Electrokinetic characteristic and coagulation behavior of flocculant polyaluminum silicate chloride (PASiC)

The electrokinetic characteristics and coagulation behaviors of polyaluminum silicate chloride (PASiC) and polyaluminum chloride (PAC) were studied and compared by streaming current (SC) measurement and jar test method. The experimental results showed that the interaction between polysilicic acid characterized negative charge and hydrolyzed aluminum species result in a decrease of the charge neutralizing ability of PASiC, compared to PAC. The decrease has a close relationship with the basicity ( B ) and Al/Si molar ratio in PASiC. The less the B value and the Al/Si molar ratio, the lower the charge neutralizing ability of PASiC is. In contrast, the preparation technique for PASiC affects the charge-neutralization of PASiC to a smaller extent. In addition, compared with PAC, PASiC may enhance aggregating efficiency and give better coagulating effects.

Coal Gasification Wastewater Pretreatment with Coagulation and N_2 Flotation Combined System

A N 2 flotation tank combined with coagulation was developed as a pretreatment equipment of biological process to remove oil and other pollutants in coal gasification wastewater( CGW). With optimal PAC dosage of 20 mg / L,the sole coagulation process achieves removal efficiencies of 29. 34% and 26. 83% for oil and COD,respectively. For the sole N 2 floatation process,the optimal N 2 flux and HRT are 20 m3/ h and 20 min. Meanwhile,the oil and COD removal efficiencies are 35. 41% and 14. 26%,respectively. For the combined system of coagulation and N 2 floatation,the optimal parameter values are the same as the ones of separate processes. Correspondingly,the removal efficiencies are 46. 28% and 31. 89% for oil and COD, respectively. Besides,BOD 5 / COD of the effluent is improved. In contrast with conventional dissolved air floatation,the inert gas- N 2 prevents the formation of cyclopentenone, pyridine derivatives, and other heterocyclic aromatic hydrocarbons,thus improving the biodegradability of influent for the subsequent biological processes.

Treating oil wastewater with pulse electro-coagulation flotation technology

Pulse electro-coagulation flotation was used to treat oil wastewater of high oil content.Different operational conditions were examined,including current density,reactive time,electrode distance,pH and pole switching time.Orthogonal tests were carried out to identify the optimal operational conditions for this technique.Considering the treatment cost and efficiency together,the optimal operational conditions were an electrode distance of 3.3 cm,pH of 4,current density of 49.38 mA/cm2,reaction time of 15 min and pole switching time of 10 s.The removal efficiency of oil wastewater under normal conditions reached up to 96.21%.The influences of different factors on removal efficiency were in the following decreasing sequence:pH> current density > pole switching time > reactive time > board distance.

The effect of coupling coagulation and flocculation with membrane filtration in water treatment:A review

Water supply and sanitation demands are foreseen to face enormous challenges over the coming decades to meet the fast growing needs in a global perspective. Significant growth in the industry is predicted and membrane separation technologies have been identified as one of the possible solutions to meet future demands. Application and implementation of membrane technology is expected both in production of potable water as well as in treatment of wastewater. In potable water production membranes are substituting conventional separation technologies due to the superior performance, potential for less chemical use and sludge production, as well as the potential to fulfill hygienic barrier requirements. Membrane bio-reactor （MBR） technology is probably the membrane process which has had most success and has the best prospects for the future in wastewater treatment. Trends and developments indicate that this technology is becoming accepted and is rapidly becoming the best available technology for many wastewater treatment applications. A major drawback of MBR systems is membrane fouling. Studies have shown that fouling mitigation in MBR systems can potentially be done by coupling coagulation and flocculation to the process.

Purification of AS-CMP effluent by combined photosynthetic bacteria and coagulation treatment

The effluent from the pulping of E. urophylla by alkali sodium sulfite chemi mechanical process(AS-CMP) was characterized for its biodegradability by photosynthetic bacteria (PSB). Chemical coagulation post treatment of biotreated wastewater was also studied. One month continuous treatment in the laboratory indicated that the COD Cr , BOD 5 and SS removals in biotreatment stages reached 56%, 83% and 89% respectively, and the CH 2Cl 2 extractives decreased from 10.7 mg/L to 7.7 mg/L. In chemical coagulation post treatment stage, the effects of process conditions, such as coagulant dosage, pH value and the coordinated coagulation flocculation treatment of three kinds of coagulants on coagulation effectiveness were discussed. The optimum operating conditions were given.

Extracting Gold Fines from Pyrite Slag by Hydrophobic Flocculation Flotation

In order to extract gold fines from pyrite slag, the hydrophobic flocculation flotation (HFF) was studied and compared with conventional flotation. The main parameters of HFF such as flotation reagent, surfactant dosage. the duration of agitation and the amount of non-polar oil were investigated, and the effect of non-polar oil was analyzed particularly. It is demonstrated that the HFF is better for gold extraction from pyrite slag than the conventional flotation, and the non-polar oil and the intensive agitation are the key to improve the Au contents and recovery in the concentrate. HFF was used to treat the pyrite slag from the west of Jiangxi province, whose gold contentsare 2.949/t and the size of which are smaller than 10μm. The gold concentrate with gold grade 126.3 g/t and 51 .35% recovery was obtained. Thus, a new method of extracting gold fines from pyrite slag is developed using HFF.

Sludge Density Prediction in a Wastewater Chemical Coagulation Process

This paper reports an approach to estimate the sludge density in a physicochemical treatment of municipal wastewater, experiments considered 4 coagulants (aluminum sulfate SAl, iron sulfate SFe, aluminum polychloride PAX, iron polychloride PIX), and 2 flocculant products (cationic CP and anionic AP polymers). Experimental approach is based on running a set of jar tests at different coagulant concentrations. After the stirring and resting times took place, pH and conductivity were registered finding that SAl and SFe either with or without polymers are the coagulants producing the higher pH drop. Conductivity measures also establish two kind of data since higher conductivity (about 2000 ) was observed for SAl, and PIX, PIX + CP, PIX + AP;otherwise a conductivity about 1300 was observed for SAl + PC, SFe and PAX alone and with CP or AP. Settleable solids (SST) determined with an Imhoff cone were similar for sulfates and polychlorides, but dry sludge (DS) clearly set up two groups the one with higher sludge content corresponds to sulfates group. The quotient of DS divided by the SST provided an estimation of the apparent sludge density, in this way it was observed that higher densities were obtained for sludge from sulfates at lower coagulant concentrations;also sludge from SFe was heavier than the one from SAl. Otherwise, polychlorides produced a lighter sludge in respect to the one obtained with sulfates, and between them the PIX coagulant provided a heavier sludge than the PAX coagulant.

Feasibility Study on the Treatment of Wastewater Containing High-concentration Hg by Coagulation Sedimentation-Adsorption

For the wastewater containing high-concentration Hg,the feasibility of high-concentration Hg in wastewater treated by coagulation sedimentation,adsorption and the combined process was studied. Research results showed that if using the single coagulation sedimentation process,when FeSO_4·7H_2O dosage was 1. 39 g / L,and NaOH dosage was 0. 40 g / L,it could meet discharge requirement,but the reagent cost was 13. 1yuan / t,which was high. Because that there was subsequent adsorption process,it was selected 0. 28 g / L of FeSO_4·7H_2O and 0. 36 g / L of NaOH,and the estimated reagent cost was 2. 62 yuan / t. In selection process of adsorption materials,powdered activated carbon,granular activated carbon and diatomite all could effectively adsorb Hg,and the technology was feasible. When using the combined process of coagulation sedimentation + adsorption to treat the wastewater containing high-concentration Hg( 800 μg / L),removal rate could reach 99%,and operation cost was 2. 71 yuan. It could meet the requirement of sewage discharged into sewer( 20 μg / L) at the technology,and was acceptable at the economy.Therefore,treatment of wastewater containing high-concentration Hg by the combined process was feasible at the aspects of technology and economy.

FLOCCULATION/COAGULATION OF NATURAL ORGANIC MATTER FOR PRETREATMENT OF WATER ANDWASTE WATER

Characterization of water, waste water and natural organic matter are involved in this paper, and as well as the features of flocculation and coagulation for removing natural organic matter from water and waste water Novel flocculant and coagualant is strongly asked for improving removal efficiency and environment friendly. Enhanced coagulation is introduced to meet the experimental and practical requirement.

Nature of (001) and (00) faces and flocculation flotation of kaolinite

Flotation mechanism of kaolinite was investigated through flotation test, SEM analysis and quantum chemical simulation calculation. It is shown that the (001) face of kaolinite easily adsorb cationic collector to exhibit hydrophobicity; the (001) face is easily interacted with the reagent carrying the group of high electronegativity (-O-, -N-, F-) to show hydrophilicity. The cationic and anionic polyacrylamide are adsorbed onto the (001) face of kaolinite and the flocculation of kaolinite particles may take place; the (001) faces are exposed to interact with cationic collector to be rendered hydrophobicity. Thus, the macromolecules can evidently enhance the flotation of kaolinite in alkaline media.

Pilot Study on Powder Active Carbon / Flotation/Microflocculation / Ultrafiltration Combined Process for Treatment of Reservoir Water

[Objective] The study aimed to discover the effects of powder active carbon（ PAC） /flotation /micro-flocculation /ultrafiltration combined process on the treatment of reservoir water. [Method]Taken the water from a mountainous reservoir for the initial samples,the parameters such as turbidity,COD Mn,chlorophyll-a and methylisobormeol（ MIB） of water samples were monitored before and after treated with combined processes of micro-flocculation /ultrafiltration, flotation /micro-flocculation /ultrafiltration, PAC /flotation /micro-flocculation /ultrafiltration. [Result] The results showed that the removal rates of turbidity of water samples by the above three processes were 97. 5%,98. 0% and 98. 6%,respectively. The removal rates of COD Mn were 30. 9%,35. 0% and 52. 0%. The removal rates of chlorophyll-a were 80. 6%,91. 0% and 99. 0%. The removal rates of MIB were 17. 0%,34. 2% and 97. 0%. [Conclusion]The PAC /flotation /micro-flocculation ultrafiltration combined process can be flexibly combined based on the characteristics of algae and odor in water,and is suitable for water plant construction or reconstruction.

Impact of pH Variation on Coag-flocculation Behaviour of Chitin Derived Coag-flocculant in Coal Washery Effluent Medium

This work investigates the influence of pH variation on coag-flocculation kinetics and performance of Chitin Derived Coag-flocculant (CDC) in removal of Suspended and Dissolved Particles (SDP) from Coal washery effluent (CWE) medium. Key parameters such as rate constant Km, half life t1/2,, and pH etc. were investigated. The best coag-flocculation performance is recorded at Km, of 0.007 l/mg.min, t1/2, of 0.0362min, pH of 8, dosage of 100mg/l and efficiency E(%) of 99.933. Minimum efficiency (%) > 94.00 was achieved at 30 minutes of coagflocculation, establishing CDC as an effective water treatment agent at the conditions of the experiment.

微细粒矿物浮选综述:增大颗粒表观尺寸与减小气泡直径

微细粒矿物的浮选回收是世界性难题,增大颗粒表观直径与减小气泡尺寸为解决该难题的有效途径。论文综述了增大颗粒表观直径的四种方法:疏水絮凝浮选、载体浮选、选择性絮凝浮选和剪切絮凝浮选,详细阐述了其在矿物加工领域中的应用及机理,尤其是增大颗粒表观粒径过程中新药剂的最新研究进展及应用领域。从减小气泡尺寸角度出发,以微纳米气泡在矿物加工领域的应用研究为落脚点,阐述了微纳米气泡现有的稳定性机理,为后续微纳米气泡稳定性机理的深入研究提供参考;系统介绍了微纳米气泡在不同种类微细粒矿物浮选中的应用现状;从微纳米气泡与颗粒间界面作用机理出发,详细阐述了微纳米气泡在界面作用中的角色;举例介绍了微纳米气泡浮选设备的研究进展。提出微纳米气泡强化细粒浮选的机理需要进一步明确,基于微纳米气泡、矿浆精准可控的微纳米气泡浮选设备是微细粒矿物浮选的重要研究方向。

基于改性植物单宁生态絮凝-缓释气浮技术的探讨

针对城市水体黑臭现象频发且治理困难的问题,利用接枝共聚法制备获得具有较高分子量和阳离子度的植物单宁絮凝剂(TGCC),以常州市北市河原位黑臭水样为对象,配合使用缓释气浮剂(CR-CP),开展生态絮凝-缓释气浮模拟实验,验证了改性植物单宁生态絮凝-缓释气浮技术的高效性及其应用于城市黑臭河道水质净化的可行性。从“外源污染控制”“水质提升修复”“长效稳定维护”“突发应急处理”4个方面提出了城市黑臭河道治理方案。

Features and mechanism for coagulation－flocculation processes of polyaluminum chloride

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Speciation characterization and coagulation of poly-silica-ferric-chloride:The role of hydrolyzed Fe(Ⅲ) and silica interaction

The highly efficient inorganic polymer flocculants （IPFs） of the ferric-silica system is a new and promising coagulant. Interactions between ferric species and silica play a large part in the coagulation of suspensions. These effects are quite distinct from those associated with polymeric or colloid silica. However, although these species are key to coagulation efficiency, they have not been comprehensively discussed. A new type of coagulant, poly-silica-ferric-chloride （PFSC）, was synthesized by co-polymerization and characterized by time complexation spectroscopy and photon correlation spectroscopy. Compared with traditional ferric salt, the results indicated that PFSC had a higher molecular weight, lesser positive charge, lower Feb and higher Fec. The higher the Si/Fe ratio, the higher the silica and lower the silicac found. The PFSC with appropriate polysilica acid not only obtained better coagulation/flocculation efficiency in turbidity removal, enhanced the flocculation index （FI） and provided less residual ferric, it also lowered water treatment costs compared to traditional ferric salt. Results showed that PFSC could remove colloid particles in water by charge neutralization and sweeping, adsorption bridging mechanism.

Synthesis and evaluation of cationic flocculant P(DAC-PAPTAC-AM) for flocculation of coal chemical wastewater

In this study,a high-efficiency cationic flocculant,P(DAC-MAPTAC-AM),was successfully prepared using UV-induced polymerization technology.The monomer Acrylamide(AM):Acryloxyethyl Trimethyl ammonium chloride(DAC):methacrylamido propyl trimethyl ammonium chloride(MAPTAC)ratio,monomer concentration,photoinitiator concentration,urea content,and cationic monomer DAC:MAPTAC ratio,light time,and power of highpressure mercury lamp were studied.The characteristic groups,characteristic diffraction peaks,and characteristic proton peaks of P(DAC-MAPTAC-AM)were confirmed by fourier transform infrared spectroscopy(FTIR),X-Ray diffraction(XRD),1H nuclear magnetic resonance spectrometer(1H NMR),and scanning electron microscopy(SEM).The effects of dosage,pH value,and velocity gradient(G)value on the removal efficiencies of turbidity,COD,ammonia nitrogen,and total phenol by poly aluminum ferric chloride(PAFC),P(DACMAPTAC-AM),and PAFC/P(DAC-MAPTAC-AM)in the flocculation treatment of coal chemical wastewater were investigated.Results showed that the optimal conditions for the flocculation of coal chemical wastewater using P(DAC-MAPTAC-AM)alone are as follows:dosage of 8-12 mg/L,G value of 100-250 s^-1,and pH value of 4-8.The optimal dosage of PAFC is 90-150 mg/L with a pH of 2-12.The optimal dosage for PAFC/P(DAC-MAPTAC-AM)is as follows:PAFC dosage of 90-150 mg/L,P(DAC-MAPTAC-AM)dosage of 8-12 mg/L,and pH range of 2-6.When P(DAC-MAPTAC-AM)was used alone,the optimal removal efficiencies of turbidity,COD,ammonia nitrogen,and total phenol were 81.0%,35.0%,75.0%,and 80.3%,respectively.PAFC has good tolerance to wastewater pH and good pH buffering.Thus,the flocculation treatment of coal chemical wastewater using the PAFC/P(DAC-MAPTAC-AM)compound also exhibits excellent resistance and buffering capacity.

磁性浮珠VMB@Fe_(3)O_(4)@CS对鱼腥藻和微囊藻的去除

为了有效处理有害藻华,并避免化学物质二次污染,结合磁絮凝与浮珠浮选方法,以玻化微珠、Fe_(3)O_(4)、壳聚糖为原料合成磁浮珠VMB@Fe_(3)O_(4)@CS,对水华鱼腥藻和铜绿微囊藻进行去除实验.结果表明,磁浮珠对2种水华藻的最佳去除效率分别达到99.01%(0.12g/L)、98.6%(0.21g/L).VMB@Fe_(3)O_(4)@CS在较宽的pH值范围(4~10)和水温范围(5℃~35℃)内实现较高的去除率(>60%),离子强度的增加对微藻的去除起负面影响.通过形态学观察、表面疏水率及Zeta电位分析确定静电吸引、吸附架桥是磁浮珠对藻细胞主要的絮凝机理.制备的VMB@Fe_(3)O_(4)@CS去除有害藻华具有很大应用潜力.

微细粒锡石选别难点及浮选药剂应用研究现状

锡资源日益匮乏,微细粒锡石成为一种重要的矿石资源,对其难选、嵌布粒度低等特性及与影响浮选过程的相关因素进行探讨。指出了嵌布粒度和细泥罩盖是影响微细粒锡石浮选的两个关键问题,阐述了难免离子对微细粒锡石浮选的影响。在锡石浮选过程中,不同类型捕收剂和调整剂均对锡石浮选效果有影响,介绍了pH调整剂、活化剂和抑制剂在锡石浮选中的作用,以及絮凝剂与锡石的作用机理。研究浮选药剂的应用现状,可以为提高微细粒锡矿的浮选指标,解决矿物细泥罩盖和难免离子问题提供参考。