好氧颗粒污泥脱氮除磷效率研究

以实验室模拟废水为进水,在SBR反应器中利用好氧颗粒污泥进行N、P的去除效率研究.研究表明:在运行周期约为4h,进水COD控制在500～1200 mg/L之间,室温条件下,好氧颗粒污泥对COD、氨氮、硝氮、TP的去除率稳定维持在97％、95％、92％、86％,说明好氧颗粒污泥特有的结构特性和生物特性有利于脱氮除磷.     

好氧颗粒污泥处理高浓度及难降解废水研究进展

好氧颗粒污泥以其在反应器中污泥沉降速度快、泥水分离简单、污泥浓度高,能够同时实现脱氮除磷等特点成为目前污(废)水处理领域的研究热点之一。对好氧颗粒污泥在高浓度有机废水及难降解废水(硝基苯废水、苯酚废水、氯酚废水、苯胺和氯苯胺废水、含盐废水、染料废水)处理中的研究现状进行综述,重点探讨了好氧颗粒污泥处理该类物质的影响因素、去除机制及其微生物特性等,指出其在难降解废水处理方面具有良好的应用前景。     

好氧颗粒污泥快速恢复活性的试验研究

利用正交实验法,采用啤酒废水,在SBR反应器中对在4℃的冰箱中储存7周的好氧颗粒污泥进行活性恢复,观察储存对颗粒污泥的影响及确定颗粒污泥的最佳恢复条件。经过储存的好氧颗粒污泥,其粒径、平均沉降速率无明显变化;上层变黑的好氧颗粒污泥能较快恢复至棕黄色。好氧颗粒污泥恢复活性的最佳操作条件为进水COD持续800 mg/L,水力停留时间8 h,曝气量0.15 m3/h,沉降时间10 min。     

聚集交联固定化脱色菌活性污泥处理印染废水

本文总结了在上向流厌氧污泥过滤反应器-好氧接触氧化反应器-生物滤池内投加固定化脱色菌处理针织印染废水的动态试验结果,试验结果表明:聚集交联固定化法能有效地将筛选出的优良菌种固定在活性污泥载体上,厌氧反应器内易形成颗粒污泥,好氧反应器内滤料易挂膜,全处理流程色度平均去除率为97.6%,COD平均去除率为92.9%.     

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.     

废水好氧生物处理工艺中F/M的影响

好氧颗粒污泥因其优异的沉降性能和较高的处理负荷等优势,成为近年水处理领域的研究热点。以不同结构的好氧污泥为分析对象,综述了F/M对污染物处理效率和污泥生长特性的影响,揭示了F/M在废水好氧生物处理工艺性能与污泥结构稳定中的重要作用。     

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.     

常温纵向折流套筒式厌氧污泥床反应器处理淀粉废水研究

本文采用常温纵向折流套筒式厌氧污泥床反应器在常温下处理淀粉废水，当ＨＲＴ＝１２ｈ，平均ＣＯＤ容积负荷为９０３ｋｇ／（ｍ３·ｄ）时，ＣＯＤ平均去除率可达８１４７％，并且在反应器中培养出了活性良好的颗粒污泥，反应器出水水质适于进一步好氧生物处理。     

生物颗粒活性炭处理苯酚废水

研究了生物颗粒活性炭(BGAC)处理合成苯酚废水的效果和机理。结果表明,BGAC能够高效处理苯酚废水,处理效果优于活性污泥法和颗粒活性炭(GAC)吸附。BGAC、活性污泥和GAC分别对75 mg/L的苯酚废水连续处理,平均去除率分别为98%、60%和90%。通过苯酚出水pH值和反应器中溶解氧的变化情况分析,BGAC对苯酚废水的处理主要借助于活性炭的吸附和微生物降解的交替作用。     

Performances of a granular sequencing batch reactor (GSBR).

Aerobic granulation in sequencing batch reactors is widely reported in literature and in particular in SBAR (Sequencing batch airlift reactor) configuration, due to the high localised hydrodynamic shear forces that occur in this type of configuration. The aim of this work was to observe the phenomenon of the aerobic granulation and to confirm the excellent removal efficiencies that can be achieved with this technology. In order to do that, a laboratory-scale plant, inoculated with activated sludge collected from a conventional WWTP, was operated for 64 days: 42 days as a SBAR and 22 days as a SBBC (sequencing batch bubble column). The performances of the pilot plant showed excellent organics removal. COD and BOD removal efficiencies were respectively, 93 and 94%; on the contrary, N-removal efficiency was extremely low (5%-45%/o). The granules dimensions increased during the whole experimentation; change of reactor configuration contributed to further improve this aspect. The experimental work confirmed the essential role of hydraulic settling time in the formation of aerobic granules and in the sludge settleability and the need to find an optimum between granule size and oxygen supply to achieve good N-removal efficiency.     

Formation and characteristics of nitritation granules cultivated in sequencing batch reactor by stepwise increase of N/C ratio

The cultivation of nitritation granules in sequencing batch reactor (SBR) by seeding conventional floccular activated sludge was investigated using ethanol-based synthetic wastewater. Reducing settling time offers selection pressure for aerobic granulation, and stepwise increase of influent N/C ratio can help to selectively enrich ammonia oxidizing bacteria (AOB) in aerobic granules. The spherical shaped granules were observed with the mean diameter of 1.25 mm, average settling velocity of 1.9 cm s(-1) and the sludge volume index (SVI) of 18.5-31.4 ml g(-1). After 25 days of operation, the nitrogen loading rate reached 0.0455 kg NH(4)(+)-N (kg MLSS·d)(-1), which was 4.55 times higher than that of the start-up period. The mature granules showed high nitrification ability. Ammonia removal efficiency was above 95% and nitrite accumulation ratio was in the range of 80-95%. The nitrifying bacteria were quantified by fluorescence in situ hybridization analysis, which indicated that AOB was 14.9 ± 0.5% of the total bacteria and nitrite oxidizing bacteria (NOB) was 0.89 ± 0.1% of the total bacteria. Therefore, AOB was the dominant nitrifying bacteria. It was concluded that the associated inhibition of free ammonia at the start of each cycle and free nitrous acid during the later phase of aeration may be the key factors to start up and maintain the stable nitritation.     

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.     

High-rate nitrification using aerobic granular sludge.

The performance of nitrifying granules, which had been produced in an aerobic upflow fluidised bed (AUFB) reactor, was investigated in various types of ammonia-containing wastewaters. When pure oxygen was supplied to the AUFB reactor with a synthetic wastewater containing a high concentration of ammonia (500 g-N/m3), the ammonia removal rate reached 16.7 kg-N/m3/day with a sustained ammonia removal efficiency of more than 80%. The nitrifying granules possessing a high settling ability could be retained with a high density (approximately 10,000 g-MLSS/m3) in a continuous stirring tank reactor (CSTR) even under a short hydraulic retention time (44 min), which enabled a high-rate and stable nitrification for an inorganic wastewater containing low concentrations of ammonia (50 g-N/m3). Moreover, the nitrifying granules exhibited sufficient performance in the nitrification of real industrial wastewater containing high concentrations of ammonia (1000-1400 g-N/m3) and salinity (1.2-2.2%), which was discharged from metal-refinery processes. When the nitrifying granules were used in cooperation with activated sludge to treat domestic wastewater containing organic pollutants as well as ammonia, they fully contributed to nitrification even though a part of activated sludge adhered onto the granule surfaces to form biofilms. These results show the wide applicability of nitrifying granules to various cases in the nitrification step of wastewater treatment plants.     

Aerobic granulation in a mechanical stirred SBR: treatment of low organic loads

Aerobic granular sludge was produced in a sequencing batch reactor (SBR) characterized by a height to diameter ratio of 2.5 and the use of mechanical stirring. Compact and regular aerobic granules of up to 1.75 mm of average diameter were formed in the reactor with an organic loading rate of 1.75 kg COD/(m3 d). Settling properties of the obtained aggregates were: sludge volumetric index of 30-40 mL/g VSS and settling velocity higher than 8 m/h. The effects of different carbon to nitrogen ratios (TOC/N) in the feeding on the organic matter oxidation and nitrification process were studied. The concentration of organic matter in the feeding was stepwise reduced (from 190.0 to 37.5 mg TOC/L) and ammonium increased (from 25 to 50 mg NH4+ -N/L). TOC/N ratios of 7.50, 3.00, 1.50 and 0.75 g/g in the feeding were tested. The TOC removal percentage was around 80-95% during the whole operational period and the N removal percentages obtained in the reactor were up to 40%, however, physical properties of the granules were not maintained.     

Selection of slow growing organisms as a means for improving aerobic granular sludge stability.

Recently, several groups have showed the occurrence of aerobic granular sludge. The excellent settling characteristics of aerobic granular sludge allow the design of very compact wastewater treatment plants. In laboratory experiments, high oxygen concentrations were needed to obtain stable granulation. However, in order to obtain energy efficient aeration and good denitrification low oxygen concentrations would be required. From earlier research on biofilm morphology, it was learned that slow growing organisms influence the density and stability of biofilms positively. To decrease the growth rate of the organisms in the aerobic granules, easily degradable substrate (e.g. acetate) has to be converted to slowly degradable COD like microbial storage polymers (e.g. PHA). Phosphate or glycogen accumulating bacteria perform this conversion step most efficiently. In this paper it is shown that the selection of such bacteria in aerobic granules indeed led to stable granular sludge, even at low oxygen concentrations.     

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.     

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.     

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.     

Upgrading of existing aerobic plants with the LUCAS anaerobic system based on full-scale experiences.

It has been demonstrated that the combination of anaerobic-aerobic treatment is the best technological and economical solution for the treatment of high loaded wastewater. Where in the past aerobic treatment systems were still very acceptable due to the very good treatment efficiency, simplicity and robustness of the technology, this has, in most cases, been changed due to very stringent sludge disposal legislation. The anaerobic pretreatment takes care of approximately 80-90% of the overall treatment efficiency at high loading rates and low sludge production and low energy costs. The aerobic posttreatment takes care of the absolute high removal efficiency and nitrogen and phosphorus removal. Because of the low organic loading rate of the aerobic posttreatment also in this stage the sludge production is low. The combination of anaerobic-aerobic treatment results in a compact system capable of reaching high treatment efficiency at low sludge production and lower energy consumption. Waterleau Global Water Technology has developed LUCAS anaerobic-aerobic system that combines an Upflow Anaerobic Sludge Blanket (UASB) reactor with an aerobic, constant-level cyclic activated sludge system, which is very suitable for the treatment of high loaded wastewaters in general and brewery waste water in particular. It has been proven from several full scale upgrading projects that the UASB system is best suitable for implementation in the aerobic plants that have to be extended in capacity.