peroxide oxidation process and the aerated constructed wetland.

A catalytic wet peroxide oxidation process was combined with the aerated constructed wetland in order to treat the raw dyehouse wastewater to in acceptable level for reuse as washing process water. More than 90% of BOD and CODs could be removed with the wet peroxide oxidation reactor and the remaining pollutants in the treated water were transformed into biodegradable ones which could have been successfully treated at the following aerated constructed wetland. The highest values of BOD5, CODMn, CODCr, SS and T-N in the treated water were 1.6, 1.8, 2.1, 0.5 and 12.8 mg/L, respectively. These values were low enough for the treated water to be reused at the washing process.     

Oxidative treatment characteristics of biotreated textile-dyeing wastewater and chemical agents used in a textile-dyeing process by advanced oxidation process.

The oxidative treatment characteristics of biotreated textile-dyeing wastewater and typical chemicals such as desizing, scouring, dispersing and swelling agents used in the textile-dyeing process by advanced oxidation process were experimentally studied. The refractory organic matters remained in the effluent of biological treatment process without degradation may be suitable for the improvement of biodegradability and mineralized to CO2 by combined ozonation with and without hydrogen peroxide. On the other hand, the refractory chemicals contained in the scouring agent A and swelling agent may not be mineralized and their biodegradability may not be improved by ozonation. However, the BOD/DOC ratio of scouring agent B increased from 0.3 to 0.45 after ozonation. Based on the results described above, advanced treatment process involving the ozonation without and with the addition of hydrogen peroxide, followed by biological treatment was proposed for the treatment of refractory wastewater discharged from the textile-dyeing process.     

Influence of physico-chemical treatment on the subsequent biological process treating paper industry wastewater

The present paper presents the main results of the biodegradation study of paper industry wastewater through physico-chemical treatment. Indeed, around 60% of chemical oxygen demand (COD) removal can be achieved by electroflocculation treatment. Furthermore, a removal efficiency of the COD of almost 91% has been obtained by biological treatment, with activated amount of sludge for 24 h of culture. Concerning the physico-chemical pre-treatment of the untreated, filtered and electroflocculated rejection effluents, it has been investigated through the degradation curve of COD studies.     

Assessment of electrochemical and chemical coagulation as post-treatment for the effluents of a UASB reactor treating cellulose pulp mill wastewater.

This paper presents results from exploratory experiments to test the technical feasibility of electrolytic treatment and coagulation followed by flocculation and sedimentation as post-treatment for the effluent of an UASB reactor treating simulated wastewater from an unbleached Kraft pulp mill. The electrolytic treatment provided up to 67% removal of the remaining COD and 98% of color removal. To achieve these efficiencies the energy consumption ranged from 14 Wh x l(-1) to 20 Wh x l(-1). The coagulation-flocculation treatment followed by settling required 350-400 mg x l(-1) of aluminium sulfate. The addition of a high molecular weight cationic polymer enhanced both COD and color removal. Both post-treatment processes are technically feasible.     

Aqua-Biomant: integrated biological and electrochemical oxidation for industrial wastewater treatment.

An innovative technology for industrial wastewater treatment has been developed. The main focus of the new system is a transformation of persistent organic compounds (biorecalcitrant COD) into a biodegradable fraction, followed by high efficient biological elimination using specialised bacteria's. To fulfill these targets the Aqua-Biomant process integrates two treatment steps: an aerated biological upflow filter and a electrochemical oxidation technique using boron doped-diamond electrodes. The advantages of the process are high efficient COD removal with reduced energy consumption combined with low total residence time.     

光催化氧化降解活性艳红X-3B模拟染料废水试验

研究Fenton氧化技术处理偶氮染料活性艳红X-3B模拟废水的反应条件及处理效果,主要考察了Fe2+和H2O2的用量、温度以及废水的pH值等条件对色度和化学耗氧量(COD)去除率的影响。实验结果显示,Fenton氧化反应对废水色度和COD都有较好的去除效果,去除率分别为99.78%和94.34%。考察了不同光照条件Fenton试剂对废水的处理效果,结果表明光照能够加快Fenton反应速度、提高COD去除率。     

Winery and distillery wastewater treatment by anaerobic digestion.

Anaerobic digestion is widely used for wastewater treatment, especially in the food industries. Generally after the anaerobic treatment there is an aerobic post-treatment in order to return the treated water to nature. Several technologies are applied for winery wastewater treatment. They are using free cells or flocs (anaerobic contact digesters, anaerobic sequencing batch reactors and anaerobic lagoons), anaerobic granules (Upflow Anaerobic Sludge Blanket--UASB), or biofilms on fixed support (anaerobic filter) or on mobile support as with the fluidised bed. Some technologies include two strategies, e.g. a sludge bed with anaerobic filter as in the hybrid digester. With winery wastewaters (as for vinasses from distilleries) the removal yield for anaerobic digestion is very high, up to 90-95% COD removal. The organic loads are between 5 and 15 kgCOD/m3 of digester/day. The biogas production is between 400 and 600 L per kg COD removed with 60 to 70% methane content. For anaerobic and aerobic post-treatment of vinasses in the Cognac region, REVICO company has 99.7% COD removal and the cost is 0.52 Euro/m3 of vinasses.     

Use of agro-food wastewaters for the optimisation of the denitrification process.

The aim of this work was to study the feasibility of the denitrification process enhancement, in the Ciudad Real (Spain) WWTP, by dosing agro-food wastewaters generated nearby the city. The studied agro-food wastewaters were characterised by a high COD and low nutrients concentration. The denitrification rates with these wastewaters were lower than those obtained either with acetate or urban sewage, however the dose of agro-food wastewaters raised significantly the denitrification capacity in the WWTP because of the significant increase of easily biodegradable substrates in the wastewater. From the laboratory NUR batch test it was observed that the best agro-food wastewater to enhance the denitrification process was that coming from tomato processing, which presented an average denitrification rate of 1.9 mg NOx-N/(g VSS.h) and an average denitrification yield of 0.2 mg NOx-N/mg COD. The viability of the use of tomato processing wastewater was checked in a pilot plant optimised for urban sewage treatment with biological nutrient removal. The optimum dose, 5.9 mg COD/mg NOx-N, was applied and 99% of the nitrate was removed from the wastewater without influencing negatively either the COD or P effluent concentrations.     

Biomass adaptation to complex substrate degradation in membrane bioreactors: appropriated operating conditions.

The aim of this work is to analyse the biological performances of two immersed membranes bioreactors focusing on the biomass adaptation to complex substrate degradation and the performance in term of permeate quality. Two influents were selected: a synthetic complex influent (acetate/Viandox, MBR1) and a real seafood processing wastewater (surimi product, MBR2). The MBR systems were operated for long periods without any sludge extraction except for sampling. Organic matter removal, sludge production and quality of the treated wastewater were analysed and studied. COD removal efficiencies after a period of biomass adaptation were higher than 97% and 95% for the synthetic and real wastewater respectively. In both cases, the COD of the treated wastewater was lower than 50 mg.L(-1). In spite of salt concentration in the real wastewater a biomass adaptation process occurs. In the overall operational period, a 0.058 gCOD P.gCOD T(-1) and a 0.12 gCOD P.gCOD T(-1) observed sludge yields were obtained for the MBR1 and MBR2 respectively. These values are approximately 5 to 10 times lower than those measured in conventional activated sludge process. These results showed that the presence of particular and some of non-easily degradable compounds in the influent of MBR2 didn't limit the performance of MBR in term of COD removal achieved. The results have also confirmed the excellent permeate quality for water reuse from MBRs systems.