Fenton法处理垃圾渗滤液的参数优化及反应动力学模型

采用Fenton法处理垃圾渗滤液,研究反应时间、初始浓度、pH、Fenton试剂用量对垃圾渗滤液TOC去除率的影响。研究结果表明,最优反应条件是反应时间30 min,初始pH为3.0,初始[H2O2]0=7 310 mg/L,最佳[H2O2]/[Fe2+]摩尔比为5,反应温度为室温,此时渗滤液的TOC去除率达到70.3%。渗滤液矿化过程符合一级反应动力学,并建立了符合该渗滤液的反应动力学模型。     

应用自动识别和定量系统评价两种污水再生工艺对微量有机污染物的去除效果

采用气质联用分析,并结合自动识别与定量系统(AIQS-DB)考察2种再生水厂采用的深度处理工艺对微量有机污染物的去除效果。结果表明,以污水为原水的膜生物反应器(MBR)+臭氧氧化+生物活性炭滤池(BAC)工艺用于再生水生产,MBR工艺对有机污染物的去除起主要作用;城市污水厂二级出水为原水的混凝沉降+浸没式超滤(SMF)/连续微滤(CMF)+部分反渗透(RO)+臭氧氧化工艺用于再生水生产,其SMF和CMF工艺段的膜截留作用均可有效消减有机污染物含量,SMF的效果优于CMF;2种工艺中采用的臭氧技术都能进一步加强部分物质的去除效果。气质联用结合AIQS-DB可用于再生水中污染物的筛查和不同污水再生工艺对微污染物消减效果的评价。     

氧活性粒子氧化NO生成HNO_3

采用强电离介质阻挡放电方法制取高浓度氧活性粒子(O+2、O3)并注入气体外排烟道中,实现O+2、O3氧化NO转化成资源酸(HNO3)的等离子化学反应。描述强电离放电的氧活性粒子产生器,讨论烟道中O+2、O3氧化NO成HNO3等离子体反应机制,分析回收酸液的NO-2、NO-3离子种类及浓度。考察强电离放电等离子体源的输入功率、水体积百分比、气体温度、气体流速对NOx氧化率的影响。氧化率为97.2%的最佳实验条件是:O+2浓度为1.38×1010个/cm3,O3浓度为210 mg/L,烟气温度为65℃,H2O体积浓度为5.6%,停留时间为0.94 s。     

发酵类抗生素废水处理工艺及运行效果

介绍了内蒙古某抗生素废水处理厂的处理工艺流程、处理单元类型及其详细设计参数,通过对该污水处理厂半年内运行效果的调研,分析评价该污水处理系统的处理效果及出水指标;该水厂工艺流程对COD、TOC、氨氮、总氮、总磷、BOD和急性毒性的平均去除率分别为96.52%、95.83%、50.24%、55.20%、62.05%、98.52%和99.14%,COD、氨氮、总氮、总磷出水水质分别为477、438、556.7和7.69 mg/L,达到排放到城区下水道要求,园区内所有废水汇集到园区污水处理厂进行集中深度处理达标后排放水体。通过对该水厂工艺的介绍和水质分析,为我国抗生素生产企业面临的废水处理工艺类型选择及工程改造升级提供一定参考。     

Fenton氧化与铁炭微电解组合预处理DMF废水

对COD表征模拟废水中DMF去除率的可行性进行了探讨。在此基础上,分别对铁炭微电解、Fenton氧化-铁炭微电解和铁炭微电解-Fenton氧化组合工艺对DMF废水的处理效果进行分析,结果表明,Fenton氧化-铁炭微电解工艺的处理效果较好。在pH=5,反应时间为1 h,FeSO4·7H2O投加量为1 000 mg/L、H2O2投加量为2.67 mL/L和不曝气的最佳反应条件下,Fenton氧化-铁炭微电解工艺对实际废水和废液中COD的去除率分别达到66.67%和72.22%,从而验证了该工艺处理DMF废水的可行性。此外,Fenton氧化处理DMF废水过程实际上是将酰胺基团和羰基的不饱和双键氧化分解的过程。     

Comparison of Fenton and Photo-Fenton Processes for Livestock Wastewater Treatment

In this study, the photochemical degradation of livestock wastewater was carried out by the Fenton and Photo-Fenton processes. The effects of pH, reaction time, the molar ratio of Fe^{2 +}/H₂O₂, and the Fe^{2 +} dose were studied. The optimal conditions for the Fenton and Photo-Fenton processes were found to be at a pH of 4 and 5, an Fe^{2 +} dose of 0.066 M and 0.01 M, a concentration of hydrogen peroxide of 0.2 M and 0.1 M, and a molar ratio (Fe^{2 +}/H₂O₂) of 0.33 and 0.1, respectively. The optimal reaction times in the Fenton and Photo-Fenton processes were 60 min and 80 min, respectively. Under the optimal conditions of the Fenton and Photo-Fenton processes, the chemical oxygen demand (COD), color, and fecal coliform removal efficiencies were approximately 70–79, 70–85 and 96.0–99.4%, respectively.     

Treating solid dairy manure using microwave-enhanced advanced oxidation process

The microwave enhanced advanced oxidation process (MW/H₂O₂-AOP) was used to treat separated solid dairy manure for nutrient release and solids reduction. The MW/H₂O₂-AOP was conducted at a microwave temperature of 120°C for 10 minutes, and at three pH conditions of 3.5, 7.3 and 12. The hydrogen peroxide dosage at approximately 2 mL per 1% TS for a 30 mL sample was used in this study, reflecting a range of 0.53–0.75 g H₂O₂/g dry sludge. The results indicated that substantial quantities of nutrients could be released into the solution at pH of 3.5. However, at neutral and basic conditions only volatile fatty acids and soluble chemical oxygen demand could be released. The analyses on orthophosphate, soluble chemical oxygen demands and volatile fatty acids were re-examined for dairy manure. It was found that the orthophosphate concentration for untreated samples at a higher % total solids (TS) was suppressed and lesser than actual. To overcome this difficulty, the initial orthophosphate concentration had to be measured at 0.5% TS.     

Adsorption of chlorpyrifos,penconazole and metalaxyl from aqueous solution by modified clays

Sorption of three pesticides (chlorpyrifos, metalaxyl and penconazole) has been measured on a commercial clay montmorillonite and on the same mineral modified with either of two cationic-surfactant micelles. Both micelle–clay complexes, commercial names Cloisite 20A and Cloisite 30B, showed a good capacity to sorb all three pesticides from water, whereas their sorption on the natural montmorillonite was not described by an isotherm. Modelling sorption on both micelle–clay complexes showed that the Freundlich sorption constant (K _F) was higher for chlorpyrifos on Cloisite 20A (K _F = 7.76) than on Cloisite 30B (K _F = 5.91), whereas the sorption of metalaxyl was stronger on Cloisite 30B (K _F = 1.07) than on Cloisite 20A (K _F = 0.57). Moreover the micelle–clay complex Cloisite 20A also showed a good affinity for penconazole, the maximum quantity adsorbed (q _m) of 6.33 mg g^?1 being 45% more than that on Cloisite 30B. Single-batch adsorption of each pesticide onto both micelle–clay complexes was studied using the Freundlich isotherm for chlorpyrifos and metalaxyl and the Langmuir isotherm for penconazole. The Cloisite 20A micelle–clay complex was predicted to require 23% less adsorbent to treat certain volumes of wastewater containing 30 mg L^?1 chlorpyrifos, 43% more to treat metalaxyl similarly and 57% less to treat penconazole compared with Cloisite 30B.     

Microwave enhanced advanced oxidation process for treating dairy manure at low pH

This study investigated the treatment of dairy manure using the microwave enhanced advanced oxidation process (MW-AOP) at pH 2. An experimental design was developed based on a statistical program using response surface methodology to explore the effects of temperature, hydrogen peroxide dosage and heating time on sugar production, nutrient release and solids destruction. Temperature, hydrogen peroxide dosage and acid concentration were key factors affecting reducing sugar production. The highest reducing sugar yield of 7.4% was obtained at 160°C, 0 mL, 15 min heating time, and no H₂O₂ addition. Temperature was a dominant factor for an increase of soluble chemical oxygen demand (SCOD) in the treated dairy manure. The important factors for volatile fatty acids (VFA) production were microwave temperature and hydrogen peroxide dosage. Temperature was the most important parameter, and heating time, to a lesser extent affecting orthophosphate release. Heating time, hydrogen peroxide dosage and temperature were significant factors for ammonia release. There was a maximum of 96% and 196% increase in orthophosphate and ammonia concentration, respectively at 160°C, 0.5 mL H₂O₂ and 15 min heating time. The MW-AOP is an effective method in dairy manure treatment for sugar production, nutrient solubilisation, and solids disintegration.     

Chemical oxidation of sulfadiazine by the Fenton process: Kinetics,pathways, toxicity evaluation

This paper investigated sulfadiazine oxidation by the Fenton process under various reaction conditions. The reaction conditions tested in the experiments included the initial pH value of reaction solutions, and the dosages of ferrous ions and hydrogen peroxide. Under the reaction conditions with pH 3, 0.25 mM of ferrous ion and 2 mM of hydrogen peroxide, a removal efficiency of nearly 100% was achieved for sulfadiazine. A series of intermediate products including 4-OH-sulfadiazine/or 5-OH-sulfadiazine, 2-aminopyrimidine, sulfanilamide, formic acid, and oxalic acid were identified. Based on these products, the possible oxidation pathway of sulfadiazine by Fenton's reagent was proposed. The toxicity evaluation of reaction solutions showed increased antimicrobial effects following the Fenton oxidation process. The results from this study suggest that the Fenton oxidation process could remove sulfadiazine, but also increase solution toxicity due to the presence of more toxic products.