颗粒滤料与纤维滤料组合过滤研究

颗粒滤料与纤维滤料组合过滤结合了颗粒滤料具有深层过滤和纤维滤料具有高精度过滤的特点,这种组合滤池避免了其他组合滤池存在的缺陷,具有较好的过滤特性和反冲洗特性。试验结果表明:在进水浊度为10～80 NTU,滤速9～20 m/h的条件下,这种组合滤池运行稳定,固体悬浮物质量浓度去除率≥95%,截污量可达24 kg/m3。与单独采用石英砂和纤维滤料的滤池相比,其具有过滤速度快、周期长、截污量大、水头损失小、反冲洗耗水耗气量小等特点。     

V型纤维滤池在污水深度处理中的运行特性

以济南市水质净化二厂的二沉池出水为原水,进行了V型纤维滤池深度处理污水的试验研究.在不同的滤速下,以出水浊度为控制指标,确定了最佳过滤周期为23 h.在过滤周期内,研究了纤维滤池对悬浮物和COD的去除效果,同时考察了其截污能力和反冲洗特点.结果表明,V型纤维滤池对悬浮物的去除效果良好,去除率在62%以上,出水SS<3 mg/L;而对溶解性有机物的去除效果不理想,对COD的去除率在5%～33%之间.此外,V型纤维滤池在一个过滤周期内的截污量为12.5 ks/m<'3>,反冲洗耗水量仅为过滤水量的3%,能反洗出90%的截污量.     

提高净水厂虹吸滤池反冲洗强度的技改新措施

针对低负荷运行条件下,鹏城水厂虹吸滤池滤料反冲洗不彻底的问题,提出增设反冲洗补水管道的新措施,通过在反冲过程中向清水渠内补水实现提高反冲洗强度的目标;并配合滤池常规大修,对虹吸滤池进行改造。运行结果表明,补水反冲措施可将滤池反冲洗强度由最低的5.5 L/(m2·s)提高至设计规范要求的15 L/(m2·s);过滤周期延长一倍;反冲洗水量节省约20%;滤池截污能力提高约35%,滤后水浊度降至0.2 NTU。此外,该措施投资、运行成本低,有效地提高了老旧虹吸滤池的经济技术指标。     

气水反冲洗滤池在供水厂中的应用

许昌市周庄水厂的供水能力为10×104m3/d,实现了PLC自动控制。现将该厂二期工程所建的气水反冲洗滤池作一简单介绍。1滤池工作概况①过滤:沉后水经滤层→滤砖→出水阀门→封闭式汇水总渠,投氯消毒后进入清水池。②反冲洗分为3种方式,a.强制反冲洗,根据实际需要随时进行;b.按照设定的运行周期进行反冲洗;c.根据水头损失确定是否进行反冲洗。滤池系统采用3种控制方式:①全自动运行,计算机根据检测到的各个滤格的水位和各项运行参数,自动控制滤池的反冲洗鼓风机、冲洗泵、阀门的开关量等;②远程手动遥控操作,通过操作计算机键盘而达到操作设…     

三种典型砂滤池过滤参数优化及过滤性能对比

通过研究国内外三种典型石英砂滤池的出水浊度、颗粒数以及水头损失,对比分析了不同滤速条件下三种滤池的过滤性能,以期达到优化过滤参数及优选滤料的目的。结果表明,水头损失是各滤池过滤周期的主要限制因素,同等条件下美国级配滤料滤池的水头损失增长速率最大,其次是国内级配滤料滤池、国内均质滤料滤池;不同滤速条件下各滤池的出水浊度均保持稳定,国内级配滤料滤池出水浊度在过滤周期末段有上升趋势;出水中颗粒数随着滤速的增加而增大,增大滤速会降低滤池对小颗粒的截留效率,国内均质滤料滤池出水的颗粒含量最低,其次是国内级配滤料滤池、美国级配滤料滤池,各滤池对粒径为3~5μm的颗粒物去除效果最差。综合各因素,国内均质滤料滤池的过滤性能最佳,其次是国内级配滤料滤池、美国级配滤料滤池,三者的最佳滤速分别为(6~7)、8、4 m/h。     

曝气生物滤池去除SS以及水头损失增长的特性研究

通过中试考察了不同气水比下,上流式曝气生物滤池(BAF)去除悬浮物以及水头损失增长的特性.结果表明:随着气水比的增大,BAF对SS的去除效率降低,对SS的主要去除区域逐步向滤层上部推移,且反冲洗后滤层对SS去除能力的恢复减慢;BAF滤柱内的生物量随着气水比的增大而增加,随着滤层高度的增加而逐步减少,滤层高度为50 cm处的生物量高达12.50 ～21.52 mgVAS/g陶粒;BAF内水头损失的增加速率随着气水比的增大而减小,当气水比由2∶1增大为10∶1时,反冲洗周期内的终点水头损失由30.1 kPa减少为10.5 kPa.     

普通快滤池加设表面冲洗的效用

介绍了金西水厂二期工程在普通快滤池中加设旋转式表面冲洗设备的安装、调试运行的情况。实践证明，该措施提高了滤池的过滤效率，减少了冲洗次数和冲洗水量，增强了滤池的截污能力，延长了过滤周期。     

陶粒生物滤池与无烟煤滤池强化过滤效果对比

以北京某自来水厂处理密云水库蓄水的出水（混凝沉后水）为试验用水，通过中试对比研究了陶粒生物滤池与无烟煤滤池的过滤效果。结果表明，陶粒生物滤池与无烟煤滤池对水中颗粒物的去除效果接近；对于水中的浊度，无烟煤滤层对其去除效果较好，而陶粒滤层的过滤效果则较差，需要依靠石英砂的截污作用来降低浊度；陶粒对有机物的过滤效果优于无烟煤的，陶粒生物滤池对TOC的去除率为14．9％～30．2％，对CODMn的去除率为13．1％～38．5％；与无烟煤滤池相比，陶粒生物滤池具有水头损失增长快、周期较短、初滤水中颗粒物较多等缺点。     

中山市长江水厂V型滤池的优化控制与管理经验

中山市长江水厂为了优化V型滤池的运行,对其过滤及反冲洗过程进行了监测,通过分析滤后水和反冲洗水的浊度变化,以及滤砂变化情况等,优化了滤池运行控制参数,包括合理控制滤速、反冲洗强度及时间、调整过滤周期、更换排气阀门等,保障了滤池的稳定运行及滤后水水质,并实现了节能降耗。     

净水厂传统虹吸滤池升级改造工程实例

分析了秦皇岛市海港水厂虹吸滤池存在的主要问题及成因,介绍了改造其进出水、排水系统,将单一利用滤后水反冲洗改造成气水联合反冲洗形式,并更换均匀配水系统和加厚均粒石英砂滤料层的技术要点,改造后滤后水浊度降低到1NTU以下,滤池反冲洗均匀彻底、节水效果明显、过滤周期延长,并实现了全自动运行。     

双阀滤池配水系统的改造

扬州自来水总公司第一水厂的双阀滤池原采用穿孔管大阻力配水系统,由于配水不均,造成砂面不平,过滤效果差且跑砂现象严重,为此进行了改造:取消原有的穿孔管,改用ABS工程塑料短柄滤头 滤板的中阻力配水系统。改造后配水效果明显改善,过滤周期延长,反冲洗效果好。     

Impact of backwashing procedures on deep bed filtration productivity in drinking water treatment

Backwash procedures for deep bed filters were evaluated and compared by means of a new integrated approach based on productivity. For this, different backwash procedures were experimentally evaluated by using a pilot plant for direct filtration. A standard backwash mode as applied in practice served as a reference and effluent turbidity was used as the criterion for filter run termination. The backwash water volumes needed, duration of the filter-to-waste period, time out of operation, total volume discharged and filter run-time were determined and used to calculate average filtration velocity and average productivity.     

Using a geotextile with flocculated filter backwash water and its impact on aluminium concentrations

The use of geotextiles (i.e. geotextile tubes) in wastewater treatment applications is ever increasing. This paper examines the potential of using a geotextile to improve upon the treatment of aluminium present in a filter backwash water that is generated from a water treatment plant in Halifax, Canada. A field investigation to ascertain the distribution of aluminium in the filter backwash water treatment process is provided and compared to regulatory guidelines at the environmental compliance point. It is shown that aluminium is undergoing incomplete treatment at various times throughout the year. To examine a potential corrective action, the results of bench scale studies are presented in which cationic additives (i.e. CaO, MgO, and Fe₃O₄) are combined with a polymer to remove aluminium from solution and flocculate particulate matter from the filter backwash water. A geotextile is utilized to retain particulate matter generated from this process. It is shown that the combined use of the cationic additive with polymer can successfully reduce aluminium concentrations in the filter backwash water and that filtration via a geotextile can retain the aluminium particulate in the filter backwash water to levels close to regulatory requirements. Further optimization with the flocculation process is recommended prior to pilot testing.     

普通快滤池改造为气水反冲洗均质滤料滤池工程实践

针对大连大沙沟净水厂原有普通快滤池过滤周期短、产水量下降、反冲洗效果不佳等问题,进行了技术改造。将原有中阻力陶瓷滤砖配水系统改为Azurfloor整体滤板小阻力长柄滤头配水,煤-砂滤料改为石英砂均质滤料,单一水反冲洗改为气水反冲洗,并完善了滤池的自动控制系统。运行情况表明,改造后滤池出水水质提高,反冲洗效果明显改善,产水量增加了10×104m3/d,运行成本减少且滤站实现了自动化运行,经济效益和社会效益显著。     

The interface between filtration and backwashing

A conceptual model of the initial degradation phase of filtration is presented as an interface effect between backwashing and filtration. It is shown that the initial degradation of effluent quality is due to the backwash water remnants within the media and the backwash water above the media. The two peak characteristics of initial degradation due to the backwash water remnants within the media and above the media is established by an extensive experimental investigation. A mathematical model for the quality of backwash water as a function of backwash water volume is developed. Deductions made from the mathematical expression confirm the validity of some accepted facts on backwashing and also lay the basis for the peaks in initial degradation.     

Biofiltration for removal of BOM and residual ammonia following control of bromate formation

Nitrification was developed within a biological filter to simultaneously remove biodegradable organic matter (BOM) and residual ammonia added to control bromate formation during the ozonation of drinking water. Testing was performed at pilot-scale using three filters containing sand and anthracite filter media. BOM formed during ozonation (e.g., assimilable organic carbon (396-572 microg/L), formaldehyde (11-20 microg/L), and oxalate (83-145 microg/L)) was up to 70% removed through biofiltration. Dechlorinated backwash water was required to develop the nitrifying bacteria needed to convert the residual ammonia (0.1-0.5 mg/L NH(3)-N) to nitrite and then to nitrate. Chlorinated backwash water resulted in biofiltration without nitrification. Deep-bed filtration (empty-bed contact time (EBCT) = 8.3 min) did not enhance the development of nitrification when compared with shallow-bed filtration (EBCT = 3.2 min). Variable filtration rates between 4.8 and 14.6 m/h (2 and 6 gpm/sf) had minimal impact on BOM removal. However, conversion of ammonia to nitrite was reduced by 60% when increasing the filtration rate from 4.8 to 14.6 m/h. The results provide drinking water utilities practicing ozonation with a cost-effective alternative to remove the residual ammonia added for bromate control.     

The theoretical analysis of the filter run time

The article presents a number of formulas for relative volume concentrations of the suspension and sediment, head loss in a uniform medium obtained as a result of a strict decision of mathematical problems of filtration of a constant discharge with linear and nonlinear mass-exchange kinetics. The procedure of accurate computation of the relative filter run time based on indicated formulas on the basis of maximum admissible quality of water purification and head loss in the medium. Using numerous typical examples we investigated the impact of the initial concentration of the suspension and sorption properties of the filtration material on the time of the filter efficient performance.     

Management and design implications of a mathematical model of a rapid gravity sand filter backwash

A model has been proposed and tested describing the removal of water from the bed surface of a rapid gravity sand filter during a backwash. The model can be used in design to predict the minimum height of the weir above the expanded bed required to prevent media loss and also the minimum length of time for a backwash to obtain a clean bed.     

地下水源除铁锰滤池调试运行实践及思考

为了解决沈阳市辽中区西水厂出水锰含量长期超标问题,对该水厂除铁除锰滤池进行调试。采用扫洗、翻砂和添加10～15 cm成熟滤料等措施对滤池进行调试,68 d后出水Mn2+浓度低于0.1 mg/L,滤池恢复期为68 d;只采用扫洗、翻砂措施时,滤池恢复期为80 d;未进行调试滤池的出水锰浓度会逐渐升高,可达到0.48～0.61 mg/L,出水铁、锰不达标。用高压水枪对滤层表面进行扫洗和翻砂能够有效解决滤池堵塞问题,调试成熟且稳定以后的滤池过滤周期可达25～30h。水厂成功运行时滤池的平均滤速为7～14 m/h、反冲洗强度为11～12 L/(s·m2)、反冲洗时间为20～25 min、过滤周期为24 h,滤池出水水质能够达到《生活饮用水卫生标准》(GB 5749—2006)的要求。     

Filter backwash and start-up strategies for enhanced particulate removal

A significant consideration in forward planning for water treatment works design and operation concerns the effectiveness of a filtration plant in providing a barrier to particulates in the low micrometre size range, including Cryptosporidium oocysts. The performance of rapid gravity filtration plants is believed to be dependent on backwash and start-up regimes. It was the aim of this study to optimize direct sand filtration by identifying optimum filter backwash and start-up conditions which minimized the passage of particulates into the filtrate. The filter ripening period has long been identified as a cause for concern with respect to particulate passage into the filtrate; this work has shown that up to 40% of all particles that pass into supply during a 48 h run, do so in the first hour of operation. Optimum combined air water “collapse-pulsing” backwash durations were identified that reduced the number of 2–5 μm particles entering the filtrate, especially during the ripening period. Slow start-up was also found to reduce the number of 2–5 μm particles in the filtrate during the ripening period. The reductions in particulate passage resulting from a slow start was found to be media dependent, with smaller media requiring a longer slow start duration than coarser media.