The plant-enhanced bio-cathode: Root exudates and microbial community for nitrogen removal

A plant bio-electrochemical system(PBES) was constructed for organic pollutant removal and power generation. The bio-cathode, composed of granular activated carbon(GAC), stainless wire mesh and a plant species(Triticum aestivum L.), was able to catalyze cathodic reactions without any requirement for aeration or power input. During the 60-day-long operation, an average voltage of 516 m V(1000 Ω) and maximum power density(Pmax) of 0.83 W/m~3 were obtained in the PBES. The total nitrogen removal and total organic carbon removal in the PBES were 85% and 97%, respectively. Microbial community analyses indicated that bacteria associated with power generation and organic removal were the predominant species in the bio-cathode, and plant-growth-promoting rhizobacteria were also found in the PBES. The results suggested that the coupling of plants with the GAC cathode may enhance the organicmatter degradation and energy generation from wastewater and therefore provide a new method for bio-cathode design and promote energy efficiency.     

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.     

Particle properties in granular activated carbon filter during drinking water treatment

The elemental composition and bacteria attached in particles were investigated during granular activated carbon (GAC) filtration.The experimental results showed that trapped influent particles could form new,larger particles on GAC surface.The sloughing of individuals off GAC surface caused an increase in effluent particles in the size range from 5 to 25 μm.The selectivity for element removal in GAC filters caused an increasing proportion of metallic elements in the effluent particles.The distribution of molar ratio indicated a complicated composition for large particles,involving organic and inorganic substances.The organic proportion accounted for 40% of total carbon attached to the particles.Compared with dissolved carbon,there was potential for the formation of trihalomethanes by organic carbon attached to particles,especially for those with size larger than 10 μm.The pure carbon energy spectrum was found only in the GAC effluent and the size distribution of carbon fines was mainly above 10 μm.The larger carbon fines provided more space for bacterial colonization and stronger protection for attached bacteria against disinfection.The residual attached bacteria after chorine disinfection was increased to 10 2-10 3 CFU/mL within 24 hours at 25°C.     

Combination of adsorption and biodegradation processes for textile effluent treatment using a granular activated carbon-biofilm configured packed column system

The objective of this study was to investigate the feasibility of using a granular activated carbon-biofilm configured packed column system in the deeolodzation of azo dye Acid Orange 7-containing wastewater.The Acid Orange 7-degrading microbial from anaerobic sequencing batch reactor which treating the azo dye-containing wastewater for more than 200 d was immobilized on spent granular activated carbon(GAC)through attachment.The GAC-biofilm configured packed column system showed the ability to decolorize...     

Stability of expanded granular sludge bed process for terylene artificial silk printing and dyeing wastewater treatment

Terylene artificial silk printing and dyeing wastewater(TPD wastewater), containing averaged 710 mg/L terephthalic acid(TA) as the main carbon source and the character pollutant, was subjected to expanded granular sludge bed(EGSB) process. The stability of the EGSB process was firstly conducted by laboratory experiment. TA ionization was the predominated factor influencing the acid-base balance of the system. High concentration of TA in wastewater resulted in sufficient buffering capacity to neutralize the volatile fatty acids(VFA)generated from substrate degradation and provided strong base for anaerobic system to resist the pH decrease below 6.5. VFA and UFA caused almost no inhibition on the anaerobic process and biogas production except that pH was below 6.35 and VFA was at its maximum value. Along with the granulating of the activated sludge, the efficiency of organic removal and production rate of biogas increased gradually and became more stable. After start-up, the efficiency of COD removal increased to 57%—64%, pH stabilized in a range of 7.99—8.04, and production rate of biogas was relatively high and stable. Sludge granulating, suitable influent of pH and loading were responsible for the EGSB stability. The variation of VFA concentration only resulted in neglectable rebound of pH, and the inhibition from VFA could be ignored in EGSB. The EGSB reactor was stable for TPD wastewater treatment.     

Production and application of anaerobic granular sludge produced by landfill

Sludge granulation is considered to be the most critical parameter governing successful operation of an upflow anaerobic sludge blanket and expanded granular sludge bed(EGSB)reactors.Pre-granulated seeding sludge could greatly reduce the required start- up time.Two lab-scale and a pilot-scale EGSB reactors were operated to treat Shaoxing Wastewater Treatment Plant(SWWTP) containing wastewater from real engineering printing and dyeing with high pH and sulfate concentration.The microbiological structure and the particle size distribution in aerobic excess sludge,sanitary landfill sludge digested for one year,and the granular sludge of EGSB reactor after 400 d of operation were analyzed through scanning electron microscopy (SEM) and sieves.The lab-scale EGSB reactor seeded with anaerobic sludge after digestion for one year in landfill showed obviously better total chemical oxygen demand (TCOD)removal efficiency than one seeded with aerobic excess sludge after cation polyacrylamide flocculation-concentration and dehydration.The TCOD removed was 470.8 mg/L in pilot scale EGSB reactor at short hydraulic retention time of 15 h.SEM of sludge granules showed that the microbiological structure of the sludge from different sources showed some differences.SEM demonstrated that Methanobacterium sp.was present in the granules of pilot-scale EGSB and the granular sludge produced by landfill contained a mixture of anaerobic/anoxic organisms in abundance.The particle size distribution in EGSB demonstrated that using anaerobic granular sludge produced by sanitary landfill as the seeding granular sludge was feasible.     

Removal of anaerobic soluble microbial products in a biological activated carbon reactor

The soluble microbial products (SMP) in the biological treatment effluent are generally of great amount and are poorly biodegradable. Focusing on the biodegradation of anaerobic SMP, the biological activated carbon (BAC) was introduced into the anaerobic system. The experiments were conducted in two identical lab-scale up-flow anaerobic sludge blanket (UASB) reactors. The high strength organics were degraded in the first UASB reactor (UASB1) and the second UASB (UASB2, i.e., BAC) functioned as a polishing step to remove SMP produced in UASB1. The results showed that 90% of the SMP could be removed before granular activated carbon was saturated. After the saturation, the SMP removal decreased to 60% on the average. Analysis of granular activated carbon adsorption revealed that the main role of SMP removal in BAC reactor was biodegradation. A strain of SMP-degrading bacteria, which was found highly similar to Klebsiella sp., was isolated, enriched and inoculated back to the BAC reactor. When the influent chemical oxygen demand (COD) was 10,000 mg/L and the organic loading rate achieved 10 kg COD/(m 3 ·day), the effluent from the BAC reactor could meet the discharge standard without further treatment. Anaerobic BAC reactor inoculated with the isolated Klebsiella was proved to be an effective, cheap and easy technical treatment approach for the removal of SMP in the treatment of easily-degradable wastewater with COD lower than 10,000 mg/L.     

Identical full-scale biogas-lift reactors (BLRs) with anaerobic granular sludge and residual activated sludge for brewery wastewater treatment and kinetic modeling

Two identical full-scale biogas-lift reactors treating brewery wastewater were inoculated with different types of sludge to compare their operational conditions, sludge characteristics, and kinetic models at a mesophilic temperature. One reactor （R1） started up with anaerobic granular sludge in 12 weeks and obtained a continuously average organic loading rate （OLR） of 7.4 kg chemical oxygen demand （COD）/（m3.day）, COD removal efficiency of 80%, and effluent COD of 450 mg/L. The other reactor （R2） started up with residual activated sludge in 30 weeks and granulation accomplished when the reactor reached an average OLR of 8.3 kg COD/（m^3·day）, COD removal efficiency of 90%, and effluent COD of 240 mg/L. Differences in sludge characteristics,biogas compositions, and biogas- lift processes may be accounted for the superior efficiency of the treatment performance of R2 over R1. Grau second-order and modified StoverKincannon models based on influent and effluent concentrations as well as hydraulic retention time were successfully used to develop kinetic parameters of the experimental data with high correlation coefficients （R2 〉 0.95）, which further showed that R2 had higher treatment performance than R1. These results demonstrated that residual activated sludge could be used effectively instead of anaerobic granular sludge despite the need for a longer time.     

Removal of disinfection by-products formation potential by biologically intensified process

The removal of disinfection by-products formation potential(DBPFP) in artificially intensified biological activated carbon(IBAC) process which is developed on the basis of traditional ozone granular activated carbon was evaluated. By IBAC removals of 31% and 68% for THMFP and HAAFP were obtained respectively. Under identical conditions, the removals of the same substances were 4% and 32% respectively only by the granular activated carbon(GAC) process. Compared with GAC, the high removal rates of the two formed potential substances were due to the increasing of bioactivity of the media and the synergistic capabilities of biological degradation cooperating with activated carbon adsorption of organic compounds. A clear linear correlation ( R^2 = 0.9562 and R^2 = 0.9007) between DOC HAAFP removal rate and Empty Bed Contact Time(EBCT) of IBAC process was observed, while that between THMFP removal rate and EBCT of GAC was R^2 = 0.9782. In addition certain linear correlations between THMFP, HAAFP and UV254 ( R^2 = 0.855 and R^2 = 0.7702) were found for the treated water. For IBAC process there are also more advantages such as long backwashing cycle time, low backwashing intensity and prolonging activated carbon lifetime and so on.     

Treatment of coking wastewater by a novel electric assisted micro-electrolysis filter

A newly designed electric assisted micro-electrolysis filter(E-ME) was developed to investigate its degradation efficiency for coking wastewater and correlated characteristics. The performance of the E-ME system was compared with separate electrolysis(SE) and micro-electrolysis(ME) systems. The results showed a prominent synergistic effect on COD removal in E-ME systems. Gas chromatography/mass spectrometry(GC–MS) analysis confirmed that the applied electric field enhanced the degradation of phenolic compounds.Meanwhile, more biodegradable oxygen-bearing compounds were detected. SEM images of granular activated carbon(GAC) showed that inactivation and blocking were inhibited during the E-ME process. The effects of applied voltage and initial p H in E-ME systems were also studied. The best voltage value was 1 V, but synergistic effects existed even with lower applied voltage. E-ME systems exhibited some p H buffering capacity and attained the best efficiency in neutral media, which means that there is no need to adjust p H prior to or during the treatment process. Therefore, E-ME systems were confirmed as a promising technology for treatment of coking wastewater and other refractory wastewater.     

强化内源反硝化脱氮及污泥减量化研究

为提高传统污水处理工艺内源反硝化脱氮效率,在系统内部实现污泥减量,设计了水解酸化/缺氧/好氧(H/A/O)生物脱氮及污泥减量化工艺.试验采用连续流处理装置,以实际生活污水为研究对象.结果表明,在进水COD(220～410 mg/L)、NH4 -N(36～58 mg/L)、总水力停留时间为11h、硝化液回流比为300%、无外加碳源和碱度条件下,COD、NH4 -N和TN的平均去除率分别超过90%、95%和75%.在缺氧段碳源充足的条件下,随着硝化液回流比的增加,系统TN平均去除率升高;当碳源不足时,随着硝化液回流比的增加,系统TN平均去除率降低.污水经水解酸化预处理后,反硝化速率大大升高.水解酸化段利用水解酸化作用对回流剩余污泥的减量达到56.2%,污水、污泥经过水解酸化处理,大大提高了系统脱氮效率.以水解酸化作为传统的城市污水及污泥处理工艺,既可有效地改善污水的可生化性,提高系统污染物平均去除率,增强污水处理系统运行的稳定性,又可实现污水、污泥一体化处理.     

SBR系统中同步硝化反硝化好氧颗粒污泥的培养

采用人工配制的模拟生活污水,研究序批式反应器(SBR)中好氧颗粒污泥的培养.实验结果表明:通过对进水碳源进行调控,反应器中形成了高活性具有同步硝化反硝化能力的好氧颗粒污泥,反应器中COD和NH₃-N的去除率分别为74.0%～92.8%和82.3%～98.5%.颗粒污泥的粒径一般为0.5～1.0mm,MLSS达到4.5g·L^-1以上,SVI值约为32.5,其有效生物量及脱氮性能远远高于一般的好氧活性污泥.     

异养硝化好氧颗粒污泥培养条件研究

以具有好氧反硝化功能的异养硝化菌剂作初始接种物,粉末状活性炭对该菌剂进行预固定,批次进水的方式培养出了异养硝化好氧颗粒污泥,研究了颗粒污泥的培养条件.结果表明,有机负荷、进水水质、曝气量和沉降时间都对异养硝化好氧颗粒污泥的形成发育起着重要作用.模拟废水和猪场废水都可以培养出异养硝化好氧颗粒污泥.在COD负荷4.0 g·(L·d)~(-1),氨氮负荷0.212 g·(L·d)~(-1),曝气量为200 L·h~(-1),沉降时间为2.0～4.0 min条件下可形成颗粒污泥.采用葡萄糖为碳源的模拟废水培养颗粒污泥容易引起丝状菌的增殖,导致颗粒污泥沉降性能变差和脱氮功能减退.采用猪场配水能够将丝状菌有效地淘汰出反应器,恢复颗粒污泥沉降性能和脱氮功能,并促进颗粒污泥发育成熟.成熟的颗粒污泥性状稳定,当COD负荷为6.6～8.6 g·(L·d)~(-1),总氮负荷为0.409～0.474 g·(L·d)~(-1),氨氮负荷为0.285～0.304 g·(L·d)~(-1)时,颗粒污泥对以葡萄糖为补充碳源的猪场废水的总氮去除率为84.75%～88.33%,氨氮去除率为99.9%以上,COD去除率为97.29%～98.62%.     

低温条件下分流式侧流-AAO工艺污水处理及同步污泥减量效果研究

当前剩余污泥产量巨大及低温条件下运行不稳定是城市污水处理厂活性污泥技术面临的主要挑战和制约.基于此,本文通过向厌氧-缺氧-好氧(AAO)系统中的污泥回流系统引入分流式侧流厌氧系统,以实现强化污水处理和同步污泥减量的目标.结果发现,当侧流分流比例为30%时,分流式侧流-AAO系统能够实现最好的污泥减量效果,污泥累计排放量减少18.43%,污泥表观产率下降19.70%;并且分流式侧流-AAO系统的COD、氨氮和总氮去除效率分别为88.56%、83.12%和71.60%,均略高于AAO系统.同时该条件下,分流式侧流-AAO系统能够在51 d后实现良好的总磷去除效率,并维持出水TP浓度稳定在0.50 mg·L,而AAO系统则需要93 d后才能实现稳定的总磷去除效果.在适当的分流比条件下,分流式侧流厌氧池内能够实现TN的有效去除,可以作为提升水处理系统脱氮能力的潜在手段.     

Nitrogen removal and simultaneous nitrification and denitrification in a fluidized bed step-feed process

For urban wastewater treatment, we conducted a novel four-stage step-feed wastewater treatment system combined with a fluidized bed laboratory experiment to investigate chemical oxygen demand (COD), NH₄⁺-N, and total nitrogen (TN) removal performance. The removal rates of COD, NH₄⁺-N and TN were 88.2%, 95.7%, and 86.4% with effluent concentrations of COD, NH₄⁺-N and TN less than 50, 8, and 10 mg/L, respectively. Biomass and bacterial activities were also measured, with results showing more nitrobacteria in the activated sludge than in the biofilm; however, bacterial activity of the biofilm biomass and the activated sludge were similar. Nitrogen concentrations during the process were also detected, with simultaneous nitrification and denitrification found to be obvious.     

基于短程反硝化厌氧氨氧化的低碳源城市污水深度脱氮特性

短程反硝化厌氧氨氧化是一种新型生物脱氮技术,应用于城市污水深度脱氮有望大幅降低外碳源投加量.本研究接种厌氧氨氧化污泥,考察了短程反硝化厌氧氨氧化的深度脱氮性能与污泥特性.结果表明,接种厌氧氨氧化污泥可迅速启动短程反硝化厌氧氨氧化系统,在进水COD/TN为2.19±0.08时,出水TN浓度为(4.82±1.84)mg·L~(-1),实现了低碳源污水深度脱氮.系统粒径大于0.20 mm的污泥占86.16%,污泥实现了颗粒化,有助于厌氧氨氧化菌在系统内的有效持留.将短程反硝化厌氧氨氧化深度脱氮应用于城市污水处理厂二沉池出水深度脱氮,可降低外碳源投加量,同时可降低污水处理厂硝化池耗氧量.     

生物活性炭厌氧氨氧化反应器启动过程研究

采用生物活性炭反应器进行厌氧氨氧化启动实验,以考察生物活性炭对该启动过程的加速作用.在3个相同的UASB反应器中接种由厌氧颗粒污泥和厌氧絮状污泥组成的混合污泥,以含NH4+-N和NO2--N的人工配水为进水,连续运行,并分别在反应器运行的第0、33、56 d添加颗粒状活性炭载体.结果表明,第0 d添加载体的反应器在运行90 d后脱氮性能无显著提高,暂停运行1个月后,经过33 d(累计123 d)二次启动成功.而第33 d、56 d添加载体的反应器分别历经49 d、85 d成功启动,实现了厌氧氨氧化反应器的快速启动.3个反应器启动后总氮的平均去除率分别为89.8%、86.7%、86.7%.反应器启动运行过程可分为菌体自溶期、停滞期、活性提高期和稳定脱氮期,最适宜加入GAC载体的时间为停滞期开始之后.     

Enhancing nitrogen removal from low carbon to nitrogen ratio wastewater by using a novel sequencing batch biofilm reactor

Removing nitrogen from wastewater with low chemical oxygen demand/total nitrogen (COD/TN) ratio is a difficult task due to the insufficient carbon source available for denitrification. Therefore, in the present work, a novel sequencing batch biofilm reactor (NSBBR) was developed to enhance the nitrogen removal from wastewater with low COD/TN ratio. The NSBBR was divided into two units separated by a vertical clapboard. Alternate feeding and aeration was performed in the two units, which created an anoxic unit with rich substrate content and an aeration unit deficient in substrate simultaneously. Therefore, the utilization of the influent carbon source for denitrification was increased, leading to higher TN removal compared to conventional SBBR (CSBBR) operation. The results show that the CSBBR removed up to 76.8%, 44.5% and 10.4% of TN, respectively, at three tested COD/TN ratios (9.0, 4.8 and 2.5). In contrast, the TN removal of the NSBBR could reach 81.9%, 60.5% and 26.6%, respectively, at the corresponding COD/TN ratios. Therefore, better TN removal performance could be achieved in the NSBBR, especially at low COD/TN ratios (4.8 and 2.5). Furthermore, it is easy to upgrade a CSBBR into an NSBBR in practice.     

污泥厌氧产酸发酵液作碳源强化污水脱氮除磷中试研究

为研究城市污泥厌氧产酸发酵液作为补充碳源强化生活污水脱氮除磷系统的效果和可行性,建造了一个总有效体积为4 660 L的A2/O中试反应系统,以实际城市污水为研究对象,考察了添加污泥产酸发酵液后的污水脱氮除磷效果并和单纯添加乙酸作碳源的效果进行了比较.结果表明,在进水COD为243.7 mg·L-1、NH+4-N为30.9 mg·L-1、TN为42.9 mg·L-1、TP为2.8 mg·L-1、硝化液回流比为200%和污泥回流比为100%的条件下,向缺氧池中投加乙酸能增强系统脱氮除磷效果,反应器的最佳进水流量和投加碳源SCOD增量分别为7 500 L·d-1和50 mg·L-1.污泥发酵液代替乙酸作为外加碳源时的平均出水COD、NH+4-N、TN和TP去除率分别为81.60%、88.91%、64.86%和87.61%,相对应的出水浓度分别为42.18、2.77、11.92和0.19 mg·L-1,满足我国《城镇污水处理厂污染物排放标准》GB 18918-2002所规定的一级A标准.结果表明,投加污泥产酸发酵液作为脱氮除磷碳源可达到和乙酸同样的效果,具有实际可行性,这为城市污泥处理处置实现资源化提供了一条新的可行途径.     

PACT工艺系统中的吸附和生物降解性能研究

通过对比研究生物活性炭法(PACT)中各作用相对实际废水和模拟废水中污染物的吸附和生物降解性能,以及活性炭用量和污泥量对PACT降解污染物动力学的影响,探讨了PACT系统对废水处理的特征和作用机理.结果表明:PACT工艺对污染物的去除效果要优于纯活性炭吸附和活性污泥法,且对污染物具有更好的持续去除效果.活性炭用量越大,PACT工艺的处理效果越好,最佳污泥量〔以ρ(MLSS)计〕在1500mg/L以上.动力学曲线拟合结果表明,伪二级动力学方程可以精确拟合PACT工艺降解有机物的过程,表明PACT工艺中吸附过程并非系统的控制步骤,生物降解性能至关重要.PACT系统污泥中活性炭的扫描电镜照片证明了活性炭作为微生物载体进行生物作用的事实,固定化载体作用是PACT系统主要的强化作用机理.