大丰水厂斜管沉淀池排泥系统的几点改造措施

穿孔排泥管是斜管沉淀池常采用的一种排泥形式，以其构造简单，投资省，排出泥浆含水率低。特别是中小型水厂斜管沉淀池尺寸、构造不便采用其它形式排泥设备时，穿孔排泥管往往得以首选。但在运行中也发现存在以下不足：1．穿孔排泥管孔眼易堵塞，造成斜管沉淀池积泥严重，大量矾花从斜管内涌出；2．孔眼清疏困难，必须停产。且排空整池水时间长，浪费大量沉淀水，3．本厂采用的排泥阀为普通闸阀，排泥操作劳动强度大，给运行管理带来不便。针对上述问题，着重分析了斜管沉淀池排泥系统存在的问题，并提出了几点改造措施。     

水旋澄清池悬浮层的自动监控与排泥

水旋澄清池排泥不及时、不畅会影响澄清池的正常运行,针对该问题,通过对水旋澄清池悬浮层的研究,采用引出式自动监控系统来控制排泥,可避免污泥翻床对监控系统的影响,实现监控、排泥一体化,避免出水受进水浊度的影响。现场实验表明该控制系统排泥效果良好,自动化程度高,可改善水旋澄清池出水水质。     

斜管沉淀池排泥系统改造

本文介绍了桑植县自来水公司八斗溪水厂斜管沉淀池排泥系统改造,即将V形槽穿孔管排泥系统改造成漏斗式集中排泥系统,排泥管由钢管改用阻力系数较小的PVC-U管。改造后不仅改善了排泥效果,延长了排泥周期,增加了供水能力,而且提高了出厂水质,降低了操作强度。     

论高浊度水的排泥与排砂

针对主同浊度水影响水处理构筑物正常运行的问题，作者对排泥系统作了较详尽的论述。结果生产实践，设计了排砂斗及排泥斗合理的斗面倾角和斗内对角凹沟与水平面的夹角，排泥效果明显提高。最后，为保证良好的排泥效果，提出了值得注意的几个具体问题。     

自来水厂穿孔排泥管的复核计算和改造

为了改善中心城水厂的反应、沉淀池穿孔排泥管的排泥效果，对原排泥管进行了复核计算，并重新布孔，改造后提高了排泥效率，减少了自用水量。     

穿孔排泥管排泥均匀性模拟计算及工艺参数分析

分析了排泥管排泥均匀性的影响因素及排泥管的水力特性,建立了排泥管内的水头损失计算模型.结果表明,穿孔排泥管的排泥均匀性可通过减小排泥孔眼孔径,增大排泥管管径及选择粗糙度较小的管道来提高;排泥管长度对排泥均匀性影响很大,当排泥管管径为200 mm,排泥孔眼孔径为30 mm时,长度为9,12和16 m排泥管的排泥均匀系数分别为0.70,0.65和0.58,排泥管长度不宜大于12 m,但可通过增大排泥管管径来增加排泥管的长度;穿孔排泥管的流态为非均匀流,为提高排泥均匀性,穿孔管管径、孔眼间距及其分布须通过水力计算来确定.     

排泥机同步运行自动化控制系统设计

为解决排泥机运行不同步的问题，设计了一种全新模式的排泥机全自动化控制电路，该电路中的核心器件为MMC电动机管理控制器，可保证排泥机的同步运行。     

新河水厂斜管沉淀池排泥系统改造

针对斜管沉淀池排泥效果不佳、沉泥上浮等问题,对天津塘沽新河水厂斜管沉淀池排泥系统进行了改造,结合测试结果分析了改造后排泥系统存在的问题以及排泥不畅的原因,并提出了具体的建议和解决方法,为同类改造提供了参考.     

无线电遥控双速虹吸式排泥机的设计及其特点

介绍了无经电摇控双速虹吸式排泥机的设计及其特点，这种新式排泥机吸取了老式排泥机的长处，克服了其缺点，在运行，自动控制，外观和水耗，电耗方便更先进。     

机械加速澄清池的改造

针对机械加速澄清池回流缝堵塞、净化效果不佳等问题,通过采取改造排泥系统、增加搅拌桨的长度和外缘直径、加大回流缝等措施,有效改善了出水浊度和沉降比,提高了出水水质。新的排泥方式开辟了一条安全、可靠、节能的新途径,为同类改造提供了参考。     

Steady-state model-based evaluation of sulfate reduction, autotrophic denitrification and nitrification integrated (SANI) process

Recently we developed a process for wastewater treatment in places where part of the fresh water usage is replaced by seawater usage. The treatment of this saline sewage consists of sulfate reduction, autotrophic denitrification and nitrification integrated (SANI) process. The process consists of an up-flow anaerobic sludge bed (UASB) for sulfate reduction, an anoxic filter for autotrophic denitrification using dissolved sulfide produced in the UASB and an aerobic filter for nitrification. The system was operated for 500 days with 97% COD removal and 74% total nitrogen removal without withdrawal of sludge. To verify these results and to understand this novel process, a steady-state model was developed from the COD, nitrogen and sulfur mass and charge balances based on the stoichiometries of the sulfate reduction, the autotrophic denitrification and the autotrophic nitrification. The model predictions agreed well with measured data on COD, nitrate and sulfate removal, sulfide production, effluent TSS, and mass balances of COD, sulfur and nitrogen in the three reactors. The model explains why withdrawal of sludge from the SANI system is not needed through comparisons of the predictions and measurements of effluent TSS and phosphorus concentrations.     

Selective sludge removal in a segregated aerobic granular biomass system as a strategy to control PAO-GAO competition at high temperatures

An aerobic granular sludge (AGS) reactor was run for 280 days to study the competition between Phosphate and Glycogen Accumulating Organisms (PAOs and GAOs) at high temperatures. Numerous researches have proven that in suspended sludge systems PAOs are outcompeted by GAOs at higher temperatures. In the following study a reactor was operated at 30 °C in which the P-removal efficiency declined from 79% to 32% after 69 days of operation when biomass removal for sludge retention time (SRT) control was established by effluent withdrawal. In a second attempt at 24 °C, efficiency of P-removal remained on average at 71 ± 5% for 76 days. Samples taken from different depths of the sludge bed analysed using Fluorescent in situ hybridization (FISH) microscopy techniques revealed a distinctive microbial community structure: bottom granules contained considerably more Accumulibacter (PAOs) compared to top granules that were dominated by Competibacter (GAOs). In a third phase the SRT was controlled by discharging biomass exclusively from the top of the sludge bed. The application of this method increased the P-removal efficiency up to 100% for 88 days at 30 °C. Granules selected near the bottom of the sludge bed increased in volume, density and overall ash content; resulting in significantly higher settling velocities. With the removal of exclusively bottom biomass in phase four, P-removal efficiency decreased to 36% within 3 weeks. This study shows that biomass segregation in aerobic granular sludge systems offers an extra possibility to influence microbial competition in order to obtain a desired population.     

Biomass growth and activity in a membrane bioreactor with complete sludge retention

This work reports the main results of a bench scale membrane bioreactor operated for more than 100 days without sludge withdrawal and fed on real municipal wastewater. The experiments were oriented towards three main objectives. Firstly, the performance of the system was evaluated under two different volumetric loading rates (0.8 and 1.7 g CODL(react.)(-1)d(-1)). Secondly, biomass growth and accumulation of solids were assessed and a relationship between sludge concentration and volumetric loading rates was proposed. Thirdly, biomass activity was evaluated through respirometric tests, and endogenous and maximum respiration rates of heterotrophic and nitrifying bacteria were determined. The experimental campaign showed that these systems are easy to manage and very rapid to start-up. The SS concentrations under equilibrium conditions for both experimental periods were slightly lower than 10 times the volumetric loading rates, and the organic loading rates reached the same equilibrium value of 0.12 g CODgTSS(-1)d(-1). Furthermore, under equilibrium conditions the system showed very limited sludge production (0.12 g VSSgCOD(rem)(-1)) and low biomass activity, although it readily responded to load variations. Further work is being carried out to evaluate the performance over the long term.     

Ferric chloride and lime conditioning of activated sludges: an electron microscopic study on resin-embedded samples

Ferric chloride and lime conditioning of sewage sludge is usually interpreted in terms of enhanced aggregation of sludge components. In this study, transmission electron microscopy was used to investigate the conditioning mechanism at a submicronic scale. Samples were collected from two municipal wastewater treatment plants at different stages of the process, embedded in an epoxy resin, and sectioned with an ultramicrotome. Transmission electron microscopy examination of thin sections revealed that clumps of crystalloids develop on external surfaces of flocs after the application of both conditioners. This precipitate creates a rigid structure around the flocs which, upon mechanical dewatering, transmits the stresses applied to the inner parts of flocs. The porous structure of the precipitate may also participate to the withdrawal of water as a draining media. Energy dispersive X-ray spectroscopy revealed that Fe, P, and Ca are the dominant elements in the precipitate with Fe/P and Fe/Ca elemental ratios close to 2.8-3 and 1.1-3, respectively.     

黄河高浊度水处理构筑物排泥管道水头损失试验研究

高浊度水处理构筑物成功与否的关键是排泥问题。通过对辐流工沉淀池处理黄河高浊度水排泥管道、输泥管道水头损失的研究，推导出阻力计算的基本公式，为给排水构筑物设计及运行管理提供依据。     

A novel sulfate reduction, autotrophic denitrification, nitrification integrated (SANI) process for saline wastewater treatment

This paper reports on a lab-scale evaluation of a novel and integrated biological nitrogen removal process: the sulfate reduction, autotrophic denitrification and nitrification integrated (SANI) process that was recently proposed for saline sewage treatment. The process consisted of an up-flow anaerobic sludge bed (UASB) for sulfate reduction, an anoxic filter for autotrophic denitrification and an aerobic filter for nitrification. The experiments were conducted to evaluate the performance of the lab-scale SANI system with synthetic saline wastewater at various hydraulic retention times, nitrate concentrations, dissolved oxygen levels and recirculation ratios for over 500 days. The system successfully demonstrated 95% chemical oxygen demand (COD) and 74% nitrogen removal efficiency without excess sludge withdrawal throughout the 500 days of operation. The organic removal efficiency was dependent on the hydraulic retention time, up-flow velocity, and mixing conditions in the UASB. Maintaining a sufficient mixing condition in the UASB is important for achieving effective sulfate reduction. For a typical Hong Kong wastewater composition 80% of COD can be removed through sulfate reduction. A minimum sulfide sulfur to nitrate nitrogen ratio of 1.6 in the influent of the anoxic filter is necessary for achieving over 90% nitrate removal through autotrophic denitrifiers which forms the major contribution to the total nitrogen removal in the SANI system. Sulfur balance analyses confirmed that accumulation of elementary sulfur and loss of hydrogen sulfide in the system were negligible.     

半干污泥焚烧工程设计分析及探讨

为减少污泥运输体积,减轻污泥运输对环境的影响,污水厂出厂污泥处理趋势逐渐由含水率80%的脱水污泥转变为含水率40%~50%左右的半干污泥。上海市石洞口污泥处理二期工程采用“脱水干化(石洞口本厂污泥)+焚烧及烟气处理(泰和及石洞口污泥)”工艺,是针对半干污泥的焚烧工程。半干污泥接收储运采用“接收坑+抓斗提升”的方式,半干污泥焚烧产生的系统富余热能用于加热污泥调蓄池内的污泥,改善污泥浓缩脱水效果。在此基础上,进一步探讨了选址相对独立的半干污泥焚烧项目需注意的污泥泥质控制、热能利用方式及炉温控制措施等相关因素。     

Aerobic granulation with industrial wastewater in sequencing batch reactors

Granular sludge formation was promoted in two laboratory scale sequencing batch reactors (SBRs), R1 and R2 fed with industrial wastewater produced in a laboratory for analysis of dairy products. Both reactors were operated under similar conditions during most of the experimental period. However, an anoxic phase between 10 and 30 min was included at the beginning of every cycle of operation of R1, but not in R2. Organic and nitrogen loading rates applied to both systems were high, up to 7 g COD/(L d) and 0.7 g N/(L d). Nitrogen removal efficiency was 70% in both units even considering that R2 was operated always under aerobic conditions. Granules with similar morphology were developed in both systems. Size distribution was comprehended between 0.25 and 4.0 mm for both systems. The presence of TSS in the effluent of the SBRs was strongly affected by either the length of the withdrawal period or by the particulated COD to biomass ratio (CODp/VSS) applied to the systems. The lower concentrations of TSS in the effluent were attained when the systems were operated with a CODp/VSS ratio lower than 0.12 g COD/g VSS. There was a strong reduction of the average TSS content in the effluent from 450 to 200 and 150 mg TSS/L when the length of the withdrawal period was diminished sequentially from 3 to 1 and 0.5 min, respectively. This was caused by a more intensive washout of small suspended biomass aggregates that took place when the length of this period was shortened.     

旁路微氧污泥减量效果及其影响因素

通过对旁路微氧污泥减量技术中好氧污泥在微氧池中的减量效果及其影响因素的研究,发现污泥减量效果与微氧池的污泥浓度(MLSS)、好氧污泥与厌氧污泥的比例(α)、微氧池的氧化还原电位(ORP)、微氧池的污泥停留时间有关。当微氧池的α=2∶8、MLSS为10 000 mg/L时,减量效果最佳;通过不同MLSS和不同α值两组试验,得出在最佳值时的减量率分别为19.15%和19.61%。低ORP值条件下微氧池污泥颗粒细碎,中位粒径为20.24μm,而好氧污泥的中位粒径为32.18μm。同时,混合液中溶解性大分子有机物含量明显增加。该工艺使污泥有更充分的时间进行内源呼吸和EPS的离解释放,从而实现了污泥减量。     

Critical operational parameters for zero sludge production in biological wastewater treatment processes combined with sludge disintegration

Mathematical models were developed to elucidate the relationships among process control parameters and the effect of these parameters on the performance of anoxic/oxic biological wastewater processes combined with sludge disintegrators (A/O-SD). The model equations were also applied for analyses of activated sludge processes hybrid with sludge disintegrators (AS-SD). Solubilization ratio of sludge in the sludge disintegrator, alpha, hardly affected sludge reduction efficiencies if the biomass was completely destructed to smaller particulates. On the other hand, conversion efficiency of non-biodegradable particulates to biodegradable particulates, beta, significantly affected sludge reduction efficiencies because beta was directly related to the accumulation of non-biodegradable particulates in bioreactors. When 30% of sludge in the oxic tank was disintegrated everyday and beta was 0.5, sludge reduction was expected to be 78% and 69% for the A/O-SD and AS-SD processes, respectively. Under this condition, the sludge disintegration number (SDN), which is the amount of sludge disintegrated divided by the reduced sludge, was calculated to be around 4. Due to the sludge disintegration, live biomass concentration decreased while other non-biodegradable particulates concentration increased. As a consequence, the real F/M ratio was expected to be much higher than the apparent F/M. The effluent COD was maintained almost constant for the range of sludge disintegration rate considered in this study. Nitrogen removal efficiencies of the A/O-SD process was hardly affected by the sludge disintegration until daily sludge disintegration reaches 40% of sludge in the oxic tank. Above this level of sludge disintegration, autotrophic biomass concentration decreases overly and TKN in the effluent increases abruptly in both the A/O-SD and AS-SD processes. Overall, the trends of sludge reduction and effluent quality according to operation parameters matched well with experimental results found in literatures.