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.     

研究生论文摘要

沼气自动提升内循环厌氧反应器处理淀粉废水的生产性试验研究研究生 :吕卫利　导师 :陈吕军(清华大学环境科学与工程系　 10 0 0 84 )对内循环厌氧反应器处理玉米淀粉废水进行了生产性试验研究 ,探讨了利用厌氧絮状污泥和厌氧颗粒污泥作为接种污泥 ,内循环厌氧反应器的启动方法、运行特性及运行效果。试验结果表明 :①利用厌氧絮状污泥和厌氧颗粒污泥作为接种污泥 ,均可成功地启动内循环厌氧反应器 ;②本次生产性试验的反应器有效容积为 110m3 ,反应器直径 3m ,反应器高 16m ,处理能力为 18m3 /h ,反应器水力停留时间为6 1h。当进水COD负…     

厌氧颗粒污泥悬浮床反应器的研究与应用

提出厌氧复合循环颗粒污泥悬浮床反应器的新型反应器理论.通过引入分级三相分离器,使悬浮床反应器上部处理区液体和沼气的上升速度大大降低,创造了污泥颗粒沉降的良好环境.底部利用高负荷产生的沼气形成内循环,同时设置外回流系统,内、外循环实现了进水与颗粒污泥间的充分接触及保持了良好的反应条件,创造了大幅度提高CODCr容积负荷的条件.对反应器的启动、运行和在不同负荷条件下的去除效果和悬浮流态进行了研究.研究表明,厌氧颗粒污泥悬浮床反应器处理淀粉废水,可在负荷30～40 kg CODCr/(m3·d)条件下稳定运行,最高负荷达57.2kgCODCr/(m3·d),平均CODCr去除率可达90%.     

厌氧氨氧化工艺及其污泥颗粒化的试验研究

厌氧氨氧化工艺是目前最经济简捷的一种新型生物脱氮工艺.本文以两种普通污泥分别接种两个UASB反应器,实现了厌氧氨氧化工艺的启动和稳定运行,培养获得了厌氧氨氧化颗粒污泥,并研究了各种因素对工艺运行的影响规律,结果表明:(1)以厌氧颗粒污泥与好氧活性污泥的混合物以及河底沉积物分别接种启动运行两个小试UASB反应器,以含氨氮和亚硝酸盐氮的无机配水为进水,分别经过115 d和210 d的运行,两个反应器均成功实现了厌氧氨氧化过程,氨氮去除率分别达50%和70%,氨氮去除负荷达0.35和0.29 kgNH3-N/(m3·d),相应的亚硝酸盐氮去除率分别为55%和67%;(2)在两个反应器随后146 d和306 d的稳定运行期间,工艺性能逐步上升,氨氮去除率分别达86%和95%,氨氮去除负荷达0.71和1.20 kgNH3-N/(m3·d),相应的亚硝酸盐氮去除率分别为83%和92%,所产气体中氮气含量高于96%;厌氧氨氧化工艺对进水负荷的突然变化有一定抵抗能力,但温度和溶解氧对工艺性能影响较大;(3)在两个反应器中均获得了厌氧氨氧化颗粒污泥,粒径约为0.6～1 mm,VSS/SS为0.6～0.8,颜色多呈棕黄色,也有少量小粒径颗粒呈红色,在扫描电镜下观察,发现颗粒中的优势菌为不规则球菌,与文献报道的厌氧氨氧化细菌类似;(4)在对颗粒污泥内部微观结构观察和研究的基础上,提出了三种厌氧氨氧化颗粒污泥的形成机理:蜕变附着生物膜机理、无机晶核附着生物膜机理和自凝聚机理;(5)对厌氧氨氧化工艺的主要影响因素进行了系统的研究,发现其最适温度在30～35℃之间,最适pH约为8.2,溶解氧对工艺的抑制作用很强,其浓度应控制在0.01 mg/L以下,由河底污泥培养获得的厌氧氨氧化污泥在上述最适条件下,最高氨氧化速率可达0.184 mgNH3-N/(mgVSS·d);(6)进水中一定浓度的有机物会对厌氧氨氧化工艺产生较大影响,有机物的引入会导致反硝化反应,产生基质竞争性抑制,进水中有机物的长期存在会导致污泥中异养细菌的生长,对厌氧氨氧化工艺产生不利影响.     

好氧颗粒污泥反应器快速启动及除碳脱氮试验

为快速启动好氧颗粒污泥反应器,在SBR反应器中同时接种硝化污泥和厌氧颗粒污泥,控制反应条件,温度23~25℃,pH值7.5~8.5,DO质量浓度1.5 mg/L左右,15 d即完成反应器快速启动。形成的好氧颗粒污泥粒径1.5~2.5 mm,SVI值54 mL/g。颗粒污泥结构紧密,沉降性能良好。反应器连续运行40多天,改变进水COD及NH4+-N浓度,COD和NH4+-N去除率均能稳定在80%以上,反应器内发生了同步硝化反硝化过程。     

生产规模UASB反应器处理柠檬酸废水启动试验研究

本文论述了容积为786.4m~3的生产性UASB反应器中温条件下处理柠檬酸废水的启动过程.当反应器稳定运行时,容积负荷为7.5～10kgCOD/(m~3·d),水力停留时间为38～49h,COD平均去除率达85%,出水COD≤2500mg/L.采用农村沼气池厌氧污泥和好氧活性污泥作为种泥(接种量均为6kgVSS/m~3)均可培养出颗粒污泥,并可实现快速启动.     

厌氧颗粒污泥培养过程中的特性研究

根据试验进程,每当COD去除率稳定在60%以上时,就以20%的比率提高进水流量,当COD去除率稳定后再以25%的比率提高进水COD浓度,循环操作直至培养出颗粒污泥。试验中还要通过监测pH值、SS、温度来判断和校正反应器的运行情况。试验末期COD去除率为78.6%,容积负荷为33.4 kg/(m3.d)时厌氧颗粒污泥培养结束。     

IC反应器中颗粒污泥特性研究

采用自行研制的IC反应器在低温下(15～25℃)处理马铃薯淀粉生产废水,反应器运行稳定后进行了厌氧颗粒污泥特性研究,包括启动前后颗粒污泥特性差异、颗粒污泥保存条件以及颗粒污泥运输条件。结果表明:不同温度条件下培养出的颗粒污泥有不同的特性;低温、较短的保存时间有利于保持颗粒污泥活性;兼顾方便运输和节约成本,20.5%的脱水率为颗粒污泥最佳脱水率。     

膨胀颗粒污泥床(EGSB)反应器高效处理链霉素有机废水试验研究

介绍了厌氧中温发酵 (35± 1℃ )条件下 ,采用膨胀颗粒污泥床 (EGSB)反应器日处理 2 16m3链霉素有机废水的生产性试验研究。试验结果表明 :在控制低浓度进料 ,COD在 2 0 0 0～ 70 0 0mg/L、COD/SO4 2 - =7～ 10的条件下 ,有效地降低了毒性物质的抑制作用 ,使反应器成功启动并培养出颗粒污泥 ;当进料COD在 70 0 0～ 130 0mg/L ,HRT为 3～ 5h ,pH为 6 8～ 7 2时 ,COD去除率可达 75 % ,反应器容积负荷最高可达 15 8kgCOD/ (m3·d) ,而SO4 2 - 去除率可有效地控制在 6 0 %～70 % ;实现了EGSB反应器对链霉素废水中有机物和硫酸盐的有效去除。     

改良ABR预处理生活污水的启动研究

采用改良的折流式厌氧反应器预处理生活污水,在存在自然接种厌氧污泥的前提下,考察了反应器的启动情况,并研究了HRT对CODCr和SS去除效果的影响.结果表明:反应器在2周后完成启动,CODCr去除率达到80%以上,且运行稳定;HRT对污染物去除影响较大,当HRT为4.8 h时,CODCr和SS的去除率均达到75%以上,实现了较好的预处理效果.     

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.     

Influence of effluent-recirculation condition on the process performance of expanded granular sludge bed reactor for treating low strength wastewater.

A 2.0 L volume of EGSB reactor was operated at 20 degrees C for more than 500 days with 0.3-0.4 g COD/L of sucrose base wastewater to investigate the influence of effluent-recirculation on the process performance. At the start up period, the reactor was operated in EGSB mode with 5 m/h upflow velocity by continuous effluent recirculation. The COD loading was set to 7.2-9.6 kg COD/m(3) day with HRT of 1 hour. However, in this mode, EGSB reactor exhibited insufficient COD removal efficiency, i.e., 50-60%. Therefore, UASB mode (without recirculation, 0.7 m/h upflow velocity) was used for 30 minutes in every 40 minutes cycle to increase the COD concentration in the sludge bed. As a result, an excellent process performance was shown. The COD removal efficiency increased from 65% to 91% and the reactor could maintain a good physical property of retained sludge (sludge concentration: 33.4 g VSS/L and SVI: 25 mL/g VSS). Furthermore, retained sludge possessed sufficient level of methanogenic activity at 20 degrees C.     

Microbial sulphate reduction during anaerobic digestion: EGSB process performance and potential for nitrite suppression of SRB activity.

The present study investigated mesophilic anaerobic treatment of sulphate-containing wastewater in EGSB reactors and assessed the inclusion of nitrite in the reactor influent as a method for control of biological sulphate reduction. Two EGSB reactors, R1 and R2, were operated for a period of 581 days at varying volumetric loading rates, COD/SO4(2-) ratios and influent nitrite concentrations (R2 only). COD removal efficiencies of > 93% were achieved in both reactors at influent sulphate concentrations of up to 3,000 mg l(-1). A two-fold increase in the influent sulphate concentration, giving an influent COD/SO4(2-) ratio of 2, resulted in a reduction in reactor COD removal efficiency to 84% and 89%, in R1 and R2, respectively. Despite inclusion of nitrite in the R2 influent at concentrations up to 500 mg NO2-N l(-1), sulphate reduction proceeded similarly in R2 and R1, suggesting the ineffectiveness of nitrite as a potential inhibitor of SRB     

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.     

Treatment of textile dyes in two-phase and single-phase anaerobic bio-treatment systems.

This research integrates two different concepts of anaerobic biotechnology- two-phase anaerobic treatment and anaerobic granular sludge bed technology, in treatment of colored wastewaters from textile industries. Four anaerobic reactors based on upflow anaerobic sludge blanket (UASB) technology were used as acid reactors and an expanded granular sludge bed (EGSB) reactor was used as a methane reactor. A conventional single-phase anaerobic reactor, working on EGSB technology was run in parallel to compare the performances of the two systems. Reactors were operated at different hydraulic retention times. The results from the study, which span over a period of 400 days, indicated that the two-phase system produces a higher quality of effluent in terms of color, COD and suspended solids than single-phase anaerobic treatment when operated under similar conditions. Alkalinity requirement of two-phase system was also observed to be lower than that of single-phase system which is important regarding design consideration.     

Changes of microbial characteristics of retained sludge during low-temperature operation of an EGSB reactor for low-strength wastewater treatment.

In this study, a lab scale EGSB reactor was operated for 400 days to investigate the influence of temperature-decrease on the microbial characteristic of retained sludge. The EGSB reactor was started-up at 15 degrees C seeding with 20 degrees C-grown granular sludge. The influent COD of synthetic wastewater was set at 0.6-0.8 gCOD/L. The process-temperature was stepwise reduced from 15 degrees C to 5 degrees C during 400 days operation. Decrease of temperature of the reactor from 15 degrees C to 10 degrees C caused the decline of COD removal efficiency. However, continuous operation of the EGSB reactor led the efficient treatment of wastewater (70% of COD removal, 50% of methane recovery) at 10 degrees C. We confirmed that the both acetate-fed and hydrogen-fed methanogenic activities of retained sludge clearly increased under 15 to 20 degrees C. Changes of microbial profiles of methanogenic bacteria were analyzed by 16S rDNA-targeted DGGE analysis and cloning. It shows that genus Methanospirillum as hydrogen-utilizing methanogen proliferated due to low temperature operation of the reactor. On the other hand, genus Methanosaeta presented in abundance as acetoclastic-methanogen throughout the experiment.     

Comparison of some characteristics of aerobic granules and sludge flocs from sequencing batch reactors.

Physical, chemical and biological characteristics were investigated for aerobic granules and sludge flocs from three laboratory-scale sequencing batch reactors (SBRs). One reactor was operated as normal SBR (N-SBR) and two reactors were operated as granular SBRs (G-SBR1 and G-SBR2). G-SBR1 was inoculated with activated sludge and G-SBR2 with granules from the municipal wastewater plant in Garching (Germany). The following major parameters and functions were measured and compared between the three reactors: morphology, settling velocity, specific gravity (SG), sludge volume index (SVI), specific oxygen uptake rate (SOUR), distribution of the volume fraction of extracellular polymeric substances (EPS) and bacteria, organic carbon and nitrogen removal. Compared with sludge flocs, granular sludge had excellent settling properties, good solid-liquid separation, high biomass concentration, simultaneous nitrification and denitrification. Aerobic granular sludge does not have a higher microbial activity and there are some problems including higher effluent suspended solids, lower ratio of VSS/SS and no nitrification at the beginning of cultivation. Measurement with CLSM and additional image analysis showed that EPS glycoconjugates build one main fraction inside the granules. The aerobic granules from G-SBR1 prove to be heavier, smaller and have a higher microbial activity compared with G-SBR2. Furthermore, the granules were more compact, with lower SVI and less filamentous bacteria.     

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.     

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.     

Anaerobic thermophilic digestion of sewage sludge with a thickened sludge recycle

The process of anaerobic thermophilic digestion of municipal wastewater sludge with a recycled part of thickened digested sludge, was studied in semi-continuous laboratory digesters. This modified recycling process resulted in increased solids retention time (SRT) with the same hydraulic retention time (HRT) as compared with traditional digestion without recycling. Increased SRT without increasing of HRT resulted in the enhancement of volatile substance reduction by up to 68% in the reactor with the recycling process compared with 34% in a control conventional reactor. Biogas production was intensified from 0.3 L/g of influent volatile solids (VS) in the control reactor up to 0.35 L/g VS. In addition, the recycling process improved the dewatering properties of digested sludge.