SBR工艺短程硝化快速启动条件的优化

以低COD/TN的实际生活污水为研究对象,采用SBR反应器,对短程硝化的启动条件进行了优化.结果表明,温度30℃、溶解氧(DO) 2.0mg/L、污泥龄为7d时,系统在实时控制条件下运行32周期,可以成功启动短程硝化.在总氮(TN)去除率>95%的情况下,亚硝酸盐积累率(NO2--N /NOx--N)>90%,随后的64d,温度恢复到常温(20~24℃),系统仍稳定运行.荧光原位杂交技术(FISH)检测表明,经过32个周期种群优化,污泥中氨氧化菌(AOB)的含量提高了38.9%,亚硝酸盐氧化菌(NOB)的含量降低了53.2%.在线动态控制DO浓度和曝气时间可以逐渐淘汰系统中的NOB,从而获得稳定的短程硝化,提高系统脱氮效率.     

实际垃圾渗滤液短程生物脱氮的常温实现及低温维持

采用单级UASB-SBR生化系统处理实际垃圾渗滤液,主要考察了常、低温条件下,该生化系统短程生物脱氮的长期稳定性,同时研究了SBR内短程硝化的实现机理及微生物种群特性.598d试验结果表明:单级UASB-SBR生化系统对渗滤液内COD,NH4+-N和TN的去除率分别为92.0%,99.2%和98.0%以上,实现渗滤液内有机物和氮的深度去除.经过116d运行,SBR系统实现了短程硝化,亚硝积累率(NAR)达到90%以上,此后稳定运行,成功跨越2个冬季,15℃以下共计171d,最低温度为10.2℃.游离氨(FA)和过程控制的协同作用是实现与维持SBR 内短程硝化的决定因素.荧光原位杂交(FISH)技术检测表明:氨氧化菌(AOB)已经成为SBR硝化菌群中的优势菌属.扫描电子显微镜(SEM)检测表明:AOB菌属以活椭球状亚硝化球菌属(Nitrosococcus)和杆状亚硝化单胞菌属(Nitrosomonas)为主.     

SBR法常、低温下生活污水短程硝化的实现及特性

采用序批式反应器(SBR)处理实际生活污水,通过实时控制好氧曝气时间,在常温下快速实现短程硝化,并在低温下长期维持稳定的短程硝化.结果表明,随着温度逐渐降低,比氨氧化速率略微减缓,27℃的平均比氨氧化速率是13℃时的1.68倍,但亚硝化积累率始终维持在90%以上,该温度区间内氨氧化反应的温度系数为1.051.通过荧光原位杂交(FISH)技术对低温下维持稳定短程硝化的污泥进行种群分析发现,实时控制策略为氨氧化菌(AOB)成为优势硝化菌群创造了有利条件,AOB的相对百分含量达到8%~9%,而亚硝酸盐氧化菌(NOB)逐渐被淘洗出反应器.在低温下要实现短程硝化,可首先在常温下利用好氧曝气时间实时控制实现亚硝态氮的积累和AOB的优势生长,然后通过逐渐降温使AOB适应在低温下生长.     

交替好氧/缺氧短程硝化反硝化生物脱氮Ⅰ.方法实现与控制

采用实时控制策略和曝气 搅拌交替运行方式在 ( 2 6± 1 )℃下开发了一种新型短程硝化反硝化生物脱氮工艺 :实时控制交替好氧 缺氧短程硝化反硝化脱氮工艺 .并对其与实时控制传统SBR法短程硝化反硝化脱氮和预先设定时间控制交替好氧 缺氧短程硝化反硝化脱氮工艺进行了比较研究 .结果显示 ,实时控制交替好氧 缺氧短程硝化反硝化脱氮工艺无论从硝化速率、反硝化速率还是从硝化时间、反硝化时间上均优于实时控制传统SBR法短程硝化反硝化脱氮和预先设定时间控制交替好氧 缺氧短程硝化反硝化脱氮两种工艺 .其硝化速率和反硝化速率分别是预先设定时间控制交替好氧 缺氧短程硝化反硝化工艺的 1 3 8倍和 1 2 5倍 ,是实时控制传统SBR法短程硝化反硝化脱氮工艺的 1 82倍和 1 6 1倍 .因此 ,实时控制交替好氧 缺氧短程硝化反硝化脱氮工艺不但能够合理分配曝气和搅拌时间 ,而且还能提高硝化、反硝化速率 ,缩短反应时间 ,从而达到降低运行成本的目的     

A/O生物脱氮工艺处理生活污水中试(一)短程硝化反硝化的研究

应用A/O生物脱氮中试试验装置处理实际生活污水,从pH、污泥浓度(MLSS)、自由氨(FA)、温度、污泥龄(SRT)、溶解氧(DO)和水力停留时间(HRT)等方面系统的分析了A/O工艺实现短程硝化反硝化的主要影响因素.结果表明,DO浓度是A/O工艺实现短程硝化反硝化的主要因素,由FISH检测发现长期控制低DO浓度(0.3～0.7 mg·L-1)可以导致亚硝酸盐氧化菌(NOB)的淘洗,从而实现稳定的亚硝酸盐积累率,试验获得平均亚硝酸氮积累率为85%,有时甚至超过95%.提高DO浓度,1周内亚硝酸氮积累率从85%降到10%,继续维持低DO浓度,大约需要2个污泥龄时间才可重新恢复到较高的亚硝酸氮积累率(＞75%).低DO浓度下,试验初期污泥沉淀性能随着亚硝酸氮积累率的增加而变差,而在试验后期,无论亚硝酸氮积累率多高,污泥沉淀性能一直很好,SVI值处于80～120 mL·g-1     

生物强化MBR-AF工艺短程硝化反硝化研究

本试验将短程硝化功能菌和反硝化功能菌分别接种至膜生物反应器(MBR)和上流式厌氧生物滤池(AF)中,构建了生物强化的MBR-AF短程硝化反硝化工艺,并以活性污泥作空白对照,考察该工艺对高氨氮废水的短程脱氮性能.结果表明,强化体系MBR的启动期短,仅需30d,而活性污泥体系MBR的启动期长达100d;强化体系MBR亚硝酸氮积累率始终维持在95%以上;在30℃下,随着运行时间的延长,强化体系MBR-AF工艺总氮去除率不断升高,最高达90%以上,比活性污泥体系高20%;强化体系MBR膜污染程度轻,膜的使用寿命长.说明功能菌强化在高效亚硝酸氮积累和氨氮转化方面起关键作用,可作为实现短程硝化反硝化的有效手段.     

短程硝化生物脱氮工艺的稳定性

采用序批式活性污泥法 (SBR)处理实际豆制品废水 ,系统研究了温度和曝气时间对短程硝化反硝化生物脱氮工艺稳定性的影响 .结果表明 ,反应器内温度只有超过 28℃时 ,利用温度实现的短程硝化反硝化生物脱氮工艺才能稳定地运行 ;另外 ,首次发现过度曝气对短程硝化影响较大 ,在过度曝气条件下运行12d ,硝化类型就由NO₂^--N累积率为 96 %的短程硝化转变为NO₂^--N累积率为39.3%的全程硝化 .因此 ,为使短程硝化反硝化生物脱氮工艺稳定、持久地运行必须实现该工艺的实时控制 .     

SBR反应器内短程硝化系统快速启动及影响因素研究

探讨了采用序批式反应器(SBR)快速启动自养短程硝化系统的方法,研究了溶解氧(DO)、pH、温度、外加有机碳源对自养短程消化系统的影响。以硝化污泥接种反应器(SBR),在纯自养条件下利用高浓度溶解氧1.0～1.6mg/L和中温(35±1)℃达到亚硝酸氮的快速积累。结果表明,在进水氨氮浓度为280～300mg/L,HRT为12h,控制pH值为7.5～8.5、温度在(28±1)℃、溶解氧浓度为0.8～1.2mg/L条件下,氨氮去除率达到90%以上,亚硝酸氮积累率高达95%。试验证明投加有机碳源(COD)50mg/L左右时,不会对短程硝化系统产生影响,且能实现较高氨氮去除率和稳定的亚硝酸氮积累率。     

生活污水短程硝化脱氮工艺的快速启动及稳定性研究

以低碳氮比的生活污水为研究对象,采用SBR反应器,通过减少好氧阶段的搅拌时间快速启动短程硝化脱氮过程,对典型运行周期内氮去除规律进行研究,并从微生物角度进一步验证了短程硝化脱氮工艺的实现。结果表明:减少50%好氧搅拌时间后,亚硝酸盐积累率(NAR)由36.05%增加到54.06%,好氧阶段停止搅拌后,NAR被提高到90.17%,并且以此状态持续稳定运行;典型运行周期内SBR具有良好的NH₄+-N去除效果和较高的NAR,实测NH₄+-N去除率达89.46%,出水NAR达89.13%;实时荧光定量PCR技术(q-PCR)检测表明,经过140 d的种群优化,污泥中氨氧化菌(AOB)和亚硝酸盐氧化菌(NOB)含量分别占总菌数的70.3%和2.1%,从分子生物学角度验证了短程硝化工艺的实现。     

低温条件下好氧颗粒污泥培养及其脱氮性能研究

为研究在低温条件下好氧颗粒污泥（AGS）的形成及其脱氮性能,在序批式反应器（SBR）中15℃条件下60d内培养出了成熟的具有良好短程硝化功能的AGS,稳定运行阶段亚硝酸盐氮积累率（NAR）可以达到90%以上,扫描电镜显示AGS主要由短杆菌和球菌构成.通过批次实验研究了温度在15℃时,粒径为R1（1.0~2.0mm）、R²（2.0~3.0mm）和R3（>3.0mm）的短程硝化AGS的脱氮特性.其中R1亚硝酸盐氮积累效果最差,R²、R3相差不大,其NAR均可达到90%左右,效果较好.AGS粒径的增大会对基质的传质产生影响,这为氨化细菌（AOB）、硝化细菌（NOB）和反硝化细菌的生长提供了适宜的场所,有利于短程硝化的实现.通过微电极测定,在温度为15℃、水中溶解氧（DO）浓度为6~7mg/L时,AGS中氧气的传质深度为600~700μm.     

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.