原水浊度对透光率脉动混凝投药控制技术的影响分析

透光率脉动混凝投药控制技术应用于常规浊度水处理中仍存在着许多不完善的地方 ,尤其原水浊度对以R值为控制参数的控制系统具有极大的不利影响。为此 ,对常规浊度水进行了大量的试验研究 ,提出以 β值为控制系统的控制参数来控制混凝剂的投加 ,并通过试验证明 β值与混凝剂投加量、沉后水浊度之间存在着良好的相关性 ,并且对于不同浊度的原水 ,β值与沉后水浊度之间仍存在着一一对应的关系 ,β值有望替代R值控制混凝剂的自动投加。     

南水北调滤后水残余铝的影响因素试验研究

为控制残余铝浓度,以南水北调水为原水,研究混凝剂种类及投加量、助凝剂投加比例、pH值调节方式及pH值、沉淀时间等因素对滤后水中残余铝的影响。从除浊效果、UV254去除效果及滤后水残余铝浓度3个方面进行了试验研究,结果表明:混凝剂为聚合氯化铝(PAC)、最佳投加量为25 mg/L、助凝剂为活化硅酸、混凝剂与助凝剂投加比例为5∶1、原水pH值为7.5、沉淀时间为30min时,浊度和UV254均有较好的去除效果,同时可控制残余铝浓度远低于国标规定的浓度限值(0.2 mg/L)。     

郑州段南水北调水微絮凝-直接过滤试验研究

以南水北调水为原水、聚合氯化铝(PAC)为混凝剂,进行微絮凝-直接过滤的中试试验。运用浊度仪、紫外分光光度计等对过滤前后水的浊度、UV_(254)、COD_(Mn)、NH_3-N和残余铝浓度进行检测,以确定PAC的最佳投加量,同时观察不同PAC投加量下滤柱内水头上涨幅度随时间的变化情况。结果表明:南水北调水河南受水区微絮凝-直接过滤工艺的PAC最佳投加量为24 mg/L,此时对浊度、COD_(Mn)、UV_(254)和NH_3-N的去除率分别为45.0%、59.3%、28.1%、80.0%,残余铝浓度未超标;该PAC投加量下,滤柱的反冲周期缩短为9 h,且滤柱内水头增长幅度与过滤时间呈线性关系。     

采用颗粒计数仪监测过滤过程对颗粒物的去除效果

采用颗粒计数检测技术监测过滤过程中的颗粒物去除情况,研究了滤层厚度和混凝剂投量对滤池过滤效能的影响,并与浊度检测方法进行对比。结果表明,相比浊度检测,颗粒计数检测技术可以非常灵敏地反映出滤后水悬浮颗粒数量及颗粒粒径分布的变化情况,能从更深层次描述过滤过程对颗粒物的截留特性,能够分辨出滤层厚度和投药量对滤后水水质及颗粒物含量的影响程度,可以弥补或替代浊度检测,是非常有效的监测和控制技术。     

正交试验优选控制初滤水浊度最佳工艺

降低初滤水浊度是提高出水水质的关键,以深圳水库水作为原水进行初滤水浊度控制的研究。通过正交试验方法,比较了四种影响初滤水浊度的因素。中试结果表明:降低沉后水浊度和采用二次微絮凝对改善初滤水浊度起主要作用,调节流速与向反冲洗残留水投药的影响较小,并提出了以二次微絮凝和调节过滤初期流速为控制初滤水浊度的组合工艺,采用聚氯化铝作为微絮凝剂,投加量0.2mg/L,调节初滤水流速从3m/h到8m/h,时间间隔10min。     

应用搅拌机指导水厂投矾探讨

正在水处理工艺过程中,混凝处理是一个十分重要的环节,是去除色度的主要方法。混凝过程的完善程度对后续沉淀、过滤以至消毒工艺的效果影响很大。为了取得良好的混凝效果,必须投加恰当、适量的混凝剂。而混凝剂的投加量除了与源水浊度密切相关,还与氨氮、pH值等其它水质条件、化学反应条件以及水力条件等因素相关。如何在各种变化的条件下投加适量的混凝剂,是各自来水厂一直致力研究的问题。惠州市水务投资集团中心化验室于2007年6月份购进一台六联自动搅拌仪,能实现转速和时间程序的自动控制、自动测温、G值与GT值的自动计算等功能。现拟用此搅拌仪配合江北水厂一期工艺设计参数,设计一套符合实际工艺的搅拌程序,从而实现指导生产的目的。     

载粉末活性炭过滤处理微污染原水的试验研究

载粉末活性炭(PAC)过滤集PAC吸附与过滤于一体,能够应用于微污染原水处理。配水试验结果表明:粒径为1.25-2.5mm,厚度为1000mm的聚苯乙烯滤料层能够用于载PAC过滤。影响过滤效果的主要因素为PAC载量和混凝剂投加量,当混凝剂T3010和聚氯化铝的投加量分别为0.09mg/L和2.5mg/L,PAC载量为2-3g/L滤料时,载PAC过滤处理浊度为20-40NTU的微污染原水的效果达到最佳,对CODMn和浊度都具有很好的去除效果。Z河水作为原水的试验结果表明:载PAC过滤对河水浊度、UV254、CODMn的去除率分别为97%-97.9%、50.9%-63.4%、68.5%-71.4%。     

新型混凝剂CPF改善水厂沉淀排泥水沉降性能研究

应用新型高分子混凝剂CPF改善水厂沉淀排泥水沉降性能的研究表明 ,CPF比聚丙烯酰胺及硫酸铝能更有效地改善污泥的沉降性能 :当投药量为污泥干重的 1 7‰时 ,与无混凝剂时的结果相比 ,CPF使污泥沉降性能提高了 5 1% ,而使用聚丙烯酰胺及硫酸铝时仅分别提高了 2 3%和0 5 %。在试验条件下 ,出水浊度可达 4NTU以下。此外 ,高强度的快速搅拌 ,常温范围内水温升高均有助于增强CPF对污泥的混凝沉降效果。     

微絮凝直接过滤法在电厂工业废水回用中的应用研究

本实验选择微絮凝直接过滤技术处理电厂中的工业废水，使其经过处理后能被作为冷却水加以回用。通过小型实验观察混凝剂投量、助滤剂投量、过滤速度等因素对CODMn去除率及浊度去除率的影响，从而得出最佳投药量的范围。此外通过微絮凝直接过滤的实验，确定了过滤实验的运行周期。     

压力强化混凝沉淀过滤除藻工艺中藻毒素去除研究

为了探究压力强化混凝沉淀过滤除藻工艺中藻毒素的去除效果,试验对比研究了预加压和预氧化后的含藻水,经混凝沉淀、粉末活性炭吸附后的藻毒素去除效果,考察了不同粉末活性炭投加点及投加量对藻毒素去除效果的影响。结果表明,含藻水加压后混凝沉淀,藻类和浊度物质去除效果最优,蓝藻去除率达到96.2%,浊度降至0.49NTU。含藻水在加压和高锰酸钾预氧化后,水中藻毒素浓度未增加,而次氯酸钠预氧化后水中藻毒素浓度最大增幅为215.78%;对于加压水样,在混凝剂投加前30min或投加后7min投加粉末活性炭效果较好,粉末活性炭投加量为5~20 mg/L时,沉淀水藻毒素平均去除率分别达54.13%和53.57%,而与混凝剂同时投加则效果不佳。对次氯酸钠预氧化的水样,粉末活性炭与混凝剂同时投加时效果最好,沉淀水藻毒素平均去除率15.84%。     

Dynamic analysis of coagulation of low turbidity water sources using Al- and Fe-based coagulants.

The direct filtration system is widely used in the treatment of source waters with low and stable turbidity. We have previously indicated the importance of optimizing agitation strength GR and time TR in rapid mixing tanks in order to decrease filter head loss and treated water turbidity in direct filtration. In the present study, we employ a batch-type coagulation experimental apparatus that incorporates a high-sensitivity particle counter, where the particulate concentrations are measured continuously after injection of coagulant, in order to clarify the fundamental coagulation and microfloc formation dynamics. Specifically, it is shown that, after injection of the coagulant, coagulation and microfloc formation occur through distinct periods: an agglomeration preparation period, followed by an agglomeration progression period, and then finally an agglomeration stabilization period, and that optimization of the GR value is the most important consideration, although both the coagulant concentration and GR influence the time at which agglomeration begins in the preparatory period, the time at which agglomeration stabilizes after the progression period, and the concentration of initial particles with diameters of 1-3 microm at completion of agglomeration.     

Roughing filtration as an effective pre-treatment system for high turbidity water

Effective water treatment is the prime goal of every water treatment facility. Chakwal Water Treatment Plant in Pakistan has been treating high-turbidity surface water through crude coagulation, sedimentation and slow sand filtration since the early 1980s. The process has always been tedious in terms of high coagulant dosage, large volumes of sludge and short filter runs especially after wet spells. A laboratory-scale study was conducted to see if roughing filtration, as the pre-treatment process, would help in reducing coagulant dose and sludge volume and improving effluent quality. Results indicated that up-flow rouging filtration with media grades decreasing in the direction of flow could reduce wet weather raw water turbidity (by more than 90%) and coagulant dose. Overall, the plant could save over US $54,000 annually in terms of coagulant cost only. Longer filter runs, improved product water quality leading to lower chlorine dose requirement, would be additional benefits.     

利用溶气气浮工艺强化处理低浊高色富含有机物地表水

低浊高色富含有机物地表水难于混凝,试验采用“混凝-溶气气浮”(“混凝-DAF”)工艺处理此类水,并与常规“混凝-沉淀”工艺进行了比较。结果表明,“混凝-DAF”工艺在较低投药量时能取得更好的处理效果;对于“混凝-DAF”工艺,增大混凝剂投量后出水浊度基本不变,但出水色度及CODMn可进一步降低;“混凝-DAF”工艺去除水中有机物的能力优于“混凝-沉淀”工艺。最后,对“混凝-DAF”工艺去除水中有机污染物的机理进行了探讨。     

低温低浊水絮凝工艺的数值模拟与响应面优化试验研究

为探究微涡流絮凝工艺处理低温低浊水时,絮凝区流场流态的变化以及水中浊度、CODMn、UV254的最优去除效果,采用CFD数值模拟探究不同流量(絮凝时间)下絮凝区流场流态,确定最佳絮凝时间;应用响应面中Box-Behnken的中心组合设计方法,研究了流量、混凝剂投加量与涡流反应器投配比及其交互作用对微涡流絮凝工艺去除浊度...     

龙滩纳付堡水厂最佳混凝剂投用量试验

分析龙滩电站纳付堡水厂的水净化工艺选择适宜的搅拌试验条件,提高搅拌试验与实际混凝过程的相似性。结果表明,在进水浊度为34．2～47．9NTU,水温在0～15℃的条件下,最佳理论聚合铝投加量为14mg／L,此时沉淀池出水浊度可控制在3NTU左右,滤池出水可达1NTU以下。     

The effect of polymeric flocculants on floc strength and filter performance.

Polymeric flocculants are widely used throughout the water industry as flocculant aids, they are known to increase floc density and aid settlement in the clarification stage of the water treatment process. In this research, polymeric flocculants were used to improve floc strength prior to filtration on a dissolved air flotation (DAF) plant in an attempt to prevent filter breakthrough. A modified jar test procedure using a PDA (photometric dispersion analyser) optical flocculation monitor was developed in order to evaluate the system floc strength. Filtration trials were carried out on a pilot filter rig situated on a surface water treatment works in Yorkshire. The filter feed originated from the main plant filter channel. Filter performance was assessed by continuous online monitoring of effluent particle counts, turbidity and headloss over the period of the filter run. Results indicated that low doses of polymeric flocculants had a beneficial effect on filtered water quality, as measured by particle counts, turbidity, UV254 absorption and dissolved organic carbon (DOC). Polymeric flocculants also had the effect of extending filter run length. The modified jar test results indicated that the flocculants used improved the floc strength and enhanced reflocculation of the micro flocs present after the flotation process.     

Particle and microorganism removal in floating plastic media coupled with microfiltration membrane for surface water treatment.

Floating plastic media followed by hollow fiber microfiltration membrane was applied for surface water treatment. The performance of the system in terms of particle and microorganisms was investigated. The floating filter was examined at different filtration rates of 5, 10 and 15 m3/m2 x h. Treated water was then fed into a microfiltration unit where different filtration rates were examined at 0.6, 1.0 and 1.4 m3/m2 x d. It was found that polyaluminum chloride was the best coagulant for the removal of particle, algae and coliform bacteria. Average turbidity in treated water from the floating plastic media filter was 3.3, 12.2 and 15.5 NTU for raw water of 80 NTU and 12.9, 11.7 and 31.2 NTU for raw water of 160 NTU after 6 hours at the filtration rates of 5, 10 and 15 m3/m2 x h, respectively. The microfiltration unit could further reduce the turbidity to 0.2-0.5 NTU with low transmembrane pressure development of 0.3-3.7 kPa. Microfiltration membrane could retain most of algae and coliform bacteria remaining in the effluent from the pretreatment unit. It was found that at higher turbidity, algae and coliform bacteria removal efficiencies were achieved at lower filtration rate of the system of 5 m3/m2 x h whereas a higher filtration rate of 15 m3/m2 x h yielded better coliphage removal.     

Monitoring of coagulation performance and determination of coagulant dosage using a pilot in-line filter.

A rapid method using the pilot in-line filter to detect any change in coagulation performance was a proposed in this study. This method attempted to detect a change in coagulant dosage and mixing intensity by evaluating the filtrate quality of the in-line filter, which took the rapidly mixed water. Since the response time of this method was less than 10 min, it could be valuable to monitor the coagulation performance. The in-line filter was found more useful without underdrain. The in-line filter was more sensitive to a change in filtrate quality without underdrain than with underdrain. A new method, which combines a jar test with the in-line filter, was proposed to determine the coagulant dosage. This method reflected the actual plant situation more accurately than a jar test.     

Pretreatment chemistry for dual media filtration: model simulations and experimental studies.

Laboratory dual media filtration experiments were conducted (a) in direct filtration mode using model raw water moderate in turbidity and low in DOC, and (b) in conventional filtration mode treating water moderate in turbidity and high in DOC. Model simulations of filter performance for the removal of particles provided hypotheses for the experimental studies of dual media filtration. An increase in alum dose in direct filtration mode, while improving filter performance, also showed some disadvantages, including rapid development of head loss. Suboptimal dose in direct filtration significantly impaired the filter performance. In conventional mode, the effect of alum dose on the filter performance, while obvious, was not as dramatic as in direct filtration. Ripening indicated by particle counts occurred earlier than by turbidity and breakthrough of particle counts started earlier than breakthrough of turbidity, suggesting that turbidity can be used as a more conservative monitor of filter performance during the ripening period to minimise the risk of passage of small particles, while particle counts can be considered a more sensitive indicator of deteriorating filter performance during the breakthrough period. The lower sand layer served as a multiple barrier for particle when the performance of the anthracite layer was not effective.     

Screening optimisation for indirect potable reuse

An automatic backflush pre-filter used for pre-treatment for secondary wastewater re-use was evaluated and optimised at two different mesh sizes over an 18 month period. The filter was initially run with a 500 microm rating mesh size, as recommended by the supplier of the downstream membrane filtration process, and then at 100 microm to investigate any change in water quality produced and associated improved membrane performance. With the 500 microm mesh in place, the filter fouling rate was low and a backflush was initiated every 3.5 h. For the 100 microm mesh the fouling rate was extremely rapid. Fouling was found to be caused by reverse side blockage of the pre-filter due to biofilm growth, and not by improved solids capture; there was no improvement in water quality with the smaller mesh size, since particle unloading from the biofilm took place. The pre-filter fouling rate was found to be related to turbidity. At a turbidity of 5 NTU the filter backflushed around 200 times per day, while at 10 NTU this increased to over 300 times. Further analysis enabled the backflush water volume to be decreased by reducing the backflush duration and increasing the backflush cycle time (i.e. the time between backflushes).