南方某污水处理厂精确曝气技术示范及评估分析

曝气系统是活性污泥法工艺污水处理厂的最大能耗单元,基于污水生物处理需氧量的曝气风量精确控制及分配是降低污水处理厂能耗的重要手段。对南方某污水处理厂实施精确曝气改造,通过稳定运行一年的数据分析,结果表明:生化池出水口溶解氧基本维持在(2.0±0.5)mg/L;在处理水量、进水耗氧污染物浓度高于改造前的情况下,全年鼓风机总电耗降低且出水水质更优,年平均鼓风机能耗降低20.59%,年平均单位耗氧污染物鼓风机能耗降低37.5%。精确曝气系统能稳定生化池溶解氧,优化生物处理效果并能显著节省曝气系统能耗。     

曝气过程控制系统在污水处理厂节能中的应用与评价

曝气控制系统作为污水处理厂实现节能降耗的重要手段越来越受到重视。阐述了开发的针对城市污水处理厂A2/O工艺的曝气过程控制系统,该系统能够维持生化段溶解氧稳定、保障出水水质达标、降低曝气系统能耗。在实际工程应用案例数据深入分析基础上,提出了评价曝气过程控制系统的性能指标,分析了影响控制效果的因素,对污水处理厂曝气过程控制系统的设计与运行具有借鉴意义。     

城市污水处理工艺及其发展

介绍国内外目前运用较多和正在开发、研究的城市污水一级、二级、三级处理工艺流程 ,讨论了这些工艺的发展状况和发展趋势 ,介绍了一些适用于我国城市污水处理的新工艺。指出 ,在我国 ,一级污水处理工艺以混凝沉淀强化法的应用较多。二级污水处理中 ,鼓风曝气的完全混合式活性污泥法和氧化沟工艺适用于日处理能力大于 2 0万t的城市污水处理厂 ,日处理能力在 5万～ 2 0万t的污水处理厂可以采用鼓风曝气的完全混合式活性污泥法、氧化沟工艺及SBR工艺 ,日处理能力在 1万～ 5万t的污水处理厂总体上以活性污泥法为主。常规处理工艺比较适用于三级污水处理工艺。     

CASS工艺中曝气系统节能技术探讨

随着城市污水处理率的提高,污水处理的能耗问题越来越受到人们的重视,研究污水处理厂的节能问题是节能减排的重要工作.CASS工艺运行能耗分布与传统活性污泥法有所不同,其中曝气能耗占总运行能耗的比例大.探讨了CASS工艺中曝气系统的节能技术,说明了通过在工程中采取相应技术措施可以获得节能效果.     

底曝氧化沟工艺在污水处理工程中的设计应用

针对我国南方部分地区污水处理厂进水水质浓度变化较大,为保证出水水质稳定达标,提出了采用水下推进器和鼓风曝气相结合的底曝氧化沟处理工艺,不仅可以根据进水水质灵活地调节曝气量,满足出水水质标准,而且可以节省能耗。结合具体工程实践,提出了工艺设计要点和需要注意的问题。     

城市污水处理厂能量优化策略研究

分析了我国城市污水处理厂能耗现状,从污水内能及外加能量两个方面研究节能优化策略并进行了相应试验研究,试验得出智能控制溶解氧浓度可节省约20%的曝气能耗,在倒置A2/O工艺的厌氧段有COD损失也可节省大量曝气能耗。     

分离式曝气装置

历来广泛使用活性污泥曝气方法有鼓风曝气法、表面加速曝气法及组合法等。鼓风曝气是从池底喷出空气,空气管或扩散板经常淹没在污水中,易被腐蚀、阻塞,曝气池深度大时,鼓风机的动力也大。所以池深度有一定限制。而当所用鼓风机动力过大时,空气急速喷出,造成过分搅拌,影响绒     

成都市三瓦窑污水处理厂工程设计介绍

成都市三瓦窑污水处理厂一期设计规模10万 m~3/d,远期规模40万 m~3/d,采用鼓风曝气活性污泥法二级生化处理工艺。在进厂水质 BOD_5=200mg/L,SS=260mg/L条件下,出厂水质可望达到 BOD_5≤20mg/L,SS≤30mg/L。为降低能耗,减少基建投资和便于运行管理,本工程还采用了钟氏沉砂池、微孔曝气器、周边进水周边出水二沉池、污泥气浮浓缩池等新技术。     

城市污水处理厂运行决策支持系统(WWTP ODSS~)的介绍和应用

介绍了基于经验知识和活性污泥数学模型ASMs的城市污水处理厂运行决策支持系统(WWTP ODSS)的开发历程、主要结构功能以及应用情况,重点介绍了ODSS中专家系统和模拟系统在北京市清河污水处理厂的应用实例。ODSS系统集预警、故障诊断、过程模拟和预测等多种功能于一体,通过系统内置的溶解氧、回流比和排泥量等单元控制模块实现了前馈-反馈控制策略,为污水处理厂的运行和控制提供有力的指导和支持。     

改良AAO工艺间歇曝气对微生物群落特征及运行效果影响

为保证出水水质稳定达标及达到降低能耗的目的,原采用连续曝气方式的某污水处理厂改良AAO工艺改为间歇曝气方式运行.在连续曝气和间歇曝气方式下,处理工艺均能对污染物进行有效去除.从连续曝气调整为间歇曝气后,活性污泥微生物群落的α-多样性无明显变化,同时,间歇曝气条件下的缺氧池和好氧池内微生物群落结构更加相似.间歇曝气策略能...     

Aeration of large-scale municipal wastewater treatment plants: state of the art.

Aeration is the most energy-intensive operation in wastewater treatment, amounting to 45-75% of plant energy costs. Fine-pore diffusers are today almost ubiquitous in municipal wastewater aeration, due to their advantageous aeration efficiency (mass of oxygen transferred per unit energy required). Nevertheless, older municipal treatment facilities and many industrial treatment plants are still equipped with coarse-bubble or surface aerators. Fine-pore diffusers are subject to two major disadvantages: a) fouling, if not cleaned periodically; b) decrease in oxygen transfer efficiency caused by dissolved surfactants. Coarse-bubble and surface aerators are typically not subject to the traditional problems affecting fine-pore diffusers. Nonetheless, they achieve oxygen transfer at the expense of increased energy intensity. The increased biomass concentration associated with high mean cell retention time (MCRT) operations has a beneficial effect on aeration. Nutrient-removing selectors are able to further increase aeration efficiency, as they sorb and utilize the readily available substrate which otherwise would accumulate at bubble surfaces and dramatically decrease aeration efficiency. We summarise here our 30-year long experience in aeration research, and results obtained with clean- and process-water tests are used to show the beneficial effects of high MCRT operations, the beneficial effect of selectors, and the decline of aeration efficiency due to dissolved surfactants.     

不同条件对高效菌去除污水中氨氮效果影响研究

本文研究了pH值、温度、曝气时间、茵投入量（体积比）、溶解氧、水力停留时间、进水碳氮比、冲击负荷等影响因素对氨氮去除率的影响,对项目参数进行了优化。研究结果如下：在高效菌处理氨氮废水时,为了得到较好的去除效果,pH值应控制在7．0到8．O之间;温度应控制在25℃到35℃之间;曝气时间应保持在5h到6h之间;茵投入量（体积比）应保持在0．004到0．006之间;溶解氧浓度应保持在2mg／L到3mg／L之间：水力停留时间为16h．高效茵对污水中氨氮的去除效果最佳。     

精确曝气系统在污水厂中应用

精确曝气系统旨在通过污水厂区进水参数数据来精确控制生物池的溶解氧DO值,即合理控制曝气量,实现自动对风机风量的控制,对风机的能源损耗有一定降低。     

阶梯式跌水与微孔曝气一体化氧化沟性能研究

为解决我国丘陵地带中小城镇生活污水处理厂的建设和运行费用偏高等实际问题,利用丘陵地势条件,将阶梯式跌水曝气装置、微孔曝气器、潜水推进器等节能技术应用到一体化氧化沟工艺中,设计出一种新型污水处理工艺。小试和中试结果均表明:该工艺具有良好的充氧性能,在处理污水能达标排放的同时取得了很好的节能效果。结合混合液流态和阶梯式跌水装置复氧过程等方面的节能机理分析,导出的阶梯式跌水曝气装置复氧过程中氧亏比的数学计算模型为该工艺指导实践提供了理论依据。     

Potential of OUR and OTR measurements for identification of activated sludge removal processes in aerated basins.

In order to develop a process control scheme to reduce energy costs for aeration in activated sludge systems with biological P removal, pre-denitrification and nitrification stages, the spatial distribution of carbon oxidation and nitrification was evaluated over a long full-scale plug flow aeration basin using an externally measured specific oxygen uptake rate (sOUR) and in basin measurement of the actual specific oxygen transfer rate (sOTR) with off-gas testing as well as with the calculated oxygen demand from NH4-N concentrations (sOTR(N)). Using a simple static model, a gas phase balance on oxygen and carbon dioxide, sOTR(N) values were also calculated from off-gas testing. Comparison of sOTR(N) to sOTR and sOUR for carbon oxidation (sOUR(C)) to nitrification (sOUR(N)) at different loading conditions allowed the oxidation processes to be followed over the three zones of the aeration basin. As expected, the distribution depended on the dissolved oxygen concentration (DO) in the basin. However, the major change was in the C-oxidation rate and not the nitrification rate. At a low DO, and when NH4-N was present in the zone, the amount of oxygen transferred for nitrification was nearly the same, but the overall sOTR was lower. The externally measured sOUR was only useful when it was differentiated into sOUR(N) and sOUR(C). sOUR(N) could be used to predict the nitrification rate in the basin. With further refinement, the gas phase balance model has potential to be used to monitor the degree of nitrification over the basin length. This can be integrated into a control scheme to reduce aeration costs by adjusting the DO setpoint according to loading conditions in the     

空气曝气与纯氧曝气生物滤池应用于污水深度处理的研究

采用两种不同气源的曝气生物滤池对污水处理厂二级出水进行深度处理中试研究.结果表明,空气曝气和纯氧曝气生物滤池对COD_(Mn)的去除率相近,分别为30.5%和30.9%;以纯氧为气源的生物滤池硝化能力远强于空气曝气生物滤池,氨氮总去除率77.4%,出水氨氮为2.1～6.3 mg/L;纯氧曝气提高了滤池上部氨氮去除效果,维持滤池内溶解氧在6 mg/L以上,沿水流方向使pH逐渐下降.纯氧曝气生物滤池是污水深度处理中去除氨氮的有效工艺.     

Membrane bioreactors in industrial wastewater treatment--European experiences, examples and trends.

In wastewater treatment, micro- and ultra-filtration membranes are used for the separation of the activated sludge (biomass) from the treated water. This offers the advantages of a complete removal of solids and bacteria, as well as most of the viruses, namely those attached to the suspended solids. Compared to the conventional activated sludge process (CAS) this technology allows a much higher biomass concentration (MLSS) whereby the reactor volume and the footprint decreases. With increasing MLSS, the viscosity of the sludge increases, which leads to reduced oxygen transfer rates. Depending on the type of membrane and membrane module, the pre-treatment has to be more sophisticated to prevent clogging and sludging of the modules. Due to fouling and scaling, the flux through the membranes will decrease with time. The decrease depends on the water quality as well as on the measurements taken to minimize fouling. Mainly, three strategies are available: lowering the flux, increasing the "crossflow" and cleaning of the membranes. Different strategies including backwash and chemical cleaning "in situ", "on air" and "ex situ" can be applied. It has been proven more effective to apply preventive regular cleaning. Besides the energy demand for oxygen supply--which is typically in the range of 0.3 kWh/m3 for municipal wastewater--the energy for fouling prevention is substantial. Immersed membranes need approximately 0.4 to 1 kWh/m3 for the coarse bubble aeration, whereas tubular modules require 1 to 4 kWh/m3 pump energy. For proper design of industrial wastewater treatment, the verification of applicability and the development of adequate cleaning strategies, it is a precondition to run pilot tests for a sufficient period of time with the wastewater to be treated. More than 100 industrial wastewater treatment membrane bioreactors (MBR) are in operation in Europe. Data of three case studies for a sewage sludge dewatering plant in UK (12,000 m3/d), a plant for the treatment of pharmaceutical wastewater in Germany (3600 m3/d), as well for revamping of an chemical WWTP >2000 m3/d in Italy, are given. MBRs will be used in future wherever high quality effluent is required, because of a sensitive receiving water body or due to the fact of water reuse as process water. MBRs are a perfect pre-treatment in industrial applications when further treatment with nanofiltration or reverse osmosis is considered. The technique is advanced and can be applied both in municipal and industrial wastewater treatment. Higher operational costs must be balanced by superior effluent quality.     

Catchment-scale fluorescence water quality determination.

Chemical water quality determinants and river water fluorescence were determined on the River Tyne, northeast England. Statistically significant relationships between nitrate (r = 0.87), phosphate (r = 0.80), ammonia (r = 0.70), biochemical oxygen demand (BOD) (r = 0.85) and dissolved oxygen (r = -0.65) and tryptophan-like fluorescence intensity were observed. The strongest correlations are between tryptophan-like intensity and nitrate and phosphate, which in the Tyne catchment derive predominantly from point and diffuse source sewage inputs. The correlation between BOD and the tryptophan-like fluorescence intensity suggests that this fluorescence centre is related to the bioavailable or fluorescence intensity and ammonia concentration and dissolved oxygen. The weaker correlation with ammonia is due to good ammonia treatment within the wastewater treatment plants within the catchment, and that with dissolved oxygen due to the natural aeration of the river such that this is not a good indicator of water quality. Mean annual tryptophan-like fluorescence intensity, measured by both bench and portable spectrometers, agrees well with the General Water Quality Assessment as determined by the England and Wales environmental regulators, the Environment Agency.     

Improvement of oxygen transfer efficiency in aerated ponds using liquid-film-assisted approach.

In aerated ponds, oxygen is generally supplied through either diffused or mechanical aeration means. Surface transfer and bubble transfer both contribute significantly to oxygen transfer in a diffused aeration system. In the present study, a liquid-film-forming apparatus (LFFA) is successfully developed on a laboratory scale to improve considerably the surface transfer via the unique liquid film transfer technique. The experimental results show that the volumetric mass transfer coefficient for LFFA alone is found to be as much as 5.3 times higher than that for water surface and that the total volumetric mass transfer coefficient for the liquid film aeration system increases by 37% in comparison with a conventional aeration system. Additionally, by tuning finely the structural parameters of the LFFA, it can also lead to high dissolved oxygen (DO) water with the DO percent saturation greater than 90%. More importantly, this result is accomplished by simply offering a single-pass aeration at a depth as shallow as 26 cm. As a result, the objective of economical energy consumption in aerated ponds can be realized by lowering the aeration depth without sacrificing the aeration efficiency. It is noteworthy that the data presented in this study are acquired either numerically or experimentally.     

Reactive tracers reveal hydraulic and control instabilities in full-scale activated sludge plant.

The hydraulic characteristics of aeration tanks in WWTPs have a major impact on the degradation of pollutants, as well as on the control of the aeration. In particular in long reactors, which are not separated by baffles, hydraulic shortcuts or large scale recirculation can lead to a loss of performance. This work demonstrates that reactive tracers such as ammonium and oxygen can be used to investigate the hydraulics of aeration tanks in detail. With the use of electrochemical sensors it is possible to investigate effects in a broad range of time scales.In the present case study a slow oscillation of the aeration control loop was investigated. Large scale recirculation in the aeration tank and fast fluctuations of the ammonium concentrations close to the oxygen sensor were identified as the cause of these oscillations. Both, the recirculation as well as the fluctuation of the ammonium have a substantial influence on the performance of the aeration tank and the aeration control loop.