Improving nitrogen removal in two modified decentralized wastewater systems

Efficient nutrient removal in decentralized wastewater treatment systems is a challenging task. To improve the removal of organic matter and nitrogen from wastewater, two types of bioreactors using membrane-aerated biofilm reactor (MABR) and microbial fuel cell (MFC) techniques were evaluated. During more than 250 days of continuous-flow reactor operation, both reactors showed consistently high chemical oxygen demand removal (>86%). At an influent ammonium-nitrogen (NH4(+)-N) concentration of 30 mg N/L, the average effluent NH4(+)-N concentrations were 6.2 and 0.5 mg N/L for the MABR and MFC reactor, respectively, while the effluent nitrate-nitrogen (NO3(-)-N) concentrations were 5.4 mg/ L in the MABR and 19.2 mg/L in the MFC-based reactor. The overall total inorganic nitrogen removal efficiencies were 64% and 36% for the MABR and MFC reactor, respectively. At the measured dissolved oxygen concentrations of 5.2 and 0.23 mg/L in the aerobic/anoxic zone of the MFC and MABR, respectively, a specific oxygen uptake rate of 0.1 g O2/g VSS-d, resulting from ammonia oxidation, was detected in the settled sludge of the MFC, while no nitrifying activity of the sludge from the MABR was detected. Molecular microbial analysis demonstrated a link between the bacterial community structure and nitrifying activity. The relatively high abundance of Nitrosomonas europaea was associated with its detectable nitrification activity in the settled sludge of the MFC. The results suggest that MABR and MFC techniques have the potential to improve organic and nitrogen removal in decentralized wastewater systems.     

污水低氧脱氮机制及其应用研究进展

阐述了污水低氧脱氮的基本原理,即抑制或去除亚硝酸盐氧化菌(NOB),同时保留氨氧化菌(AOB),并保持其活性;探讨了污水低氧脱氮实现途径;详细介绍了几种典型的污水低氧脱氮工艺(短程硝化(SHARON)工艺、厌氧氨氧化(ANAMMOX)工艺、好氧反氨化(DEMON)工艺、低氧自养硝化反硝化(OLAND)工艺、甲烷营养型硝化反硝化工艺和亚硝酸盐型完全自养脱氮(CANNON)工艺)的应用研究进展;最后对污水低氧脱氮处理工艺的工程运用进行了展望.     

短程硝化—厌氧氨氧化组合工艺在脱氮领域的研究进展

基于全程硝化反硝化的传统生物脱氮工艺在硝化过程中需要大量氧气供应,反硝化过程需要有机物作为碳源,存在能耗与药耗过大的问题.为了降低废水脱氮的成本,短程硝化(PN)—厌氧氨氧化(ANAMMOX)组合工艺(PNA工艺)得到了高速发展.综述了PNA工艺的影响因素,重点介绍了4种基于PN与ANAMMOX原理开发的衍生PNA工艺...     

全自养生物脱氮新工艺研究进展

目前,国际研究较热的自养亚硝化、自养反硝化和全自养脱氮新工艺,有节省外加碳源和能耗低的特点,尤其适合于低碳氮比(C/N)类氨氮废水的处理.介绍了这些工艺的原理和特点,并展望了它们的研究发展方向和应用前景.     

序批式生物膜反应器不同填料挂膜及短程硝化特性研究

以实际生活污水为研究对象,采用序批式生物膜反应器(SBBR),填充不同种类的填料,针对其各自的挂膜特征和短程硝化的实现与稳定的特性进行了研究.结果表明,与立方体海绵填料相比,炭纤维填料的SBBR能够更快地实现挂膜启动,硝化效果稳定、高效(NH_4~+-N去除率高达99.3%);立方体海绵填料更易在常温下,实现NO_2~--N大量积累的短程硝化,但是相比而言,硝化效率不高.升高温度至30 ℃左右时,能够在30 d内实现炭纤维填料的短程硝化,通过过程控制可以实现短程硝化的稳定.荧光原位杂交技术(FISH)检测结果证实,SBBR中短程硝化的实现与稳定是因为菌群得到了优化,氨氧化细菌成为优势菌种.     

高氨氮废水的半硝化工艺影响因素

采用泳动床反应器对含高浓度氨氮的污泥脱滤液进行了半硝化反应影响因素研究。实验结果表明,半硝化工艺可以在较高负荷条件下运行,其出水NO2--N/NH4+-N比例稳定在1.1±0.05∶1,基本满足了厌氧氨氧化工艺的进水要求。此外,温度和溶解氧对工艺运行具有重要影响,控制适宜无机碳含量与NH4+-N比值、碱度与氨氮比值有利于半硝化工艺的进行。     

全自养生物脱氮新工艺研究进展

目前，国际研究较热的自养亚硝化、自养反硝化和全自养脱氮新工艺，有节省外加碳源和能耗低的特点，尤其适合于低碳氮比（C／N）类氨氮废水的处理。介绍了这些工艺的原理和特点，并展望了它们的研究发展方向和应用前景。     

Improving Anammox start-up with bamboo charcoal

Three Upflow Anaerobic Sludge Blanket (UASB) reactors were compared for Anammox enrichment using synthetic wastewater with Spherical Plastic (SP) and Bamboo Charcoal (BC) addition, and without carrier (CK). After four months of operation, the Anammox activity occurred in all reactors allowing continuous removal of ammonium and nitrite. Ammonium and nitrite removal efficiencies were all higher than 98% in steady phase with the effluent concentrations below 1 mg L⁻¹. The start-up time could be shortened from 117 to 97 d in CK and SP reactor to 85 d in BC amendment reactor. Quantitative PCR (q-PCR) analyses indicated a significant increase in the number of Anammox bacteria in BC amended reactor as compared with CK and SP during the entire start-up periods. The copy numbers of Anammox of 16S rRNA gene in the reactor with BC amendment could reach up to 6 × 10⁹ copies g⁻¹ Volatile Suspended Solids, around 22.5 times and 12.3 times greater than that in CK and SP reactor, respectively. BC addition could accelerate the start-up of Anammox and significantly increase the Anammox bacteria number.     

有机负荷对膜-生物反应器硝化性能的影响

采用厌氧动态膜-生物反应器(AnDMBR)组合自养膜-生物反应器(MBR)工艺,研究冬季低温条件下系统的硝化效果以及TP的去除效果,并与单级MBR工艺进行对比。结果表明:(1)AnDMBR对COD的去除率基本保持在50%～60%,AnDMBR组合自养MBR工艺对COD的去除率为80%～85%;单级MBR工艺对COD的去除率为80%左右。(2)总体上,AnDMBR组合自养MBR工艺对NH4+-N的去除率大于95%;单级MBR对NH4+-N的去除效果比AnDMBR组合自养MBR工艺差。(3)AnDMBR组合自养MBR工艺中,出水NO2--N与NO3--N均有积累;单级MBR工艺中,出水NO2--N积累不明显。(4)相对于亚硝酸盐氧化菌(NOB),氨氧化菌(AOB)对有机负荷更敏感,当有机负荷高时,AOB更易受到异养菌活动的抑制;当有机负荷降低、异养菌活性减弱时,AOB活性明显增强,系统的硝化效果得到明显改善。(5)AnDMBR组合自养MBR工艺对TP的去除率高于80%,单级MBR工艺稳定后对TP的去除率仅为20%～30%。(6)从呼吸速率和硝化速率可知,自养MBR的硝化效果优于单级MBR。     

Nitrifying community analysis in a single submerged attached-growth bioreactor for treatment of high-ammonia waste stream.

This study investigated the nitrifying community structure in a single-stage submerged attached-growth bioreactor (SAGB) that successfully achieved stable nitrogen removal over nitrite of a high-strength ammonia wastewater. The reactor was operated with intermittent aeration and external carbon addition (methanol). With influent ammonia and total Kjeldahl nitrogen ranging from 537 to 968 mg/L and 643 to 1510 mg/L, respectively, 85% nitrogen removal was obtained, and effluent was dominated by nitrite (NO2-/NOx > 0.95). Nitrifying community analysis using fluorescence in situ hybridization (FISH), with a hierarchical set of probes targeting known ammonia-oxidizing bacteria (AOB) within beta-proteobacteria, showed that the AOB community of the biofilter consists almost entirely of members of the Nitrosomonas europaea/eutropha and the Nitrosococcus mobilis lineages. Image analysis of FISH pictures was used to quantify the identified AOB, and it was estimated that Nitrosomonas europaea/eutropha-like AOB accounted for 4.3% of the total volume of the biofilm, while Nitrosococcus mobilis-like AOB made up 1.2%; these numbers summed up to a total AOB fraction of 5.5% of the total volume on the biofilm. Nitrite-oxidizing bacteria (NOB) were not detectable in the biofilm samples with probes for either Nitrospira sp. or Nitrobacter sp., which indicated that NOB were either absent from the biofilters or present in numbers below the detection limit of FISH (< 0.1% of the total biofilm). Nitrite oxidizers were likely outcompeted from the system because of the free ammonia inhibition and the possibility that the aeration period (from intermittent aeration) was not sufficiently long for the NOB to be released from the competition for oxygen with heterotrophs and AOB. The nitrogen removal via nitrite in a SAGB reactor described in this study is applicable for high-ammonia-strength wastewater treatment, such as centrate or industrial wastes.     

SBR单级自养脱氮系统氮素转化途径

利用氮素计量关系和批式实验研究了SBR系统中基于短程硝化的单级自养脱氮特性和脱氮途径。结果表明,SBR系统获得良好脱氮效果,TN最高去除负荷和去除速率分别达0.49 kg N/(m3.d)和0.20 kg N/(kg VSS.d);系统中82%的氨氮转化成气体脱除,10%的氨氮转化成硝酸盐氮。批式实验结果表明,SBR系统中的污泥同时具有厌氧氨氧化、亚硝酸盐氧化和自养反硝化活性,三者的反应速率分别为0.12 kg NH4+-N/(kg VSS.d)、0.04 kg NO2--N/(kg VSS.d)和0.03 kg NO2--N/(kg VSS.d)。综上,SBR系统中氮的脱除是短程硝化、厌氧氨氧化和反硝化共同作用的结果,产生的硝酸盐是厌氧氨氧化和硝化作用所致。     

Optimizing nutrient supply in a rotatory-switching biofilter for toluene vapor treatment

The influence of nutrient conditions on the degradation of toluene vapor in a rotatory-switching biofilter (RSB) was investigated. The biofilter consists of four segments connected in series, each with a packing layer made of polyvinyl formal. The influent airstreams including toluene vapors were passed through segments 1-3 as up-flow with a toluene concentration of 0.9-1.2 g m(-3) and with an empty-bed retention time of 26-52 sec. Nutrient solutions were fed to all packed segments once a day by means of immersion. The nutrient solution was used repeatedly and replenished by the addition of (NH4)2SO4. The result at 155 days showed nitrogen depletion was particularly obvious and the lack of nitrogen affected toluene removal. By adding 161 g of nitrogen solution per volumetric cubic meter of reactor, toluene removal efficiency was immediately increased to greater than 99%. With long-term biofilter operation, 21%-32% of ammonium was utilized for nitrification because of the growth of nitrifying bacteria such as Nitrosomonas sp. Based on the carbon-nitrogen balance, the daily nitrogen demand for toluene removal was estimated 2.1 g day(-1) at a toluene load of 70 g m(-3) hr(-1).     

Anammox enrichment from different conventional sludges

Three sets of sequencing batch reactor (SBR) were used for Anammox enrichment from conventional sludges including upflow anaerobic sludge blanket, activated sludge, and anaerobic digestion sludge. After four months of operation, the Anammox activity occurred in all reactors allowing continuous removal of ammonium and nitrite. The morphology of the cultivated Anammox sludge was observed using scanning electron microscope. The photographs showed that the obtained culture was mostly spherical in shape, presumably Anammox culture. There were also filamentous-like bacteria co-existing in the system. Fluorescence in situ hybridization (FISH) analysis using 16S rRNA targeting oligonucleotide probes PLA46 and Amx820 showed that the dominant population developed in all SBRs was hybridized with both PLA46 and Amx820 gene probes. It means that the cultivated biomass in all SBRs was classified in the group of Planctomycetales bacteria with respect to the anaerobic ammonium-oxidizing bacteria, Candidatus Brocadia anammoxidans and Candidatus Kuenenia stuttgartiensis. Numerous time sequences were tested in this experiment. The shortest workable reaction time was found in the range from 5 to 7 h. Good quiescence of sludge was obtained at 30 min of settle period followed by a discharge period of 15 min. A long-term performance showed a near perfect removal of nitrite based on the influent NO2(-)-N concentration of 50-70 mg l(-1). The maximum ammonia removal efficiency was 80% with the influent NH4(+)-N concentration of 40-60 mg l(-1). It is, therefore, concluded that Anammox cultivation from conventional sludges was highly possible under control environment within four months.     

一体化生物膜反应器处理生活污水试验研究

根据传统好氧硝化和缺氧反硝化生物脱氮的工艺原理,开发了一体化生物膜反应器,并对其进行了处理生活污水的试验研究。试验结果表明,在有机负荷提高的前提下,通过对进水方式和曝气速率的调节,反应器对COD和TN的去除率达到97％和82％;污泥活性测定表明,硝化反应和反硝化反应分别在反应器的好氧区和缺氧区占优势,但由于生物膜内部微环境的存在,反应器不同区域均有同时硝化和反硝化(SND)现象的发生。     

Microbial activity in a combined UASB-activated sludge reactor system

A combined upflow anaerobic sludge bed-activated sludge (UASB-AS) reactor system with consistently wasting of excess biomass was used to treat suspended-solids pre-settled piggery wastewater (COD=2000 mg l(-1), total Kjeldahl nitrogen TKN=400 mg l(-1), suspended solids=250-400 mg l(-1)). Thus, the activity of nitrogen-related microbial groups in each individual bioreactor was investigated. When the granules retention time (GRT) of 20-50 d in the UASB reactor, the solids retention time (SRT) of 10-25 d in the AS reactor and the recycle-to-influent ratio (Re) of 1 were maintained, the combined system removed 95-97% of chemical oxygen demand (COD), 100% of TKN and 54-55% of total nitrogen (TN). Denitrification and methanogenesis occurred in the UASB reactor so that both biochemical processes contributed to most of the COD removal and, complete nitrification (most of the TKN removal) occurred in the AS reactor. Compact granules with good settling abilities developed in the UASB reactor, and rapid rates of granulation of break-up granules in the UASB reactor were confirmed by experiments. The activity of nitrifiers and denitrifiers (an=0.68-0.87; adn=0.55-0.70) and the calculated specific nitrification and denitrification rates (qn=0.26-0.47 mg NH4+ -N mg VSS(-1)d(-1); qdn=0.046-0.076 mg NOx- -N mg VSS(-1)d(-1)) significantly increased with decreasing SRT and GRT, respectively. Accordingly, the combined UASB-AS reactor system should be regarded a promising alternative for the removal of organic carbon and nitrogen from piggery wastewater.     

T-RFLP detection of nitrifying bacteria in a fluidized bed reactor of achieving simultaneous nitrification-denitrification

Steady simultaneous nitrification-denitrification (SND) was achieved in a fluidized bed reactor (FBR) by the control of DO concentration without physical separation of the aerobic and anoxic zones. The performance and composition of nitrifying bacteria were examined in this study. The ammonium removal efficiency was higher than 80% and the DO concentration (1-5 mg l(-1)) had little influence on it. More than 50% total nitrogen (TN) removal efficiency was achieved when DO was less than 3 mg l(-1) and in many cases the removal efficiency varied between 60-70%. The volumetric loading of TN varied between 0.12 and 0.20 kg Nm(-3)d(-1). 16S rRNA-based terminal restriction fragment length polymorphism analysis was used to characterize the diversity and distribution of the ammonia oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in the FBR. The results indicated that, the composition and number of both AOB and NOB changed with position in the reactor and operating time. Nitrosomonas sp. was found to be dominant species of the AOB community, and Nitrobacter sp. also existed in the system. The SND mechanism in the FBR was proved to be the vertical stratification of active populations; however, the presence of microenvironments within the biofilm cannot be ruled out.     

分段进水多级生物膜反应器脱氮效能影响因素研究

采用分段进水多级生物膜反应器处理高氮低碳小城镇污水,考察负荷、溶解氧和温度对反应器脱氮效能的影响。实验结果表明:负荷、溶解氧和温度对反应器脱氮效能有显著影响。在水温为20～25℃,DO为5 mg/L,负荷为1 kgCOD/(m3.d),挂膜密度为30%,第1、3、6级分段进水,流量分配比为2∶2∶1的条件下,在反应器中可成功构建出高效同时硝化反硝化系统,出水COD、NH4+-N和TN浓度分别为33 mg/L、2.6 mg/L和29.4 mg/L,去除率分别为90.1%、96.0%和63.9%。当水温≤15℃时,硝化速率受温度的影响显著。     

高氨氮污泥脱水液短程硝化反硝化的启动及稳定

采用A/O-CSTR工艺处理高氨氮污泥脱水液。进水氨氮浓度浓度约为375 mg/L,C/N比小于1.0,反硝化碳源明显不足。A/O反应器完成短程硝化反应,CSTR定期投加初沉污泥作为碳源进行反硝化。两者联合达到总氮去除的目的。实验研究短程硝化反应的启动过程,以及CSTR出水回流对短程硝化和系统脱氮效果的影响。实验结果表明系统具有良好的硝化反硝化效果。A/O反应器亚硝酸盐积累率迅速提高并稳定在90%以上。CSTR有效利用初沉污泥实现了稳定的反硝化。出水回流有利于提高总氮去除率,在回流比为200%时,系统平均总氮去除率达到85%以上。     

Influence of gas flow-induced shear stress on the operation of the Anammox process in a SBR

The start up and performance of the Anammox process were tested in sequencing batch reactors with two different configurations: a bubble column (SBR-B) and a gas-lift reactor (SBR-G). Different off-gas upflow velocities were tested (3.53-12.3 cm min(-1)) in order to expose the biomass to different shear conditions and to study their effects on both efficiency and physical properties of the Anammox granular biomass. For the SBR-B the minimum gas upflow velocity needed to achieve biomass suspension inside the reactor was 12.3 cm min(-1). Such velocity made impossible the stable operation of the process. The fluidization of biomass for the SBR-G was reached at a gas upflow velocity of 3.52 cm min(-1). This system maintained an efficiency of nitrite removal around 98% at values up to 5.29 cm min(-1) but when the gas upflow velocity was increased from 5.29 to 9.70 cm min(-1) a significant decrease of the specific Anammox activity of the biomass from 0.35 to 0.05 g Ng(-1) VSS d(-1) was measured. The system lost 85% of its nitrogen removal efficiency which was not restored in spite of returning the gas upflow velocity to its initial value.     

以羟胺为底物的自养脱氮微量热研究

羟胺（NH₂OH）是单级自养脱氮系统物质转化的重要中间产物。从稳定运行（氨氮去除率维持90%以上,总氮去除率维持在80%以上）的单级自养脱氮工艺（SBBR）取活性污泥放入量热池,加入不同浓度N-NH₂OH（40～200 mg/L）进行量热实验研究。结果表明,用Boltzmann模型可以很好地表达量热值与NH₂OH浓度的关系,超过一定浓度的羟胺会抑制微生物活性,自营养脱氮过程的产热增量降低。