城市废水磁混凝预处理及其表征分析

采用响应面分析法建立 T P、COD去除率与因素（药剂投加量）之间的Central Composite数学模型,对磁混凝工艺进行优化,聚氯化铝（PAC）、聚丙烯酰胺（PAM）和磁粉（MP）最优的药剂投加量分别为319 mg/L、0.44 mg/L、414.16 mg/L ;城市废水 T P、COD 去除率分别达到87.34％、51.03％。通过多种研究手段对磁混凝的过程、絮体形态结构进行表征分析,并与常规混凝工艺进行了对比研究。研究表明磁混凝工艺在处理效率和效果上优于常规混凝,磁絮体结构较普通絮体结构更利于沉淀和分离。     

混凝缓解纳滤膜有机污染研究

对3种混凝剂去除水中有机物的性能进行了对比,确定了适用于纳滤预处理的混凝剂种类。研究了混凝剂投加量、沉淀时间对纳滤膜通量衰减的影响,并对纳滤膜有机污染物的亲水性进行分析。研究结果表明较高的混凝剂投加量能提高有机物的去除率,但混凝剂本身会造成纳滤膜污染,引起通量的下降,而沉淀过程不能完全分离水中的微小絮体。研究还表明混凝过程对水中有机物的去除具有选择性,对疏水性有机物的去除率明显高于亲水性有机物。将混凝与活性炭过滤结合能够显著缓解纳滤通量衰减过程。     

高锰酸钾强化混凝处理洗车废水的研究

混凝工艺是洗车废水处理中必要的工艺环节,其处理程度直接影响到后续工艺的处理效果。采用高锰酸钾预氧化技术可以加强混凝效果,提高有机物的去除率。试验结果表明,投加不同剂量高锰酸钾强化混凝效果都很显著,与单独投加PAC相比,采用高锰酸钾强化混凝可大幅度降低水的浊度,使浊度曲线明显下移。高锰酸钾投加量为2mg/L时,即能有效去除洗车废水中有机物。与低有机物含量废水相比,改变高锰酸钾投加量时,高有机物含量的废水浊度去除率低。随着高锰酸钾投加量的增加,有机物含量高低对浊度去除率的影响减弱。     

强化混凝技术处理东太湖原水研究

在常规混凝工艺确定的最佳处理条件下,考察了单独高锰酸钾(KMnO4)和次氯酸钠(NaClO)预氧化、单独投加粉末活性炭(PAC)以及KMnO4和PAC联用对混凝处理东太湖原水的强化效果。结果表明,聚氯化铝和硫酸铝的最佳投加量分别为20mg/L和30mg/L,聚氯化铝的混凝效果明显优于硫酸铝;投加KMnO4对浊度、CODMn和UV254的去除均有一定程度提高,但不利于原水氨氮的去除;投加PAC有显著的强化混凝作用,各指标去除率均有所提高;KMnO4和PAC联用能进一步提高水中UV254的去除率;预氧化大大提高了混凝对氨氮的去除效果,投加1mg/L NaClO对氨氮去除率可达100%。     

混凝-微滤膜净化微污染水源水的研究

通过改进的烧杯混凝试验确定了混凝 微滤膜组合工艺的混凝剂 (PAC)适宜投加量为 2～ 3mg/L。在该混凝剂投加量条件下 ,进行了混凝 微滤膜组合工艺处理微污染水源水的连续试验。结果表明 ,该工艺对浊度 ,OC以及UV2 54 的去除效率分别为 85%～ 95% ,37%～ 52 %和 58%～ 81% ,优于膜直接过滤时的去除效果     

压力作用后蓝藻混凝沉淀性能研究

为了强化蓝藻混凝沉淀去除效果,采用压力作用后混凝沉淀除藻工艺进行试验,研究加压后蓝藻的沉淀性能。结果表明,未经加压的蓝藻水混凝沉淀后藻类絮体部分上浮;而在试验压力下,随着加压压力增大,蓝藻混凝沉淀后沉降性能变好。经0.4MPa压力作用后混凝沉淀,绝大部分藻类絮体下沉,少量藻类上浮;经0.5~0.7 MPa作用后混凝沉淀,絮体均下沉。经0.7 MPa加压后沉淀速度u≤0.5cm/min、0.5cm/minu≤1.5cm/min、1.5cm/minu≤2.5cm/min、2.5u≤3.5cm/min、u3.5cm/min的藻类占藻类总量的比例分别为10.15%、4.03%、5.31%、6.59%、73.92%,蓝藻去除率为93.89%~96.90%。加压混凝沉淀后蓝藻絮体在沉淀池中稳定,不再上浮。压力作用不会造成藻细胞破裂而导致微囊藻毒素泄漏。     

含腐殖酸低浊原水的改性凹土强化混凝效果分析和参数确定

研究了改性凹土联合聚氯化铝强化混凝耦合去除浊度和腐殖酸的效果。试验原水条件为腐殖酸浓度10mg/L,浊度为(30±1)NTU。采用静态混凝搅拌试验,考察了聚氯化铝和改性凹土的混凝沉淀时间、复配投加量、pH、投加顺序、搅拌速率等工艺参数对腐殖酸和浊度耦合去除效果的影响。结果表明,在强化混凝中,当聚氯化铝投加量为15mg/L,改性凹土投加量为30mg/L,沉淀时间30min,pH=7时,腐殖酸和浊度的同步去除率分别达到95.5%和96.8%,对比单投加聚氯化铝混凝工艺,聚氯化铝投加量可降低25%,并减少沉降时间。     

臭氧组合工艺深度处理酒精废水

研究了混凝-O3、O3-混凝、混凝-H2O2-O3等臭氧组合工艺对某酒精废水的深度处理效果.结果表明:混凝-O3工艺中臭氧的加入同样可以达到单独混凝所达到的出水效果,处理效率高,减少了混凝剂的投加量,从而减少了产泥量;O3-混凝工艺的试验表明,臭氧对混凝存在促进作用,在相同混凝剂和臭氧投加量的条件下,O3-混凝工艺对有机物的去除效果好于混凝-O3工艺;混凝-H2O2-O3工艺中,H2O2的加入提高了臭氧对CODCr的去除效果,H2O2的投加量存在最优值,在本试验中一次性投加H2O2 165 mg/L时CODCr去除率最高,达75%,比未投加H2O2时对CODCr的去除率提高了45%.H2O2分次投加比一次性投加对CODCr的去除率高,同时,随着臭氧投加量的增加,分次投加与一次性投加对CODCr的去除率差距变小.     

强化混凝处理微污染原水的试验研究

混凝是水处理的基本工艺之一,如何提高混凝的效率是饮用水处理的关键。以微污染原水中的有机污染物为对象,对比研究了几种强化混凝工艺的技术特征,结果如下:预氧化、粉末活性炭吸附、助凝剂和回流污泥的方式均能强化混凝的效率,有效提升处理过程中的COD_(Mn)、色度去除率;几种强化混凝工艺的机理不同,预氧化强化混凝是通过氧化作用将大分子有机物转化为分子量较小、疏水性较高的有机物;粉末活性炭吸附强化混凝是利用粉末活性炭对特定分子量的有机物的吸附作用;助凝剂强化混凝沉淀是通过助凝剂提高絮体颗粒尺寸,加速颗粒沉降;污泥强化混凝则是利用回流污泥提供混凝反应的凝聚核心的方式提升混凝的效率,提高COD_(Mn)去除率。     

黄河高浊度水混凝沉淀试验的研究

介绍了高浊度水混凝沉淀时HPAM(水解聚丙烯酰胺 )一次投加、HPAM分步投加、PAC HPAM联合投加的试验。结果表明 :PAC HPAM联合投加与HPAM一次投加相比 ,处理后水的浊度可降低 1 15～ 9 2 7倍 ,有利于去除水中的有机物。并且在沉淀后浊度大致相等时 ,HPAM用量可减少 4 0 %～ 6 0 % ,有利于降低饮用水中单体丙烯酰胺含量和其它有机物 ,保证饮用水水质     

Colloidal silica removal in coagulation processes for wastewater reuse in a high-tech industrial park.

Four experiments of coagulation and flocculation were conducted to investigate the characteristics of colloidal silica removal in a high-tech industrial wastewater treatment plant for reclamation and reuse of the effluent. Experimental results illustrated that poly-aluminium chloride (PACl) showed higher performances on colloidal silica removal than alum. Interestingly, the two coagulants demonstrated the same capacity on silica removal. The specific silica removal capacity was approximately 0.135 mg SiO2/mg Al2O3 when the dosage of coagulants was in the range 30-150 mg/L Al2O3. In addition, the silica was reduced significantly at the condition of pH above 8. Experimental data implied that precipitation of aluminium flocs was the major mechanism for colloid silica removal in PACl and alum coagulation, besides, charge adsorption was also important for improving removal efficiency. Moreover, the addition of polyacrylic acid (PAA) as a flocculant could slightly advance silica removal in the PACl coagulation. The combined PACl/PAA/flocs coagulation was effective for the removal of colloidal silica, soluble COD, and turbidity and also suitable as a pretreatment unit in wastewater reclamation and reuse processes.     

高锰酸钾强化混凝—陶瓷微滤膜集成工艺处理水源水研究

采用高锰酸钾强化混凝—陶瓷微滤膜集成工艺处理水源水,主要考察了不同高锰酸钾投加量对集成工艺中膜污染状况和出水水质的影响。结果表明,在混凝过程中投加高锰酸钾进行预氧化,与单独的混凝—陶瓷微滤膜集成工艺相比,膜污染速率下降,降低了不可逆膜污染;出水水质得到一定程度的提高,其中UV254、CODMn、DOC、TN去除率分别提高了约3%、10%、5%、16%。另外,出水浊度<0.1 NTU,出水颗粒数水平也得到了很大改善。     

高锰酸盐-聚丙烯酰胺联用强化混凝处理太湖支流原水研究

太湖B支流地表水受水土流失、水体富营养化和环境污染等因素影响,水体污染严重,水中有机物浓度和藻密度相对较高。常规的"混凝—沉淀—砂滤—加氯消毒"处理工艺难以有效地去除水中有机物、铁锰、藻类等物质。采用高锰酸盐(PPC)-聚丙烯酰胺(PAM)联用强化混凝工艺对原水进行处理。高锰酸盐投量在0.45 mg/L和聚丙烯酰胺投量在0.07 mg/L条件下联用强化混凝的静态试验结果表明:PPC-PAM联用强化混凝对浊度、色度、铁、锰和耗氧量的平均去除率为90%、73%、92%、99%和38%。PPC在0.3～0.5 mg/L投量和PAM在0.05～0.10 mg/L投量下联用强化混凝生产试验的出厂水浊度、色度、铁、锰等指标,均比历史同期水平要好。     

沼液预处理最优混凝搅拌条件的研究

通过混凝法对沼液进行预处理最优条件的研究,为沼液预处理提供参考。在实验室条件下,对COD、TN、TP、色度和SS的去除率综合评价混凝工艺效果。实验中依次进行混凝剂投加量、助凝剂投加量、pH和搅拌强度的单因素实验,进而通过正交实验确定沼液预处理最优的混凝搅拌条件。试验结果表明:PAC投加量为4 g/L、PAM投加量为50 mg/L、搅拌速度为200 r/min、混凝阶段同时投加PAC和PAM,处理后的水样COD、TN、TP、色度和SS分别为216.20、181.99、0.18、11.77和71.67 mg/L,去除率分别达到92.51%、88.85%、99.75%、98.37%和89.46%,达到畜禽养殖业污染物排放标准(GB18596-2001),减轻了后续污水处理的负荷,为沼液实际处理提供了理论支持。     

Effect of enhanced coagulation by KMnO(4) on the fouling of ultrafiltration membranes

Pre-coagulation enhanced by KMnO(4) before ultrafiltration (KCUF) was compared with normal pre-coagulation by alum (CUF) in the ultrafiltration of water from the Songhua River, China. The trans-membrane pressure (TMP) with KCUF was much lower than that when alum alone was used. With KCUF a slower increment of TMP occurred, even under conditions of high river water turbidity. The results also showed that the removal of COD, UV(254) and TOC was appreciably higher after adding 0.5mg/L KMnO(4) compared with CUF. Although assimilable organic carbon (AOC) was increased by permanganate treatment, the AOC of the permeate from KCUF was nearly the same as that from CUF, showing that the cake layer on the surface of KCUF membrane could adsorb small molecules more effectively than that of CUF. This result was confirmed by the apparent molecular weight (MW) distribution measured by size exclusion chromatography (SEC). It was shown that flocs formed by KMnO(4) and alum were larger than those formed only by alum, causing higher removal of flocs and higher permeation flux. Lower NOM was found in the permeate from the KCUF systems because oxidation and adsorption of organic matter on the flocs occurred. The membrane was partly clogged by organic matter or other materials including some small flocs.     

The duplicity of floc strength.

The breakage of flocs is dependent upon the strength of the bonds holding the aggregate together. The present work describes the breakage and re-growth behaviour of three different types of floc, these were: 1) coagulant precipitate flocs, 2) turbidity flocs and 3) organic matter flocs. Floc aggregates were exposed to increased levels of shear on a conventional jar tester and the sizes of the flocs were observed dynamically using a laser diffraction instrument. The organic flocs showed most resistance to breakage across the whole range of shears under investigation. The dynamic procedure provided detailed information on particle size distributions (PSD). Large and small scale degradation events could be identified from analysis of the PSD data. All of the flocs under investigation showed little re-growth potential after breakage. The precipitate and organic flocs showed slightly better re-aggregation of the small floc sizes.     

Removal of organic impurities in waste glycerol from biodiesel production process through the acidification and coagulation processes

Treatment of waste glycerol, a by-product of the biodiesel production process, can reduce water pollution and bring significant economic benefits for biodiesel facilities. In the present study, hydrochloric acid (HCl) was used as acidification to convert soaps into salts and free fatty acids which were recovered after treatment. The pH value, dosages of polyaluminum chloride (PACl) and dosage of polyacrylamide (PAM) were considered to be the factors that can influence coagulation efficiency. The pH value of waste glycerol was adjusted to a pH range of 3-9. The PACl and PAM added were in the range of 1-6 g/L and 0.005-0.07 g/L. The results showed best coagulation efficiency occurs at pH 4 when dosage of PACl and PAM were 2 and 0.01 g/L. The removal of chemical oxygen demand (COD), biochemical oxygen demand (BOD(5)), total suspended solids (TSS) and soaps were 80, 68, 97 and 100%, respectively. The compositions of organic matters in the treated waste glycerol were glycerol (288 g/L), methanol (3.8 g/L), and other impurities (0.3 g/L).     

Performance of ultrafiltration membrane process combined with coagulation/sedimentation.

Effects of coagulation/sedimentation as a pre-treatment on the dead-end ultrafiltration (UF) membrane process were studied in terms of membrane fouling and removal efficiency of natural dissolved organic matter, using Chitose River water. Two types of experiment were carried out. One was a bench scale membrane filtration with jar-test and the other was membrane filtration pilot plant combined with the Jet Mixed Separator (JMS) as a pre-coagulation/sedimentation unit. In the bench scale experiment, the effects of coagulant dosage, pH and membrane operating pressure on the membrane fouling and removal efficiency of natural dissolved organic matter were investigated. In the pilot plant experiment, we also investigated the effect of pre-coagulation/sedimentation on the membrane fouling and the removal efficiency of natural dissolved organic matter. Coagulation/sedimentation prior to membrane filtration process controlled the membrane fouling and increased the removal efficiency of natural dissolved organic matter.     

The effects of polymer characteristics on nano particle separation in humic substances removal by cationic polymer coagulation.

Removal of humic substances by coagulation involves nano- and microparticle transport processes. The objective of this paper has been to describe the effects of polymer characteristics on the initial coagulation of nano-sized humic substances and on the aggregates' ability to form larger flocs. The study offers a direct comparison of four different low molecular weight polycations, with charge densities ranging from 4.0 to 7.0 meq/g, as well as of a low and medium molecular weight cationic polyacrylamide with practically equal charge densities. The extent of coagulation of humic substances, determined as the percentage removal of humic substances after filtration through 0.1 microm, could, regardless of the polymer type, be explained by the amount of cationic charge equivalents added per mg TOC of humic substances. The optimal polymer dosage with respect to the extent of flocculation, determined as the percentage removal after filtration through 11 microm could not be explained by this, but the maximum extent of flocculation obtained with each polymer type increased with increasing polyelectrolyte charge density. However, the weak polycation chitosan showed a significantly higher maximum extent of flocculation than would be predicted from its charge density. Polyelectrolyte molecular weight did not show any significant effect on the coagulation of humic substances, nor did it increase the extent of floc separability at 11 microm.     

The relationship between the structure of activated sludge flocs and the sorption of hydrophobic pollutants

The relationships between the structure of minimally perturbed activated sludge flocs and the sorption of organic contaminants were studied. Sorption, settling velocity, size distributions, floc structure and EPS composition were all examined. The results show significant removal of selected halogenated hydrocarbons and polycyclic aromatic hydrocarbons by biosorption to activated sludge flocs. However, statistically significant effects on the settling or size of the flocs caused by this sorption were not observed. The addition of chromium (Cr(III)) metal ions to the biomass caused observable changes in the floc structure and decreased ruthenium red binding to the acidic polysaccharides of the floc matrix. At low concentrations (0.6 mg/1), chromium caused an increase in the sorption of organic compounds to flocs, suggesting that changes in the floc structure can be induced, which can have an impact on the sorption of pollutants to the flocs.