[Dry goods] The history of the most complete wastewater treatment commonly used pharmaceutical summary, after reading the decisive collection!
来源：From the network Release time:2022-06-20 Number of readings:
1.What are the types of chemicals commonly used in wastewater treatment？In order to make the wastewater discharged or reused after treatment, a variety of chemical agents need to be used in the treatment process。Depending on their use, these agents can be divided into the following categories:
⑴絮凝剂：有时又称为混凝剂，可作为强化固液分离的手段，用于初沉池、二沉池、浮选池及三级处理或深度处理等工艺环节。
(2) Coagulant aid: auxiliary flocculants play a role in strengthening the coagulation effect。⑶调理剂：又称为脱水剂，用于对脱水前剩余污泥的调理，其品种包括上述的部分絮凝剂和助凝剂。⑷破乳剂：有时也称脱稳剂，主要用于对含有乳化油的含油废水气浮前的预处理，其品种包括上述的部分絮凝剂和助凝剂。(5) Defoamer: mainly used to eliminate a large number of bubbles in the process of aeration or agitation。(6) pH regulator: used to adjust the pH value of acidic wastewater and alkaline wastewater to neutral。Oxidizing reducing agent: used for the treatment of industrial wastewater containing oxidizing or reducing substances。(8) Disinfectant: Used to disinfect wastewater after treatment before discharge or reuse。
以上药剂的种类虽然很多，但一种药剂在不同的场合使用，起到的作用不同，也就会拥有不同的称呼。For example, Cl2 is called a coagulant when it is used to enhance the coagulant treatment effect of sewage, it is called an oxidant when it is used to oxidize cyanide or organic matter in wastewater, and it is naturally called a disinfectant when it is used for disinfection treatment。
2.What is a flocculant？What is its role？
As a means of strengthening solid-liquid separation in the field of sewage treatment, flocculants can be used to strengthen the primary precipitation of sewage, flotation treatment and secondary precipitation after activated sludge method, and can also be used for tertiary treatment or advanced treatment of sewage。When used for conditioning of residual sludge before dewatering, flocculants and coagulants become sludge conditioners or dehydrating agents。
In the application of traditional flocculant, the method of adding coagulant aid can be used to enhance the flocculation effect。例如把活化硅酸作为硫酸亚铁、硫酸铝等无机絮凝剂的助凝剂并分前后顺序投加，可以取得很好的絮凝作用。因此，通俗地讲，无机高分子絮凝剂IPF其实就是把助凝剂与絮凝剂结合在一起制备然后合并投加来简化用户的操作。Coagulation treatment is usually placed in front of the solid-liquid separation facility, combined with the separation facility, effectively remove the suspended matter and colloidal matter with a particle size of 1nm ~ 100μm in the raw water, reduce the turbidity of the effluent and CODCr, which can be used in the pretreatment and advanced treatment of the sewage treatment process, and can also be used for residual sludge treatment。Coagulation treatment can also effectively remove microorganisms and pathogens in water, and can remove emulsified oil, chroma, heavy metal ions and some other pollutants in sewage. The removal rate of phosphorus contained in sewage can be as high as 90 ~ 95% when using coagulation precipitation treatment, which is the cheapest and efficient phosphorus removal method。3.What is the mechanism of action of flocculants？水中胶体颗粒微小、表面水化和带电使其具有稳定性，絮凝剂投加到水中后水解成带电胶体与其周围的离子组成双电层结构的胶团。采用投药后快速搅拌的方式，促进水中胶体杂质颗粒与絮凝剂水解成的胶团的碰撞机会和次数。水中的杂质颗粒在絮凝剂的作用下首先失去稳定性，然后相互凝聚成尺寸较大的颗粒，再在分离设施中沉淀下去或漂浮上来。
搅拌产生的速度梯度G和搅拌时间T的乘积GT可以间接表示在整个反应时间内颗粒碰撞的总次数，通过改变GT值可以控制混凝反应效果。Generally, the GT value is controlled between 104 and 105. Considering the impact of impurity particle concentration on collision, GTC value can be used as a control parameter to characterize coagulation effect, where C represents the mass concentration of impurity particles in sewage, and it is recommended that GTC value be about 100。
The process of promoting the flocculant to spread rapidly into the water and mix evenly with all the wastewater is mixing。水中的杂质颗粒与絮凝剂作用，通过压缩双电层和电中和等机理，失去或降低稳定性，生成微絮粒的过程称为凝聚。凝聚生成微絮粒在架桥物质和水流的搅动下，通过吸附架桥和沉淀物网捕等机理成长为大絮体的过程称为絮凝。混合、凝聚和絮凝合起来称为混凝，混合过程一般在混合池中完成，凝聚和絮凝在反应池中进行。
4.What are the types of flocculants？絮凝剂是能够降低或消除水中分散微粒的沉淀稳定性和聚合稳定性，使分散微粒凝聚、絮凝成聚集体而除去的一类物质。According to the chemical composition, flocculants can be divided into inorganic flocculants, organic flocculants and microbial flocculants three categories。
Inorganic flocculants include aluminum salts, iron salts and their polymers。Organic flocculants can be divided into anionic type, cationic type, non-ionic type and amphoteric type according to the charge properties of the charged group of polymeric monomers, and can be divided into two categories of synthetic and natural polymer flocculants according to their sources。在实际应用中，往往根据无机絮凝剂和有机絮凝剂性质的不同，把它们加以复合，制成Inorganic organic compound絮凝剂。微生物絮凝剂则是现代生物学与水处理技术相结合的产物，是当前絮凝剂研究发展和应用的一个重要方向。
5.What are the types of inorganic flocculants？The traditional inorganic flocculants are low molecular weight aluminum salt and iron salt，Aluminum salts are mainly aluminum sulfate (AL2(SO4)3∙18H2O), AL2(SO4)3∙K2SO4∙24H2O), sodium aluminate (NaALO3).，铁盐主要有三氯化铁(FeCL3∙6H20)、硫酸亚铁(FeSO4∙6H20)和硫酸铁(Fe2(SO4)3∙2H20)。
一般来讲，无机絮凝剂具有原料易得，制备简便、价格便宜、处理效果适中等特点，因而在水处理中应用较多。6.What are the characteristics of inorganic flocculant aluminum sulfate？自19世纪末美国最先将硫酸铝用于给水处理并取得专利以来，硫酸铝就以卓越的凝聚沉降性能而被广泛应用。硫酸铝是目前世界上使用最多的絮凝剂，全世界年产硫酸铝约500万吨，其中将近一半用于水处理领域。Aluminum sulfate on the market has two forms of solid and liquid, solid and according to the content of insoluble matter is divided into refined and crude two, China's folk often used for drinking water purification of solid products alum, is aluminum sulfate and potassium sulfate double salt, but in industrial water and wastewater treatment applications are not much。
The pH range applicable to aluminum sulfate is related to the hardness of raw water, and the appropriate pH value is 5 to 6 when treating soft water.6, when dealing with medium hard water, the appropriate pH value is 6.6～7.2, treat high hard water, suitable pH value of 7.2～7.8。The applicable water temperature range of aluminum sulfate is 20oC ~ 40oC, and the coagulation effect is very poor when it is lower than 10oC。Aluminum sulfate is less corrosive and easy to use, but the hydrolysis reaction is slow, and a certain amount of alkali needs to be consumed。Seven.What are the characteristics of inorganic flocculant ferric chloride？三氯化铁是另一种常用的无机低分子凝聚剂，产品有固体的黑褐色结晶体，也有较高浓度的液体。其具有易溶于水，矾花大而重，沉淀性能好，对温度、水质及pH的适应范围宽等优点。三氯化铁的适用pH值范围是9～11，形成的絮体密度大，容易沉淀，低温或高浊度时效果仍很好。固体三氯化铁具有强烈的吸水性，腐蚀性较强，易腐蚀设备，对溶解和投加设备的防腐要求较高，具有刺激性气味，操作条件较差。
The action mechanism of ferric chloride is to use various hydroxyl iron ions generated by step-by-step hydrolysis of trivalent iron ions to achieve flocculation of impurity particles in water, and the formation of hydroxyl iron ions requires the use of a large number of hydroxyl groups in water, so a large amount of alkali will be consumed during the use of the process, when the raw water alkalinity is not enough, it is necessary to supplement lime and other alkali sources。硫酸亚铁俗称绿矾，形成絮凝体快而稳定，沉淀时间短，适用于碱度高、浊度大的情况，但色度不易除净，腐蚀性也较强。8.What are the types of inorganic polymer flocculants？无机高分子絮凝剂（IPF）是从60年代起发展起来的新型絮凝剂，目前，IPF的生产和应用在全世界都取得了迅速进展。The inorganic polymer flocculants of aluminum, iron and silicon are actually the intermediate products of their hydrolysis, sol and precipitation processes respectively, that is, the hydroxyl and oxyl polymers of Al(Ⅲ), Fe(Ⅲ) and Si(Ⅳ)。铝和铁是cationic荷正电，硅是Anionic type荷负电，它们在水溶态的单元分子量约为数百到数千，可以相互结合成为具有分形结构的集聚体。Their agglomeration-flocculation process is a comprehensive reflection of the electric neutralization and adhesion bridging of particles in water。The particle size of suspended particles in water is in the nanometer to micron level, most of them carry negative charge, so the charge positive and negative of the flocculant and its form, the strength of electricity and molecular weight, and the particle size of the aggregate are the main factors determining its flocculation effect。At present, there are dozens of types of inorganic polymer flocculants (the main varieties are shown in Table 8-1), and the output has reached 30% to 60% of the total output of flocculants, of which polyaluminum chloride is widely used。
Table 8-1 Categories and varieties of inorganic polymer flocculants commonly used | Polyaluminum chloride (PAC, PACL), polyaluminum sulfate (PAS), polyferric chloride (PFC), polyferric sulfate (PFS), polyaluminum phosphate (PAP), polyiron phosphate (PEP) |
| Activated silica (AS), polymerized silica (PS) |
| Polyaluminium ferric chloride (PAFC)，Polyferric Aluminum sulfate (PAFS)，Polymerized aluminum silicate (PASiC，PASiS)，Polymerized iron silicate (PFSiC)，PFSiS)，Polymerized aluminum ferric silicate (PAFSi)，Polyferric aluminum phosphate (PAFP)，Aluminum chloride polyphosphate (PAPCL)，Polychlorinated aluminum sulfate (PASCL)，Polychlorinated aluminum ferric sulfate (PAFSCL)，Polycompound calcium aluminate，Polyaluminum silicate sulfate (PSiAS) |
| Inorganic organic compound | Polyaluminum-polyacrylamide (PACM), Polyiron-polyacrylamide (PFCM), Polyaluminum-cationic Organic Polymer (PCAT), Polyiron-cationic Organic Polymer (PCFT), Polyaluminum-chitin (PAPCh) |
| Polyaluminum chloride (PAC, PACL), polyaluminum sulfate (PAS), polyferric chloride (PFC), polyferric sulfate (PFS), polyaluminum phosphate (PAP), polyiron phosphate (PEP) |
| Activated silica (AS), polymerized silica (PS) |
| Polyaluminium ferric chloride (PAFC)，Polyferric Aluminum sulfate (PAFS)，Polymerized aluminum silicate (PASiC，PASiS)，Polymerized iron silicate (PFSiC)，PFSiS)，Polymerized aluminum ferric silicate (PAFSi)，Polyferric aluminum phosphate (PAFP)，Aluminum chloride polyphosphate (PAPCL)，Polychlorinated aluminum sulfate (PASCL)，Polychlorinated aluminum ferric sulfate (PAFSCL)，Polycompound calcium aluminate，Polyaluminum silicate sulfate (PSiAS) |
| Inorganic organic compound | Polyaluminum-polyacrylamide (PACM), Polyiron-polyacrylamide (PFCM), Polyaluminum-cationic Organic Polymer (PCAT), Polyiron-cationic Organic Polymer (PCFT), Polyaluminum-chitin (PAPCh) |
9.What are the characteristics of inorganic polymer flocculants？The hydroxyl and oxyl polymers of Al(Ⅲ), Fe(Ⅲ) and Si(Ⅳ) are further combined into aggregates, which are kept in aqueous solution under certain conditions, and their particle size is roughly in the nanoscale range, so that the coagulation and flocculation effect can be achieved with low dosage and high effect。若比较它们的反应聚合速度，由Al→Fe→Si是趋于强烈的，同时由羟基桥联转为氧基桥联的趋势也按此顺序。Therefore, the reaction of aluminum polymer is more moderate and the form is more stable, the hydrolyzed polymer of iron reacts quickly and is easy to lose stability and precipitate, and the silicon polymer tends to generate sol and gel particles。
IPF的优点反映在它比传统絮凝剂如硫酸铝、氯化铁的效能更优异，而比有机高分子絮凝剂（OPF）价格低廉。现在它成功地应用在给水、工业废水以及城市污水的各种处理流程，包括预处理、中间处理和深度处理中，逐渐成为主流絮凝剂。但是，在形态、聚合度及相应的凝聚—絮凝效果方面，无机高分子絮凝剂仍处于传统金属盐絮凝剂与有机高分子絮凝剂之间的位置。其分子量和粒度大小以及絮凝架桥能力仍比有机絮凝剂差很多，而且还存在对进一步水解反应的不稳定性问题。These weaknesses of IPF have promoted the research and development of various composite inorganic polymer flocculants。10.What are the characteristics of polyaluminum chloride？Polyaluminum chloride (PAC), also known as basic aluminum chloride, chemical formula ALn(OH)mCL3n-m。PAC is a polyvalent electrolyte, which can significantly reduce the colloidal charge of clay-like impurities (mostly negatively charged) in water。Due to the large molecular weight and strong adsorption capacity, the flocculant formed is larger, and the flocculation precipitation performance is better than other flocculants。PAC has a high degree of polymerization and rapid stirring after addition can greatly shorten the formation time of flocculant。PAC is less affected by water temperature, and the effect is also very good when the water temperature is low。它对水的pH值降低较少，适用的pH范围宽(可在pH=5～9范围内使用)，故可不投加碱剂。PAC的投加量少，产泥量也少，且使用、管理、操作都较方便，对设备、管道等腐蚀性也小。Therefore, PAC has a trend of gradually replacing aluminum sulfate in the field of water treatment, and its disadvantage is that the price is higher。
In addition, from the point of view of solution chemistry, PAC is a kinetic intermediate product of aluminum brine hydrolysis - polymerization - precipitation reaction process, which is thermodynamically unstable, and the general liquid PAC products should be used within half a year。添加某些无机盐（如CaCl2、MnCl2等）或高分子（如聚乙烯醇、聚丙烯酰胺等）可提高PAC的稳定性，同时可增加凝聚能力。From the production process，Introduction of one or more different anions (e.g. SO42-, PO43-, etc.) in the manufacturing process of PAC，The structure and morphological distribution of the polymer can be changed by increasing polymerization，To improve the stability and efficacy of PAC;If other cationic components are introduced in the manufacturing process of PAC，Such as Fe3+，The cross-hydrolysis polymerization of Al3+ and Fe3+ was made，A composite flocculant polyaluminum-iron can be prepared。三氧化二铝含量是聚合氯化铝有效成分的衡量指标，一般而言，絮凝剂产品密度越大，三氧化二铝含量越高。一般来说，碱化度越高的聚合氯化铝吸附架桥能力越好，但因接近[Al(OH)3]n而易产生沉淀，因此稳定性也较差。11. What is the alkalinity of PAC？Since polyaluminum chloride can be regarded as an intermediate product in the process of gradual hydrolysis of AlCl3 into Al(OH)3, that is, Cl- is gradually replaced by hydroxyl OH-。聚合氯化铝的某种形态中羟基化程度就是碱化度，碱化度是聚合氯化铝中羟基当量与铝的当量之比。
Practice shows that the degree of alkalinity is one of the most important indicators of polyaluminum chloride, and the degree of polymerization, charge, coagulation effect, pH value of the finished product, dilution rate in use and storage stability of polyaluminum chloride are closely related to the degree of alkalinity。The alkalization degree of commonly used polyaluminum chloride is mostly 50% ~ 80%。12.What are the characteristics and precautions for the use of composite flocculants？The composite flocculant has various components, and its main raw materials are aluminum salt, iron salt and silicate。In terms of manufacturing process, they can be separately hydroxylated and polymerized in advance, or they can be mixed and then hydroxylated and polymerized, but in the end, it is always necessary to form an inorganic polymer form of higher polymerization degree of hydroxylation to achieve excellent flocculation effect。复合剂中每种组分在总体结构和凝聚—絮凝过程中都会发挥一定作用，但在不同的方面，可能有正效应，也可能有负效应。
IPF products usually consider three factors: stability, electric neutralization capacity and adsorption bridging capacity。The weakness of polymeric aluminum and polymeric iron flocculants is that the molecular weight and particle size are not high enough and the adhesion bridging ability of aggregates is not strong enough, so it is necessary to add silica polymers with larger particle size to enhance the flocculation performance。However, after the addition of anionic silicon polymers, the overall charge will be reduced, thus weakening the electric neutralization ability。因此，目前的复合絮凝剂即使制造质量优良，与聚合铝相比，其效果只能提高10～30%。作为使用IPF的废水处理技术人员，必须了解不同种类复合絮凝剂的特性、适应性、优点及不足是同样重要的。在选用最合适的絮凝剂和投加工艺操作程序时，只有根据废水水质特点，仔细分析和判断，才能获得最佳的处理效果。13.What are the types of synthetic organic polymer flocculants？Synthetic organic polymer flocculants are mostly polypropylene, polyethylene substances, such as polyacrylamide, polyethylene imide and so on。这些絮凝剂都是水溶性的线型高分子物质，每个大分子由许多包含带电基团的重复单元组成，因而也称为聚电解质。A cationic polyelectrolyte containing a positively charged group, and an anionic polyelectrolyte containing a negatively charged group, which contains both a positively charged and a negatively charged group, are called non-ionic polyelectrolytes。
目前使用较多的高分子絮凝剂是Anionic type，它们对水中负电胶体杂质只能发挥助凝作用。Often can not be used alone, but with aluminum salt, iron salt use。Cationic flocculants can play both flocculation and flocculation at the same time and can be used alone, so they have been developed rapidly。At present, polyacrylamide non-ionic polymers are commonly used in China, which are often combined with iron and aluminum salts。利用铁、铝盐对胶体微粒的电性中和作用和高分子絮凝剂优异的絮凝功能，从而得到满意的处理效果。Polyacrylamide in use has the characteristics of less dosage, fast coagulation rate, large and strong flocculant particles。At present, 80% of the synthetic organic polymer flocculants produced in China are this product。14.What are the characteristics of polyacrylamide flocculants？聚丙烯酰胺PAM是一种目前应用最广泛的人工合成有机高分子絮凝剂，有时也被用作助凝剂。聚丙烯酰胺的生产原料是聚丙烯腈CH2＝CHCN，在一定条件下，丙烯腈水解生成丙烯酰胺，丙烯酰胺再通过悬浮聚合得到聚丙烯酰胺。Polyacrylamide is a water-soluble resin, and the product has two kinds of granular solid and a certain concentration of viscous aqueous solution。
The actual existence of polyacrylamide in water is the random wire group, because the random wire group has a certain particle size, and there are some amide groups on its surface, so it can play the corresponding bridging and adsorption capacity, that is, it has a certain flocculation capacity。But because of the polyacrylamide long chain curled into a ball，Make its bridge range smaller，After the two amides are concluded，It is equivalent to the loss of two adsorption sites because the effects cancel each other，In addition, part of the amide base is embedded in the interior of the online group structure，Cannot contact and adsorb with impurity particles in water，So its adsorption capacity can not be fully developed。In order to separate the amide groups concluded together again and expose the embedded amide groups to the surface, people try to extend the random wire groups appropriately, and even try to add some cationic or anionic groups on the long molecular chain, while improving the adsorption bridging capacity and the role of electric neutralization and compression of the double electric layer。In this way, a series of polyacrylamide flocculants or coagulants with different properties have been derived on the basis of PAM。For example, by adding a base to the polyacrylamide solution, the amide group on part of the chain is converted to sodium carboxylate, and sodium carboxylate is easy to dissociate sodium ions in water, so that the COO- group remains on the branch chain, so that the partially hydrolyzed anionic polyacrylamide is generated。The COO- group on the molecular structure of anionic polyacrylamide makes the molecular chain with negative charge, repel each other and pull apart the amide group originally concluded together, prompting the molecular chain to gradually extend from the wire group to the chain, thus expanding the bridging range and improving the flocculation ability, and its advantages as a coagulant are more excellent。Anionic type聚丙烯酰胺的使用效果与其“水解度”有关，“水解度”过小会导致混凝或助凝效果较差，“水解度”过大会增加制作成本。Fifteen.What is the degree of hydrolysis of anionic polyacrylamide？The "degree of hydrolysis" of anionic polyacrylamide is the percentage of the amide group converted into carboxyl group in the PAM molecule during hydrolysis, but because the carboxyl group number is difficult to determine, the "hydrolysis ratio" is commonly used in practical applications, that is, the weight ratio of the amount of sodium hydroxide and the amount of PAM during hydrolysis。
水解比过大，加碱费用较高，水解比过小，又会使反应不足、Anionic type聚丙烯酰胺的混凝或助凝效果较差。Generally, the hydrolysis ratio is controlled at about 20%, and the hydrolysis time is controlled at 2 ~ 4h。16.What are the factors affecting the use of flocculants？水的pH值对无机絮凝剂的使用效果影响很大，pH值的大小关系到选用絮凝剂的种类、投加量和混凝沉淀效果。水中的H+和OH-参与絮凝剂的水解反应，因此，pH值强烈影响絮凝剂的水解速度、水解产物的存在形态和性能。Taking aluminum salts that achieve coagulation by forming Al(OH)3 charged colloid as an example, when pH value <4, Al3+ cannot be hydrolyzed to Al(OH)3 in large quantities, mainly in the form of Al3+ ions, and the coagulation effect is very poor。The pH is 6.5～7.When between 5, Al3+ was hydrolyzed and polymerized into Al(OH)3 neutral colloid with high degree of polymerization, and the coagulation effect was good。After pH >8, Al3+ hydrolyzes to AlO2-, and the coagulation effect becomes very poor again。
The alkalinity of water has a buffering effect on the pH value, and when the alkalinity is not enough, agents such as lime should be added to supplement it。When the pH value of water is high, it is necessary to add acid to adjust the pH value to neutral。In contrast, polymer flocculants are less affected by pH。Water temperature affects the hydrolysis rate of flocculant and the formation rate and structure of alum flowers。The hydrolysis of coagulation is mostly endothermic reaction, and the hydrolysis rate is slow and incomplete when the water temperature is low。At low temperatures，Water has a high viscosity，Reduced Brownian motion，The number of collisions between colloidal particles of flocculant and impurity particles in water is reduced，At the same time, the shear force of water increases，Hinder the mutual adhesion of flocs;therefore，Although the dosage of flocculant was increased，Floc formation is still very slow，Moreover, the structure is loose and the particles are fine，Hard to remove。Low temperature has little effect on polymer flocculants。However, it should be noted that when using organic polymer flocculants, the water temperature can not be too high, high temperature is easy to make organic polymer flocculants aging or even decomposition into insoluble substances, thereby reducing the coagulation effect。
The size of impurity particles in water is uneven, which is beneficial to coagulation, and small and uniform will lead to poor coagulation effect。Too low concentration of impurity particles is often unfavorable to coagulation. At this time, reflux sediment or adding coagulant aid can improve the coagulation effect。水中杂质颗粒含有大量有机物时，混凝效果会变差，需要增加投药量或投加氧化剂等起助凝作用的药剂。水中的钙镁离子、硫化物、磷化物一般对混凝有利，而某些阴离子、表面活性物质对混凝有不利影响。
The choice of flocculant mainly depends on the properties and concentration of colloid and suspended matter in water。If the pollutants in the water are mainly in a colloidal state, inorganic flocculants should be preferred to destabilize and condense, and if the floc is small, it is necessary to add high molecular flocculants or use activated silica gel and other coagulants。很多情况下，将无机絮凝剂与高分子絮凝剂联合使用，可明显提高混凝效果，扩大应用范围。对于高分子而言，链状分子上所带电荷量越大，电荷密度越高，链越能充分伸展，吸附架桥的作用范围也就越大，混凝效果会越好。
使用混凝法处理任何废水，都存在最佳絮凝剂和最佳投药量，通常都要通过试验确定，投加量过大可能造成胶体的再稳定。Generally, the dosage range of ordinary iron salt and aluminum salt is 10 ~ 100mg/L, the dosage of polysalt is 1/2 ~ 1/3 of the ordinary salt, and the dosage range of organic polymer flocculant is 1 ~ 5mg/L。
(6) Flocculant dosage sequenceWhen a variety of flocculants are used, the optimal dosing sequence needs to be determined by testing。一般来说，当无机絮凝剂与有机絮凝剂并用时，应先投加无机絮凝剂，再投加有机絮凝剂。而处理杂质颗粒尺寸在50μm以上时，常先投加有机絮凝剂吸附架桥，再投加无机絮凝剂压缩双电层使胶体脱稳。
In the mixing stage, the flocculant and water are required to be quickly and evenly mixed, and in the reaction stage, it is necessary to create enough collision opportunities and good adsorption conditions for the floc to have enough opportunities for growth, but also to prevent the generated small floc from being broken, so the stirring intensity should be gradually reduced, and the reaction time should be long enough。17.What are the types of natural organic polymer flocculants？The application of natural organic polymer flocculants in water treatment has a long history，直到今天，Natural polymers are still an important flocculant，But the amount of use is much lower than the synthetic polymer flocculant，The reason is that the charge density of natural polymer flocculants is small，Lower molecular weight，It is easy to biodegrade and lose flocculation activity。
Compared with synthetic flocculant，The toxicity of natural organic polymer flocculant is low，Simple extraction process，Both the chemical composition and the production process，Are in perfect harmony with nature，Therefore, the research and utilization of these natural resources as water treatment agents has become a hot spot at present，This is in line with the global emphasis on rational use of resources，The situation of protecting and improving the environment is inextricably linked。At present, there are many kinds of natural polymer flocculants，In accordance with its main natural composition (including the base composition used for modification)，It can be divided into: chitosan flocculant, modified starch flocculant, modified cellulose flocculant, lignin flocculant, gum flocculant, brown algin flocculant, animal glue and gelatin flocculant。Most of these natural polymers have polysaccharide structure, in which starch main chain contains only one monosaccharide structure, belonging to the same polysaccharide;Chitosan, gum and algin contain a variety of monosaccharide structures and belong to heteropolysaccharides.Lignin is a special aromatic natural polymer.Animal glue and gelatin belong to the protein group。18.What matters should be paid attention to when using polymer organic flocculants？Organic polymer flocculants belong to long chain macromolecules with wire group structure, which must undergo a melting and swelling process in water. Solid products or high-concentration liquid products must be prepared into an aqueous solution before use and then added to the water to be treated。配制水溶液的溶药池必须安装机械搅拌设备，溶药连续搅拌时间要控制在30min以上。The concentration of an aqueous solution is usually 0.About 1%, higher, the viscosity of the solution increases, it is difficult to add, and lower, the volume of the required solution pool will be too large。溶药使用的水中应尽量避免含有大量的悬浮物，以避免有机高分子絮凝剂与这些悬浮物进行絮凝反应形成矾花，影响投加后的使用效果。
When the solid organic polymer flocculant is dissolved，The injection point of solid particles must be in the place where the water turbulence is strongest，At the same time, it must be put into the dissolving tank slowly with the minimum dosage，Disperse the solid particles into the water，To prevent solids from being dispersed too quickly in water and bonding to form clumps，The structure of the mass is a solid particle inside, surrounded by a partial hydrolysate outside，Once such clumps form，It often takes a long time to dissolve evenly back into the water，It can even exist for several days in a continuous dissolving tank。The point of solid particles must be far away from the stirring shaft of the mechanical agitator，Because the stirring shaft is usually the worst turbulent place in the dissolving tank，Insufficiently dissolved organic polymer flocculants often adhere to the shaft，Accumulate day by day，Sometimes quite large sticky clumps can form，If it is not cleaned up in time and seriously，The clump will get bigger and bigger，The sphere of influence gets bigger and bigger。作为助凝剂时，一般要先在处理水中投加无机絮凝剂进行压缩双电层脱稳后，再投加有机高分子絮凝剂实现架桥作用。在无机絮凝剂投加充足的条件下，有机高分子絮凝剂的助凝效果不会因投加量的差异而有较大差别。Therefore, when used as a coagulant aid, the dosage of organic polymer flocculant is generally 0.1mg/L。固体有机高分子絮凝剂容易吸水潮解成块，必须使用防水包装，保存地点也必须干燥，避免露天存放。19.What are the types of microbial flocculants？微生物絮凝剂与传统无机或有机絮凝剂有显著不同，它们或是直接利用微生物细胞，或是利用微生物细胞壁提取物、代谢产物等。The former is the main aspect of the study of microbial flocculants. So far, more than 17 kinds of microorganisms with flocculating properties have been found, including mold, bacteria, actinomyces and yeast, and the latter is similar to organic flocculants。微生物絮凝剂具有传统无机或有机絮凝剂所不能比拟的许多优点，如不产生二次污染、生产成本低等。
The flocculation performance of microbial flocculants is affected by many factors, including the inheritance and expression of flocculation genes, and the external factors include the composition of microbial medium, the change of cell surface hydrophobicity, and the presence of divalent metal ions in the environment。At present, there are foreign microbial flocculants with good performance, such as NOC--1 produced in Japan。微生物絮凝剂从研究到生产的关键问题是发展成熟的微生物育种技术，同时努力降低生产成本。The development of microbiological flocculant in our country is approaching this direction, but there is still a long distance from industrial production。20.How to determine the type and dosage of flocculant to be used？絮凝剂的选择和用量应根据相似条件下的水厂运行经验或原水混凝沉淀试验结果，结合当地药剂供应情况，通过技术经济比较后确定。选用的原则是价格便宜、易得，净水效果好，使用方便，生成的絮凝体密实、沉淀快、容易与水分离等。
混凝的目的在于生成较大的絮凝体，由于影响因素较多，一般通过混凝烧杯搅拌试验来取得相应数据。The coagulation test was carried out in a beaker and consisted of three steps: rapid stirring, slow stirring and static settling。After rapid stirring, the flocculant is quickly dispersed and in contact with the colloidal particles in the water sample, the colloidal particles begin to condense and produce microfloc.Through slow stirring, the microfloc further contact with each other to grow into larger particles;After the stirring is stopped, the formed colloidal aggregates naturally settle to the bottom of the beaker by gravity。通过对混凝效果的综合评价，如絮凝体沉降性、上清液浊度、色度、pH值、耗氧量等，确定合适的絮凝剂品种及其最佳用量。试验用六联搅拌机，它有六个可垂直移动的转轴，其底部位置处带有搅拌叶片，叶片尺寸6cm×2cm。The rotation speed and rotation time of the rotating shaft can be preset and can work automatically。一般试验按快速搅动2min，n=300r/min；慢速搅动3min，n=60r/min。During the test, 1L of raw water was added to 6 1000mL large beakers，Placed directly below each of the six rotating axes，Move the shaft down to the bottom;Then inside six small glass beakers attached to a horizontal rotating shaft，Add different amounts of liquid medicine in turn，Horizontal axis of rotation，The liquid medicine in the tube is poured into the corresponding raw water at the same time。Then start the blender and make it work automatically。After the agitation stopped automatically, the blade was slowly pulled up from the beaker and stood for 20min. 25ml of water sample was drawn from about 10cm below the water surface with a pipette, and the turbidity of the supernatant was measured with a turbidimeter。With the dosage as the horizontal coordinate and the remaining turbidity of the supernatant as the vertical coordinate, a curve was drawn to compare the effects of different flocculants. According to the turbidity removal effect and comprehensive technical and economic factors, the flocculant for treating this wastewater was selected。The test method of beaker stirring can be divided into single factor test and multi-factor test。During the test, the raw water used should be exactly the same as the actual water quality, and the type, dosage and dosage sequence of the flocculant should be determined according to the pH value of the water, the nature of impurities and other factors, and the test should be a simulation of the actual process, and the hydraulic conditions (mainly GT value) of the two must be the same or close。Twenty-one.What is a coagulant？What is its role？In the coagulation treatment of wastewater, sometimes the use of a single flocculant can not achieve good coagulation effect, often need to add some auxiliary agents to improve the coagulation effect, this auxiliary agent is called coagulant aid。Commonly used coagulants are chlorine, lime, activated silicic acid, bone glue and sodium alginate, activated carbon and various clays。
有的助凝剂本身不起混凝作用，而是通过调节和改善混凝条件、起到辅助絮凝剂产生混凝效果的作用。有的助凝剂则参与絮体的生成，改善絮凝体的结构，可以使无机絮凝剂产生的细小松散的絮凝体变成粗大而紧密的矾花。Twenty-two.What are the types of commonly used coagulants？There are many types of coagulants, but according to their role in the coagulation process, they can be roughly divided into the following two categories:
(1) Agents that regulate or improve coagulation conditions
混凝过程应该在一定的pH值范围内进行，如果原水pH值不能满足此要求，则应调整原水的pH值，这类助凝剂包括酸和碱。When the pH value of raw water is low and the alkalinity is insufficient, the hydrolysis of flocculant is difficult, CaO, Ca(OH)2, Na2CO3, NaHCO3 and other alkaline substances (commonly used for lime) can be added.When the PH value is high, sulfuric acid or CO2 is commonly used to reduce the pH value of raw water。对溶解性有机物含量较大的废水，可用Cl2等氧化剂来破坏有机物，提高对溶解性有机物的去除效果。另外亚铁盐作絮凝剂时，可用氯气将亚铁(Fe2+)氧化成高价铁(Fe3+)，以提高混凝效果。The above alkali, sulfuric acid and CO2, chlorine, etc., do not play a coagulation role in themselves, only play an auxiliary coagulation role。(2) To increase the size, density and fruity of alum flower coagulantThe result of coagulation requires the formation of large particle size, density and strong alum flowers, which are conducive to precipitation and not easy to break。In order to achieve this result, combined with the characteristics of the water quality, sometimes it is necessary to add a substance or pharmaceutical to the water。For example, low turbidity wastewater containing light impurities that are not suitable for settling，Adding silica, activated carbon, clay and other coarse particles or reflux partial sediment sludge can play a role in aggravating and increasing alum;When aluminum salt and iron salt are used as flocculants, only small and loose flocculants can be produced，Polymer coagulants such as polyacrylamide, activated silicic acid and bone glue can be added，Use their strong adsorption bridging effect，To make the small and loose flocs large and dense。Twenty-three.What are the applications of flocculant and coagulant aid in enhanced wastewater treatment？废水处理中投加絮凝剂可加速废水中固体颗粒物的聚集和沉降，同时也能去除部分溶解性有机物。这种方法具有投资少，操作简单，灵活等优点，特别适合于处理水量小，悬浮杂质含量较大的废水。When inorganic flocculant is used, because of the large dosage and the large amount of sludge produced, the synthetic organic polymer flocculant OPF is mainly used in practical application, or the combination of inorganic flocculant and OPF is used。It has been reported that in the primary sedimentation tank, anionic polyacrylamide is often used to remove suspended impurities in the wastewater, but the effect of using non-ionic polyacrylamide (PAM) is not good。经验表明，在初级沉淀池中投加1mg/L水解聚丙烯酰胺，可去除进场废水中50%以上的悬浮粒子及40%以上的BOD5。
在废水的初级沉淀处理中，将有机高分子聚电解质与无机絮凝剂的混合使用，要比它们各自单独使用效果更好。由于进场废水中悬浮粒子的浓度、粒径分布及种类等随时会发生变化，就使得絮凝剂的最佳剂量有时难以控制。At this time, if excessive inorganic flocculant is added, the method is feasible to precipitate and remove suspended impurities by the rolling mechanism, but its disadvantages are also very prominent, one is that the action time is relatively long (15 ~ 30min), and the formed floc is easily broken。如果在投加无机絮凝剂的同时，再加入一定量的有机高分子聚电解质，可使絮凝时间减少到2～5min，而且形成的絮体也比较结实。In the removal of colored organic colloidal impurities from water by precipitation, a dual-electrolyte system can be used。These organic colloids were first destabilized by cationic polyelectrolytes with high positive charge, and then by large molecular weight non-ionic or anionic polyelectrolytes, the stabilized organic colloids were flocculated into readily precipitated floc。Cationic polyelectrolytes are often used as flocculants in secondary sedimentation tanks, such as polydimethylhexadiene ammonium chloride or polyaminomethyldimethylhexadiene ammonium chloride, etc., but the dosage is less than that in primary sedimentation tanks。The reason is that part of the anionic polyelectrolyte added in the primary sedimentation tank continues to play a role after entering the secondary sedimentation tank, and the polyelectrolyte added in the secondary sedimentation tank can be used repeatedly in the sludge reflux。In addition, coagulation can also remove phosphates and heavy metal ions from wastewater。For a long time, people have been using the method of adding metal salt inorganic flocculant to remove part of phosphate in wastewater。However, experiments show that the same phosphorus removal effect can be obtained by using cationic polymer instead of inorganic flocculant on the premise that the removal rate of phosphate is not reduced, which indicates that the polymer participates in the adsorption of anionic phosphate。例如某废水处理场在混凝处理工艺中，用12mg/L硫酸铁和3mg/L高电荷密度的阳离子聚合物，以及0.2mg/L high molecular weight anionic polymer composite, instead of the original 23mg/L iron sulfate, with the same phosphorus removal rate, the removal rate of BOD5 in the effluent increased from 30% to 55%。同时，采用混凝处理后，可以使活性污泥阶段产生的污泥中无机物成分减少，提高活性污泥的生物降解功能。废水处理中使用的过滤、浮选等处理工艺中，通过使用无机絮凝剂和聚电解质助凝剂，可以提高出水水质。结合废水水质特点，絮凝剂可以单独使用，也可以多种絮凝剂复合使用或一主一辅复配使用（辅者作为助凝剂）。The selection of flocculant can be preliminatively screened by static beaker test, and then verified on the production plant。24.What are the types of commonly used sludge conditioners？Conditioner, also known as dehydrating agent, can be divided into two categories: inorganic conditioner and organic conditioner。无机调理剂一般适用于污泥的真空过滤和板框过滤，而有机调理剂则适用于污泥的离心脱水和带式压滤脱水。
(1) Inorganic conditionerThe most effective, cheapest and most commonly used inorganic conditioners are mainly iron salt and aluminum salt two categories。Ferric salt conditioners mainly include ferric chloride (FeCl3∙6H2O), ferric sulfate (Fe2(SO4)3∙4H2O), ferrous sulfate (FeSO4∙7H2O) and polyferric sulfate (PFS) ([Fe2(OH)n(SO4)3-n/2]m)，Aluminum salt conditioners mainly include aluminum sulfate (Al2(SO4)3∙18H2O), aluminum trichloride (AlCl3), basic aluminum chloride (Al(OH)2Cl), polyaluminum chloride (PAC) ([Al2(OH)n∙Cl6-n]m), etc。Adding inorganic conditioner can greatly accelerate the thickening process of sludge and improve the effect of filtration and dehydration。And the combination of iron salt and lime can further improve the conditioning effect。The disadvantage of adding inorganic conditioner is that the dosage is large, in general, the dosage should reach 5% to 20% of the dry solid weight of the sludge, resulting in an increase in the size of the filter cake;Second, the inorganic conditioner itself is corrosive (especially iron salt), and the dosing system should have anti-corrosion properties。It should be noted that when ferric chloride is used as an adjuster, the corrosiveness of the metal components of the dehydrated sludge treatment equipment will be increased, so the corrosion grade of the dehydrated sludge treatment equipment equipped should be appropriately improved。There are many kinds of organic synthetic polymer adjusters, which can be divided into two kinds according to the polymerization degree: low polymerization degree (molecular weight is about 1 thousand to tens of thousands) and high polymerization degree (molecular weight is about hundreds of thousands to millions);According to the ionic type, it can be divided into cationic type, anionic type, non-ionic type and Yin and Yang ionic type。Compared with inorganic conditioner, the dosage of organic conditioner is less, which is generally 0 of the dry solid weight of the sludge.1%～0.5%, and not corrosive。The organic conditioners used for sludge conditioning are mainly flocculant products of polyacrylamide series with high polymerization degree, mainly cationic polyacrylamide, anionic polyacrylamide and non-ionic polyacrylamide。其中cationic聚丙烯酰胺能中和污泥颗粒表面的负电荷并在颗粒间产生架桥作用而显示出较强的凝聚力，调理效果显著，但费用较高。In order to reduce the cost, a cheaper anionic polyacrylamide-lime combination method can be used to adsorb the negatively charged flocculant and the sludge particles together by using the positively charged Ca(OH)2 floc to form a composite condensation system。
Source: From the Internet
