高含硫废水中硫的受限氧化过程及影响因素研究

针对含硫气田采出水硫化物浓度高及氧化产物种类多的特点,通过控制氧化反应使得单质硫为主要产物,实验考察了偏重亚硫酸钠投加量、初始pH和反应时间对硫化物氧化过程及氧化产物组成的影响。结果表明,偏重亚硫酸钠氧化法是处理含硫废水的一种有效手段,最佳反应条件为偏重亚硫酸钠的投加量为6 g/L,初始pH=6,反应时间35 min,此时硫化物的质量浓度从800 mg/L降至21.34 mg/L,硫化物去除率可达97.33%;主要产物为单质硫和硫代硫酸盐,在最佳反应条件下,这2种主产物的转化率为36.63%和57.57%,固体产物元素分析结果表明,其主要成分为S(质量分数为92.056%),偏重亚硫酸钠氧化硫化物过程符合表观二级反应动力学规律,R2=0.9819,反应速率常数为k=0.0063 L/(mg·min)。     

Effects of pH and iron concentrations on sulfide precipitation in wastewater collection systems.

Sulfide precipitation by addition of iron salts is a widely used strategy for sulfide control in wastewater collection systems. Several parameters, such as pH, oxidation-reduction conditions, and reactant concentrations, are known to affect the feasibility of the method. However, their combined effects are difficult to predict for complex media, such as wastewater. This study investigates the effect of pH and reactant concentrations on the efficiency of iron sulfide precipitation in anaerobic municipal wastewater. Laboratory experiments showed that, when the pH was below 7, typically less than 40% of the added ferrous iron reacted by sulfide precipitation, although sulfide was in excess. However, when the pH was above 8, almost complete precipitation of all the added ferrous iron was observed. Varying the ferric-iron-to-ferrous-iron ratio demonstrated that improved efficiency could be achieved when using a 1:1 mixture of ferric chloride and ferrous sulfate.     

Online oxygen control for sulfide oxidation in anaerobic treatment of high-sulfate wastewater.

A new technique for sulfide control was investigated in an upflow-anaerobic filter (UAF) treating high-strength, sulfate-rich wastewater. The technique used periodic oxygen injection using oxidation-reduction potential (ORP) as a controlling parameter to regulate oxygen injection. The UAF was operated at a constant influent total-organic carbon of 6740 mg/L but with different influent sulfates of 1000, 3000, and 6000 mg/L. At 1000 and 3000 mg/L influent sulfates, the produced sulfide did not impose any inhibition to methane-producing bacteria (MPB). However, at 6000 mg/L influent sulfate, the produced dissolved sulfide of 804 mg S/L (free sulfide = 280 mg S/L) severely inhibited the methanogenesis, but not the sulfidogenesis. Upon oxygen injection at elevated ORP of -265 mV, sulfides were almost completely eliminated with a concomitant improvement in methane yield by 46%. If oxygenation was excessive because of an oversetting of ORP, the excess oxygen could be used rapidly by facultative heterotrophs, thereby protecting the MPB from oxygen stress. Regarding online sulfide oxidation, it was found that the biogas and injected oxygen needed to pass through an aqueous layer containing trace metals, which were found to have a significant catalytic effect on abiotic sulfide oxidation.     

气田高浓度含硫废水的化学氧化处理

采用亚硫酸钠(Na2SO3)氧化法对气田高含硫废水进行了实验研究.考察了硫化物初始浓度、Na2SO3/Na2S(摩尔比)、初始pH值和反应时间对Na2SO3氧化去除硫化物效果的影响,进行了对氧化产物的元素分析.结果表明,在Na2SO3/Na2S(摩尔比)为0.7、初始pH值为5和反应时间为5 min时,硫化物从1 100 mg/L降至1.80 mg/L,去除率高达99.84%,达到了气田回注水水质标准.元素分析发现,氧化产物中C、N、S、H和O元素的含量分别为0.11%、0.06%、98.73%、0.90%和1.10%,且其产率达到90.59%.     

丙烯酸废水超临界水氧化动力学研究

用H2O2作为氧化剂,对丙烯酸生产废水进行超临界水氧化研究.得到了反应速率方程表达式.COD、H2O2和水的反应级数分别为1、0和0,指前因子A为4.97 s-1,反应活化能Ea为20.64 kJ/mol,诱导时间为8 s左右.     

Combination of ozonation with conventional aerobic oxidation for distillery wastewater treatment

Laboratory-scale experiments were conducted in order to investigate the effect of ozone as pre-aerobic treatment and post-aerobic treatment for the treatment of the distillery wastewater. The degradation of the pollutants present in distillery spent wash was carried out by ozonation, aerobic biological degradation processes alone and by using the combinations of these two processes to investigate the synergism between the two modes of wastewater treatment and with the aim of reducing the overall treatment costs. Pollutant removal efficiency was followed by means of global parameters directly related to the concentration of organic compounds in those effluents: chemical oxygen demand (COD) and the color removal efficiency in terms of absorbance of the sample at 254 nm. Ozone was found to be effective in bringing down the COD (up to 27%) during the pretreatment step itself. In the combined process, pretreatment of the effluent led to enhanced rates of subsequent biological oxidation step, almost 2.5 times increase in the initial oxidation rate has been observed. Post-aerobic treatment with ozone led to further removal of COD along with the complete discoloration of the effluent. The integrated process (ozone-aerobic oxidation-ozone) achieved approximately 79% COD reduction along with discoloration of the effluent sample as compared to 34.9% COD reduction for non-ozonated sample, over a similar treatment period.     

pH对污水好氧处理过程N2O产生的影响

采用能够同时监测气态和溶解态N2O功能的污水好氧处理过程模拟装置,研究了不同pH条件下氨氧化细菌(AOB)好氧反硝化途径N2O的产生特点、污染物转化过程、胞内聚合物聚羟基脂肪酸酯(PHA)含量的变化以及它们之间的内在联系。结果表明,pH在6.5~8.0范围内,N2O产生量随pH的升高而减小。pH较低时,氧化亚氮还原酶活性受到抑制,导致好氧反硝化过程中产生的N2O大量积累并逸散;随着pH得升高,氧化亚氮还原酶活性增强,N2O产生量随之减少。     

催化湿式氧化处理高含硫废水的研究

利用催化湿式氧化法对一高含硫废水的处理效果进行了系统的研究。筛选出适合处理该种废水的WH型合金催化剂 ,并在此催化剂上考察了反应温度、压力、空速以及气水比 (体积 )等工艺条件对废水处理效果的影响 ,同时考察了废水在催化湿式氧化反应处理前后可生化性的变化。在 2 6 5℃、7.0MPa、空速 =1.0h- 1 、气 H2 O(体积 ) =2 0 0条件下 ,废水COD去除率可达到 77.1%。经过催化湿式氧化处理后 ,废水的BOD5 CODCr值显著提高 ,其值由 0 .0 16提高至 0 .6 4 ,可生化性良好     

类Fenton氧化—好氧移动床生物膜法处理抗生素发酵废水

采用类Fenton氧化-好氧移动床生物膜(MBBR)法处理难降解抗生素发酵废水,探讨了H2O2和草酸投加量对类Fenton氧化工艺以及HRT和曝气量对好氧MBBR反应器的影响.实验结果表明,当类Fenton氧化工艺的最佳操作参数为反应溶液H2O2和草酸初始质量浓度分别为150、45 mg/L、30 W/154 nm紫外灯照射1 h、pH为3.0,在曝气搅拌条件下,COD平均去除率为80.9%.当类Fenton氧化工艺出水pH在7.0时,废水中的污染物还可以进一步被混凝去除.好氧MBBR反应器的最佳工艺参数为HRT 12 h、曝气量0.10 m3/h以及填料填充比(体积比)30%,最终废水COD平均去除率为99.1%,达到<污水综合排放标准>(GB 8978-1996)三级标准要求.     

Simultaneous nitrification and denitrification of municipal wastewater in aerobic membrane bioreactors.

Simultaneous nitrification-denitrification (SND) of municipal wastewater was investigated in a laboratory-scale membrane bioreactor (MBR) operated at two different hydraulic retention times (HRTs), 0.5 and 1 day, dissolved oxygen 3.0 to 0.5 mg/L, and solids retention time (SRT) between 28 and 120 days. The organic loading rate (OLR) (0.11 to 0.64 kg chemical oxygen demand [COD]/m3/d) and influent soluble COD (SCOD)/ total Kjeldahl nitrogen (TKN) ratio (5 to 19) were varied by the addition of glucose. The ammonia-nitrogen and TKN removals were over 97%, and total nitrogen removal was approximately 89% in the MBR. The maximum specific nitrification rates (98 mg N/d/g VSS) and specific denitrification rates (81 mg N/d/g VSS) occurred at an SCOD/TKN ratio of 9.1. The optimum conditions for maximum total nitrogen removal by SND in a single reactor MBR have been found to be low dissolved oxygen (< 0.6 mg/L) and high OLR (approximately 0.64 kg COD/m3/d) at an HRT of 0.5 day and SRT of approximately 85 days.     

Integrated catalytic wet air oxidation and aerobic biological treatment in a municipal WWTP of a high-strength o-cresol wastewater

This study examines the feasibility of coupling a Catalytic Wet Air Oxidation (CWAO), with activated carbon (AC) as catalyst, and an aerobic biological treatment to treat a high-strength o-cresol wastewater. Two goals are pursued: (a) To determine the effect of the main AC/CWAO intermediates on the activated sludge of a municipal WasteWater Treatment Plant (WWTP) and (b) To demonstrate the feasibility of coupling the AC/CWAO effluent as a part of the influent of a municipal WWTP. In a previous study, a high-strength o-cresol wastewater was treated by AC/CWAO aiming to establish the distribution of intermediates and the biodegradability enhancement. In this work, the biodegradability, toxicity and inhibition of the most relevant intermediates detected in the AC/CWAO effluent were determined by respirometry. Also, the results of a pilot scale municipal WWTP study for an integrated AC/CWAO-aerobic biological treatment of this effluent are presented. The biodegradation parameters (i.e. maximum oxygen uptake rate and oxygen consumption) of main AC/CWAO intermediates allowed the classification of the intermediates into readily biodegradable, inert or toxic/inhibitory compounds. This detailed study, allowed to understand the biodegradability enhancement exhibited by an AC/CWAO effluent and to achieve a successful strategy for coupling the AC/CWAO step with an aerobic biological treatment for a high-strength o-cresol wastewater. Using 30%, as COD, of AC/CWAO effluent in the inlet to the pilot scale WWTP, the integrated AC/CWAO-biological treatment achieved a 98% of total COD removal and, particularly, a 91% of AC/CWAO effluent COD removal without any undesirable effect on the biomass.     

Functional biodiversity of microbial communities in aerobic selector slaughterhouse wastewater.

The biodiversity of the microbial communities of an aerobic selector and a conventional system treating slaughterhouse wastewater were evaluated using the Biolog technique (Biolog Inc., Hayward, California). Principal components analysis of patterns and level of microbial activity indicate that microbial communities statistically differentiate between the selector and conventional system. Biolog data indicated that there was seasonal variation in the structure and function of the microbial community in conventional samples, which may be a useful indicator of wastewater community disturbance and unsteadiness, while, for the selector system, there were no recognizable statistical differences between winter and summer data communities, Biodiversity indices indicated that the selector system maintained a high functional diversity (Shannon-Weaver diversity index [H'] from 3.8 to 4.6) than the conventional system (H' from 1.8 to 2.8). The high values in the selector system were a reflection of the fact that most of the carbon sources were used, contributing to the very high Shannon indices. In addition, the high substrate equitability values (J) obtained for the selector samples indicated that the microbial communities between the summer and winter samples used the carbon sources in the same proportion. In contrast, differences in the equitability of the microbial communities within the conventional system were observed. This indicated a pattern representing unevenness.     

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。     

水解酸化/好氧生化/Fenton氧化工艺处理制药废水的研究

进行了"水解酸化/好氧生化/Fenton氧化"工艺处理制药废水的试验研究,研究表明,该工艺的处理效果显著.水温为45～55℃时,经过16～20 h的水力停留时间,水解酸化可将废水的B/C比提高至0.30～0.35;好氧生化选用AB法,2～3 h曝气后的A段COD去除率可达到65%以上,7～9 h曝气后的B段COD去除率可达到40%以上;经过5～6 h的Fenton反应后,出水水质指标符合一级排放标准的要求.     

硫化物废水形成生物脱硫污泥中单质硫的回收

针对生物脱硫污泥中单质硫回收困难的问题,以生物脱硫系统产生的污泥为实验对象,研究了生物硫污泥的特性。经过测定得到了如下结果:生物脱硫污泥中单质硫的含量为51.2%,蛋白质5%、Na+ 8.32%、Ka+ 7.47%、Mg2+ 4.82%、SO42-10.5%、Cl-4.45%和灰分8.24%,单质硫被带电聚合物所包裹。根据污泥的特性,设计了一套高温溶解-低温析出的单质硫回收工艺。生物硫污泥和萃取剂(甲苯/四氯乙烯=5/95)在80℃下萃取30 min,萃取剂的用量为20 mL/g生物硫污泥,萃取完成后高温过滤,滤液在4℃下过夜保存,再次过滤析出的单质硫晶体。单质硫的回收率为91.2%,析出的单质硫纯度可达98%,可以直接用于其他工业。萃取剂重复使用5次后单质硫的回收率仍可达到79.6%。结果表明,高温溶解-低温析出法可有效从含硫化合物产生的生物硫污泥中提取单质硫。     

常温常压催化湿式氧化降解偶氮染料废水的研究

以过渡金属Fe、Mn、Cu和Zn的硝酸盐为活性组分的前驱物,以γ-Al2O3为载体,制备了负载型催化剂Fe2O3/γ-Al2O3、MnO/γ-Al2O3、CuO/γ-Al2O3和ZnO/γ-Al2O3,并分别以H2O2和NaClO为氧化剂,对比了在常温常压条件下催化湿式氧化工艺处理甲基橙模拟废水的效果.结果表明,Fe2...     

超临界水氧化活性艳红M-2B染料废水动力学研究

用H2O2作为氧化剂,在595～704 K、18～30 MPa条件下,对活性染料废水进行超临界水氧化反应.实验结果表明,COD去除率随温度、压力、停留时间和氧化剂量的增加而上升,在704 K、28 MPa时,COD去除率可达到98.4%,停留时间小于35 s.COD、H2O2和水的反应级数分别为1、0和0;反应活化能Ea为37.21 kJ/mol;指前因子A为76.69 s-1.     

Effect of pH and temperature on the kinetics of odor oxidation using chlorine dioxide

Increasing public concerns over odors and air regulations in nonattainment zones necessitate the remediation of a wide range of volatile organic compounds (VOCs) generated in the poultry-rendering industry. Currently, wet scrubbers using oxidizing chemicals such as chlorine dioxide (ClO2) are utilized to treat VOCs. However, little information is available on the kinetics of ClO2 reaction with rendering air pollutants, limiting wet scrubber design and optimization. Kinetic analysis indicated that ClO2 does not react with hexanal and 2-methylbutanal regardless of pH and temperature and implied that aldehyde removal occurs primarily via mass transfer. Contrary to the aldehydes, ethanethiol or ethyl mercaptan (a model compound for methanethiol or methyl mercaptan) and dimethyl disulfide (DMDS) rapidly reacted with ClO2. The overall reaction was found to be second and third order for ethanethiol and DMDS, respectively. Moreover, an increase in pH from 3.6 to 5.1 exponentially increased the reaction rate of ethanethiol (e.g., k2 = 25-4200 L/mol/sec from pH 3.6 to 5.1) and significantly increased the reaction rate of DMDS if increased to pH 9 (k3 = 1.4 x 10(6) L2/mol2/sec). Thus, a small increase in pH could significantly improve wet scrubber operations for removal of odor-causing compounds. However, an increase in pH did not improve aldehyde removal. The results explain why aldehyde removal efficiencies are much lower than methanethiol and DMDS in wet scrubbers using ClO2.