Photo-oxidation of cork manufacturing wastewater

Several photo-activated processes have been investigated for oxidation of a cork manufacturing wastewater. A comparative activity study is made between different homogeneous (H2O2/UV-Vis and H2O2/Fe2+/UV-Vis) and heterogeneous (TiO2/UV-Vis and TiO2/H2O2/UV-Vis) systems, with degradation performances being evaluated in terms of total organic carbon (TOC) removal. Results obtained in a batch photo-reactor show that photo-catalysis with TiO2 is not suitable for this kind of wastewater while the H2O2/UV-Vis oxidation process, for which the effect of some operating conditions was investigated, allows to remove 39% of TOC after 4 h of operation (for C(H2O2)=0.59 M, pH=10 and T=35 degrees C). The combined photo-activated process, i.e., using both TiO2 and H2O2, yields an overall TOC decrease of 46% (for C(TiO2)=1.0 gl(-1)). The photo-Fenton process proved to be the most efficient, proceeds at a much higher oxidation rate and allows to achieve 66% mineralization in just 10 min of reaction time (for C(H2O2)=0.31 M, T=30 degrees C, Fe2+:H2O2=0.12 (mol) and pH=3.2).     

Temperature activated degradation (mineralization) of 4-chloro-3-methyl phenol by Fenton's reagent

With the aim to evaluate the effect of temperature, 4-chloro-3-methyl phenol (CMP) degradation by Fenton's reagent was investigated at 25 and 70 degrees C under the following initial conditions: [CMP]0 = 10 mM, [Fe2+]0 = 0.5 mM; ([H2O2]0/[CMP]0) = 80, pH0 = 3. The results indicated that CMP degradation was strongly influenced by temperature. In fact, the maximum TOC removal, achieved after ca. 24h, was by far greater at 70 degrees C (85%) than at 25 degrees C (36%). The same happened for organic chlorine (TOX) conversion into inorganic chloride, i.e. 100%, after 3 h at 70 degrees C, and 87%, after 27 h at 25 degrees C. As the recorded trends of CMP removal and chloride formation were basically the same, hydroxy substitution (ipso-substitution) was hypothesised as one likely mechanism of CMP degradation. The higher level of mineralization recorded at 70 degrees C was ascribed to: (i) a greater *OH concentration; (ii) a consequently greater extent of CMP oxidation to organic acids; (iii) a higher decarboxylation rate of such acids. An interesting consequence of such extended organic acids decarboxylation was a pH increase up to 8 that, in turn, caused, in the treated mixture, the decomposition of excess H2O2 as well as the precipitation of iron ions. These two latter outcomes are technologically important considering that usually, before discharging Fenton treated wastewater, specific polishing steps are required just to remove iron ions, decompose excess hydrogen peroxide and neutralise the pH.     

吸附饱和活性炭的Fenton试剂再生

颗粒活性炭吸附有机废水中二异丙基苯等有机物后，采用Fenton试剂对活性炭进行氧化再生。研究H2O2与Fe2＋的摩尔配比及投加量、pH、温度、再生时间等因素对活性炭再生效果的影响。实验结果表明，Fenton体系中Fe2＋和H2O2的摩尔比为1：20，H2O2投加量为120mmol／L，pH为3，再生温度为25℃，再生时间为70min时，为最佳再生条件，再生率可达85．6％，且6次连续再生的平均效率仍能达到84．9％。Fenton试剂再生活性炭的方法表现出较高的经济和环境效益。     

Effects of dissolved organic carbon on sorption of 3,4-dichloroaniline and 4-bromoaniline in a calcareous soil

To evaluate the effects of dissolved organic carbon on sorption of 3,4-dichloroaniline (3,4-DCA) and 4-bromoaniline (4-BA) on soils, batch sorption experiments were carried out. The soil used was a typical calcareous soil from south-eastern Spain. Two different types of dissolved organic carbon were used, that is, dissolved organic carbon extracts from a commercial peat (DOC-PE) and high-purity tannic acid (DOC-TA). The experiments were carried out in a 0.01 M CaCl2 aqueous medium at 25 degrees C. The results obtained from the sorption experiments show that the presence of both DOC-PE and DOC-TA, over a concentration range of 15-100 mg l-1, produced in all cases, an increase in the amount of 3,4-DCA and 4-BA adsorbed on the soil studied.     

焦化废水泡沫分离液的Fenton催化氧化预处理

以焦化废水处理过程产生的泡沫分离液为研究对象，对其进行Fenton催化氧化处理实验，考察H₂O₂用量、Fe²⁺浓度、pH和反应时间4个因素对处理效果的影响，并结合GC/MS方法比较处理前后泡沫分离液中有机物的种类及其生物降解性的变化。结果表明，采用［H₂O₂］=100 mmol/L、［Fe²⁺］=100 mg/L、pH=3、反应时间为30 min的Fenton催化氧化反应条件，可以使分离液的COD去除率达到68%以上；经Fenton处理后，分离液的B/C值由0.12提高至0.38，生物降解性明显改善；通过GC/MS的分析，基本明确分离液中含有的有机物主要为酚、胺、腈、酯类有机物及喹啉、吡啶等杂环化合物，大多数属于难降解且生物毒性较强的有机物。针对这些复杂组分共存的泡沫分离液，利用Fenton试剂较强的氧化能力能够将其含有的有毒/难降解有机物转化为低毒或无毒的小分子有机物，为其后续的生物处理创造良好的条件。     

Response surface modeling for optimization heterocatalytic Fenton oxidation of persistence organic pollution in high total dissolved solid containing wastewater

The rice-husk-based mesoporous activated carbon (MAC) used in this study was precarbonized and activated using phosphoric acid. N₂ adsorption/desorption isotherm, X-ray powder diffraction, electron spin resonance, X-ray photoelectron spectroscopy and scanning electron microscopy, transmission electron microscopy, ²⁹Si-NMR spectroscopy, and diffuse reflectance spectroscopy were used to characterize the MAC. The tannery wastewater carrying high total dissolved solids (TDS) discharged from leather industry lacks biodegradability despite the presence of dissolved protein. This paper demonstrates the application of free electron-rich MAC as heterogeneous catalyst along with Fenton reagent for the oxidation of persistence organic compounds in high TDS wastewater. The heterogeneous Fenton oxidation of the pretreated wastewater at optimum pH (3.5), H₂O₂ (4 mmol/L), FeSO₄?7H₂O (0.2 mmol/L), and time (4 h) removed chemical oxygen demand, biochemical oxygen demand, total organic carbon and dissolved protein by 86, 91, 83, and 90 %, respectively.     

Fenton氧化法深度处理甲醛废水

采用Fenton氧化法深度处理经生化降解后的甲醛废水,结果表明,Fenton氧化法深度处理甲醛废水是可行的,在合适的反应条件下,降解初始COD为150 mg/L左右的甲醛废水,COD去除率达30%以上;Fe2+与H2O2的投加比例、投加量及投加方式、反应温度、pH、反应时间对处理效果都有不同程度的影响。     

二级Fenton氧化高浓度有机硅废水研究

采用二级Fenton氧化技术对可生化性差的高浓度有机硅废水进行处理,考察了不同因素对COD去除率的影响,对比了一级氧化和二级氧化的效果。结果表明对于COD为9 600 mg/L的高浓度有机硅废水,pH为3,[H2O2]/[Fe2+]=2∶1为最佳的反应条件,COD去除率随着H2O2的投加量的增大先增大而后减小,每200 mL水样中先投加20%的硫酸亚铁12 mL,然后分2次投加30%的H2O2各4 mL,氧化完成后调整pH值为7~8静止沉淀,COD去除率达89.2%。对于某绝缘电器厂的生产废水经二级Fenton氧化处理后,出水有机物浓度显著降低,可生化性提高,Fenton二级氧化可以作为高浓度有机硅废水的预处理工艺。     

新型水处理活性炭选型技术

活性炭依其原料不同、生产工艺不同,而有不同的吸附性能.使用简易的活性炭选型方法,可以减少应用测试时的备选炭型,从而大大降低活性炭水处理技术的运行成本.以碘值、甲基蓝值、苯酚值和丹宁酸值4种吸附容量性能指标为依据的活性炭选型技术,可以有效地预测活性炭对于水中各种大小不同污染物的去除能力.BET测试结果证明了这4项指标数据对于活性炭孔径分布预测的准确性.2,4-二氯苯酚和腐殖酸等目标化合物的吸附容量实验结果也都验证了这4项指标的预测功用,说明这种简便的活性炭选型技术有着广泛的应用价值.     

Transformation of effluent organic matter during subsurface wetland treatment in the Sonoran Desert

The fate of dissolved organic matter (DOM) during subsurface wetland treatment of wastewater effluent in a hot, semi-arid environment was examined. The study objectives were to (1) discern changes in the character of dissolved organics as consequence of wetland treatment (2) establish the nature of wetland-derived organic matter, and (3) investigate the impact of wetland treatment on the formation potential of trihalomethanes (THMs). Subsurface wetland treatment produced little change in DOM polarity (hydrophobic-hydrophilic) distribution. Biodegradation of labile effluent organic matter (EfOM) and internal loading of wetland-derived natural organic matter (NOM) together produced only minor changes in the distribution of carbon moieties in hydrophobic acid (HPO-A) and transphilic acid (TPI-A) isolates of wetland effluent. Aliphatic carbon decreased as a percentage of total carbon during wetland treatment. The ratio of atomic C:N in wetland-derived NOM suggests that its character is determined by microbial activity. Formation of THMs upon chlorination of HPO-A and TPI-A isolates increased as a consequence of wetland treatment. Wetland-derived NOM was more reactive in forming THMs and less biodegradable than EfOM. For both HPO-A and TPI-A fractions, relationships between biodegradability and THM formation potential were similar among EfOM and NOM isolates; the less biodegradable isolates exhibited greater THM formation potential.     

A comparative study of the removal of 3-indolebutyric acid using advanced oxidation processes

In this study, advanced oxidation technologies, namely Fenton Process (FP), Fenton-Like Process (FLP), ozonation (O3) and O3/H2O2 processes, were applied to synthetic wastewater containing 3-indolebutyric acid (IBA). The effectiveness of each process was investigated at different pH values, Fe(+2), Fe(+3), O3 and H2O2 concentrations with respect to the removal efficiencies for chemical oxygen demand (COD) and total organic carbon (TOC). The best removal efficiencies were seen at pH 3 and 2 mM Fe concentration in both FP and FLP, in which the optimum H2O2 concentrations were 6 mM for FP and 10 mM for FLP. Optimum process conditions were pH 12 for the O3 process, pH 9 for the O3/H2O2 process and 1:1 O3/H2O2 molar ratio. The highest COD removal efficiency was 86 percent, obtained in the O3/H2O2 process and the highest TOC removal efficiency was obtained at 77 percent in the FP.     

Fe/C微电解和Fenton氧化联合处理印刷电路板废水

研究了Fe/C微电解和Fenton氧化处理印刷电路板废水的最佳条件和联合工艺的处理效果。结果表明,Fe/C微电解最佳工艺条件为：pH=2,Fe/C质量比为2∶1,投加药剂量为30 g/L,停留时间为30 min;Fenton氧化最佳工艺条件为：pH=3,H2O2投加量为6 mL/L,停留时间为2 h。将2种方法联用并进行中试实验,结果表明,对原水的COD去除率可达80%,而且Fenton反应可利用微电解产生的Fe2＋,节约成本,运行稳定,效果良好。     

Post-treatment of bio-treated acrylonitrile wastewater using UV/Fenton process: degradation kinetics of target compounds

In this study, post-treatment of bio-treated acrylonitrile wastewater was performed using the UV/Fenton process. Five target compounds (furmaronitrile, 3-pyridinecarbonitrile, 1,3-dicyanobenzene, 5-methyl-1H-benzotriazole, and 7-azaindole) were selected as target compounds and their degradation kinetics were examined. Under optimal reaction conditions (H₂O₂ dosage 3.0 mM, Fe²⁺ dosage 0.3 mM, and initial pH 3.0), more than 85% of total organic carbon (TOC) was eliminated in 30 min when a 10-W UV lamp was employed, and the electrical energy per order of magnitude for TOC removal was as low as 2.96 kWh m^?3. Furthermore, the target compounds and the toxicity were largely removed from the bio-treated effluent. Size exclusion chromatography with organic carbon detector analysis revealed that organic components with a wide range of molecular weights were greatly reduced after the UV/Fenton process. A simplified pseudo steady-state (SPSS) model was applied to predict the degradation of target compounds during the UV/Fenton process. The concentrations of generated hydroxyl radicals were estimated to be 3.06 × 10^?12 M, 6.37 × 10^?12 M, and 10.9 × 10^?12 M under 5-, 10-, and 15-W UV lamps, respectively. These results demonstrate that the proposed SPSS model fitted well with experimental data on the post-treatment of real wastewater, and consequently indicate that this model can be a useful tool in the prediction of degradation of target compounds during the UV/Fenton process.

     

Biodegradation and biotransformation of wastewater organics as precursors of disinfection byproducts in water

Laboratory experiments were carried out to investigate wastewater organics as the precursors of disinfection byproducts (DBPs) in drinking water supply. The focus was on the change in wastewater DBP precursors during biological degradation under simulated natural conditions. The wastewater and its treated secondary effluent were characterized for DBP formation potential (DBPFP) and DBP speciation profile, including trihalomethanes, haloacetic acids, chloral hydrate, and nitrogen-containing DBPs. Several model organic compounds, including humic acid, tannic acid, glucose, starch, glycine, and bovine serum albumin (BSA), were used to represent the different types of organic pollutants in wastewater discharge. The results show that the DBPFP of wastewater decreased after biodegradation, but the remaining organic matter had a greater DBPFP yield with chlorine. Different model organics displayed different changes in DBPFP during biodegradation. The DBPFP remained largely unchanged for the glycine solution, decreased greatly for the tannic acid and BSA solutions, and increased nearly 3-fold for the glucose and starch solutions after 10d of biodegradation. Meanwhile, the DBPFP yield increased from 3 for glycine to 51μg DBP mg(-1) C for its degradation residue, and from 1 for glucose and starch to 87 and 38μg DBP mg(-1) C for their organic residues, respectively. Although biodegradation may effectively remove some DBP precursors, biotransformation during the process produces new DBP precursors in the form of soluble microbial products (SMPs). The experimental results reveal that SMPs may be an important source of wastewater-derived DBP precursors in natural waters.     

An analysis of nitrification during the aerobic digestion of secondary sludges

Investigations were undertaken to study the occurrence and progress of nitrification during aerobic digestion of activated sludge in a wide range of initial concentrations of total solids (1000 to 80 000 mg litre(-1), initial pH range of 4.5 to 10.4 and digestion temperature range of 5 degrees to 60 degrees C. Batch aerobic digestion studies on activated sludge grown on wastewater (enriched with organic solids from human excretal material) indicate that almost complete elimination of the 'biodegradable' matter of the activated sludge was one of the essential prerequisites to initiate nitrification. Favourable ranges of temperature and pH for nitrification were observed to be 25 degrees to 30 degrees C and 6.0 to 8.3, respectively. With all favourable conditions, a minimum period of about 2 days was necessary for population build-up of genera Nitrosomonas and Nitrobacter, and to initiate nitrification. Nitrate formation invariably lagged behind nitrite formation, but under certain conditions both phases of nitrification were observed to progress hand in hand.     

Treatment of coking wastewater by an advanced Fenton oxidation process using iron powder and hydrogen peroxide

In this study the treatment of coking wastewater was investigated by an advanced Fenton oxidation process using iron powder and hydrogen peroxide. Particular attention was paid to the effect of initial pH, dosage of H₂O₂ and to improvement in biodegradation. The results showed that higher COD and total phenol removal rates were achieved with a decrease in initial pH and an increase in H₂O₂ dosage. At an initial pH of less than 6.5 and H₂O₂ concentration of 0.3 M, COD removal reached 44-50% and approximately 95% of total phenol removal was achieved at a reaction time of 1 h. The oxygen uptake rate of the effluent measured at a reaction time of 1 h increased by approximately 65% compared to that of the raw coking wastewater. This indicated that biodegradation of the coking wastewater was significantly improved. Several organic compounds, including bifuran, quinoline, resorcinol and benzofuranol were removed completely as determined by GC-MS analysis. The advanced Fenton oxidation process is an effective pretreatment method for the removal of organic pollutants from coking wastewater. This process increases biodegradation, and may be combined with a classical biological process to achieve effluent of high quality.     

铁炭微电解-Fenton试剂法预处理半焦废水

采用铁炭微电解／Fenton试剂法对半焦废水进行预处理，探索材料粒径、铁炭比、废水pH、H2O2用量以及反应时间对处理效果的影响。结果表明，在铁屑粒径为5～7mm，活性炭粒径为2～3mm，铁炭体积比为1：1，微电解反应90min，进水pH为8．0～9．0，H2O2投加量为4mL／L，Fenton试剂反应90min的条件下，半焦废水COD去除率可达55％以上，B／C由处理前的0．24提高到0．43，可生化性能良好，铁炭微电解／Fenton试剂法可作为半焦废水一种有效的预处理方式。     

Effects of nitrosation on the formation of cyanide in publicly owned treatment works secondary effluent.

Cyanide has been detected in the effluents of some publicly owned treatment works (POTWs) at levels exceeding the influent concentration. The presence of nitrite ion (NO2-) as a common constituent in domestic wastewater effluents may play an important role in the formation of cyanide through reaction with certain kinds of organic compounds, especially aromatic compounds. Laboratory studies with seven organic compounds (aniline. p-toluidine, phenol, 1,2,4-trihydroxybenzene, L-serine, glycine, and benzoic acid) revealed that cyanide can be formed by reaction of nitrite with some of these compounds. The most substantial free cyanide (HCN. CN-) production observed at 25 degrees C was 0.15 mg/L from reaction of 0.01 mM 1.2.4-trihydroxybenze with 5 mg/L nitrite for 72 hours. Substantial free cyanide formation was also observed at pH 2-4 in experiments with POTW effluents when reactive organics and nitrite were both added to wastewater. Formation of cyanide through nitrosation was strongly pH dependent, being most significant at low pH (2 to 4) and negligible at neutral-to-high pH. This result points to nitrous acid (HNO2) as being more reactive than the dissociated NO2- ion. The reaction of these nitrite species with organics also occurs in conventional analyses for total cyanide which involve distillation under strongly acidic conditions. Sufficient sample pretreatment with sulfamic acid at the time of sampling, not at the time of analysis. is highly recommended to prevent biasing analytical measurement of total cyanide in POTW effluents.     

不同工艺对含高浓度腐殖酸地下水处理的可行性

针对内蒙古农村地区高腐殖酸地下水的处理问题，分别对（pH调节）-PAC强化混凝、高锰酸钾预氧化／混凝、活性炭吸附／混凝、Fenton氧化等技术处理的可行性进行了研究，同时利用三维荧光和高效体积排阻色谱分析处理前后水中有机物的组成变化特征。有机分析结果显示，水中的有机物为腐殖酸类物质，分子量分别为1600和3500，腐殖酸类物质为水中色度的主要贡献者。原水PAC强化混凝、高锰酸钾预氧化／PAC混凝对有机物的去除效果不佳，处理前后水样DOC浓度无明显变化，而pH调节．PAC强化混凝、微米活性炭吸附和Fenton氧化均能有效去除有机物。将原水pH调节至6．5，经300mg／LPAC混凝后出水DOC降至5．99mg／L。活性炭投加量为0．6g／L时，DOC降至7．6mg／L，然后采用60mg／LPAC混凝出去高度分散而不易沉降的小颗粒活性炭。此外，当反应初始pH值为3，过氧化氢投加量为0．5％（v／v），亚铁和双氧水摩尔比为0．05时，出水DOC降至5．6mg／L，氧化后有小分子有机物生成。     

Potential applications of immobilized bitter gourd (Momordica charantia) peroxidase in the removal of phenols from polluted water

The potential applications of immobilized bitter gourd peroxidase in the treatment of model wastewater contaminated with phenols have been investigated. The synthetic water was treated with soluble and immobilized enzyme preparations under various experimental conditions. Maximum removal of phenols was found in the buffers of pH values 5.0-6.0 and at 40 degrees C in the presence of 0.75 mM H(2)O(2). Fourteen different phenols were independently treated with soluble and immobilized bitter gourd peroxidase in the buffer of pH 5.6 at 37 degrees C. Chlorinated phenols and native phenol were significantly removed while other substituted phenols were marginally removed by the treatment. Phloroglucinol and pyrogallol were recalcitrant to the action of bitter gourd peroxidase. Immobilized bitter gourd peroxidase preparation was capable of removing remarkably high percentage of phenols from the phenolic mixtures. Significantly higher level of total organic carbon was removed from the model wastewater containing individual phenol or complex mixture of phenols by immobilized bitter gourd peroxidase as compared to the soluble enzyme. 2,4-dichlorophenol and a phenolic mixture were also treated in a stirred batch reactor with fixed quantity of enzyme for longer duration. The soluble bitter gourd peroxidase ceased to function after 3h while the immobilized enzyme was active even after 6h of incubation with phenolic solutions.