Effect of copper(II) on natural organic matter removal during drinking water coagulation using aluminum-based coagulants.

Coagulation has been proposed as a best available technology for controlling natural organic matter (NOM) during drinking water treatment. The presence of heavy metals such as copper(II) in source water, which may form copper-NOM complexes and/or interact with a coagulant, may pose a potential challenge on the coagulation of NOM. In this work, the effect of copper(II) on NOM removal by coagulation using alum or PAX-18 (a commercial polymerized aluminum chloride from Kemiron Inc., Bartow, Florida) was examined. The results show that the presence of 1 to 10 mg/L of copper(H) in the simulated waters improved the total organic carbon (TOC) removal by up to 25% for alum coagulation and by up to 22% for PAX-18 coagulation. The increased NOM removal with the presence of copper(II) in the waters can most likely be ascribed to the formation copper-NOM complexes that may be more adsorbable on aluminum precipitates and to the formation of copper(II) co-precipitates that may also adsorb NOM. The presence of 1 to 5 mg/L of copper(I) in the waters containing 3 mg/L NOM as carbon was reduced below the maximum contaminant level goal (1.3 mg/L as copper) using either coagulant. The results suggest that the presence of copper(H) in source water may not adversely affect the NOM removal by coagulation. A good linear correlation was observed between the TOC removal efficiency and the log-total moles of the precipitated metals, which include the metal ion from a coagulant and the divalent metal ion(s) in source water.     

Effects of polyelectrolytes on reduction of model compounds via coagulation

The objective of this research work was to evaluate the performance of enhanced coagulation by alum and polymer. Synthetic source waters containing high molecular weight humic acids, medium molecular weight tannic acids and low molecular weight p-hydroxybenzoic acid were formulated by adjusting the concentration of turbidity and pH; and jar tests were used to study the effect of various types and dosages of polymer on reducing the above model compounds. At a specific pH condition, the applied alum dosage would efficiently decrease the turbidity to 2 NTU follows the order: humic>tannic>p-hydroxybenzoic acid. Adjustment of pH influenced the performance of alum obviously but not of p-DADMAC. High p-DADMAC dosage overwhelming the effects of alum is less affected by pH adjustment. The results of this investigation reveal that enhanced coagulation with p-DADMAC was founded to be very effective for removing high-molecular-weight THM precursors, i.e., humic acid and tannic acid, and markedly reduced the alum dosages required for turbidity removal. The other two polymers, i.e., cationic PAM and non-ionic PAM, which had higher molecular weight but lower charge density than p-DADMAC, were not capable of removing organic precursors. It was thus concluded that enhanced coagulation with polymer, p-DADMAC, could be considered as a promising technique for removal of NOMs with hydrophobic and higher-molar-mass (>1K) in water treatment plants.     

The exploration of potassium ferrate(VI) as a disinfectant/coagulant in water and wastewater treatment

This paper aims to explore potassium ferrate(VI) (K2FeO4) as an alternative water treatment chemical for both drinking water and wastewater treatment. The performance of potassium ferrate(VI) was evaluated in comparison with that of sodium hypochlorite (NaOCl) and that of NaOCl plus ferric sulphate (FS) or alum (AS). The dosages of ferrate(VI), NaOCl and FS/AS and sample pH values were varied in order to investigate the effects of these factors on the treatment performance. The study demonstrates that in drinking water treatment, ferrate(VI) can remove 10-20% more UV(254)-abs and DOC than FS for the same dose compared for natural pH range (6 and 8). The THMFP was reduced to less than 100 microg l(-1) by ferrate(VI) at a low dose. In addition to this, ferrate(VI) can achieve the disinfection targets (>6 log10 inactivation of Escherichia coliform (E. coli)) at a very low dose (6 mg l(-1) as Fe) and over wide working pH in comparison with chlorination (10 mg l(-1) as Cl2) plus coagulation (FS, 4 mg l(-1) as Fe). In wastewater treatment, ferrate(VI) can reduce 30% more COD, and kill 3log10 more bacteria compared to AS and FS at a similar or even smaller dose. Also, potassium ferrate(VI) can produce less sludge volume and remove more pollutants, which could make sludge treatment easier.     

高铁酸钾预氧化并复合高岭土与PAC絮凝去除水中的颤藻

对高铁酸钾预氧化并复合高岭土与PAC絮凝法除水中颤藻的效果进行了研究。通过正交实验得出了在实验水质条件下,去除颤藻的最佳条件为:高铁酸钾的投加量2.4 mg/L、高岭土24 mg/L、PAC 5 mg/L及pH值为6.5。在此条件下,K2FeO4除藻效果明显优于传统的PAC絮凝工艺。考察了K2FeO4对接种到培养液中的颤藻生长活性的影响,结果表明,随着K2FeO4量的增加,颤藻生长活性抑制时间增长。数码生物显微镜观察表明:K2FeO4在低浓度2.4 mg/L下不能破坏颤藻细胞结构,高浓度50 mg/L下可使其细胞破裂死亡。     

不同工艺对含高浓度腐殖酸地下水处理的可行性

针对内蒙古农村地区高腐殖酸地下水的处理问题,分别对（pH调节）-PAC强化混凝、高锰酸钾预氧化／混凝、活性炭吸附／混凝、Fenton氧化等技术处理的可行性进行了研究,同时利用三维荧光和高效体积排阻色谱分析处理前后水中有机物的组成变化特征。有机分析结果显示,水中的有机物为腐殖酸类物质,分子量分别为1600和3500,腐殖酸类物质为水中色度的主要贡献者。原水PAC强化混凝、高锰酸钾预氧化／PAC混凝对有机物的去除效果不佳,处理前后水样DOC浓度无明显变化,而pH调节．PAC强化混凝、微米活性炭吸附和Fenton氧化均能有效去除有机物。将原水pH调节至6．5,经300mg／LPAC混凝后出水DOC降至5．99mg／L。活性炭投加量为0．6g／L时,DOC降至7．6mg／L,然后采用60mg／LPAC混凝出去高度分散而不易沉降的小颗粒活性炭。此外,当反应初始pH值为3,过氧化氢投加量为0．5％（v／v）,亚铁和双氧水摩尔比为0．05时,出水DOC降至5．6mg／L,氧化后有小分子有机物生成。     

改性粉煤灰和高铁酸钾联合处理矿井水的研究

利用高铁酸钾处理经过改性粉煤灰混凝后的矿井水,形成改性粉煤灰和高铁酸钾联合处理矿井水工艺。研究表明,粉煤灰在使用硫酸改性前后,在投加量为50 g/L,对去除矿井水中浊度的变化是53.18～25.42 NTU,对COD_(Mn)的去除效率也由29%升高到50%;在改性粉煤灰中混入高铁酸钾5 mg/L时,矿井水中浊度和悬浮物分别降到18.3 NTU和10 mg/L,COD_(Mn)去除率为53.23%;此后,上清液中投加高铁酸钾10 mg/L时,水中的浊度由18.3 NTU降到5.1 NTU,悬浮物由10 mg/L降到3 mg/L,COD_(Mn)的总去除率也增加到68.88%。在使用该工艺进行小试时,改性粉煤灰用量为50 g/L,并在其中掺杂高铁酸钾5 mg/L,上清液再用10 mg/L的高铁酸钾处理后,出水水质都优于地表水环境质量Ⅳ级标准。     

混凝-Fenton氧化-Fe0还原预处理高浓度硝基苯生产废水

采用混凝-Fenton氧化-Fe0还原工艺预处理高浓度硝基苯废水,考察各反应阶段硝基苯去除效果及影响因素。研究表明,聚铁混凝性能优于聚铝;初始COD为17 350 mg/L、硝基苯浓度为10 050 mg/L的废水,在pH=4,聚铁投加浓度3 300 mg/L时,COD和硝基苯去除率分别为63%和62%;混凝沉降后的上清液用Fenton试剂氧化,可在较宽pH(3～6)范围内降解硝基苯,当H2O2(30%)浓度为6 000 mg/L,Fe2+浓度为168 mg/L时,氧化效率最高;聚铁混凝-Fenton氧化后的出水用Fe0还原,最佳还原条件为:pH=3,Fe0浓度1 500 mg/L。原水经聚铁混凝-Fenton氧化-Fe0还原后,COD和硝基苯总去除率分别达90%和98%,总药剂成本约12.4元/t。处理后废水硝基苯浓度为168 mg/L,适宜进行后续的厌氧-好氧生物处理。     

Effect of ferrate on green algae removal

Green algae Cladophora aegagropila, present in cooling water of thermal power plants, causes many problems and complications, especially during summer. However, algae and its metabolites are rarely eliminated by common removal methods. In this work, the elimination efficiency of electrochemically prepared potassium ferrate(VI) on algae from cooling water was investigated. The influence of experimental parameters, such as Fe(VI) dosage, application time, pH of the system, temperature and hydrodynamics of the solution on removal efficiency, was optimized. This study demonstrates that algae C. aegagropila can be effectively removed from cooling water by ferrate. Application of ferrate(VI) at the optimized dosage and under the suitable conditions (temperature, pH) leads to 100% removal of green algae Cladophora from the system. Environmentally friendly reduction products (Fe(III)) and coagulation properties favour the application of ferrate for the treatment of water contaminated with studied microorganisms compared to other methods such as chlorination and use of permanganate, where harmful products are produced.

     

二氧化氯杀灭小球藻

实验研究了二氧化氯投加量、小球藻的初始浓度、pH、有机物和氨氮含量对ClO2杀灭来自于水库水的小球藻的影响,考察了ClO2氧化与混凝工艺结合时去除小球藻的效果并对工艺条件进行优化。结果表明,ClO2在投加量1.1 mg/L下,接触10 min,小球藻的杀灭率为71.93%。小球藻的杀灭率随着ClO2投加量的增大和藻初始浓度的升高而提高,随水中有机物含量的增加而显著降低,氨氮含量对小球藻杀灭的效果影响很小。在酸性条件和碱性条件下,小球藻的杀灭率均随pH升高而急剧下降,而在中性至弱碱性区间内,藻的杀灭率随pH升高而缓慢下降。对于某以小球藻为优势藻的供水水库源水,ClO2氧化与混凝工艺结合,藻的去除率高达98.47%。除藻的最佳工艺条件为：二氧化氯投加量为0.5 mg/L,聚合氯化铝为5 mg/L,二氧化氯与混凝剂同时投加。     

超声强化混凝去除蓝藻实验研究

研究了超声波对藻类的混凝去除强化,证明超声波可以快速、高效地提高藻类混凝去除效率,减少混凝剂用量.在混凝剂投加量为0.8 mg/L时,5 s超声处理,藻类去除效果比对照样好30%.同样,藻类去除率都为92%时,5 s超声预处理可以将混凝剂投加量降低至1/3.超声预处理时间对强化混凝效果有很大的影响,在实验条件下,1～5 s的超声处理均可产生满意的结果,1 s为最优、最经济时间,而预处理超过30 s反而降低混凝效果.低频下不同处理频率对超声强化混凝效果影响不大,在80 kHz的频率下,最佳功率为50 W.最佳pH值在8～9范围内.     

基于改性凹凸棒土的强化混凝处理高藻低浊原水工艺

针对水厂低浊高藻水的处理难题,研究了改性凹凸棒土(改性凹土)联合聚合氯化铝(PAC)强化混凝的除藻除浊效果。设计实验原水条件为叶绿素a(chl-a)浓度为98.58~110.35μg/L,浊度(5.6±0.5)NTU。考察了PAC和改性凹土的复配投加量、混凝沉淀时间、pH、投加顺序、搅拌速率等工艺参数对Chl-a和浊度耦合去除效果的影响。结果表明,"PAC+改性凹土"对Chl-a和浊度的去除效果明显优于单投PAC的效果。当PAC投药量12 mg/L,改性凹土投药量10 mg/L,沉淀时间20 min时,对Chl-a和浊度的去除率可分别达到92.5%和89.2%,可至少减少40%的PAC投量,且形成的矾花密实,沉降速度快,去除效率高。最适pH范围为7~8。投加顺序应为先投加改性凹土,混合搅拌转数宜慢速,可控制为50 r/min。     

地表水中隐孢子虫和贾第鞭毛虫微球的混凝去除

以向地表水中投加的隐孢子虫微球和贾第鞭毛虫微球为对象,研究通过对给水混凝工艺对其的去除效果进行比较,着重考察了不同混凝剂种类、投加量及水样pH值对去除效果的影响.结果表明,混凝工艺可较为有效地去除地表水中的两虫微球,去除率最高可达4 lg.相比常规的金属盐类混凝剂,高分子的PAC、PAFC混凝剂对两虫微球的混凝去除率更...     

Biomass-derived materials in the remediation of heavy-metal contaminated water: removal of Cadmium(II) and copper(II) from aqueous solutions

Manganese-coated activated carbon (MCAC) and activated carbon were used in batch experiments for the removal of cadmium(II) and copper(II). Results showed that uptake of Cd(II) and Cu(II) was unaffected by increases in pH (3.0 to 8.5) or concentration (1 to 20 mg/L). Increased ionic strength (from 0.001 to 1 M NaNO3), however, significantly affected the uptake of Cd(II); adsorption of Cu(II) was not affected. Freundlich adsorption isotherm results indicated that MCAC possessed higher sorption capacity than activated carbon. Second-order rate constants were found to be 0.0386 for activated carbon and 0.0633 g/mg x min for MCAC for Cd(II) and 0.0774 for AC and 0.1223 g/mg x min for MCAC for Cu(II). Column experiments showed that maximum sorption capacity of MCAC was 39.48 mg/g for Cu(II) and 12.21 mg/g for Cd(II).     

Effectiveness and kinetics of ferrate as a disinfectant for ballast water

This study examined whether ferrate could meet the international standards for successful ballast water treatment, including final concentrations of less than 1 CFU/mL of Enterococci, less than 2.5 CFU/mL of Escherichia coli, and less than 1 CFU/100 mL of Vibrio cholerae. Pure cultures of E. coli, Klebsiella pneumoniae, and V. cholerae, and a mixed culture of Enterococcus faecium and E. faecilis were grown in saline solution to simulate ballast water and were treated with dosages of ferrate ranging from 0.25 to 5.0 mg/L. A ferrate dose of 5 mg/L resulted in complete disinfection of all organisms tested, and smaller dosages were also very effective. Tailing was consistently observed, and the Hom's model (1972) appeared to most accurately represent the action of ferrate on these organisms. Salinity and pH did not adversely affect results, and regrowth was not a problem. Ferrate shows good potential as an effective disinfectant in the treatment of ballast water.     

Enhanced removal of heavy metals in primary treatment using coagulation and flocculation.

The goal of this study was to determine the removal efficiencies of chromium, copper, lead, nickel, and zinc from raw wastewater by chemically enhanced primary treatment (CEPT) and to attain a total suspended solids removal goal of 80%. Operating parameters and chemical doses were optimized by bench-scale tests. Locally obtained raw wastewater samples were spiked with heavy metal solutions to obtain representative concentrations of metals in wastewater. Jar tests were conducted to compare the metals removal efficiencies of the chemical treatment options using ferric chloride, alum, and anionic polymer. The results obtained were compared with those from other studies. It was concluded that CEPT using ferric chloride and anionic polymer is more effective than CEPT using alum for metals removal. The CEPT dosing of 40 mg/L ferric chloride and 0.5 mg/L polymer enhanced heavy metals removal efficiencies by over 200% for chromium, copper, zinc, and nickel and 475% for lead, compared with traditional primary treatment. Efficient metals capture during CEPT can result in increased allowable headworks loadings or lower metal levels in the outfall.     

高锰酸盐复合药剂强化混凝改善再生水景观湖水质研究

实验通过投加助凝剂以强化混凝沉淀过程,从而达到去除再生水景观水中的藻类。以PAC为混凝剂,高锰酸盐复合药剂(PPC)为预氧化助凝剂,通过烧杯实验确定PPC、PAC同时投加,最佳投量分别为1 mg/L、60 mg/L。生产性实验中,机械加速澄清池强化混凝对TP、叶绿素、藻密度的去除率分别为54%、32.3%和35.4%,湖水中TP、TN逐渐降低分别由4.9 mg/L、23 mg/L降至0.72 mg/L、10.3 mg/L。PPC提高了混凝沉淀对藻类的去除效果,改善了再生水景观湖水质,降低水中氮磷营养盐的含量。     

二氧化氯杀灭小球藻

实验研究了二氧化氯投加量、小球藻的初始浓度、pH、有机物和氨氮含量对ClO2杀灭来自于水库水的小球藻的影响,考察了ClO2氧化与混凝工艺结合时去除小球藻的效果并对工艺条件进行优化。结果表明,ClO2在投加量1.1 mg/L下,接触10 min,小球藻的杀灭率为71.93%。小球藻的杀灭率随着ClO2投加量的增大和藻初始浓度的升高而提高,随水中有机物含量的增加而显著降低,氨氮含量对小球藻杀灭的效果影响很小。在酸性条件和碱性条件下,小球藻的杀灭率均随pH升高而急剧下降,而在中性至弱碱性区间内,藻的杀灭率随pH升高而缓慢下降。对于某以小球藻为优势藻的供水水库源水,ClO2氧化与混凝工艺结合,藻的去除率高达98.47%。除藻的最佳工艺条件为:二氧化氯投加量为0.5 mg/L,聚合氯化铝为5 mg/L,二氧化氯与混凝剂同时投加。     

微波强化Fenton/活性炭工艺处理制药废水的影响因素

为了研究微波强化Fenton/活性炭工艺处理高浓度制药废水的影响因素,以阜新某集团公司生产制药原料排出的废水为研究对象,利用静态实验,采用混凝-微波强化Fenton/活性炭工艺对高浓度制药废水进行实验。实验用水为100 mL、COD为576~1 440 mg/L的制药废水,当活性炭投加量为2 g,H2O2投加量为3/4Qth,pH值为5,微波辐照功率和时间分别为500 W和7 min时,COD去除率可达到92.6%,出水COD在42.6~106.6 mg/L范围内。实验结果表明,活性炭的投加量、H2O2的投加量、pH值、微波辐照功率和辐照时间对微波强化Fenton/活性炭工艺的处理效果影响都较显著。     

高铁酸盐对活性及分散染料的脱色研究

采用湿法制备了高铁酸钾(K₂FeO₄)氧化剂,研究了其对染料活性艳红X-3B(X-3B) 和分散蓝2BLN(2BLN)在不同pH条件下的脱色效果,并对Al₂ (SO₄)₃、K₂FeO₄及O₃对活性及分散染料的脱色效果进行了比较。结果表明：高铁酸钾对活性及分散染料的脱色效果明显, X-3B脱色率随pH的增加不断提高,2BLN脱色率在pH 6～10范围内无明显变化,在pH＝5时达到最大值。在X-3B及2BLN浓度同为100 mg／L,pH分别为10、5, K₂FeO₄浓度分别为100 mg／L和200 mg／L时,BLN及X-3B的脱色率分别达到92.3％和87.3％。在相同条件下,K₂FeO₄对活性艳红X-3B的脱色效果好于Al₂(SO₄)₃和O₃; 而K₂FeO₄对分散蓝2BLN的脱色效果虽比Al₂ (SO₄)₃稍差,但比臭氧的脱色效果要好。同时还研究了K₂FeO₄对活性及分散染料的脱色机理,结果表明： 高铁酸钾对X-3B的脱色依赖于K₂FeO₄的氧化作用,而对的2BLN的脱色则以絮凝为主。     

Coagulation and precipitation as post-treatment of anaerobically treated primary municipal wastewater.

The main objective of this study was to investigate the feasibility of coagulation as a post-treatment method of anaerobically treated primary municipal wastewater. Both mesophilic and ambient (20 degrees C) temperature conditions were investigated in a laboratory-scale upflow anaerobic sludge bed (UASB) reactor. In addition, optimization of the coagulant, both in terms of type and dose, was performed. Finally, phosphorus removal by means of aluminum and iron coagulation and phosphorus and ammonia nitrogen removal by means of struvite precipitation were studied. Anaerobic treatment of primary effluent at low hydraulic retention times (less than 15 hours) resulted in mean chemical oxygen demand (COD) removals ranging from 50 to 70%, while, based on the filtered treated effluent, the mean removals increased to 65 to 80%. Alum coagulation of the UASB effluent gave suspended solids removals ranging from approximately 35 to 65%. Turbidity removal reached up to 80%. Remaining COD values after coagulation and settling were below 100 mg/L, while remaining total organic carbon (TOC) levels were below 50 mg/L. Filterable COD levels were generally below 60 mg/L, while filterable TOC levels were below 40 mg/L. All coagulants tested, including prepolymerized aluminum and iron coagulants, demonstrated similar efficiency compared with alum for the removal of suspended solids, COD, and TOC. Regarding struvite precipitation, optimal conditions for phosphorus and nitrogen removal were pH 10 and molar ratio of magnesium: ammonia-nitrogen: phosphate-phosphorus close to the stoichiometric ratio (1:1:1). During struvite precipitation, removal of suspended solids reached 40%, while turbidity removal reached values up to 80%. The removal of COD was approximately 30 to 35%; yet, when removal of organic matter was based on the treated filterable COD, the removal increased to approximately 65%. In addition, nitrogen was removed by approximately 70%, while phosphorus removal ranged between approximately 30 and 45% on the basis of the initial phosphorus concentration. Finally, size fractionation of the organic matter (COD) showed that the various treatment methods were capable of removing different fractions of the organic matter.