混凝-粉末活性炭吸附-超滤工艺去除砂滤池反洗水溶解性有机物

通过混凝-粉末活性炭(PAC)吸附-浸没式超滤膜(UF)组合工艺去除砂滤池反洗水(FBWW)中溶解性有机物(DOM),以降低后续回用过程中消毒副产物(DBPs)生成量。试验对3种混凝药剂——聚合硫酸铁(PFS)、三氯化铁(FeCl3)、聚合氯化铝(PACl)处理FBWW的效果进行了比较,探讨其对UV254和水溶性有机物(DOC)的去除效果。结果表明,PFS对有机物去除效果优于PACl和FeCl3;PFS与粉末活性炭混合投加可增加有机物去除率,粉末活性炭为20mg/L,PFS为8mg/L时出水浊度为0.85NTU,UV254和DOC去除率分别为43%和31%;采用混凝-PAC吸附-超滤膜(UF)处理FBWW对UV254和DOC去除率分别达到51%和41%,出水浊度为0.19NTU,UV254为0.031cm-1,DOC为2.76mg/L.此工艺可有效降低反冲洗水中DOM含量,达到重新利用净水厂废水的目标.     

高锰酸钾强化混凝/砂滤/超滤组合工艺处理松花江水试验研究

进行中试试验考察了高锰酸钾对混凝/砂滤/超滤组合工艺去除松花江水中污染物的强化效能及对膜渗透性能的影响.结果表明,高锰酸钾可以强化对水中污染物的去除,DOC去除率由21.4%提高到33.4%,UV254去除率由14.2%提高到28.0%,膜出水浊度低于0.1NTU,大于2μm颗粒物少于10个/mL;此外,高锰酸钾可以改善膜渗透性能,延缓了膜通量的降低速率,提高了膜通量.     

粉末活性炭-超滤膜联用去除水体藻类

针对日益严重的水体藻类污染问题,分别选用粉末活性炭(PAC)、超滤(UF)及其组合工艺对富藻水体藻类物质(铜绿微囊藻)去除特性进行研究.实验结果表明,单独的粉末活性炭工艺即使在高投加量情况下(PAC投加量为120 mg/L)对藻类物质去除效果不佳;单独的超滤膜工艺虽然对藻类物质有较好的去除效果(去除率达到95％),但是...     

微絮凝-砂滤-超滤处理淮河原水的试验研究

采用微絮凝-砂滤-超滤工艺对淮河原水进行了中试规模的试验．重点考察预处理条件如滤速和混凝剂投加量的变化对后续膜处理性能的影响．结果表明，试验工艺去除CODMn的效果随着混凝剂投加量的增加而提高．在投加量(大于4mg／L)不变的条件下，滤速的变化不会影响砂滤出水的浊度和CODMn，当投加量为4mg／L时，较高的滤速导致砂滤出水的浊度和CODMn的增加．由于后续超滤膜的截留作用，膜出水的浊度和CODMn令人满意．     

用超滤膜处理长江水

采用混凝-砂滤-超滤膜的联用工艺对长江原水进行了中试研究,结果表明,混凝一砂滤作为预处理能有效地去除大分子的有机物．5个月的试验中,膜压差增长缓慢,实现了长期稳定运行．出水的浊度、CODMn和DOC的平均值分别为0．068NTU,1．23mg／L和1．3mg/L。     

预处理方式对纳滤工艺性能及膜污染影响研究

对比了混凝、活性炭过滤、生物活性炭过滤、超滤膜过滤几种工艺及其组合作为纳滤膜预处理工艺对纳滤工艺整体性能的影响;研究了几种组合工艺对水中总有机物、可生化有机物和氮的去除效果,并分析各自的膜污染特点.结果表明,对水中有机物的去除效果:超滤膜混凝生物活性炭过滤活性炭过滤;对水中氨氮的去除效果:生物活性炭过滤混凝活性炭过滤超滤膜.超滤作为预处理能够有效去除水中有机物,减缓纳滤膜的污染过程,而其它预处理方式单独运用不能有效延缓纳滤膜通量衰减.混凝与生物活性炭组合、混凝与超滤组合以及超滤与生物活性炭组合三种预处理方式能够有效提高预处理过程的效果,有机物和氨氮的去除率分别达到70%和60%以上.     

城市污水COD深度降解技术研究

为了对经过生物处理后COD仍不能达标排放的含不饱和有机化合物的城市污水进行深度降解,采用高纯二氧化氯和复合二氧化氯对该类污水进行选择性氧化,试验结果和工程案例表明:采用高纯二氧化氯处理试验污水时,30mg/L的投加量,常温条件下反应30min,可使污水的COD从87mg/L降到50mg/L以下;采用复合二氧化氯处理试验污水时,10-50mg/L的投加量,常温条件下反应30min,对于去除COD效果并不明显,且去除率在10%以下。经济技术评估表明,采用生物处理和选择性氧化处理组合工艺来处理不饱和有机化合物含量较高的城市污水,有广阔应用前景。     

环境因子对磁性瓜环去除腐殖酸的影响及其稳定性研究

采用紫外可见分光技术研究了磁性瓜环(MQ[n])对水体污染物腐殖酸(HA)的去除性能、稳定性及磁性能。考察了MQ[n]的投加量、HA的初始浓度、溶液温度、作用时间及pH值等因素对去除HA的影响。结果表明,MQ[n]对HA具有很好的去除作用,其中,MQ[n]投加量与pH值对HA的去除效果影响较大。其较优条件为MQ[n]投加量20mg、HA初始质量浓度10 mg/L、吸附温度315 K、平衡时间360 min、pH值7.0,在此条件下,MQ[n]对HA的去除率达到98.73%。MQ[n]稳定性好,且易于磁性分离。     

环境因子对磁性瓜环去除腐殖酸的影响及其稳定性研究

采用紫外可见分光技术研究了磁性瓜环(MQ[n])对水体污染物腐殖酸(HA)的去除性能、稳定性及磁性能。考察了MQ[n]的投加量、HA的初始浓度、溶液温度、作用时间及pH值等因素对去除HA的影响。结果表明,MQ[n]对HA具有很好的去除作用,其中,MQ[n]投加量与pH值对HA的去除效果影响较大。其较优条件为MQ[n]投加量20mg、HA初始质量浓度10 mg/L、吸附温度315 K、平衡时间360 min、pH值7.0,在此条件下,MQ[n]对HA的去除率达到98.73%。MQ[n]稳定性好,且易于磁性分离。     

仿生态Zn/Ti/Fe复合金属氧化物对水中NO3-N的吸附

以棉花为模板,类水滑石为前驱体,制备仿生态Zn/Ti/Fe复合金属氧化物(LDO)并用于水中NO_3-N的去除;考察了吸附时间、投加量、pH和初始浓度等因素对NO_3-N去除效果的影响,分析了吸附行为和机理。利用扫描电镜对样品的形貌进行表征分析。结果表明:棉花模板自身的纤维形态遗留到了LDO上。在25℃下,反应时间为120min,LDO投加量为0.67g/L,NO_3-N浓度50mg/L,pH=7,LDO达到吸附平衡,平衡吸附量为66.57mg/g,NO_3-N去除率为88.76%,出水浓度符合我国《生活饮用水卫生标准》(GB 5749—2006)。LDO对NO_3-N的吸附有较宽的pH范围。LDO吸附NO_3-N的过程符合准二级动力学模型,属于化学吸附。吸附等温线符合Langmuir吸附等温方程,表现为单分子层吸附。再生实验结果表明:LDO在紫外光照射下,再生性能好,可重复使用3次以上。     

Phosphorus removal performance of acid mine drainage from wastewater

Acid mine drainage (AMD) in Yunfu iron sulfide mine contain Fe(2+), Fe(3+), and Al(3+) up to 8000, 1700 and 1200 mg/L, respectively. Phosphorus removal from synthetic wastewater with 10mg/L of total phosphorus (TP) concentration and second municipal effluent with 3.5-4.0mg/L of TP concentration were conducted with the AMD by jar tests. Dosage of the AMD and initial pH of water are the two most important parameters affecting the performance of phosphorus removal of the AMD. The optimal phosphorus removal efficiency and residual iron ions (TFe) concentration are 97.0% and 3.0mg/L, respectively, at 1.61 Fe/P molar ratio and pH 8.03 for synthetic wastewater, and 92.1% and 0.32 mg/L, respectively, for second municipal effluent at 1.41 Fe/P molar ratio and pH 7.3. Resultant heavy metal concentration in effluents and precipitate was very low, and the risk of resultant heavy metal contamination was very small. The phosphorus removal performance of the AMD was much similar to that of ferric sulfate (FS) and polyferric sulfate (PFS), and better than that of FeSO(4). And residual TFe concentration in treated water arising from utilization of the AMD was similar to that of FeSO(4), and higher than that of FS and PFS. The AMD could be used as coagulant for phosphorus removal from wastewater directly due to the presence of Fe(2+), Fe(3+), and Al(3+) largely.     

Degradation characteristics of secondary effluent of domestic wastewater by combined process of ozonation and biofiltration

The performance of the combined process of ozonation and biofiltration was studied for treating the secondary effluent from sewage treatment plant. It was found that COD, NH(3)-N, and TOC were removed from 40-52, 10-19, and 9-13 mg/L in the raw water to 18-23, 0.5-1.5, and 7-8.5 mg/L in the effluent water (removal efficiency were 58, 89, and 25%, respectively), respectively, with an ozone dose of 10 mg/L (0.7-1.1 mg O(3)/(mg TOC) and 0.2-0.25 mg O(3)/(mg COD)), and contacting time of 4 min. Under the operation conditions, ozonation enhanced the biodegradability of the organics in the secondary effluent, as illustrated by increasing biodegradable dissolved organic carbon (BDOC) value from 0.8-1.1 mg/L in the raw water to the 2.0-2.7 mg/L in the effluent water. Meanwhile, the percentage of the organics with molecular size less than 1k Da in the secondary effluent increased from 52.9 to 72.6%. The experimental results supported the expectation that the combined process of O(3)/Biofiltration might enhance the overall treatment efficiency of secondary effluent treatment.     

Removal of bromide by aluminium chloride coagulant in the presence of humic acid

Bromide can form disinfection by-products (DBPs) in drinking water disinfection process, which have adverse effects on human health. Using aluminium chloride as a model coagulant, removal of bromide by coagulation was investigated in the absence or presence of humic acid (HA) in synthetic water and then was conducted in raw water. Results demonstrated that in synthetic water, 93.3-99.2% removal efficiency of bromide was achieved in the absence of HA with 3-15 mg/L coagulant, while 78.4-98.4% removal efficiency of bromide was obtained in the presence of HA with the same coagulant dosage and 86.8-98.8% HA was removed simultaneously. Bromide in raw water was removed 87.0% with 15 mg/L coagulant. HA apparently reduced the removal of bromide with low coagulant dosage or at high pH, while minor influence on removal of bromide was observed with high coagulant dosage or at low pH. Thus, bromide could be reduced effectively by enhanced coagulation in drinking water treatment.     

用混凝-超滤法处理低温低浊水

考察了采用混凝-超滤法处理低温低浊时期松花江水的中试试验效果,并与水厂常规处理水质进行了比较.试验结果表明:混凝-超滤法出水浊度恒低于0.3 NTU;投加20 mg/L聚合氯化铝,超滤膜对CODMn去除率达到50%~58%,膜出水色度为6~8度;此外,投加混凝剂可以使膜渗透性能得以改善.因此混凝-超滤法可以作为低温低浊水处理的有效方法.     

Performance optimization of coagulant/flocculant in the treatment of wastewater from a beverage industry

This study investigated the effect of coagulation/flocculation treatment process on wastewater of Fumman Beverage Industry, Ibadan, Nigeria. The study also compared different dosages of coagulant, polyelectrolyte (non-ionic polyacrylamide) and different pH values of the coagulation processes. The effect of different dosages of polyelectrolyte in combination with coagulant was also studied. The results reveal that low pH values (3-8), enhance removal efficiency of the contaminants. Percentage removal of 78, 74 and 75 of COD, TSS and TP, respectively, were achieved by the addition of 500 mg/L Fe2(SO4)3.3H2O and 93, 94 and 96% removal of COD, TSS and TP, respectively, were achieved with the addition of 25 mg/L polyelectrolyte to the coagulation process. The volume of sludge produced, when coagulant was used solely, was higher compared to the use of polyelectrolyte combined with Fe2(SO4)3.3H2O. This may be as a result of non-ionic nature of the polyelectrolyte; hence, it does not chemically react with solids of the wastewater. Coagulation/flocculation may be useful as a pre-treatment process for beverage industrial wastewater prior to biological treatment.     

AC/O3-BAC processes for removing refractory and hazardous pollutants in raw water

Granular activated carbon (AC)/O(3)-biological activated carbon (BAC) process was employed to treat raw water and compared to O(3)-BAC process in its optimum parameters (3 mg/L ozone dosage with 15 min oxidation time and 15 min empty bed contact time in BAC). The results showed that the presence of AC improved ozone utilization and biodegradability of the effluent. For dissolved organic carbon (DOC) removal, AC/O(3)-BAC was more efficient than O(3)-BAC and its synergetic effect could be noticed. It was showed that small molecules with molecular weight (MW)<3 kDa predominated in the raw water accounting for more than 56% DOC, and their amount increased after oxidation, accounting for more than 64% DOC. Except for organic pollutants with MW>10 kDa, those of other MW range were decomposed better by AC/O(3) process than by O(3) process alone. GC/MS analysis showed that AC/O(3)-BAC process was effective in removing phthalate esters (PAEs) and persistent organic pollutants (POPs). PAEs' removal ratio reached more than 93% and reduced with the increase of the length of the alkyl side chains and the alkyl branch chains. POPs-polybromobiphenyls' removal reached more than 94% except for 2,2',4,5',6-pentabromophenyl and decreased with the substitutional bromines increase except for 2,2',5,5'-tetrabromobiphenyl, which could be completely removed.     

Treatment of olive mill effluents by coagulation-flocculation-hydrogen peroxide oxidation and effect on phytotoxicity

The pre-treatment of olive mill effluents (OME) by means of coagulation-flocculation coupling various inorganic materials and organic poly-electrolytes was investigated. Tests were conducted with two different OME with chemical oxygen demand (COD) contents of 61.1 and 29.3 g/L, total suspended solids (TSS) of 36.7 and 52.7 g/L and total phenolic contents (TP) of 3.5 and 2.5 g/L, respectively. Inorganic materials such as lime, iron, magnesium and aluminum as well as four cationic and two anionic commercial poly-electrolytes were employed either alone or in various combinations and screened with respect to their efficiency in terms of TSS, TP and COD removal, the amount of sludge produced and the phytotoxicity of the resulting liquid to lettuce seeds. Coupling lime or ferrous sulphate (in the range of several g/L) with cationic poly-electrolytes (in the range of 200-300 mg/L) led to quantitative TSS removal, while COD and TP removal varied between about 10-40% and 30-80%, respectively, depending on the materials and the effluent in question; separation efficiency generally decreased with decreasing coagulant and/or flocculant concentration. To enhance organic matter degradation, iron-based coagulation was coupled with H(2)O(2), thus simulating a Fenton reaction and this increased COD reduction to about 60%. The original, untreated OME was strongly phytotoxic to lettuce seeds even after several dilutions with water; however, phytotoxicity decreased considerably following treatment with lime and cationic poly-electrolytes; this was attributed to the removal of phenols and other phytotoxic species from the liquid phase.     

Coagulation/flocculation process and sludge conditioning in beverage industrial wastewater treatment

Attempts were made in this study to examine the effectiveness of coagulation and flocculation process using ferric chloride and polyelectrolyte (non-ionic polyacrylamide) for the treatment of beverage industrial wastewater. Removal of organic matter (expressed as chemical oxygen demand, COD), total phosphorus (TP) and total suspended solid (TSS) using ferric chloride and organic polyelectrolyte during coagulation/flocculation process were investigated. Also, the optimum conditions for coagulation/flocculation process, such as coagulant dosage, polyelectrolyte dosage, and pH of solution were investigated using jar-test experiment. The effect of different dosages of polyelectrolyte in combination with coagulant was also studied. The results revealed that in the range of pH tested, the optimal operating pH was 9. Percentage removals of 73, 95 and 97 for COD, TP and TSS, respectively, were achieved by the addition of 300mg/L FeCl(3).6H(2)O, whereas 91, 99 and 97% removal of COD, TP and TSS, respectively, were achieved with the addition of 25mg/L polyelectrolyte to 100mg/L ferric chloride. The volume of sludge produced, when ferric chloride was used solely, was higher compared to the use of combination of polyelectrolyte and FeCl(3).6H(2)0. The combined use of coagulant and polyelectrolyte resulted in the production of sludge volume with reduction of 60% of the amount produced, when coagulant was solely used for the treatment. It can be concluded from this study that coagulation/flocculation may be a useful pre-treatment process for beverage industrial wastewater prior to biological treatment.     

Disinfection by-product precursors reduction by various coagulation techniques in Istanbul water supplies

Coagulation process can be used to control natural organic matter (NOM) during drinking water production. The effectiveness of the coagulation process appeared to depend on the pH of coagulation rather than coagulant dosages. Jar tests conducted with depressed pH levels at different coagulation conditions removed more dissolved organic carbon (DOC) than those at moderate pH levels. For low DOC waters, like Omerli Lake Water (OLW), additional treatment would be necessary to achieve enhanced removal of NOM. In this study, three different coagulation techniques were used to remove disinfection by-products (DBP) precursors from three Istanbul surface water supplies. Jar test results indicate that optimize coagulation (OC) can enhance the removal of DBP precursors, and the removal of DOC could be improved from the current average of 15% to an average of 56% at the three sites tested. At lower pH, ferric coagulants generally performed better for removal of DBP precursors than did alum.     

TiO2/UV/O3-BAC processes for removing refractory and hazardous pollutants in raw water

TiO2/UV/O3-BAC (biological activated carbon) process was employed to treat raw water and compared to UV/O3-BAC process in its optimum parameters (3 mg/L ozone dosage with 15 min oxidation time and 15 min empty bed contact time in BAC). The results showed that the presence of TiO2 improved ozone utilization and biodegradability of the effluent. For the dissolved organic carbon (DOC) removal, TiO2/UV/O3-BAC was more efficient than UV/O3-BAC and its synergetic effect is more than that in UV/O(3)-BAC process. It was showed that small molecules with MW<3000 Da predominated in the raw water accounting for more than 56% DOC, they were increased after oxidation, accounting for more than 64% DOC. GC/MS analysis showed that TiO2/UV/O3-BAC process was effective in removing phthalate esters (PAEs) and persistent organic pollutants (POPs). PAEs' removal ratio reached more than 94% and reduced with the increase of the length of the alkyl side chains and the alkyl branch chains. TiO2/UV/O3-BAC process was also very effective in removing POPs. Polybromobiphenyls' removal rate reached more than 89% and decreased with the increase of substitutional bromines except for 2,2',5,5'-tetrabromobiphenyl, which can be completely removed.