Integration of ozonation and an anaerobic expanded granular sludge bed reactor for micropollutant removal from sewage

Environmental Science and Pollution Research - Conventional sewage treatment systems are generally not designed to remove micropollutants, requiring the development of new technologies, such as the...     

Improvement of upflow anaerobic sludge bed performance using chitosan.

Chitosan, with a degree of deacetylation of 85% and a molecular weight of 2.5 x 10(5) Da, yielding high flocculation efficiency (85 to 100% flocculation) and a broad flocculation region (2 to 45 mg/g suspended solids), was selected for accelerating granulation in a 30-L upflow anaerobic sludge bed (UASB) used to treat wastewater from a tropical fruit-processing industry. Compared with other studies, smaller amounts of chitosan were applied (two injections with 2 mg chitosan/g suspended solids in the reactor at each injection). Comparison with the UASB without chitosan addition, the UASB had a 24 to 37% larger particle size and a 6 to 41% longer solids retention time. In addition, the reactor performances were also enhanced. The UASB with chitosan addition had a 9 to 59% lower effluent chemical oxygen demand (COD), 4 to 10% higher COD removal, up to 35% higher biogas production rate, and a 16 to 68% lower biomass washout. The paired t-test analysis indicated that these performance parameters were significantly different (P < 0.05).     

USB反应器进行生物反硝化的研究现状与应用前景

综述了USB反应器进行生物反硝化的历史沿革、研究现状 ,并对其在研究中存在的问题进行了描述。最后 ,对USB反应器进行生物反硝化的应用前景作了科学的分析     

Simultaneous nitrification and denitrification of municipal wastewater in aerobic membrane bioreactors.

Simultaneous nitrification-denitrification (SND) of municipal wastewater was investigated in a laboratory-scale membrane bioreactor (MBR) operated at two different hydraulic retention times (HRTs), 0.5 and 1 day, dissolved oxygen 3.0 to 0.5 mg/L, and solids retention time (SRT) between 28 and 120 days. The organic loading rate (OLR) (0.11 to 0.64 kg chemical oxygen demand [COD]/m3/d) and influent soluble COD (SCOD)/ total Kjeldahl nitrogen (TKN) ratio (5 to 19) were varied by the addition of glucose. The ammonia-nitrogen and TKN removals were over 97%, and total nitrogen removal was approximately 89% in the MBR. The maximum specific nitrification rates (98 mg N/d/g VSS) and specific denitrification rates (81 mg N/d/g VSS) occurred at an SCOD/TKN ratio of 9.1. The optimum conditions for maximum total nitrogen removal by SND in a single reactor MBR have been found to be low dissolved oxygen (< 0.6 mg/L) and high OLR (approximately 0.64 kg COD/m3/d) at an HRT of 0.5 day and SRT of approximately 85 days.     

Characteristics of granular sludge developed in an upflow anaerobic sludge fixed-film bioreactor treating palm oil mill effluent.

In the present study, characteristics of the granular sludge (including physical characteristics under stable conditions and process shocks arising from suspended solid overload, soluble organic overload, and high temperature; biological activity; and sludge kinetic evaluation in a batch experiment) developed in an upflow anaerobic sludge blanket fixed-film reactor for palm oil mill effluent (POME) treatment was investigated. The main aim of this work was to provide suitable understanding of POME anaerobic digestion using such a granular sludge reactor, particularly with respect to granule structure at various operating conditions. The morphological changes in granular sludge resulting from various operational conditions was studied using scanning electron microscopy and transmission electron microscopy images. It was shown that the developed granules consisted of densely packed rod- (Methanosaeta-like microorganism; predominant) and cocci- (Methanosarsina) shaped microorganisms. Methanosaeta aggregates functioned as nucleation centers that initiated granule development of POME-degrading granules. Under the suspended solid overload condition, most of the granules were covered with a thin layer of fiberlike suspended solids, so that the granule color changed to brown and the sludge volume index also increased to 24.5 from 12 to 15 mL/g, which caused a large amount of sludge washout. Some of the granules were disintegrated because of an acidified environment, which originated from acidogenesis of high influent organic load (29 g chemical oxygen demand [COD]/L d). At 60 degrees C, the rate of biomass washout increased, as a result of disintegration of the outer layer of the granules. In the biological activity test, approximately 95% COD removal was achieved within 72 hours, with an initial COD removal rate of 3.5 g COD/L d. During POME digestion, 275 mg calcium carbonate/L bicarbonate alkalinity was produced per 1000 mg COD(removed)/ L. A consecutive reaction kinetic model was used to simulate the data obtained from the sludge activity in the batch experiment. The mathematical model gave a good fit with the experimental results (R2 > 0.93). The slowest step was modeled to be the acidification step, with a rate constant between 0.015 and 0.083 hours(-1), while the rate constant for the methanogenic step was obtained to be between 0.218 and 0.361 hours(-1).     

Influence of a three-phase separator configuration on the performance of an upflow anaerobic sludge bed reactor treating wastewater from a fruit-canning factory.

The objective of this study was to investigate the influence of a three-phase separator configuration on the performance of an upflow anaerobic sludge bed (USAB) treating wastewater from a fruit canning factory. The performances of two 30-L UASB reactors--one with a modified three-phase separator giving a spiral flow pattern and the other with a conventional configuration-were investigated in parallel. Wastewater, with a chemical oxygen demand (COD) concentration between 2000 and 7000 mg/L, was obtained from a fruit-canning factory. Based on the effluent data of the first 100 operation days, the UASB with the three-phase separator giving spiral flow patterns yielded up to 25% lower biomass washout. It also showed better efficiencies in treating wastewater--up to 60% lower effluent COD, up to 20% higher COD percent removal, and up to 29% higher biogas production. This work presents evidence of an improvement on the conventional physical design of a UASB.     

好氧反硝化菌TAD1的同步硝化反硝化性能

研究发现嗜热螯台球菌(Chelatococcus daeguensis)TAD1具有同步硝化反硝化性能,可将水中的氨氮去除。重点考察50℃下,碳氮比、碳源、初始pH值、DO浓度等因素对菌株TAD1同步硝化反硝化脱氮性能的影响规律及菌株TAD1的耐氨能力,最后用Minitab软件进行综合优化。结果表明,菌株TAD1在高浓度氨氮(500～3 000 mg/L)下仍具有很高的脱氮能力,pH值和碳源用量是影响TAD1同步硝化反硝化最显著的因素,综合优化后总氮最大去除率达到了70%,证实利用菌株TAD1的同步硝化反硝化性能具有潜在的废水脱氮应用前景。     

Anaerobic bioconversion of carbon dioxide to biogas in an upflow anaerobic sludge blanket reactor

The increasing concentration of carbon dioxide (CO2)--the most dominant component of greenhouse gases--in the atmosphere has been of growing concern for many years. Many methods focus on CO2 capture and storage and there is always the risk of CO2 release to the environment. In this study, a new method to convert CO2 to biogas with a high content of methane (CH4) in an anaerobic system with a lab-scale upflow anaerobic sludge blanket reactor at 35 degrees C was developed. In a series of experiments, the reactor was run with and without CO2-saturated solutions including volatile fatty acids (VFAs) as sources of hydrogen. The concentration of dissolved CO2 in the influent solutions was 2.2-6.1 g/L, with corresponding chemical oxygen demand (COD) values of 2.6-8.4 g/L for the solutions. Overall CO2 removal values of 2.7-20 g/day (49-88% conversion) were obtained for the organic loading rates (OLR) and CO2 loading rates of 8-36 gCOD/L day and 6-26 gCO2/L x day, respectively with CH4 purity of above 70%. Also, VFA and COD removal were in the range of 79-95% and 75-90%, respectively. Methanogenic activities of the cultures with the concentrations measured as volatile suspended solids (VSSs) were 0.12-0.40 L CH4/gVSS x d with the highest value for the system containing acetic acid. This anaerobic method can be applied to reduce CO2 emitted to the atmosphere from a wide variety of industrial point sources with a value-added product, CH4.     

Anaerobic mesophilic treatment of cattle manure in an upflow anaerobic sludge blanket reactor with prior pasteurization

Different autonomous communities located in northern Spain have large populations of dairy cattle. In the case of Asturias, the greatest concentration of dairy farms is found in the areas near the coast, where the elimination of cattle manure by means of its use as a fertilizer may lead to environmental problems. The aim of the present research work was to study the anaerobic treatment of the liquid fraction of cattle manure at mesophilic temperature using an upflow anaerobic sludge blanket (UASB) reactor combined with a settler after a pasteurization process at 70 degrees C for 2 hr. The manure used in this study came from two different farms, with 40 and 200 cows, respectively. The manure from the smaller farm was pretreated in the laboratory by filtration through a 1-mm mesh, and the manure from the other farm was pretreated on the farm by filtration through a separator screw press (0.5-mm mesh). The pasteurization process removed the pathogenic microorganisms lacking spores, such as Enterococcus, Yersinia, Pseudomonas, and coliforms, but bacterial spores are only reduced by this treatment, not removed. The combination of a UASB reactor and a settler proved to be effective for the treatment of cattle manure. In spite of the variation in the organic loading rate and total solids in the influent during the experiment, the chemical oxygen demand (COD) of the effluent from the settler remained relatively constant, obtaining reductions in the COD of approximately 85%.     

上流式缺氧污泥床和好氧生物膜组合脱氮工艺的研究

将上流式颗粒污泥床(USB)用于反硝化和生物膜法用于自养硝化处理蔗糖配水和小区生活污水,反硝化污泥床去除有机物和硝态氮具有节省需好氧去除有机物的能耗的优势,同时好氧生物膜法硝化效率高。试验结果表明,当工艺进水的有机负荷小于2kgCOD/m3·d时,出水COD均小于60mg/L,好氧单元进水有机负荷和氨氮负荷分别小于13kgCOD/m3·d和09kgNH3N/m3·d时,出水氨氮小于5mg/L;COD/NO-3N是影响反硝化的关键因素,处理蔗糖配水时,COD/NO-3N大于5时反硝化脱氮完全,而COD/NO-3N为10时,生活污水作为电子供体仍然脱氮不完全;有机物含量过高导致好氧单元硝化效果降低,HRT是影响好氧单元硝化效率的主要因素,HRT缩短为15h时,氨氮去除率降低了85%左右;同时处理蔗糖配水和生活污水的反硝化菌活性相当。     

上流式多级厌氧反应器中厌氧颗粒污泥特性研究

高品质厌氧颗粒污泥是厌氧反应器实现高效、稳定运行的关键和基础.在实现上流式多级厌氧反应器(UMAR)处理木薯变性淀粉废水高效运行的基础上,对厌氧颗粒污泥的浓度分布、粒径分布、沉降速度、产甲垸活性,辅酶F420和生物相等作进一步的研究.根据在实验工艺条件下培养得到的厌氧颗粒污泥的性能,探讨厌氧颗粒污泥的可能形成机制.     

Influence of nutrients on biomass evolution in an upflow anaerobic sludge blanket reactor degrading sulfate-laden organics.

This paper describes the effect of the nutrients iron (Fe), nickel (Ni), zinc (Zn), cobalt (Co), and molybdenum (Mo) on biomass evolution in an upflow anaerobic sludge blanket (UASB) reactor metabolizing synthetic sulfate-laden organics at varying operating conditions during a period of 540 days. A bench-scale model of a UASB reactor was operated at a temperature of 35 degrees C for a chemical oxygen demand-to-sulfate (COD/SO4(2-)) ratio of 8.59 to 2.0, a sulfate loading rate of 0.54 to 1.88 kg SO4(2-)/m3 x d, and an organic loading rate of 1.9 to 5.75 kg COD/m3 x d. Biomass was characterized in terms of total methanogenic activity, acetate-utilizing methanogenic activity, total sulfidogenic activity, acetate-utilizing sulfidogenic activity, and scanning electron microscopy (SEM). Nickel and cobalt limitation appears to affect the activity of hydrogen-utilizing methane-producing bacteria (HMPB) significantly without having an appreciable effect on the activity of acetate-utilizing methane-producing bacteria (AMPB). Nickel and cobalt supplementation resulted in increased availability and, consequently, restoration of biomass activity and process performance. Iron limitation and sulfidogenic conditions resulted in the growth of low-density, hollow, fragile granules that washed out, causing process instability and performance deterioration. Iron and cobalt supplementation indicated significant stimulation of AMPB with slight inhibition of HMPB. Examination of biomass through SEM indicated a population shift with dominance of sarcina-type organisms and the formation of hollow granules. Granule disintegration was observed toward the end of the study.     

Microbial community dynamics in a chemolithotrophic denitrification reactor inoculated with methanogenic granular sludge

Denitrification is applied in the tertiary treatment of wastewater to reduce nitrogen pollution. Fluorescence in situ hybridization (FISH), catalyzed reporter deposition (CARD)-FISH, cloning, and scanning electron microscopy (SEM) were applied to follow the evolution of the microbial composition and structure of granular sludge in chemolithotrophic denitrifying bioreactors fed with nitrate and thiosulfate. FISH oligonucleotide probes for the chemolitoautotrophic denitrifiers Thiobacillus denitrificans and Thiomicrospira denitrificans were designed and their utility tested. CARD-FISH and cloning data showed that bacterial diversity in the biofilms changed during the reactor operation. Chemoorganotrophic fermentative Gram-positive strains in the phyla, Actinobacteria and Firmicutes, were dominant in the methanogenic inoculum, both in terms of biodiversity and in number. Other significant phyla were Bacteroidetes and Chloroflexi. After 6 months of operation, Proteobacteria became dominant (83% of the clones). The diversity of Gram-positive bacteria was partially maintained although their abundance decreased notably. After 110 d of operation, the abundance of Tb. denitrificans cells increased considerably, from 1% to 35% of total DAPI-stained cells and from no isolated clones to 15% of the total clones. Tm. denitrificans only represented a minor fraction of the microorganisms in the sludge (1-4% of the DAPI-stained cells). These findings confirm that Tb. denitrificans was the dominant chemolitoautotrophic denitrifying microorganism in the bioreactors. The Archaeal diversity remained almost unchanged and it was represented mostly by Methanosaeta soehngenii. SEM results indicated a considerable loss in the integrity of the sludge granules during the operation, with risk of sludge buoyancy.     

好氧颗粒污泥的性质及其在脱氮除磷中的应用

阐述了好氧颗粒污泥的污泥特性、培养条件和影响因素 ,比较了三种SBR反应器中颗粒污泥特性的差异 ,介绍了好氧颗粒污泥的形成机理及其在脱氮除磷过程中的应用情况     

UASB反应器中厌氧氨氧化菌的影响因素研究

在UASB反应器中接种实验室已经驯化好的厌氧氨氧化颗粒污泥,对其进行厌氧氨氧化菌活性提高和影响因素的实验研究。研究表明厌氧氨氧化菌对NH4＋-N和N02--N的适宜浓度负荷均为200mg／L,适宜水力停留时间HRT、温度、pH和进水基质比（N02--N／NH4＋-N）分别为2h、30～35℃、7．5～8．5和0．95～1．2,NH4＋-N、NO2--N和TN的平均去除率分别为97．1％、98．3％和92．7％。     

一株贫营养异养硝化-好氧反硝化细菌的分离鉴定及脱氮特性

从水源水库沉积物中筛选出一株具有较高脱氮效率的异养硝化-好氧反硝化菌SF9.扫描电镜观察其形态特征为(0.2~0.4)μm×(0.4~0.8)μm椭球状,16S rDNA序列分析表明菌株与Delftia lacustris DSM 21246(T)相似性为100%,并分析其系统发育分类地位,对该菌进行贫营养反硝化特性研究.结果表明,该菌在分别以硝氮、亚硝氮及氨氮为唯一氮源时去除率分别达81%、64%和40%.同步硝化反硝化研究表明,该菌在氨氮存在的情况下会优先利用氨氮,在以氨氮与硝氮为氮源时和以氨氮与亚硝氮为氮源时氨氮的去除率分别达81%和74%.将菌株接种到微污染源水(总氮2.34 mg/L、C/N为1.2)水体中,总氮72 h去除率达到35%,TOC消耗30%.结果表明,菌株SF9与其他已报道的好氧反硝化菌相比,能耐受更低的C/N比,可作为微污染水源水微生物修复的高效菌剂.     

(AO)_2SBR同步脱氮除磷的研究

以人工配水为研究对象,采用厌氧/好氧/缺氧/好氧交替运行的序批式反应器,研究了(AO)2SBR系统同步脱氮除磷的效果,并结合批式实验讨论了同步脱氮除磷的反应机理。研究结果表明,该系统以厌氧1.5 h、好氧1 h、缺氧3h、好氧0.5 h的方式运行,在DO=2.5 mg/L,SRT=15 d的条件下,具有良好的脱氮除磷效果,配水中的总氮、总磷、COD和总有机碳的去除率分别为96.26%、99.87%、90.46%和85.57%。批式实验表明,合成的内碳源越多,氨氮的硝化越充分,反硝化除磷越多。     

低COD浓度废水启动EGSB反应器

以厌氧活性污泥和好氧活性污泥接种于2个膨胀颗粒污泥床(EGSB)反应器中,进水流量为10 mL/min,回流量为180 mL/min,进水COD浓度在180 mg/L左右,有机负荷率(OLR)为1.728 kg COD/m3·d左右,污泥负荷率(SLR)为0.19 kg COD/kg MLSS·d左右,出水COD浓度维持在40mg/L左右,COD去除率达80%以上.控制温度在32～35 ℃,pH在6.8～7.2,反应器内氧化还原电位在-340 mV以下,水力停留时间(HRT)4.2 h,上升流速4.86 m/h以及加入80 mg/L絮凝剂(硫酸铝钾),缩短了启动时间,促进了颗粒污泥的形成.分别经过60 d和120 d运行,反应器启动成功.结果表明,上升流速、絮凝剂和污泥类型对颗粒污泥的形成有影响;接种好氧活性污泥在低浓度COD下,合理控制负荷速率能成功启动EGSB反应器.     

异养硝化-好氧反硝化粪产碱杆菌处理高氨氮污泥厌氧消化液

具有异养硝化-好氧反硝化特性的粪产碱杆菌(Alcaligenes faecalis No.4)直接处理污泥厌氧消化液中的高浓度氨氮时,在60 h内氨氮(原始浓度441 mg/L)去除率约为18%。沼液中碳源验证实验表明,乙酸可作为其优质碳源。因而,可以通过外加乙酸钠的方式来解决污泥厌氧消化液碳源不足的问题。当污泥消化液中添加足够的碳源-乙酸钠使得C/N为10时,Alcaligenes faecalis No.4的脱氮效果良好,氨氮的去除率达到了98%以上。研究结果表明,在利用粪产碱杆菌处理高浓度氨氮沼液时,酸化污泥作为外加碳源的方式具有其理论可行性。     

外循环厌氧反应器接种好氧污泥的启动研究

内蒙古自治区某啤酒厂的外循环厌氧反应器完成了首次启动后由于操作问题,导致系统运行崩溃.第2次接种后续生物接触氧化池的好氧污泥进行重新启动,经过20 d的驯化,好氧污泥转变为活性较高的厌氧污泥;采用低负荷高去除率的方式运行40 d后,塔内形成了部分颗粒污泥;之后,为了提高颗粒污泥量快速提高进水流量,COD去除率先突然下降然后缓慢升高.当进水流量达到最大时启动结束,此时塔内颗粒污泥量和COD去除率仍在缓慢上升.