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%。     

聚合氯化铝铁强化混凝去除藻类的试验研究

采用聚合氯化铝铁,对微污染黄河水库水进行了强化混凝除藻试验.试验结果表明:针对原水水质,PAFC的最佳投加量为15 mg/L,此时浊度和叶绿素a的去除率分别为94.67 %和80.15 %;PAFC的最佳pH范围是5.0～9.0,试验过程中无需对原水进行调节pH值;投加高分子助凝剂(JY)对原水的浊度、高锰酸盐指数和叶绿素a有一定的去除效果,助凝剂与混凝剂的复配可改善PAFC的混凝去除效果,助凝剂JY的投加量为0.3 mg/L时,叶绿素a的去除率可提高12.9 %.     

聚合氯化铝铁强化混凝去除藻类试验研究

采用聚合氯化铝铁,对微污染黄河水库水进行了强化混凝除藻试验.试验结果表明:针对原水水质,PAFC的最佳投加量为15mg/L,此时浊度和叶绿素a的去除率分别为94.67%和80.15%;PAFC的最佳pH范围是5.0～9.0,试验过程中无需对原水进行调节pH值;投加高分子助凝剂(JY)对原水的浊度、高锰酸盐指数和叶绿素a有一定的去除效果,助凝剂与混凝剂的复配可改善PAFC的混凝去除效果,助凝剂JY的投加量为0.3mg/L时,叶绿素a的去除率可提高12.9%.     

苏南湖库水源地不同季节优势藻种混凝控制试验

苏南湖库水源地不同季节藻类结构存在差别,水厂混凝控藻效率也差异较大。针对苏南湖库水源地春季和夏季分别以硅藻和蓝藻为优势种的特征,分别以实验室培养的微囊藻和针杆藻为对象考察混凝工艺对不同季节优势种藻类的去除效果,以优选混凝工艺控制参数。结果表明:铜绿微囊藻在投加量10 mg/L,温度25℃,p H为8,沉降时间40 min的最佳工艺条件下藻密度、Chl-a、UV254的去除率分别为96.29%、95.11%、96.77%,剩余浊度为0.53 NTU,满足国家饮用水出水浊度标准(1 NTU);尖针杆藻在投加量12 mg/L、温度25℃、p H为8,沉降时间50 min的最佳工艺条件下藻密度、Chl-a、UV254的去除率分别为90.19%、91.99%、89.23%,剩余浊度为1.77 NTU;相比之下,尖针杆藻去除率低于铜绿微囊藻的去除率;水厂控藻工艺应根据不同季节藻类种群特征的差异作相应调整。     

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%。     

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。     

聚合铝盐混凝剂混凝除藻机理与强化除藻措施

针对微污染水处理中藻细胞的去除,研究聚合氯化铝形态分布对混凝除藻效率的影响。结果表明,混凝剂水解产物中,中等聚合物含量影响混凝过程中藻细胞去除率。中等聚合物含量越大,藻细胞去除率越高;在一定条件下,藻细胞去除率与中等聚合物含量线性相关,混凝出水中残铝含量与单体和低聚物含量线性相关。对聚合氯化铝,中等聚合物含量与碱化度线性相关。适量加聚磷酸根、硅酸根可以提高混凝除藻效率,并能显著降低混凝出水中残铝含量,所阐述的混凝除藻机理可以较好地解释实验现象。     

处理高氨氮和高有机物原水的混凝剂选择试验

以受高氨氮、高有机物污染的淀浦河原水为对象，通过混凝沉淀烧杯试验进行了硫酸铝（AS）、聚合氯化铝（PAC）混凝剂使用效果的对比性研究。比较了两者均浊度、色度、UV254、耗氧量的去除效果。研究表明，硫酸铝和聚合氯化铝的去浊最佳投加量分别为45mg／L和30mg／L．在此投加量下，剩余浊度分别降到1．5NTU和1．0NTU以下，UV254去除率均为13．3％，耗氧量去除率分别为33％和35％；当硫酸铝投加量为60mg／L，聚合氯化铝投加量为40mg／L时，色度去除效果最佳，去除率分别为36％和45％。采用最佳投加量时，每吨水使用混凝剂单位成本分别为0．0342元（硫酸铝），0．0456元（聚合氯化铝）。通过技术和经济成本核算结果，认为聚合氯化铝混凝剂更适用于淀浦河原水达到强化混凝效果。     

强化常规工艺处理深圳微污染水源水的试验研究

本文针对深圳微污染水源水的特点及各自来水厂普遍存在的水质问题,利用各种水质评价指标,首次系统地进行了包括强化混凝、强化过滤、化学预氧化和优化消毒为主要内容的强化常规工艺现场试验研究。强化混凝试验结果表明,适当增大无机混凝剂投加量,有机物的去除率可升至20%～40%,综合考虑各种因素,聚合氯化铝是最理想的适合于强化混凝的无机混凝剂。将原水的ｐＨ调至酸性(ｐＨ约65),有助于水中有机物的去除,有机物的去除率可比常规混凝提高10%以上。有机高分子助凝剂必须严格计量,如果目的是提高有机物的去除率,则投加量一般应控制在01ｍｇ/Ｌ…     

强化混凝技术处理南淝河污染水的效果

选用聚合氯化铁(PFC)、聚合硫酸铁(PFS)、聚合氯化铝(PAC)和聚合氯化铝铁(PAFC)作为混凝剂;选用阳离子型聚丙烯酰胺(CPAM)、阴离子型聚丙烯酰胺(APAM)和非离子型聚丙烯酰胺(NPAM)作为助凝剂,通过室内试验对比研究强化混凝技术中多种混凝剂单用及其和助凝剂联用对南淝河污染水的除浊和去污效果,并用于南淝河现场构建的混凝沉淀系统。结果表明,4种混凝剂单用时,PAFC对浊度、TP去除效果最优,对CODMn有良好的去除效果,且不影响原水的p H值,而PFC和PFS单用时可明显降低原水p H值,4种混凝剂单用时对TN均没有明显去除效果;PAFC与CPAM联用时对浊度的去除效果最佳,明显优于PAFC与APAM和NPAM联用和PAFC单用的效果;混凝剂与CPAM联用提高了其除浊和去除TP的能力,但不能明显改善其去除CODMn的效果,对原水p H和TN的影响与单用时相同。选取"PAFC+CPAM"作为南淝河示范工程的混凝剂和助凝剂,现场混凝沉淀出水水质稳定,浊度和TP的去除效果较好,去除率分别达到90%和80%,对CODMn的去除率约为52%,而对TN的去除效果有限,去除率约为22.4%。     

改性沸石粉和聚氯化铝铁联用对藻类去除的研究

采用"改性沸石粉+聚氯化铝铁"联用的强化混凝方法,对水中藻类和浊度的去除进行了研究。考察了改性沸石粉和聚氯化铝铁(PAFC)投加量、药剂投加方式、混凝沉淀时间、pH等因素对除藻去浊效果的影响,并对比分析了强化混凝与预氯化除藻的效果及对三氯甲烷的影响。结果表明,"改性沸石粉+聚氯化铝铁"联用强化混凝方法的除藻去浊效果良好,明显优于单独投加PAFC;将改性沸石粉先于PAFC投加,在适宜的试验条件下,浊度和藻总量的去除率可分别达到85.78%和90.07%;采用强化混凝方法替代预氯化方法除藻,不仅可以提高藻类的去除率,而且不产生预氯化副产物三氯甲烷等"三致"化合物。     

Preliminary evaluation of the performance of new pre-polymerised inorganic coagulants for lowland surface water treatment

This paper is concerned with the performance of relatively new kinds of pre-polymerised inorganic coagulants, poly-alumino-iron-sulphate (PAFS) and polyferric sulphate (PFS). Laboratory experiments were undertaken to evaluate the PAFS and PFS, in comparison with conventional coagulants such as ferric sulphate (FS) and aluminium sulphate (AS), for the coagulation of algal-type model waters and a lowland surface water containing algae and natural organic matter (NOM). Experimental results demonstrated that under the conditions studied, the performance of pre-polymerised coagulants were consistently superior to conventional coagulants (i.e., FS and AS). This is attributed to the presence of a range of pre-formed polymerised species. The coagulation mechanism of PAFS and PFS has been discussed in the paper.     

Influence of type and dose of coagulants on effectiveness of PAH removal in coagulation water treatment

This study evaluated the influence of the type and dose of coagulants on the removal of 16 polycyclic aromatic hydrocarbons (PAHs) in the coagulation process. The effects of coagulant type and dose in reducing water turbidity, colour, and the total content of organic compounds were also assessed. The surface water samples had the turbidity of 9.3–11.2 NTU and colour of 25–35 mg/L. The content of organic compounds determined with total organic carbon (TOC) was 9.2–12.5 mg/L. For the coagulation process, pre-hydrolyzed polyaluminium chloride (PACl) coagulants with basicity values of 41%, 65%, and 85% were used. This shows that water purification performance increased as the basicity of the coagulant increased. When the coagulant with the highest basicity and a dose of 3 mg Al per litre was used, a removal efficiency of 83% in the concentration of benzo(a)pyrene was achieved, and efficiencies for the remaining 15 PAHs ranged from 80% to 91%. These values were 4%–9% higher than those achieved using other coagulants. The removal efficiencies of turbidity, colour, and TOC were 80%, 60%, and 35%, respectively. The water purification performance, including PAH removal, was improved with the increased coagulant dose. Increasing the coagulant dose had more pronounced effects on PAH removal than on the reduction of turbidity and TOC.     

强化混凝技术对南淝河季节性污染物去除效果研究

针对南淝河河口水体夏秋季节藻类的质量浓度高,冬季NH_4~+-N质量浓度异常高的特点,研究强化混凝技术对藻类和NH_4~+-N的去除效果,并应用于南淝河现场构建的混凝沉淀系统。结果表明:混凝剂单独使用时,聚合氯化铝(poly aluminium chloride,PAC)的除藻效果最好,去除率为76%。选用除藻效果较好的阳离子聚丙烯酰胺(cationic polyacrylamide,CPAM)作为助凝剂,藻类的去除率显著增加,均达99%,但对NH_4~+-N的去除效果不佳;聚合氯化铝铁(poly aluminium ferrous chloride,PAFC)与CPAM的组合对NH_4~+-N的去除率最高,为7.54%。通过投加黏土矿物,增加NH_4~+-N的去除率。NaCl与MgCl_2联合改性的凹凸棒与CPAM联用时,对NH_4~+-N的去除率最高达85.65%。选用"PAFC+CPAM"作为南淝河旁路强化混凝系统的投药配方,现场应用时,夏秋季对藻类的去除率平均为88.64%;冬季对NH_4~+-N的去除率平均为24.49%。     

Temperature effects on flocculation, using different coagulants.

Temperature is known to affect flocculation and filter performance. Jar tests have been conducted in the laboratory, using a photometric dispersion analyser (PDA) to assess the effects of temperature on floc formation, breakage and reformation. Alum, ferric sulphate and three polyaluminium chloride (PACI) coagulants have been investigated for temperatures ranging between 6 and 29 degrees C for a suspension of kaolin clay in London tap water. Results confirm that floc formation is slower at lower temperatures for all coagulants. A commercial PACl product, PAX XL 19, produces the largest flocs for all temperatures; and alum the smallest. Increasing the shear rate results in floc breakage in all cases and the flocs never reform to their original size. This effect is most notable for temperatures around 15 degrees C. Breakage, in terms of floc size reduction, is greater for higher temperatures, suggesting a weaker floc. Recovery after increased shear is greater at lower temperatures implying that floc break-up is more reversible for lower temperatures.     

Application of chemical precipitation for piggery wastewater treatment.

Several series of experiments were conducted to investigate the treatment of piggery wastewater using chemical precipitation (CP) where various types of coagulants such as aluminium sulfate (Al2(SO4)3), poly aluminium chloride (PAC), ferric chloride (FeCl3), ferric sulfate (Fe2(SO4)3), ferrous sulfate (FeSO4) and ferrous chloride (FeCl2) were used. Throughout the experiments, CP was found to achieve high removal efficiencies for organic compounds and nutrients (nitrogen and phosphorus) from the piggery wastewater. Experimental results showed the optimal doses of FeCl3, Fe2(SO4)3, FeCl2 and FeSO4 was 2.0 g/L, while 0.31 g/L and 2.5 g/L were the optimum dose for PAC and Al2(SO4)3, respectively. The pH range 4-5 resulted in the best performance to all coagulants except FeCl2 and FeSO4, whose optimum pH were more than 6. Percentage removal efficiencies for COD were in the ranges of 70-80%, 90-95% for SS, 80-90% for organic-N and TP. Those removal efficiencies were achieved within 5 min of operation. Three times of repetition in CP resulted in higher removal efficiencies for COD, SS and colour up to 74%, 99% and 94% respectively, in which Al2(SO4)3 was used as the coagulant. Removal efficiencies of various water quality parameters in a continuously operated reactor were similar to those of the batch experiments. Biodegradable ratios (BOD5/COD) increased up to 65% after the application of CP.     

PDM复合混凝剂处理春季嘉陵江水的应用研究

通过小试考察了聚二甲基二烯丙基氯化铵(PDM)复配硫酸铝(AS)、氯化高铁(FC)、聚氯化铝(PAC)和聚硫酸铁(PFS)以及单独采用PAC处理某水厂春季嘉陵江水源水的效果,选择了复配比例为1:100的PAC-PDM复合混凝剂处理该时期原水。通过对矾花与沉降性能的研究,发现复配比例越低,投药量越少,矾花粒径越小。当矾花粒径达到0.5 mm以上时,矾花的沉降性能较好,且矾花的沉降性能还与矾花的密实程度有很大关系。通过对PAC和PAC-PDM连续生产对比试验研究,在出厂水满足《生活饮用水卫生标准》(GB 5749—2006)要求的情况下,PAC-PDM和PAC的平均投药量分别约为8mg/L和14.3mg/L,在春季该水厂采用PAC-PDM处理嘉陵江原水较单独采用PAC约节省30%混凝剂费用。     

天津滞缓流型城市河网水质时空分布特征

针对天津城市河网滞缓流特点突出、水质变化与天然河流不同的特征,以海河、津河、卫津河、外环河4条重点河道为研究对象,应用聚类分析、因子分析、多元线性回归分析等多元统计分析方法对11个重点河道断面2008年和2009年39周的水质监测指标进行了分析。结果表明:河道断面水质在时间和空间上具有一定的分布特征,时间上,各断面5—8月水质较其他时间更差,氨氮、总磷超标严重;空间上,呈现出从海河到津河、卫津河再到外环河水质逐步下降的特征;海河、津河、卫津河等河道氮磷类汇入是主要污染源,外环河则以有机物污染汇入为主要污染源。