微砂增效结团絮凝技术处理低浊高藻水的中试研究

针对西安市汤峪水库夏季水质特点和处理要求,提出并采用微砂增效结团絮凝工艺对该原水处理进行中试研究.微砂增效结团絮凝技术是将微砂增效与结团絮凝有机组合的新型水处理工艺.试验结果表明,利用微砂增效结团絮凝技术处理汤峪水库低浊高藻水是切实可行的,系统具有运行稳定性高、出水水质好等特点,且处理效率明显高于采用回流污泥的增效澄清技术.微砂增效结团絮凝工艺能够有效降低出水浊度和CODMn;当微砂投量0.5 g/L时的过程控制参数为PAC投量15mg/L,PAM投量0.4 mg/L,机械搅拌转速8 r/min,上升流速达35 m/h时,藻类去除率可达80％,CODMn去除率达40％,浊度可控制在1.5 NTU以下.     

二级串联生物造粒流化床对有机物的去除特性研究

为了考察延长水力停留时间对改善生物造粒流化床对有机物去除效果的影响,进行了二级串联生物造粒流化床的工艺试验,在每隔12 h进行串联顺序交替的运行条件下,两柱中的颗粒污泥均能保持108个/g数量级的生物量,且在作为二级柱运行的过程中,流化床仍能保持良好的颗粒污泥形态.两级串联的流化床中,COD_(Cr)的去除和DO的消耗具有延续性,且COD_(Cr)的去除符合相近的一级反应规律.研究结果表明,生物造粒流化床中的颗粒污泥具有良好的动态稳定性,采用二级串联的方法延长流化床的水力停留时间有望作为提高生物造粒流化床污水处理功效的方法.     

生物造粒流化床中造粒颗粒的形态及微生物特性研究

生物造粒流化床是造粒流化床高效固液分离技术在污水生物处理领域的扩展.利用显微摄像仪、扫描电子显微镜及微生物固定技术,对沿流化床不同高度处所采集的造粒颗粒污泥进行了形态学和微生物学分析.结果显示,造粒颗粒污泥球形度较好,自下而上存在粒径变小且球形度降低的趋势;流化床底部的颗粒污泥中杆菌占据优势,顶部的颗粒污泥中球菌占据优势,显示着微生物群落沿床高的一种转变;对于单个颗粒污泥,杆菌多聚于颗粒表面及外层,球菌多聚于颗粒内部及里层;认为在生物造粒流化床反应器中存在着好氧/缺氧/厌氧区域,可以起到降解有机物和脱氮的作用.     

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.     

Fluidised pellet bed bioreactor: a promising technology for onsite wastewater treatment and reuse.

A pilot-scale fluidised pellet bed (FPB) bioreactor, which combines chemical coagulation, biological degradation, particle pelletisation and separation in one unit, was applied for onsite wastewater treatment and reuse. As a result of rational use of inorganic coagulant and organic polymer and moderate mechanical agitation, spherical particles were generated in the upflow column and a well-fluidised bed was formed. With a continuous supply of dissolved oxygen through a recycling loop, an aerobic condition was kept in the bottom section of the FPB column. Under such conditions the pellets in the FPB column showed the following characteristics: (1) compact structure and high density; (2) rich in microorganisms; and (3) high MLSS and MLVSS concentrations. Therefore, the FPB bioreactor achieved more than 90% removal of SS, COD, BOD and TP from raw domestic wastewater within a total hydraulic retention time (HRT) of only about 30 minutes. It also showed nitrification and denitrification ability and the TN removal could be about 50% as the recycling ratio was increased to 1:1. The treated water quality is generally competitive with the secondary effluent from a conventional activated sludge process. With these advantages the FPB bioreactor is recommendable as a compact system for onsite wastewater treatment and reuse.     

Application of the flotation process to thicken the sludge from a DAF plant.

Dissolved air flotation (DAF) was evaluated for thickening of the sludges from a water treatment plant which uses DAF. Solid flux theory for gravity thickening was applied to the solid flux of DAF sludge. The higher the polymer dosage, at fixed solid concentration, the greater the rising velocity becomes. When applied with solid flux equations, a similar relationship to that of gravity thickening has been found. However, the values were much higher than in gravity thickening, because both the inflow solid concentration and the floating velocity were higher than for settled sludge. With this result, the proper dosage of polymer could be derived from the relationship between total solid flux and withdrawal velocity of DAF sludge.     

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.     

长江水源水厂排泥水处理研究

对长江水源水厂排泥水处理进行了研究,确定了长江水源水悬浮固体含量与浊度的关系,对水厂干泥量和排泥水总量进行了估算;通过动态浓缩试验,确定了斜板浓缩池运行优化条件;测定了排泥水的颗粒粒径分布、固体成分组成和污泥比阻;并简要介绍了污泥机械脱水和泥饼处置方法.     

Particle count and size alteration for membrane fouling reduction in non-conventional water filtration.

If coagulation is not completely successful and produces aggregates which are too small, fouling may increase. In some cases, a deep-bed filter could perhaps provide a solution. The paper examines these effects using experimental results for different waters. Activated sludge effluents, stormy seawater containing microalgae and spent filter backwash water (SFBW) were coagulated by alum or ferric chloride. Sand filtration tests were carried out. Tests were performed in a membrane filtration stirred cell, filtration pilot plant equipped with SDI analyzer (seawater) and pilot UF plant (SFBW). For activated sludge effluent, alum residual ratio curves of turbidity and total particle count (TPC) followed one another. With ferric chloride, low coagulant dosage showed negative turbidity removal. Contact granular filtration reduced membrane fouling intensity. Increasing the dose resulted in higher improvement in membrane flux. For seawater, a filter run period under storm conditions reached 35 hours with satisfactory filtrate quality. An iron chloride dose of 0.3 mg/l during normal conditions and 0.5 mg/l for stormy condition should be injected, mixed well before the filters, while maintaining 10 m/hr filtration rate and pH 6.8 value. For SFBW, alum flocculation pretreatment of SFBW was effective in reducing turbidity, TPC, viruses and protozoa. SFBW settling prior to flocculation did not enhance turbidity and TPC removal. The largest remaining particle fraction after alum flocculation was 3-10 microm in size, both Cryptosporidium and Giardia are found in this size range. Coagulation enhanced the removal of small size particles, a positive impact on reducing membrane fouling potential.     

循环流化床环核结构速度分布PIV测试

利用粒子图像测速仪（PIV）对循环流化床中颗粒流场进行了系统的实验研究。运用适合于高粒子浓度的最小方差法（MQD）图像处理算法得到了截面内典型环核流动颗粒速度矢量场。采用速度矢量场的方法可以确定出环核结构分界。定量上获得了不同时刻颗粒轴向上升和下落平均速度大小及沿床径向分布特性。在统计颗粒轴向上升速度和下落速度代数和基础上，获得了总体上颗粒轴向速度沿床径向在整个截面内形成抛物线型的环核分布规律。     

Effect of chlorination bulking control on water quality and phosphate release/uptake in an anaerobic-oxic activated sludge system.

This study evaluates the effect of chlorination bulking control on water quality and phosphate release/uptake in an anaerobic-oxic activated sludge system. A series of batch experiments with different specific NaOCl mass dose were conducted to determine the sludge settling properties, supernatant water quality and phosphate metabolism behavior of filamentous bulking sludge. The harvested sludge was from a continuous-flow anaerobic-oxic (A/O) activated sludge pilot-plant, i.e., enhanced biological phosphorus removal (EBPR) system, operated with 15 days of sludge retention time. The filamentous bacteria in the A/O pilot plant were identified to be Thiothrix according to Eikelboom's classification techniques, which was in accordance with the high influent sulfate concentration of this study (50 mg/L sulfate). Increasing NaOCI concentration, as revealed by experimental results, obviously decreased the sludge settling properties (SVI values and zone settling velocities) and meanwhile significantly reduced supernatant water quality (COD, SS, TP) mainly due to higher suspended solids caused by floc disruption. Moreover, the nine-hour batch experiments indicated that high NaOCI dosage (40 mg/gMLSS) completely deteriorated phosphate metabolism of EBPR sludge. Such a high dosage of chlorination further confirmed overdosing through disappearance of intracellular PHB and death of protozoa by microscopic investigation. Still, phosphate release/uptake behavior of EBPR sludge properly functions at low NaOCl dosage (5 mg/g MLSS). Besides, phosphate metabolism worsens rapidly before the SVI value reaches its lowest level. These findings imply that determining NaOCI requirement with merely SVI values can readily result in chlorination overdosing. Proper NaOCI dosage requires a delicately balanced consideration between sludge settling improvement, water quality demand and phosphate metabolism. Batch test of phosphate release/uptake is apparently a prerequisite to conclude an appropriate NaOCl dosage for bulking control.     

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.     

The role of SSVF and SSHF beds in concentrated wastewater treatment, design recommendation

The return flows of reject water from sewage sludge dewatering alter the activated sludge process in a conventional WWTP and increase TN concentration in the final effluent from WWTP. The objective of the investigation carried out was to consider the application of multistage treatment wetland (MTW) for the treatment of reject water from sewage sludge dewatering in a centrifuge (RWC). This paper aims to present the design and performance of each stage of the treatment as well as the efficiency of total MTW. The full scale pilot plant for RWC, consisting of two vertical flow beds (SS VF) working in series, followed by an horizontal flow bed (SS HF), was built in 2008. The applied configuration ensured a very high removal efficiency of principal pollutant (COD - 76.0% and NH4+-N - 93.6%). In the investigated facilities, the SS VF beds ensured an effective removal of nitrogen compounds, especially NH4+-N, whereas the decomposition of hardly degradable Org-N and COD took place in SS HF. This research illustrates that the MTW could be successfully applied for the treatment of RWC.     

Sludge settling processes in SBR-related sewage treatment plants according to the Biocos method.

This paper describes the investigations in a sedimentation and circulation reactor (SU-reactor) of a three-phase Biocos plant. The aim of these investigations was the determination of the temporal and depth-dependent distribution of suspended solid contents, as well as describing the sludge sedimentation curves. The calculated results reveal peculiarities of the Biocos method with regard to sedimentation processes. In the hydraulically uninterrupted (pre-)settling phase, a sludge level depth was observed, which remained constant over the reactor surface and increased linearly according to the sludge volume. The settling and the thickening processes of this phase corresponded to a large extent to the well-known settling test in a one-litre measuring cylinder. During the discharge phase, the investigated settling rate was overlaid by the surface loading rate and the sludge level changed depending on the difference between those two parameters. The solid distribution of the A-phase indicated a formation of functional zones, which were influenced by the surface loading. The formation was comparable to the formation of layers in secondary settling tanks with vertical flow. The concentration equalisation between the biological reactor and the SU-reactor proved to be problematic during the circulation phase, because a type of internal sludge circulation occurred in the SU-reactor. A permanent sludge recirculation seems to be highly recommendable.     

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。     

Improvement of the thickening and dewatering characteristics of activated sludge by electroflotation (EF).

The performances of electroflotation (EF) on the thickening of activated sludge were investigated using laboratory scale batch flotation reactors. Four activated sludges including bulking sludges were tested. After 30 minutes of EF operation, 57-84% of sludge volume reduction could be achieved by EF, while only about 1.5-14% could be obtained by gravity thickening for the same period. After thickening the effluent water quality in terms of TCOD, SS, and turbidity was improved by EF operation for all sludge samples. In addition, the EF thickened sludge showed much better dewaterability both in SRF and cake solid content. It is induced that the air bubbles entrapped in the thickened sludge play a key role in the observed dewaterbility improvement.     

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。     

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.     

带翼片侧向流斜板沉淀池内颗粒沉降过程的数值模拟

采用有限体积法研究了带翼片侧向流斜板沉淀池内水流流动的特性,并计算了带翼片与不带翼片斜板内水流的雷诺数,结果表明加入翼片可以明显降低水流的雷诺数,其数值为不带翼片斜板雷诺数的42%,并采用层流模型计算了两种情况斜板内水流的三维流场分布情况.在此基础上考察了加入稀疏颗粒后,颗粒物的运动轨迹,采用DPM模型进行计算,结果表明,加入翼片后颗粒物沉降的路径缩短,有利于固液分离;随着水流速度的增大,颗粒跟随性增强,颗粒物密度(采用1100kg/m3和1 400 kg/m3进行分析)增大,颗粒沉降性也增强.同时大颗粒粒径也有利于沉淀.     

Treatment of 14 sludge types from wastewater treatment plants using bench and pilot thermal hydrolysis

A total of 14 types of sludge from household sewage, mixture of domestic and industrial wastewater, and industrial and oil wastewater treatment plants were selected to evaluate the effectiveness and adaptability of thermal hydrolysis pre-treatment. Organic solubilization, dewatering improvement, volume reduction, high-strength filtrate biodegradation, and dewatered sludge incineration were investigated using bench and pilot thermal hydrolysis experiments (170 °C/60 min). Results showed that sludge types significantly affected the treatment effects. Organic content has a primary influence on thermal effects. The relationship between suspended solid (SS) solubilization and raw sludge organic content was linear with an R(2) of 0.73. The relationship between raw sludge organic content and treated sludge dewatering was linear with an R(2) of 0.86 and 0.65 for pilot and bench pre-treatments, respectively. Household and oil sludge possessed incineration possibilities with high heat value. Industrial and oil sludge filtrate was unsuitable for digestion to recover bioenergy.