低负荷下厌氧氨氧化处理养殖废水的启动研究

厌氧氨氧化作为新型生物脱氮技术其关键在于如何实现厌氧氨氧化反应的启动,现有研究多以模拟废水为研究对象,本文以猪场废水为对象的研究,利用ASBR为反应器,接种反硝化污泥培养厌氧氨氧化细菌,在NH+4-N与NO-2-N浓度均为100 mg/L的条件下,运行125 d,经历启动初期、过渡期、系统稳定运行期三个阶段,厌氧氨氧化反应器中NH+4-N的去除率达91.70%,NO-2-N去除率92.0%;NH+4-N的容积负荷为36.90 mg/L.d,NO-2-N的容积负荷为37.55 mg/(L.d),成功实现了厌氧氨氧化反应器的启动。该研究成果对厌氧氨氧化技术在工程实践的应用具有重要的指导意义。     

厌氧氨氧化处理养殖废水启动实验研究

立足于国内外处理高氨低碳废水相关工艺的最新研究成果,以厌氧氨氧化工艺实现养殖废水的处理.在厌氧SBR反应器中,以厌氧反硝化泥作为接种污泥进行厌氧氨氧化研究[1,2],在低负荷条件下,采用厌氧氨氧化工艺处理实际猪场废水,近2个月的时间启动厌氧氨氧化反应器,氨氮去除率有稳定提高趋势.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.     

低氧膜生物反应器(MBR)高效脱氮机理研究

由于MBR反应器内污泥浓度高,污泥、絮体存在从内到外的溶解氧梯度,相应形成好氧、缺氧和厌氧区,可实现反硝化和厌氧氨氧化脱氮;充分利用MBR工艺特点,阐述进行低氧下反硝化和厌氧氨氧化脱氮脱氮研究。     

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.     

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。     

常温亚硝化—厌氧氨氧化工艺对淀粉废水生物脱氮的研究

采用常温亚硝化—厌氧氨氧化工艺对淀粉废水生物处理出水进行生物脱氮处理,在SBR亚硝化反应器和气提式亚硝化反应器中均实现了稳定的半亚硝化反应。亚硝化—厌氧氨氧化工艺正常运行时,全流程总氮去除率基本维持在80%左右,最高达85.5%。一级亚硝化反应进水容积负荷为0.20kg/(m3·d),平均HRT为1.11d。厌氧氨氧化平均总氮进水容积负荷为1.11kg/(m3·d),最高达1.61kg/(m3·d);平均总氮去除负荷为0.83kg/(m3·d),最高去除负荷达1.29kg/(m3·d);平均HRT为0.20d。淀粉工业废水生物处理后出水中的有机物对亚硝化和厌氧氨氧化反应均未产生显著影响,所含过多的悬浮物和胶体物对亚硝化—厌氧氨氧化反应器存在潜在影响。     

影响反硝化除磷与厌氧氨氧化耦合的因素

氧对厌氧氨氧化菌有毒,但在颗粒污泥和生物膜中的厌氧氨氧化菌对氧有较高的耐受能力,并且聚磷菌能消耗影响氧氨氧化菌生长的氧。厌氧氨氧化菌的生长无需有机物的参与,聚磷菌释磷需要吸收有机物,少量有机物的加入对厌氧氨氧化菌的活性影响不大。亚硝酸盐是厌氧氨氧化菌氧化氨的电子受体,较高浓度的亚硝酸盐对反硝化聚磷有抑制作用,但合适浓度的亚硝酸盐(该浓度可以通过驯化来提高)可以作为反硝化聚磷菌吸磷的电子受体。厌氧氨氧化过程中有硝酸盐生成,反硝化聚磷菌能利用这部分硝酸盐。另外,两类菌都适宜于中温略偏碱性的环境。因此,通过创造同时对厌氧氨氧化菌和反硝化聚磷菌有利的微生态环境,发挥两者在脱氮除磷方面的协同耦合作用,达到高度脱氮除磷,是极有前景的废水厌氧(缺氧)处理研究方向。     

复合厌氧反应器的生产性快速启动研究

针对复合厌氧反应器处理高浓度难降解有机废水如何创造生产性快速启动条件及反应器的有效控制进行了相关研究。试验分别采用好氧青霉素发酵残渣和好氧活性污泥为接种污泥启动复合厌氧反应器 ,生产性中试规模 5 0m3 /d。试验表明 ,青霉素发酵残渣启动厌氧反应器在经济上和技术上都是可行的 ,启动周期短 ,试验系统表现出很好的生物降解性和抗冲击负荷能力     

Nitrogen removal from sludge digester liquids by nitrification/denitrification or partial nitritation/anammox: environmental and economical considerations.

In wastewater treatment plants with anaerobic sludge digestion, 15-20% of the nitrogen load is recirculated to the main stream with the return liquors from dewatering. Separate treatment of this ammonium-rich digester supernatant significantly reduces the nitrogen load of the activated sludge system. Two biological applications are considered for nitrogen elimination: (i) classical autotrophic nitrification/heterotrophic denitrification and (ii) partial nitritation/autotrophic anaerobic ammonium oxidation (anammox). With both applications 85-90% nitrogen removal can be achieved, but there are considerable differences in terms of sustainability and costs. The final gaseous products for heterotrophic denitrification are generally not measured and are assumed to be nitrogen gas (N2). However, significant nitrous oxide (N2O) production can occur at elevated nitrite concentrations in the reactor. Denitrification via nitrite instead of nitrate has been promoted in recent years in order to reduce the oxygen and the organic carbon requirements. Obviously this "achievement" turns out to be rather disadvantageous from an overall environmental point of view. On the other hand no unfavorable intermediates are emitted during anaerobic ammonium oxidation. A cost estimate for both applications demonstrates that partial nitritation/anammox is also more economical than classical nitrification/denitrification. Therefore autotrophic nitrogen elimination should be used in future to treat ammonium-rich sludge liquors.     

Factors affecting the activity of anammox bacteria during start up in the continuous culture reactor.

Factors affecting cultivation of extremely slow-growing bacteria (anaerobic ammonium oxidiser, doubling time 11 days) were investigated by using upflow anaerobic sludge blanket (UASB) reactors which can maintain high solid retention time. The effects of concentrations of DO, free ammonia (FA), and nitrite on activation of anammox activity were tested during the start-up period. The reactor was inoculated with granular sludge collected from a full-scale UASB reactor used for treating brewery wastewater, and sludge from a piggery wastewater treatment plant and rotating biological contactor treating sewage. Results of continuous operation showed that concentrations of DO, free ammonia (FA) and nitrite in the reactors played a key role in stimulating the anammox activity during start-up period. It is crucial to keep DO below 0.2 ppm, FA below 2 mg/L and nitrite nitrogen below 35 mg/L to cultivate anammox cells in the continuous bioreactor. When the levels of DO, FA and nitrite in the influent were controlled at less than the inhibition levels, the anammox activity increased gradually in the anaerobic condition. Addition of hydrogen sulphide into the reactor enhanced anammox activity in the continuous culture. Through the SEM, TEM and FISH analysis, anammox bacteria were detected in the granular sludge after 3 months of continuous operation.     

Anammox process for synthetic and practical wastewater treatment using a novel kind of biomass carriers

The anammox process, as an alternative to conventional nitrogen removal technologies, has abstracted much attention in recent years. In this study, one column-type reactor using a novel support material--net type acrylic fiber (Biofix)--was used for anammox treatment. The Biofix reactor was operated at 25 degrees C (peak summer temperature, 31.5 degrees C). Over 330 days of operation for synthetic wastewater treatment, the nitrogen loading rates of the reactor were increased to 3.6 kg-N/m3/d and T-N removal efficiencies reached to 81.3%. For the practical anaerobic sludge digester liquor treatment, the average TN removal efficiency of 72% was obtained. A protein substance was shown to be the most abundant extracellular polymeric substances (EPS) in the granular sludge with almost two times more in the attached sludge of the Biofix reactor. Considering the EPS levels and observation by scanning electron microscopy, the anammox granules in the Biofix reactor were showing dense state. Results of DNA analyses indicated that the KSU-1 strain might prefer relatively low nutrient levels, while the KU2 strain might be better suited for the high media concentration. Other kinds of bacteria were also identified with the potentials for consuming the dissolved oxygen in the influent and facilitating anammox bacteria surviving under aerobic conditions.     

Energy and phosphorus recovery from black water

Source-separated black water (BW) (toilet water) containing 38% of the organic material and 68% of the phosphorus in the total household waste (water) stream including kitchen waste, is a potential source for energy and phosphorus recovery. The energy recovered, in the form of electricity and heat, is more than sufficient for anaerobic treatment, nitrogen removal and phosphorus recovery. The phosphorus balance of an upflow anaerobic sludge blanket reactor treating concentrated BW showed a phosphorus conservation of 61% in the anaerobic effluent. Precipitation of phosphate as struvite from this stream resulted in a recovery of 0.22 kgP/p/y, representing 10% of the artificial phosphorus fertiliser production in the world. The remaining part of the phosphorus ended up in the anaerobic sludge, mainly due to precipitation (39%). Low dilution and a high pH favour the accumulation of phosphorus in the anaerobic sludge and this sludge could be used as a phosphorus-enriched organic fertiliser, provided that it is safe regarding heavy metals, pathogens and micro-pollutants.     

Comparison of different conditions, substrates and operation modes by dynamic simulation of a full-scale anaerobic SBR plant

Simulation studies for a full-scale anaerobic unit of a wastewater treatment plant (WWTP) were performed using the anaerobic digestion model no. 1 (ADM1). The anaerobic full-scale plant consists of one mesophilic and one thermophilic digester, operated in an anaerobic sequential batch reactor (ASBR) mode, and sludge enrichment reactors (SER) for each digester. The digesters are fed with a mixture of vegetable waste and process wastewater from the food factory. Characteristics such as COD(total), N(total) and NH(4)-N concentrations in the influent and effluent of the digester and SERs were measured and used for input fractionation. Parameters such as level, pH, biogas amount and composition in the digester were measured online and used for calibration. For simulation studies, different temperatures and operation modes with varying chemical oxygen demand (COD) input loads corresponding to feedstocks such as fruits, vegetables and grain were analysed and compared. Higher gas production and digestion efficiency in the thermophilic reactor and in shorter cycles were found and confirmed at full scale. Serial operation mode increased the gas production, but pH inhibition occurred earlier. Feeding only biosolids into digester I and the effluent of digester I together with process water into digester II further improved gas production in serial operation mode.     

Performance comparison of a continuous-flow stirred-tank reactor and an anaerobic sequencing batch reactor for fermentative hydrogen production depending on substrate concentration.

This study was conducted to compare the performance of a continuous-flow stirred-tank reactor (CSTR) and an anaerobic sequencing batch reactor (ASBR) for fermentative hydrogen production at various substrate concentrations. Heat-treated anaerobic sludge was utilized as an inoculum, and hydraulic retention time (HRT) for each reactor was maintained at 12 h. At the influent sucrose concentration of 5 g COD/L, start-up was not successful in both reactors. The CSTR, which was started-up at 10 g COD/L, showed stable hydrogen production at the influent sucrose concentrations of 10-60 g COD/L during 203 days. Hydrogen production was dependent on substrate concentration, resulting in the highest performance at 30 g COD/L. At the lower substrate concentration, the hydrogen yield (based on hexose consumed) decreased with biomass reduction and changes in fermentation products. At the higher substrate concentration, substrate inhibition on biomass growth caused the decrease of carbohydrate degradation and hydrogen yield (based on hexose added). The ASBR showed higher biomass concentration and carbohydrate degradation efficiency than the CSTR, but hydrogen production in the ASBR was less effective than that in the CSTR at all the substrate concentrations.     

Biodegradation of 2-chlorophenol (2CP) in an anaerobic sequencing batch reactor (ASBR)

The aim of this study is to contribute to the knowledge about anaerobic digestion of 2-chlorophenol (2CP) in an anaerobic sequencing batch reactor (ASBR). Two reactors were set up (ASBR(A) and ASBR(B)). The ASBR(A) was fed with 2-chlorophenol (28-196 mg 2CP-C/L) and no other exogenous electron donor. The ASBR(B) was fed with a mixture of 2CP (28-196 mg 2CP-C/L) and phenol (28-196 mg phenol-C/L) as an electron donor. The process evaluation was conducted by three means: first by substrate consumption efficiency (E(2CP)), second, by biogas yield (Y(biogas-C/2CP-C)) and third, by the specific consumption rates (q(2CP)) as response variables. The 2CP consumption efficiency (90 ± 0.4%) was not influenced by the increase in the concentrations tested. In both reactors ASBR(A) and ASBR(B), both concentration as well as speed increased. Concentration increased from 28 to 114 mg 2CP-C/L. The specific consumption rate (q(2CP)) values were fivefold higher. However, a decrease of 37% was observed at 140 mg 2CP-C/L and one of 72% at 196 mg 2CP-C/L. The biogas yields (0.80 ± 0.06) remained stable in both reactors. In both reactors the biogas yield decreased to 78 ± 3% at 196 mg 2CP-C/L. We might assume this decrease was due to the accumulation of VFA. Finally, poor sludge settleability was determined only in the SBR(B) reactor at 140 and 196 mg 2CP-C/L. An increase was observed in both SVI ≤ 140 ± 5 mL/g and over exopolymeric protein ≤120 mg EP/L.     

Development of single-stage nitrogen removal using anammox and partial nitritation (SNAP) and its treatment performances.

Single-stage Nitrogen removal using Anammox and Partial nitritation (SNAP) process was newly developed as an economical nitrogen removal process for ammonium rich wastewaters. The experimental studies for the evaluation of SNAP process were carried out using a novel biofilm reactor, in which hydrophilic net-type acryl fiber biomass carrier was applied. This SNAP reactor was operated under operational conditions of pH 7.5-7.7, 35 degrees C and DO 2-3 mg/L, and 60 to 80% of influent NH4-N was removed under loading rate of 0.48 kg-N/m3/d. Through the DNA analysis of the attached sludge, it was made clear that ammonium oxidizing bacteria (AOB) and anammox bacteria coexisted in the attach-immobilized sludge on the acryl fiber biomass carrier. Favorable conditions for the growth of anammox bacteria were created inside attach-immobilized nitrifying sludge. Two kinds of anammox bacteria and two kinds of AOB were detected in the SNAP sludge. Existence ratios of anammox and AOB were estimated to be 15% and 8.7%, respectively, based on the obtained clone numbers. This coexisting condition was confirmed by the FISH image of SNAP sludge and its confocal laser scanning microscope.     

ASBR法处理苯酚废水的动力学研究

在ASBR反应器中,以苯酚为标的物进行难降解有机物的降解,并研究反应器的降解动力学。经过前期的污泥驯化和正交试验,本试验在ASBR最有效降解污染物的工况下运行。试验结果表明:苯酚初始浓度小于146.8mg/L的情况下,反应速率随苯酚浓度的增大而增大,苯酚的降解过程符合零级动力学反应特征;苯酚初始浓度在200.5～377.9 mg/L之间时,反应速率随苯酚浓度的增大而减小,苯酚的降解过程符合一级动力学反应特征。低浓度和高浓度苯酚在ASBR中降解分别符合零级和一级动力学反应特征,且中温降解速率明显高于常温。本文试验数据与动力学方程拟合较好,能够为实际工艺中的苯酚污水处理提供参考。