驯化污泥固定化快速启动BAC反应器的研究

采用驯化污泥以动态挂膜和静态膜固定的方法进行了生物活性炭(BAC)反应器的快速挂膜和启动研究。将驯化污泥配制成500 mg/L的污泥菌液,控制挂膜污泥量为2~4 g/L、挂膜液循环流量为400~560 mL/min并以下向流循环方式运行,在1~2 d内就能实现BAC的稳定挂膜。启动后应用其处理某垃圾焚烧厂渗滤液处理站的生化处理出水,对COD的去除率70%,显著优于SBR法的处理效果。     

臭氧/生物活性炭工艺深度处理焦化废水中试

以经常规生化工艺处理后的焦化废水为研究对象,通过中试考察了臭氧/生物活性炭工艺深度处理焦化废水的效果和可行性。通过测定生化呼吸曲线及相对耗氧速率来判定焦化废水可生化性的提高程度及活性炭生物膜的成熟情况。结果表明,该工艺用于焦化废水的深度处理是完全可行的。在臭氧投加量为15 mg/L的条件下,可显著提高焦化废水的可生化性,臭氧氧化对COD的平均去除率为10.13%。采用自然挂膜方法培养生物膜,生物膜的成熟时间为25 d左右。在生物活性炭稳定运行后,其对COD和氨氮的平均去除率分别可达28.75%和43.80%,出水COD和氨氮的平均值分别为87.50和7.6 mg/L,均达到了《污水综合排放标准》(GB 8978—1996)中的一级标准。     

Heterotrophic activity compromises autotrophic nitrogen removal in membrane-aerated biofilms: results of a modeling study

A 1-d multi-population biofilm model was constructed to study the effect of heterotrophic activity on completely autotrophic ammonium (NH4+) removal in membrane-aerated (counter-diffusion) versus conventional biofilm systems (co-diffusion). Growth of heterotrophic bacteria (HB) was supported either solely by biomass decay products or by organic carbon (as chemical oxygen demand (COD)) in the influent. Three scenarios were considered: influence of HB growing on biomass decay products on steady-state performance (total nitrogen (TN) removal efficiency); influence of the influent COD/N ratio on steady-state performance (supplying COD in the influent); and impact of dynamic changes in the influent COD/N ratio on TN removal efficiency. The results revealed that the TN removal efficiency in the counter-diffusion biofilm was significantly different when HB were included in the simulations at NH4+ surface loads of LNH4>2.7 g - N m(-2) d(-1). Influent COD significantly altered the microbial community composition in the counter-diffusion biofilm and anaerobic NH4+ oxidation could not be sustained at COD/N>2. The co-diffusion system, however, was less affected and more than 50% of the TN removal originated from anaerobic NH4+ oxidation at those ratios. Perturbation experiments showed that step increases to influent COD/N ratios of 2 or higher over a period of 50 d or longer caused a loss of anaerobic NH4+ oxidation capacity which could not be regained within a reasonable time frame (>1000 d) in the counter-diffusion system. In contrast, simulating a 1-d sloughing event only caused a disturbance of 200 d although a maximum biofilm loss of 90-95% occurred. These results clearly indicate the importance of heterotrophic activity in autotrophic N removal biofilms, especially in counter-diffusion systems where they may compromise N removal capacity.     

Biofiltration of wastewater treatment plant effluent: effective removal of pharmaceuticals and personal care products and reduction of toxicity

This study investigates biofiltration for the removal of dissolved organic carbon (DOC), pharmaceuticals and personal care products (PPCPs), and for the reduction of non-specific toxicity expressed as baseline toxicity equivalent concentration (baseline-TEQ). Two filtering media, sand and granular activated carbon, were tested. The influence of pre-ozonation and empty-bed contact time (EBCT, from 30 to 120 min) was determined. The experiments were performed at a pilot-scale with real WWTP effluent. A previous study showed that biological activity had developed on the filtering media and dissolved organic removal had reached a steady state before sampling commenced. The results show that biological activated carbon (BAC) has a good potential for the removal of DOC (35-60%), PPCPs (>90%) and baseline-TEQ (28-68%) even without pre-ozonation. On the contrary, the sand shows limited improvement of effluent quality. Varying the EBCT does not influence the performance of the BAC filters; however, dissolved oxygen concentration could be a limiting factor. The performances of the BAC filters were stable for over two years suggesting that the main mechanism of organic matter and PPCPs removal is biodegradation. It is concluded that BAC filtration without pre-ozonation could be implemented as a low cost advanced treatment option to improve WWTP effluent chemical quality.     

Biofilm processes in biologically active carbon water purification.

This review paper serves to describe the composition and activity of a biologically active carbon (BAC) biofilm used in water purification. An analysis of several physical-chemical, biochemical and microbiological methods (indicators) used to characterize the BAC biofilm's composition and activity is provided. As well, the ability of the biofilm to remove and biodegrade waterborne organic substances and pollutants will be reviewed, with context to other industrial processes such as pre-ozonation and post-membrane filtration. Strategies to control the growth of the BAC biofilm, such as varying the nutrient loading rate, manipulating influent DO and pH levels, altering the frequency of BAC filter backwashing and applying oxidative disinfection, will be described in detail along with their respective process control challenges.     

常低温下EGSB处理生活污水的影响因素研究

在15～26℃的常低温条件下,采用EGSB处理生活污水,考察了进水流量、回流比、液体上升流速(Vup)、温度等因素对运行效果的影响。结果表明,当温度为26℃左右时,对于9～11 L/h的低进水流量,宜采用高回流比(1.6～2.5),对COD的去除率最高可达90%;对于15～24L/h的高进水流量,宜采用低回流比(0～0.6),对COD的去除率最高可达84%;当进水流量提高至30 L/h时,不宜回流,对COD的去除率降至77%;当进水流量分别为9、11、15、24、30 L/h时,最佳Vup分别为4.0、(3.1～3.6)、(2.7～3.4)、3.0和3.8 m/h,此时对COD的去除率分别高达90%、(87%～89%)、(83%～84%)、83%和77%;在无回流的条件下,适宜的进水流量为15～24 L/h,相应的HRT为0.5～0.8 h。当温度为15～26℃时,EGSB适宜的运行条件是高进水流量(15～24L/h)、高Vup(3.0 m/h)和低回流比(0～0.6),此时对COD的去除率高达81.9%以上。     

臭氧-生物活性炭深度处理饮用水挂膜试验研究

以中置式高密度沉淀池沉后水作为进水，考察了臭氧-生物活性炭（O3-BAC）饮用水深度处理工艺的挂膜过程，并探讨了生物活性炭挂膜的影响因素。结果表明，挂膜期间O3-BAC工艺对水中浊度、CODMn及氨氮具有较好的去除效果，运行后期浊度、CODMn及氨氮的去除率分别达到50％，62．71％和62．5％以上；运行至82天时，CODMn和氨氮去除率分别大于30％和60％．生物膜趋于成熟。     

Influence of detachment on substrate removal and microbial ecology in a heterotrophic/autotrophic biofilm

Competition between heterotrophic bacteria oxidizing organic substrate and autotrophic nitrifying bacteria in a biofilm was evaluated. The biofilm was grown in a tubular reactor under different shear and organic substrate loading conditions. The reactor was initially operated without organic substrate in the influent until stable ammonia oxidation rates of 2.1 g N/(m² d) were achieved. A rapid increase of fluid shear in the tubular reactor on day 156 resulted in biofilm sloughing, reducing the biofilm thickness from 330 to 190 μm. This sloughing event did not have a significant effect on ammonia oxidation rates. The addition of acetate to the influent of the reactor resulted in decreased ammonia oxidation rates (1.8 g N/(m² d)) for low influent acetate concentrations (17 mg COD/L) and the breakdown of nitrification at high influent acetate concentrations (55 mg COD/L). Rapidly increasing fluid shear triggered biofilm sloughing in some cases—but maintaining constant shear did not prevent sloughing events from occurring. With the addition of acetate to the influent of the reactor, the biofilm thickness increased up to 1350 μm and individual sloughing events removed up to 50% of the biofilm. Biofilm sloughing had no significant influence on organic substrate removal or ammonia oxidation. During 325 days of reactor operation, ammonia was oxidized only to nitrite; no nitrate production was observed. This lack of nitrite oxidation was confirmed by fluorescent in situ hybridization (FISH) analysis, which detected betaproteobacterial ammonia oxidizers but not nitrite oxidizers. Mathematical modeling correctly predicted breakdown of nitrification at high influent acetate concentrations. Model predictions deviated systematically from experimental results, however, for the case of low influent acetate concentrations.     

双膜法处理污水厂尾水效能分析与膜再生研究

为提高污水厂出水水质,寻求适合处理污水厂尾水滤膜的再生方法,采用超滤—纳滤双膜工艺,针对辽宁省本溪市某城市污水厂二级尾水开展深度处理研究。考察了进水流速、累积过滤水量(超滤进水流速为25 L/min,纳滤进水流速为4 L/min)对膜分离效果的影响,同时开展了超滤和纳滤膜再生方式及效果研究。结果表明:在考察范围内,超滤装置的分离性能受进水流速影响较小,主要与进水污染程度有关,对COD、TP、氨氮的平均去除率分别为48%、55%、27%。当纳滤单元进水流速为4 L/min时,双膜法对COD、TP、氨氮的平均去除率分别为87%、96%、68%。双膜法对COD、TP的去除率随着进水污染程度的减轻而降低,氨氮去除率受累积过滤水量的影响较小,这与原水污染程度有关。随着累积过滤水量的增加,膜分离性能呈减弱趋势。超滤膜轻微污染时采用物理清洗效果良好,严重污染时需采用化学清洗的方法。超滤有效延缓了纳滤膜污染,纳滤膜轻微污染时采用酸碱浸泡法再生效果良好。     

Chemisorption of oxygen onto activated carbon can enhance the stability of biological perchlorate reduction in fixed bed biofilm reactors

Fixed bed biofilm reactors with granular activated carbon (GAC) or glass beads as support media were used to evaluate the influence of short-term (12h) and long-term (23 days) increases of influent dissolved oxygen (DO) concentrations on biological perchlorate removal. The goal was to evaluate the extent by which chemisorption of oxygen to GAC can enhance the stability of biological perchlorate reduction. Baseline influent concentrations were 50 microg/L of perchlorate, 2 mg/L of acetate as C, and 1mg/L of DO. Perchlorate removal in the glass bead reactor seized immediately after increasing influent DO concentrations from 1 to 4 mg/L since glass beads have no sorptive capacity. In the biologically active carbon (BAC) reactor, chemisorption of oxygen to GAC removed a substantial fraction of the influent DO, and perchlorate removal was maintained during short-term increases of influent DO levels up to 8 mg/L. During long-term exposure to influent DO concentrations of 8.5mg/L, effluent perchlorate and DO concentrations increased slowly. Subsequent exposure of the BAC reactor bed to low DO concentrations partially regenerated the capacity for oxygen chemisorption. Microbial analyses indicated similar microbial communities in both reactors, which confirmed that the differences in reactor performance during dynamic loading conditions could be attributed to the sorptive properties of GAC. Using a sorptive biofilm support medium can enhance biological perchlorate removal under dynamic loading conditions.     

炭龄对活性炭工艺去除南水北调水中有机物的影响

基于北方某水厂中试基地,采用新炭、2.5~3.5年炭、4.5~5.5年炭等不同炭龄的活性炭滤柱,进行为期1年的连续运行,对比研究炭龄对南水北调水源水中有机物去除效果的影响。结果表明,长期运行稳定的活性炭滤柱,主要通过生物作用去除水中的有机物;2.5~3.5年和4.5~5.5年炭龄滤柱对有机物的去除效果差异较小,但二者对三氯甲烷的去除效果优于生物膜不稳定的新炭滤柱;通过高通量测序解析发现,鞘氨醇单胞菌、DSSF69等是优势功能菌,炭龄长的生物多样性更丰富,生物膜系统更稳定。此外,活性炭滤柱对有机物的去除效果与进水有机物的污染程度相关,当进水溶解性有机物浓度较低时,活性炭滤柱会出现吸附物质逆扩散的现象,所以当水质较好时,活性炭滤池的有机物去除效果会减弱。     

加压固定床生物膜反应器降解污水中有机物的研究

将加压生物氧化技术与单级BAF工艺相结合,开发出了加压固定床生物膜反应器,并考察了压力、有机负荷及进水温度对其去除有机物的影响.结果表明,随着压力的增大,对COD的去除率先增后降,当压力为0.18～0.21 MPa时,对COD的去除率最大为95.4%;在最佳压力条件下,反应器具有较强的耐有机负荷和耐低温能力;加压固定床生物膜反应器的最佳工艺参数:压力为0.18～0.21 MPa,有机负荷为8.8～10.9 kgCOD/(m3·d),进水温度为23～29℃,HRT为0.58 h,气水比为(3:1)～(6:1),采用气水联合反冲洗,反冲洗周期为6～8 d,反冲洗时间为18～22 min;在最佳运行条件下,对COD的平均去除率达94.6%,出水水质完全满足GB 18918-2002的一级A标准,达到了回用水的要求.     

The sensitivity of fixed-bed biological perchlorate removal to changes in operating conditions and water quality characteristics

Flow rate, electron donor addition, and biomass control were evaluated in order to optimize perchlorate (ClO₄⁻) removal from drinking water using biologically active carbon (BAC) filtration. Influent dissolved oxygen (DO) was lowered from ambient conditions to approximately 2.5 mg/L for all experiments using a nitrogen sparge. When influent nitrate concentration was 0-2.0 mg/L, 1.6-2.8 mg/L as carbon of acetate or ethanol was required to achieve and sustain the complete removal of 50 μg/L perchlorate in a BAC filter. Most or all of the exogenous acetate and ethanol was removed during biofiltration. When a 72-h electron donor feed failure was simulated, a maximum perchlorate breakthrough of 18 μg/L was observed and, once electron donor was reapplied, 9 days were required to reestablish complete perchlorate removal. During a 24-h electron donor feed failure simulation, the maximum effluent perchlorate concentration detected was 6.7 μg/L. Within 24 h of reactivating the electron donor, the filter regained its capacity to consistently remove 50 μg/L perchlorate to below detection. Although biomass growth diminished the filter's ability to consistently remove perchlorate, a cleaning procedure immediately restored stable, complete perchlorate removal. This cleaning procedure was required approximately every 50 days (4800 bed volumes) when influent DO concentration was 2.5 mg/L. Empty-bed contact time (EBCT) experiments showed that 80% perchlorate removal was achieved using a 5-min EBCT, and complete perchlorate removal was observed for an EBCT of 9 min. It was also demonstrated that BAC filtration consistently removed perchlorate to below detection for influent perchlorate concentrations ranging from 10 to 300 μg/L, influent sulfate concentrations between 0 and 220 mg/L, influent pH values of 6.5-9.0, and operating temperatures of 5-22°C.     

混凝/化学氧化/曝气生物滤池深度处理垃圾渗滤液

随着垃圾渗滤液的老龄化,常规的生化处理已经不能使出水达标排放,需要进行深度处理。采用混凝／化学氧化／曝气生物滤池联合工艺深度处理垃圾渗滤液,进水COD为700mg／L左右,出水COD〈100mg／L,去除率〉85％,排放口水质达到《生活垃圾填埋污染控制标准》（GB16889--1997）一级标准。     

Total nitrogen removal in a hybrid, membrane-aerated activated sludge process

The hybrid (suspended and attached growth) membrane biofilm process (HMBP) is a novel method to achieve total nitrogen removal from wastewater. Air-filled hollow-fiber membranes are incorporated into an activated sludge tank, and a nitrifying biofilm develops on the membranes, producing nitrite and nitrate. By suppressing bulk aeration, the bulk liquid becomes anoxic, and the nitrate/nitrite can be reduced with influent BOD. The key feature that distinguishes the HMBP from other membrane-aerated processes is that it is hybrid; heterotrophic bacteria are kept mainly in suspension by maintaining low bulk liquid BOD concentrations. We investigated the HMBP's performance under a variety of BOD and ammonium loadings, and determined the dominant mechanisms of nitrogen removal. Suspended solids increased with the BOD loadings, maintaining low bulk liquid BOD concentrations. As a result, nitrification rates were insensitive to the BOD loadings, remaining at 1gNm(-2)day(-1) for BOD loadings ranging from 4 to 17gBODm(-2)day(-1). Nitrification rates decreased during short-term spikes in bulk liquid BOD concentrations. Shortcut nitrogen removal was confirmed using microsensor measurements, showing that nitrite was the dominant form of oxidized nitrogen produced by the biofilm. Fluorescence in situ hybridization (FISH) showed that ammonia oxidizing bacteria (AOB) were dominant throughout the biofilm, while nitrite oxidizing bacteria (NOB) were only present in the deeper regions of the biofilm, where the oxygen concentration was above 2mg/L. Denitrification occurred mainly in the suspended phase, instead of in the biofilm, decreasing the potential for biofouling. When influent BOD concentrations were sufficiently high, full denitrification occurred, with total nitrogen (TN) removal approaching 100%. These results suggest that the process is well-suited for achieving concurrent BOD and TN removal in activated sludge.     

杭州市南星水厂O3/BAC工艺的运行效果分析

杭州市南星水厂深度处理一期工程采用预臭氧、常规处理、后臭氧、生物活性炭工艺。结合生产性试验确定了预臭氧及后臭氧段的臭氧投量分别为0．30～0．60mg／L和1．50～1．70mg／L。工程投产后的运行结果表明：O、／BAC工艺对微污染源水的处理效果良好，对浊度、CODM。NH4^＋-N、NO2^--N的去除率分别为99．2％、（57％～77％）、（61％～99．7％）、（-25％～99．74％），出水浊度〈0．2NTU、色度〈3倍，CODMn、NH4^＋-N、NO2^-N分别为0．48～1．57mg／L及0．237、0．053mg／L以下；季节对O3／BAC工艺的净化效果影响较大，春、夏、秋季的除污效果较好，冬季的相对较差。深度处理工艺的制水成本为0．561元／m^3，较常规工艺的（0．447元／m^3）仅增加约0．114元／m^3。     

Biological treatment of H(2)S using pellet activated carbon as a carrier of microorganisms in a biofilter

Biological treatment is an emerging technology for treating off-gases from wastewater treatment plants. The most commonly reported odourous compound in off-gases is hydrogen sulfide (H(2)S), which has a very low odor threshold. This study aims to evaluate the feasibility of using a biological activated carbon as a novel packing material, to achieve a performance-enhanced biofiltration processes in treating H(2)S through an optimum balance and combination of the adsorption capacity with the biodegradation of H(2)S by the bacteria immobilized on the material. The biofilm was mostly developed through culturing the bacteria in the presence of carbon pellets in mineral media. Scanning electron microscopy (SEM) was used to identify the biofilm development on carbon surface. Two identical laboratory scale biofilters, one was operated with biological activated carbon (BAC) and another with virgin carbon without bacteria immobilization. Various concentrations of H(2)S (up to 125 ppmv) were used to determine the optimum column performance. A rapid startup (a few days) was observed for H(2)S removal in the biofilter. At a volumetric loading of 1600 m(3)m(-3)h(-1) (at 87 ppmv H(2)S inlet concentration), elimination capacity of the BAC (181 gH(2)Sm(-3)h(-1)) at removal efficiency (RE) of 94% was achieved. If the inlet concentration was kept at below 30 ppmv, high H(2)S removal (over 99%) was achieved at a gas retention time (GRT) as low as 2s, a value, which is shorter than most previously reported for biofilter operations. The bacteria population in the acidic biofilter demonstrated capacity for removal of H(2)S in a broad pH range (pH 1-7). There are experimental evidences showing that the spent BAC could be re-used as packing material in a biofilter based on BAC. Overall, the results indicated that an unprecedented performance could be achieved by using BAC as the supporting media for H(2)S biofiltration.     

FeSO_4应用于SBBF强化除磷

序批式生物膜滤池(SBBF)是基于序批式生物膜法的改进污水处理新型工艺,针对SBBF处理城市污水的除磷的效果较差的弊端,通过直接投加FeSO_47H_2O到反应体系实现协同除磷,使得该工艺能够较好地应用于污水脱氮除磷。Fe(Ⅱ)的投加量从0.03~0.3mM进行协同除磷试验,结果表明0.2mM的Fe(Ⅱ)投加可为有效投加量。进一步将0.2mM的Fe(Ⅱ)在进水阶段后投加到反应体系,稳定运行1个月,发现出水的TP稳定保持在0.5mg/L以下,而COD和氮的去除基本不受影响。COD、NH_4~+-N、TN和TP的平均去除率分别为84.9%、83.2%、46.3%和88.2%。反应器出水的各项指标均稳定达到《城镇污水处理厂污染物排放标准》(GB 18918—2002)的一级A排放标准。     

Pilot scale treatment of textile wastewater by combined process (fluidized biofilm process-chemical coagulation-electrochemical oxidation)

The performance of pilot scale combined process of fluidized biofilm process, chemical coagulation and electrochemical oxidation for textile wastewater treatment was studied. In order to enhance biological treatment efficiency, two species of microbes, which can degrade textile wastewater pollutants efficiently, were isolated and applied to the system with supporting media. FeCl3 x 6H2O, pH 6 and 3.25 x 10(-3) mol/l were determined as optimal chemical coagulation condition and 25 mM NaCl of electrolyte concentration, 2.1 mA/cm2 of current density and 0.71/min of flow rate were chosen for the most efficient electrochemical oxidation at pilot scale treatment. The fluidized biofilm process showed 68.8% of chemical oxygen demand (COD) and 54.5% of color removal efficiency, even though using relatively low MLSS concentration and short sludge retention time. COD and color removals of 95.4% and 98.5% were achieved by overall combined process. The contribution of fluidized biofilm process to the overall combined process was increased over 25.7% of COD reduction and 20.5% of color reduction by adopting support media in biological treatment. It can be thought that the fluidized biofilm process was effective, and pollutant loading on post-treatment was pretty much decreased by this system. This combined process was highly competitive in comparison to the other similar combined systems. It was concluded that this combined process was successfully employed and much effectively decreased pollutant loading on post-treatment for textile wastewater treatment at pilot scale.     

进水负荷对硝化菌与异养菌竞争关系的影响

为优化反应器的脱氮设计，就水力负荷、温度对二级上向流曝气生物滤池内微生物种群结构的影响进行了研究。试验结果表明，在生物膜培养阶段，温度对氨氯氧化的影响要大于对COD降解的影响；较高的COD负荷会导致第一级反应器内的硝化点上移，第二级反应器的硝化速率固受第一级反应器出水残余有机物的影响而下降。在第二级反应器内氨氮的硝化速率明显加快，显示了单独驯化的硝化滤柱在氧化氨氮上的优势。在不同的进水COD负荷下，氨氧化菌与硝化菌的活性均有沿柱高逐渐增加的趋势，且当负荷较高时，不同高度处的氨氧化菌活性大多高于硝化菌的。异养菌的活性变化表明，生长较快的异养菌通常占据了反应器的进口区。