好氧硝化污泥启动厌氧氨氧化试验研究

以好氧硝化污泥为培养污泥,采用经稀释的猪场废水启动厌氧氨氧化反应器,经过125 d的培养,根据ASBR反应器出水水样监测结果显示:ASBR反应器稳定运行后NH4+-N、NO2--N的去除率分别达到91.7%、92.0%,说明采用ASBR反应器,接种好氧硝化污泥可成功启动厌氧氨氧化反应器,验证了利用厌氧氨氧化工艺处理类似养殖废水的高氨氮废水的可能性.     

低溶解氧对A2/O工艺脱氮的影响

采用A2/O反应器,通过控制不同的溶解氧浓度来设定3种工况,对比各工况的出水水质.结果表明:低氧工况比高氧工况节省了52.6%的曝气能量,对TN的去除率提高了约12%;低氧条件降低了污泥的硝化性能,但仍能将NH4+-N硝化,使出水NH4+-N浓度低于2 mg/L.     

同步硝化反硝化脱氮研究

在控制SBR反应器保持良好的好氧状态条件下 ,考察进水COD/NH3比值对同步硝化反硝化脱氮效率的影响。同时也对同步硝化反硝化机理进行了初步的探讨。研究表明 ,进水COD/NH3比值越高 ,总氮去除率越高 ,同步硝化反硝化现象越明显。由该试验可以推断活性污泥菌胶团中异养硝化菌和好氧反硝化菌的存在。     

不同粒径好氧颗粒污泥的性质比较

试验采用气升式内循环间歇反应器(SBAR)培养好氧颗粒污泥,筛分得到粒径分布为0.5～1.0mm,1.0～1.5mm和1.5mm以上三组好氧颗粒污泥,考察了不同粒径分布的好氧颗粒污泥的性状和去除效果。试验结果表明,在COD_(Cr)、NH_3-N分别为1000mg/L和100mg/L时,三种不同粒径的好氧颗粒污泥对COD_(Cr)、NH_3-N的去除率均在90%以上,但对总氮的去除率差异明显,粒径在1.0～1.5mm的颗粒去除效果明显优于其他两组。通过硝化反硝化速率试验也能证明,粒径范围在0.5～1.0mm和1.5mm以上的两组颗粒污泥,对反硝化反应存在抑制作用,并不是颗粒越大越好。絮体和颗粒的混合系统处理效果要优于纯颗粒系统,且纯颗粒系统在培养一段时间后,又会恢复为絮体和颗粒混合的稳定体系。     

垃圾渗滤液中有机污染物对厌氧氨氧化的影响研究

采用好氧活性污泥和厌氧颗粒污泥混合接种启动UBF厌氧氨氧化反应器,共耗时165d。反应器启动成功后,容积负荷达到了0.17kg总氮/(m3·d),NO2--N与NH4+-N去除率分别为100%和93%。在此基础上进行垃圾渗滤液有机物浓度梯度实验,研究其在不同有机物浓度下对厌氧氨氧化反应的影响作用。实验结果表明:NH4+-N和NO2--N的去除率随有机物浓度的增加依次降低。当TOC浓度小于100mg/L时,厌氧氨氧化运行稳定,NH4+-N和NO2--N的去除率分别达80%和95%以上;当TOC浓度大于200mg/L时,厌氧氨氧化反应减弱,体系中出现了明显的异氧反硝化反应;当TOC浓度大于500mg/L时,厌氧氨氧化反应几乎完全停止。由于该垃圾渗滤液有机污染物多为难降解的大分子,具有毒性、易降解,有机物的含量较少,因此认为其对厌氧氨氧化的毒性抑制远比竞争性抑制大。     

亚硝酸型硝化-厌氧氨氧化联合工艺处理"中老龄"垃圾渗滤液

亚硝酸型硝化和厌氧氨氧化有机结合构成的新型全程自养生物脱氮技术为处理高氨氮和低C/N的"中老龄"渗滤液提供了新的思路.主要针对系统内部能否实现稳定的亚硝酸氮自给和厌氧氨氧化反应器的启动这两个关键条件进行研究.结果表明,在氨氮负荷率(ALR)为0.069～0.284 3 gNH3-N/(gVSS·d)条件下,前置亚硝酸型硝化反应器(SBR)能实现稳定的亚硝酸氮积累,出水NO-2-N/NH3-N在1.45左右,NO-2-N/NO-x-N大于90%.而且,接种前置SBR中具有硝化活性的污泥用作厌氧氨氧化反应器(UASB)的接种污泥,可以加快反应器的成功启动.在进水氨氮和亚硝酸氮浓度不超过250 mg/L的条件下,厌氧氨氧化反应器稳定运行时NH3-N和NO-2-N的去除率分别可达到80%和90%左右.     

DO对短程同步硝化反硝化除磷工艺的影响

针对碳源偏低的城市污水,采用序批式活性污泥法研究DO对短程同步硝化反硝化除磷工艺的影响,同时对短程同步硝化反硝化和反硝化除磷的机理进行探讨.试验表明:控制DO浓度可在同一个反应器内既实现短程同步硝化反硝化反应又达到反硝化除磷的效果.综合考虑COD、NH4+-N、TN、TP的出水浓度达到一级A排放标准,得出最佳的DO控制...     

低温下硝化型曝气生物滤池的快速启动

为了提高我国北方地区冬季污水处理设施的生物脱氮效能,本文采用人工配水,探究低温条件下硝化型BAF的快速启动过程。结果表明:在10~16℃条件下,进水NH+4—N和COD浓度分别控制在103.16和60.00 mg/L,采用接种挂膜法与自然挂膜法相结合的方式,运行至25 d时,出水NH_4~+—N和COD的浓度分别降为36.17和6.66 mg/L,去除率分别高达62.74%和87.30%,NO_3~-—N浓度达到60.23 mg/L。采用的硝化型BAF具有良好的硝化性能。至硝化型BAF启动成功,填料表面生物膜由浅褐色黏性薄膜变为较厚的黄褐色生物膜。     

曝气生物滤池去除有机物及氨氮的影响因素分析

采用以陶粒为填料的曝气生物滤池(BAF)处理生活污水,研究气水比、水力负荷、进水COD和NH3-N负荷对BAF去除COD及NH3-N的影响,分析COD及NH3-N沿滤柱的变化规律。结果表明:当试验进水COD及NH3-N质量浓度分别为300~370mg/L和20~40mg/L时,最佳气水比为4∶1~5∶1,最佳水力负荷为1.0~2.0 m3/(m2.h)。当进水COD负荷为1.69~6.47 kg/(m3.d)时,COD去除率与进水COD负荷成正相关。BAF的硝化性能与进水NH3-N和COD负荷成负相关。     

镉对污水生物脱氮反应动力学的影响研究

通过批量试验检测COD、NH+4-N和NOx-N的去除率和比降解速率,研究了Cd2+对活性污泥生物脱氮反应动力学的影响。结果表明:在硝化反应和反硝化反应有机物降解过程中,5 mg/L的Cd2+即会对有机物的去除率产生抑制作用,20 mg/L的Cd2+对有机物去除率和有机物比降解速率有显著抑制效应;在硝化反应NH+4-N的去除过程中,20mg/L的Cd2+会显著抑制对NH+4-N的去除,10 mg/L的Cd2+可造成比硝化速率的显著降低;在反硝化反应NOx-N的去除过程中,Cd2+对NOx-N去除率没有显著影响,20 mg/L的Cd2+对比反硝化速率有显著抑制效应。     

Microbial community structure of activated sludge during aerobic granulation in an annular gap bioreactor.

A novel annular gap reactor was designed to create a controlled shear environment in which aerobic granular sludge could be developed. The bacterial and eukaryal community structures during two aerobic granular sludge experiments were tracked using denaturing gradient gel electrophoresis (DGGE). The first granule cultivation experiment, using an organic loading rate of 1.6 kg/m3d COD, resulted in biomass that was dominated by filamentous bacteria and Zoogloea ramigera colonies. A second experiment with a higher organic loading rate of 6 kg/m3d COD developed a granule-like morphology but was ultimately dominated by filamentous fungi. Species identification via DGGE band purification and DNA sequencing closely matched the observed sludge morphology and behavior.     

Effect of sludge discharge positions on steady-state aerobic granules in sequencing batch reactor (SBR)

We have investigated the effect of sludge discharge location on the steady-state aerobic granules in sequencing batch reactors (SBRs). Two SBRs were operated concurrently with the same sludge retention time using sludge discharge ports at: (a) the reactor bottom in R1; and (b) the reactor middle-lower level in R2. Results indicate that both reactors could maintain sludge granulation and stable operation, but the two different sludge discharge methods resulted in significantly different aerobic granule characteristics. Over 30 days, the chemical oxygen demand (COD) removal of the two reactors was maintained at similar levels (above 96%), and typical bioflocs were not observed. The average aerobic granule size in R2 was twice that in R1, as settling velocity increased in proportion to size increment. Meanwhile, the production yields of polysaccharide and protein content in R2 were always higher than those in R1. However, due to mass transfer limitations and the presence of anaerobes in the aerobic granule cores, larger granules had a tendency to disintegrate in R2. Thus, we conclude that a sludge discharge port situated at the reactor bottom is beneficial for aerobic granule stability, and enhances the potential for long-term aerobic granule SBR operation.     

Aerobic granular sludge: a promising technology for decentralised wastewater treatment.

In order to evaluate the characteristics of aerobic granular sludge, a sequencing batch reactor, feeding with synthetic wastewater at the organic loading rate of 8 kg COD/m3 d, was employed on the laboratory scale. Granules occurred in the reactor within 1 week after the inoculation from conventional flocculent sludge. Aerobic granular sludge was characterised by the outstanding settling properties and considerable contaminates removal efficiencies. The SVI30 values were in the range of 20 to 40 ml g(-1). However, the sludge volume index of short settling time (e.g. SVI10--10 min) is suggested to describe the fast settling properties of aerobic granular sludge. The potential application in the decentralised system is evaluated from the point view of footprint and high bioactivity. The occurrence of sloughing, resulting from the outgrowth of filamentous organisms, would be responsible for the instability of aerobic granules. The starvation phase should therefore be carefully controlled for the maintenance and stability of aerobic granular sludge system.     

Rapid start-up of a nitrifying reactor using aerobic granular sludge as seed sludge

In this study, the effectiveness of aerobic granular sludge as seed sludge for rapid start-up of nitrifying processes was investigated using a laboratory-scale continuous stirred-tank reactor (CSTR) fed with completely inorganic wastewater which contained a high concentration of ammonia. Even when a large amount of granular biomass was inoculated in the reactor, and the characteristics of influent wastewater were abruptly changed, excess biomass washout was not observed, and biomass concentration was kept high at the start-up period due to high settling ability of the aerobic granular sludge. As a result, an ammonia removal rate immediately increased and reached more than 1.0 kg N/m(3)/d within 20 days and up to 1.8 kg N/m(3)/d on day 39. Subsequently, high rate nitritation was stably attained during 100 days. However, nitrite accumulation had been observed for 140 days before attaining complete nitrification to nitrate. Fluorescence in situ hybridization analysis revealed the increase in amount of ammonia-oxidizing bacteria which existed in the outer edge of the granular sludge during the start-up period. This microbial ecological change would make it possible to attain high rate ammonia removal.     

Enhanced granulation in UASB reactor treating low-strength wastewater by natural polymers.

Reetha (Sapindus trifoliata) seed extract and Chitosan were used as additives in the sludge bed of a UASB reactor treating low strength wastewater to enhance granulation. Five parallel laboratory scale UASB reactors were operated for 250 days with synthetic wastewater feed containing COD in the range of 600-800 mg/L. The reactors were seeded with spent sludge from a full-scale 5MLD UASB treatment plant at Jajmau, Kanpur, India. The seed sludge contained little or no granules. Different additives in the five reactors were as follows: control with no additive, cationic part of Reetha extract as additive, anionic part of Reetha extract as additive, bulk Reetha extract as additive and Chitosan as additive. The granulation rapidly increased in all the reactors beyond the 90th day of operation. The mean granule sizes as well as the fraction of granular sludge (particle size > or = 100 microm) were more in the presence of some of the additives compared to the control reactor. Chitosan significantly enhanced granulation followed by the cationic and anionic fractions of the Reetha extract. The bulk Reetha extract did not show enhancement of granulation. The ESEM/EDAX results showed that the bigger granules (3-4 mm) had porous structure and appeared as conglomerates of smaller granules.     

The influence of settling time on the formation of aerobic granules.

Aerobic granular sludge, without the addition of carrier material, has only been reported in one suspended growth system, the Sequencing Batch Reactor (SBR) operated with short fill and settling periods. Recent studies have demonstrated that extracellular polysaccharides increased with the formation of aerobic granules, and that the shear force may stimulate production of these polysaccharides. In the study described herein, two SBRs were operated with the same shear force (air flow rate 275 L h(-1)) and two different settling times (2 and 10 min). Only the reactor with 2 min settling formed completely granular sludge, although granules were present in both reactors. Community analysis using 16S rRNA PCR products and DGGE showed that the communities diverged quickly after reactor start-up. For samples taken at steady-state, the granular population was more stable and less diverse than the flocculent reactor. EPS extraction of samples using cation exchange resin yielded similar values for aerobic granular sludge and previously reported anaerobic granules. While differences in the protein and TOC content between the flocculent and granular reactors increased appreciably as the sludge became more granular, the protein to polysaccharide ratio was relatively constant. The experiment confirmed previous theories that short settling times in SBRs select for granular sludge. The settling time results in granular sludge having a higher EPS protein content and a less diverse but more stable population.     

Strength characteristics of aerobic granular sludge

Aerobic granular sludge has a number of advantages over conventional activated sludge flocs, such as cohesive and strong matrix, fast settling characteristic, high biomass retention and ability to withstand high organic loadings, all aspects leading towards a compact reactor system. Still there are very few studies on the strength of aerobic granules. A procedure that has been used previously for anaerobic granular sludge strength analysis was adapted and used in this study. A new coefficient was introduced, called a stability coefficient (S), to quantify the strength of the aerobic granules. Indicators were also developed based on the strength analysis results, in order to categorize aerobic granules into three levels of strength, i.e. very strong (very stable), strong (stable) and not strong (not stable). The results indicated that aerobic granules grown on acetate were stronger (high density: >150 g T SSL(-1) and low S value: 5%) than granules developed on sewage as influent. A lower value of S indicates a higher stability of the granules.     

Granular biomass capable of partial nitritation and anammox

A novel and efficient way of removing nitrogen from wastewater poor in biodegradable organic carbon, is the combination of partial nitritation and anoxic ammonium oxidation (anammox), as in the one-stage oxygen-limited autotrophic nitrification/denitrification (OLAND) process. Since anoxic ammonium-oxidizing bacteria grow very slowly, maximum biomass retention in the reactor is required. In this study, a lab-scale sequencing batch reactor (SBR) was used to develop granular, rapidly settling biomass. With SBR cycles of one hour and a minimum biomass settling velocity of 0.7 m/h, OLAND granules were formed in 1.5 months and the nitrogen removal rate increased from 50 to 450 mg N L(-1) d(-1) in 2 months. The granules had a mean diameter of 1.8 mm and their aerobic and anoxic ammonium-oxidizing activities were well equilibrated to perform the OLAND reaction. Fluorescent in-situ hybridization (FISH) demonstrated the presence of both beta-proteobacterial aerobic ammonium oxidizers and planctomycetes (among which anoxic ammonium oxidizers) in the granules. The presented results show the applicability of rapidly settling granular biomass for one-stage partial nitritation and anammox.     

Effects of ORP, recycling rate, and HRT on simultaneous sulfate reduction and sulfur production in expanded granular sludge bed (EGSB) reactors under micro-aerobic conditions for treating molasses distillery wastewater

An expanded granular sludge bed (EGSB) reactor was adopted to incubate the sludge biogranule that could simultaneously achieve sulfate reduction and sulfide reoxidization to elemental sulfur for treating molasses distillery wastewater. The EGSB reactor was operated for 175 days at 35 °C with a pH value of 7.0, chemical oxygen demand (COD) loading rate of 4.8 kg COD/(m3 d), and sulfate loading rate of 0.384 kg SO(4)(2-)/(m3 d). The optimal operation parameters, including the oxidation reduction potential (ORP), recycling rate, and hydraulic retention time (HRT), were established to obtain stable and acceptable removal efficiencies of COD, sulfate, and higher elemental sulfur production. With an ORP of -440 mV, a recycling rate of 300%, and HRT of 15 h, the COD and sulfate removal efficiencies were 73.4 and 61.3%, respectively. The elemental sulfur production ratio reached 30.1% when the elemental sulfur concentration in the effluent was 48.1 mg/L. The performance results were also confirmed by the mass balance calculation of sulfate, sulfide, and elemental sulfur over the EGSB reactor.     

林可霉素高浓度有机废水处理技术

采用厌氧颗粒和好氧活性污泥分别对内循环厌氧反应器(IC)和间歇式活性污泥法(SBR)进行污泥接种培养,研究水解酸化-IC-SBR工艺在林可霉素生产废水处理方面的运行效果。结果表明:在进水COD的质量浓度为6 000~9 000 mg/L,IC和SBR反应器中有机负荷分别为0.82 kg/(kg.d)和0.26 kg/(kg.d)左右的情况下,IC和SBR反应器分别运行60 d和7 d,COD平均去除率分别达到91%和61%,出水COD的质量浓度在300 mg/L以下,达到GB 8978—1996《污水综合排放标准》二级标准。