An advanced anaerobic biofilter with effluent recirculation for phenol removal and methane production in treatment of coal gasification wastewater

An advanced anaerobic biofilter (AF) was introduced for the treatment of coal gasification wastewater (CGW), and effluent recirculation was adopted to enhance phenol removal and methane production. The results indicated that AF was reliable in treating diluted CGW, while its efficiency and stability were seriously reduced when directly treating raw CGW. However, its performance could be greatly enhanced by effluent recirculation. Under optimal effluent recirculation of 0.5 to the influent, concentrations of chemical oxygen demand (COD) and total phenol in the effluent could reach as low as 234.0 and 14.2 mg/L, respectively. Also, the rate of methane production reached 169.0 mL CH₄/L/day. Though CGW seemed to restrain the growth of anaerobic microorganisms, especially methanogens, the inhibition was temporary and reversible, and anaerobic bacteria presented strong tolerance. The activities of methanogens cultivated in CGW could quickly recover on feeding with glucose wastewater (GW). However, the adaptability of anaerobic bacteria to the CGW was very poor and the activity of methanogens could not be improved by long-term domestication. By analysis using the Haldane model, it was further confirmed that high effluent recirculation could result in high activity for hydrolytic bacteria and substrate affinity for toxic matters, but only suitable effluent recirculation could result in high methanogenic activity.     

Influence of phenol on ammonia removal in an intermittent aeration bioreactor treating biologically pretreated coal gasification wastewater

A laboratory-scale intermittent aeration bioreactor was investigated to treat biologically pretreated coal gasification wastewater that was mainly composed of NH_3-N and phenol.The results showed that increasing phenol loading had an adverse effect on NH_3-N removal;the concentration in effluent at phenol loading of 40 mg phenol/(L·day) was 7.3 mg/L, 36.3%of that at 200 mg phenol/(L·day). The enzyme ammonia monooxygenase showed more sensitivity than hydroxylamine oxidoreductase to the inhibitory effect of phenol, with32.2% and 10.5% activity inhibition, respectively at 200 mg phenol/(L·day). Owing to intermittent aeration conditions, nitritation-type nitrification and simultaneous nitrification and denitrification(SND) were observed, giving a maximum SND efficiency of 30.5%.Additionally, ammonia oxidizing bacteria(AOB) and denitrifying bacteria were the main group identified by fluorescent in situ hybridization. However, their relative abundance represented opposite variations as phenol loading increased, ranging from 30.1% to 17.5%and 7.6% to 18.2% for AOB and denitrifying bacteria, respectively.     

Enhanced anaerobic biodegradability of real coal gasification wastewater with methanol addition

Coal gasification effluent is a typical refractory industrial wastewater with a very poor anaerobic biodegradability due to its toxicity.Methanol was introduced to improve anaerobic biodegradability of real coal gasification wastewater,and the effect of methanol addition on the performance was investigated in a mesophilic upflow anaerobic sludge bed reactor with a hydraulic retention time of 24 hr.Experimental results indicated that anaerobic treatment of coal gasification wastewater was feasible with the addition of methanol.The corresponding maximum COD and phenol removal rates were 71% and 75%,respectively,with methanol concentration of 500 mg COD/L for a total organic loading rate of 3.5 kg COD/(m3 ·day) and a phenol loading rate of 0.6 kg/(m3 ·day).The phenol removal rate was not improved with a higher methanol concentration of 1000 mg COD/L.Substrate utilization rate (SUR) tests indicated that the SURs of phenol were 106,132,and 83 mg phenol/(g VSS·day) at methanol concentrations of 250,500,and 1000 mg COD/L,respectively,and only 45 mg phenol/(g VSS·day) in the control reactor.The presence of methanol could reduce the toxicity of coal gasification wastewater and increase the biodegradation of phenolic compounds.     

Analysis of organic compounds in coal gasification wastewater

A procedure for analysis of organic pollutants in coal gasification wastewater was developed, including a series extraction steps at different pH, followed by LC separation or resin adsorption, then analyzed by GC or GC/MS. More than 200 organic pollutants in 22 categories were determined. CH2CL2 extraction at NaHCO3 presence was used to separate carboxylic acids with phenolic compounds in aqueous. Derivatization with acetic anhydride was used for analyses of mono-, di-, poly-hydroxyl phenolic compounds. 21 mono-hydroxyl phenols and 13 di-hydroxyl phenols were determined from the coai gasification wastewater samples. Derivatization with BF3-CH3OH was used for analysis of carboxylic acid. 17 mono-carboxyl, 4 di-carboxyl acids and 6 aromatic acids were determined from coal gasification wastewater samples.     

Inhibition and recovery of nitrification in treating real coal gasification wastewater with moving bed biofilm reactor

Moving bed biofilm reactor (MBBR) was used to treat real coal gasification wastewater. Nitrification of the MBBR was inhibited almost completely during start-up period. Sudden increase of influent total NH3 concentration was the main factor inducing nitrification inhibition. Increasing DO concentration in the bulk liquid (from 2 to 3 mg/L) had little e ect on nitrification recovery. Nitrification of the MBBR recovered partially by the addition of nitrifying sludge into the reactor and almost ceased within 5 days. Nitrification ratio of the MBBR achieved 65% within 12 days by increasing dilute ratio of the influent wastewater with tap water. The ratio of nitrification decreased to 25% when influent COD concentration increased from 650 to 1000 mg/L after nitrification recovery and recovered 70% for another 4 days.     

Nitrogen removal from coal gasification wastewater by activated carbon technologies combined with short-cut nitrogen removal process

A system combining granular activated carbon and powdered activated carbon technologies along with shortcut biological nitrogen removal （GAC-PACT-SBNR） was developed to enhance total nitrogen （TN） removal for anaerobically treated coal gasification wastewater with less need for external carbon resources. The TN removal efficiency in SBNR was significantly improved by introducing the effluent from the GAC process into SBNR during the anoxic stage, with removal percentage increasing from 43.8%49.6% to 68.8%-75.8%. However, the TN removal rate decreased with the progressive deterioration of GAC adsorption. After adding activated sludge to the GAG compartment, the granular carbon had a longer service-life and the demand for external carbon resources became lower. Eventually, the TN removal rate in SBNR was almost constant at approx. 43.3%, as compared to approx. 20.0% before seeding with sludge. In addition, the production of some alkalinity during the denitrification resulted in a net savings in alkalinity requirements for the nitrification reaction and refractory chemical oxygen demand （COD） degradation by autotrophic bacteria in SBNR under oxic conditions. PACT showed excellent resilience to increasing organic loadings. The microbial community analysis revealed that the PACT had a greater variety of bacterial taxons and the dominant species associated with the three compartments were in good agreement with the removal of typical pollutants. The study demonstrated that pre-adsorption by the GAC-sludge process could be a technically and economically feasible method to enhance TN removal in coal gasification wastewater （CGW）.     

高浓度甲醇废水厌氧处理中颗粒污泥和产甲烷细菌的耐酸性

采用两段UASB处理工艺和间歇培养试验,对高浓度甲醇废水厌氧处理的运行特性进行了研究,并较深入地研究了颗粒污泥和产甲烷菌的耐酸特性及代谢活性.试验结果表明,两段UASB反应器的pH值较低,分别为4.9～5.8和5.5～6 2,显然,这不是一般产甲烷细菌适宜的pH范围.系统中的产甲烷菌即巴氏产甲烷八叠球菌,具有一定耐酸性,在pH为5.0时仍然能够降解甲醇,如果进一步培养,其耐酸性将有所提高.系统中的颗粒污泥能够保护其内部的产甲烷菌,较少地受酸性环境的影响,并在pH为4.5时仍能降解甲醇.颗粒污泥的这种性能与其结构、细菌种类和颗粒体内细菌分布情况有很大关系.     

芬顿试剂处理苯酚废水的实验研究

本文针对含苯酚废水来源广、危害大、成分复杂的特点,采用Fenton技术对苯酚废水的处理效果进行了研究,考察了催化剂的用量、氧化剂的用量、粉煤灰的用量和pH值对芬顿试剂氧化苯酚的影响。研究表明,当pH值为3,H2O2的加入量为0.3mol,Fe(II)的加入量为0.5mmo1的条件下,反应在10min内基本完成,苯酚的去除率达到97%;当Fenton试剂的组分不变,粉煤灰投加量为0.6g/L时,苯酚降解率在99%以上,去除效果稳定。     

生物膜反应器降解生物质气化洗焦废水

陶瓷球作为固定介质 ,接种本实验室保藏的Pseudomonassp1和Pseudomonassp2混合菌种 ,应用生物膜反应器处理生物质气化过程中产生的洗焦废水 ,对反应器运转整个过程的进出水COD浓度、进出水苯、萘、菲、吡啶、喹啉、异喹啉的含量、反应器内和反应器出水含菌量进行测定 ,以了解生物膜反应器处理生物质气化洗焦废水的特性 .结果表明 ,反应器经挂膜、增菌后 ,可达到稳定运转状态 ,有效的控制了反应器内微生物细胞的流失 ,使生物质气化洗焦废水中的有机物得到较好去除 .     

曝气生物流化床(ABFB)处理煤气化废水的研究

介绍一种曝气生物流化床的基本原理及特点,制作了总有效容积为1.5m³的曝气生物流化床(ABFB)中试设备,流化介质为合成高分子多孔材料,其物理性能为:持水量25倍、比表面积≥200m²/g、含氮量6.72%,载体带有-NH₂、-COOH、-OH、环氧基等活性基团可与微生物结合而固定化微生物,载体中生物量平均为28g/L(H₂O),故具有很高的处理效率.对平均值为COD 3450mg/L、NH₄⁺-N 451mg/L、挥发酚为177 mg/L的煤气化废水,经过ABFB处理后,其处理水中COD 57.7mg/L、NH₄⁺-N 0.285mg/L、挥发酚0.434mg/L,其运行效果优于曝气生物滤池(BAF)、接触氧化、活性炭流化床.ABFB具有运行稳定、抗冲击负荷强的特点,是一种先进的水处理技术.     

Advanced treatment of biologically pretreated coal gasification wastewater by a novel heterogeneous Fenton oxidation process

Sewage sludge from a biological wastewater treatment plant was converted into sewage sludge based activated carbon(SBAC) with Zn Cl2 as activation agent, which was used as a support for ferric oxides to form a catalyst(Fe Ox/SBAC) by a simple impregnation method.The new material was then used to improve the performance of Fenton oxidation of real biologically pretreated coal gasification wastewater(CGW). The results indicated that the prepared Fe Ox/SBAC significantly enhanced the pollutant removal performance in the Fenton process, so that the treated wastewater was more biodegradable and less toxic. The best performance was obtained over a wide p H range from 2 to 7, temperature 30°C, 15 mg/L of H2O2 and 1 g/L of catalyst, and the treated effluent concentrations of COD, total phenols,BOD5 and TOC all met the discharge limits in China. Meanwhile, on the basis of significant inhibition by a radical scavenger in the heterogeneous Fenton process as well as the evolution of FT-IR spectra of pollutant-saturated Fe Ox/BAC with and without H2O2, it was deduced that the catalytic activity was responsible for generating hydroxyl radicals, and a possible reaction pathway and interface mechanism were proposed. Moreover, Fe Ox/SBAC showed superior stability over five successive oxidation runs. Thus, heterogeneous Fenton oxidation of biologically pretreated CGW by Fe Ox/SBAC, with the advantages of being economical, efficient and sustainable, holds promise for engineering application.     

Supercritical gasification for the treatment of o-cresol wastewater

The supercritical water gasification of phenolic wastewater without oxidant was performed to degrade pollutants and produce hydrogen-enriched gases. The simulated o-cresol wastewater was gasified at 440-650℃ and 27.6 MPa in a continuous Inconel 625 reactor with the residence time of 0.42-1.25 min. The influence of the reaction temperature, residence time, pressure, catalyst, oxidant and the pollutant concentration on the gasification efficiency was investigated. Higher temperature and longer residence time enhanced the o-cresol gasification. The TOC removal rate and hydrogen gasification rate were 90.6% and 194.6%, respectively, at the temperature of 650℃ and the residence time of 0.83 min. The product gas was mainly composed of H2, CO2, CFL and CO, among which the total molar percentage of H2 and CFL was higher than 50%. The gasification efficiency decreased with the pollutant concentration increasing. Both the catalyst and oxidant could accelerate the hydrocarbon gasification at a lower reaction temperature, in which the catalyst promoted H2 production and the oxidant enhanced CO2 generation. The intermediates of liquid effluents were analyzed and phenol was found to be the main composition. The results indicate that the supercritical gasification is a promising way for the treatment of hazardous organic wastewater.     

粉末活性焦强化A/A/O工艺处理煤气化废水的中试研究

煤气化废水水质复杂,是一种典型的难降解工业废水,而常规A/A/O工艺生化处理效率不高,严重制约了此类废水的处理和回用.因此,试验进行了粉末活性焦强化A/A/O工艺处理煤气化废水的中试研究,向好氧池投加粉末活性焦形成生物膜-悬浮污泥复合系统,并将剩余污泥回流至系统前段对原水进行预处理.研究结果表明,在活性焦投加量为250 mg·L-1,系统总HRT为105 h的优化条件下,CODCr、氨氮、总氮的去除率分别为97.4%、98.1%和80.5%,出水浓度分别为76 mg·L-1、0.3 mg·L-1和22.4 mg·L-1,达到《循环冷却水用再生水水质标准》(HG/T3923—2007)中CODCr≤80 mg·L-1、NH3-N≤15 mg·L-1、TN≤30 mg·L-1的要求.进一步机理研究表明,向好氧池中投加的粉末活性焦可作为微生物载体和菌胶团核心,投加活性焦后,好氧池的活性污泥浓度增加了57.9%.含焦剩余污泥对原水进行吸附预处理,石油类和SS的去除率分别为34.8%和61.5%,降低了废水对生化系统的毒害作用和冲击负荷,从而提高了系统的整体效率.     

Effect of anaerobic digestion on the high rate of nitritation, treating piggery wastewater

Laboratory reactors were operated by using piggery wastewater and the effluent of anaerobic digester from piggery wastewater plants to study the effect of anaerobic digestion on nitritation rate.     

厌氧水解酸化处理含高浓度聚丙烯酰胺污水

运用厌氧瓶和厌氧折流板反应器(ABR)对含部分水解聚丙烯酰胺(HPAM)的污水进行厌氧水解酸化生物处理.选取PAM-F1和PM-2两株厌氧菌为HPAM降解菌,并优化了单株菌和混合菌的降解条件.结果发现,最佳降解条件为降解9 d,连续活化3次,温度35~40℃,初始pH=7.5.此时,混合菌对500 mg·L-1HPAM污水的降解效果最好,降解率可达到40.69%.通过生理生化特征和16S rDNA分析,确定PAM-F1为红球菌(Rhodococcus sp.).混合菌降解前后的HPAM傅里叶-红外光谱图分析表明,细菌能够降解并利用HPAM的部分胺基和碳作为生长所需的氮源和碳源,并推断出HPAM的降解过程发生在厌氧水解酸化阶段.扫描电镜(SEM)图片显示,ABR中形成了能有效促进HPAM生物降解的颗粒污泥.而经过ABR处理的HPAM污水,CODCr去除率和HPAM降解率可分别达到89.96%和75.48%.研究表明,厌氧水解酸化法是一项能够有效处理含高浓度HPAM污水的技术.     

厌氧折流板反应器处理难降解黄连素废水的研究

试验研究了4格室厌氧折流板反应器(ABR)处理浓度为50~300mg/L的难降解黄连素废水,包括启动实验和后续操作运行,共计175d,其中启动运行80d,反应温度控制在(32±1)℃.结果表明,采用低黄连素负荷的方法驯化污泥,其启动过程比较快, ABR反应器污泥经过80d的驯化培养后,微生物对黄连素具有一定的适应性;启动后逐渐提高进水黄连素浓度,最高达到300mg/L,当进水黄连素浓度为120mg/L时, ABR反应器的处理效果最好,COD和黄连素的去除率分别达到70%和95%左右,此时各格室污泥平均浓度分别达到24.06,24.76,27.76, 6.4g/L,污泥外观呈红褐色和黑色.     

Acid resistance of methanogenic bacteria in a two-stage anaerobic process treating high concentration methanol Wastewater

In this study, the two-stage upflow anaerobic sludge blanket (UASB) system and batch experiments were employed to evaluate the performance of anaerobic digestion for the treatment of high concentration methanol wastewater. The acid resistance of granular sludge and methanogenic bacteria and their metabolizing activity were investigated. The results show that the pH of the first UASB changed from 4.9 to 5.8 and 5.5 to 6.2 for the second reactor. Apparently, these were not the advisable pH levels that common methanogenic bacteria could accept. The methanogenic bacteria of the system, viz. Methanosarcina barkeri, had some acid resistance and could still degrade methanol at pH 5.0. If the methanogenic bacteria were trained further, their acid resistance would be improved somewhat. Granular sludge of the system could protect the methanogenic bacteria within its body against the impact of the acidic environment and make them degrade methanol at pH 4.5. The performance of granular sludge was attributed to its structure, bacteria species, and the distribution of bacterium inside the granule. Translated from Acta Scientiae Circumstantiae, 2004, 24(4): 633–636 [译自: 环境科学学报]     

生物质气化发电厂洗焦废水生物处理的中试研究

为使生物质气化发电厂的洗涤废水得到有效的循环使用,在以废陶瓷片作为填料的生物膜反应器中,接种优势菌,对经过物化预处理的生物质气化洗涤废水进行处理,着重考察了不同工艺条件下,生物膜反应器对废水的处理效果.采用缺氧20h,好氧10h的处理工艺,可有效降低该废水的COD,当进水COD为584～923mg·L-1时,出水COD达到118 5～230 2mg L-1,COD的平均下降率为78 6%.     

生物炭强化模拟废水中高浓度苯酚的微生物降解

采用花生壳生物质废物分别在350、550和750℃条件下限氧热解制备生物炭,之后加入到苯酚污染模拟废水中,验证其强化苯酚微生物降解的效果.结果表明,未加生物炭的系统中,苯酚浓度过低(≤110 mg·L~(-1))不能使菌体达到最大浓度,苯酚浓度过高(≥420 mg·L~(-1))则会抑制菌体生长,降解率仅为43.2%,且停滞期长.添加生物炭后,苯酚去除率大幅度提高,在6～16 h时微生物进入对数生长期,苯酚浓度快速降低.2、4和6 g·L~(-1)的生物炭添加量均可使苯酚在16 h内被完全去除,高添加量的生物炭能吸附39.3%的苯酚,降低其对微生物的毒性抑制.550℃热解温度制备的生物炭取得了最好的强化效果,其pH缓冲作用可中和苯酚降解产生的酸性物质,而750℃热解温度制备的生物炭由于pH过高而使菌体难以存活.生物炭在相对低苯酚浓度下(600、800 mg·L~(-1))可显著提高其去除率,分别从29.6%、24.5%升至46.9%、36.9%.而对于初始苯酚浓度高达1000 mg·L~(-1)以上的系统,则需要海藻酸钙凝胶固定菌体到生物炭才能获得较高的降解率.     

生物水解（酸化）法处理高浓度洁霉素废水的降解机理研究

在应用生物水解（酸化）法处理高浓度洁霉素生产废水中试试验中,着重研究水解（酸化）反应中起主要作用的微生物菌群及其降解效率。同时采用GPC（凝胶渗透色谱）、GC/MS（色谱一质谱）等分析手段对水解（酸化）反应过程中有机物形态变化进行研究。结果表明,在水解（酸化）反应中起主要作用的有埃希氏菌属、发酵单胞菌属、气单胞菌属、变形杆菌属、柠檬酸杆菌属等。同时,水解（酸化）反应具有将洁霉素废水中的大分子有机物降解为小分子有机物的作用,可提高废水的可生化性。