(4) 聚丙烯酰胺絮凝劑預處置普通占整個污泥處置費用較高的比例，因而，聚丙烯酰胺的優化選擇和投加率的合理肯定對降低污泥預處置費用相當關鍵。對選擇聚丙烯酰胺的實驗辦法的研討已展開多年，包括比阻、CST值、污泥流變性、分別液粘度、活動電流等。The synthesis and process physical properties of AM polyacrylamide: PAM is prepared by direct reaction of acrylonitrile with water under the action of framework copper catalyst, and then dried by ion exchange polymerization. The process is as follows: catalyst: catalytic hydration CH2 = CHCN + H2 humidity CH2 = CHCONH2 polymerization nCH2 = CHCONH2 - initiator - CH2CHCONH2
Industrial uses of polyacrylamide: Polyacrylamide (PAM) has high molecular weight, good water solubility, adjustable molecular weight, and can introduce various ionic groups to obtain specific properties. Low molecular weight is an effective additive or stabilizer for dispersing materials. High molecular weight is an important flocculant. It can produce hydrophilic and water-insoluble gel, which has good adhesion to many groups of surface and dissolved substances. Because of the above properties, PAM is widely used in flocculation, thickening, drag reduction, glue imitation, bonding, scale inhibition and other fields.
Anionic polyacrylamide can be used in different molecular weights according to different uses and user's requirements for product performance.
In industrial wastewater treatment, especially for suspended particles, coarser, high concentration, positive charged particles, neutral and alkaline wastewater such as iron and steel plant wastewater, electroplating plant wastewater, metallurgical wastewater, coal washing wastewater and other wastewater treatment effect is very good.
In drinking water treatment. The water source of many Waterworks in our country is low in mud and high in mineral content, which is turbid. Although it has been treated by precipitation, it still can not meet the requirements. Flocculants are needed to make the water quality clear. Many waterworks use inorganic flocculants, but the amount of inorganic flocculants is large, resulting in poor effect of sludge increase. Anionic polyacrylamide acrylamide monomer was 0.012%. The molecular weight of anionic PAM was 12.5 million and the content of acrylamide monomer was 0.013%. The concentration of two kinds of PAM is 0.05%. They are used after refrigeration for 24 hours.
(1) PAM pretreatment sludge takes lOml sludge and puts it into a 300 ml beaker. Six-unit mixers are used to mix at 1130 RPM speed for 30 seconds, and then the PAM is added to the sludge quickly and quantitatively. The PAM is stirred at lOOrpm speed for 30 seconds, then the speed of the mixer is reduced to 20-30 rpm and the slow stirring speed is 60 seconds to promote flocculation. The specific resistance of pretreated sludge, capillary water absorption time (CST), the viscosity of filtrate and the viscosity of centrifuge were measured.
(2) The specific resistance is tested by Brinell funnel according to the test method proposed by Coackley. The diameter of Brinell funnel is 80 mm. The filter paper is made of 70 mm medium speed filter paper. The vacuum degree of the test is controlled to 0.01 MPa. The experiment was repeated three times to get the average value.
(3) In order to reduce specific resistance and improve sludge dewatering effect, sludge should be pretreated before sludge dewatering. Sludge pretreatment methods include freeze-thaw pretreatment, heat treatment, acid treatment, alkali treatment, lime pretreatment and polymer flocculant pretreatment. Polymer flocculant polyacrylamide (PAM) pretreatment is the most widely used pretreatment method at home and abroad.
(6)依據CST值變化肯定PAM最投加率與測定比阻得到的最投加率分歧。并且CST值與比阻之間存在線性相關關系，比阻值越大，CST值越大，因而能夠采用CST值來近似替代污泥比阻反映污泥的脫水性能。與比阻相比，cST值測定快速、煩瑣，不但適用于實驗室研討，還可用于消費現場，快速理解污泥脫水性能的變化，使操作人員及時調楚PAM投加率，儉省藥劑費。is used as flocculant, and the dosage is inorganic flocculant. One fiftieth of the flocculants, but the effect is several times to dozens of times that of inorganic flocculants. Especially the polyacrylamide produced by our company, the residual monomers have reached the food grade (less than 0.05%), close to the advanced level abroad, non-toxic, more suitable for the treatment of drinking water, and better for the use of organic pollutants polluted river water and anionic polyacrylamide.
Polyacrylamide is used to recover lost starch and distiller's grains in starch and alcohol factories. At present, the starch in the waste water discharged by many starch factories is very high. After discharging, it affects the environment, wastes resources, and adds PAM to make starch precipitate. The precipitate is filtered by pressure filter to become cake and can be used as feed. A large number of distillers'grains in the alcohol factories are processed by this process. A certain alcohol factory in Heilongjiang Province uses polyacrylamide as flocculant, which recycles the distillers' grains and obtains a great deal of experience. Economic benefits.
Polyacrylamide is used as water shutoff agent for profile control and water shutoff in Oilfield and oil displacement agent for tertiary oil recovery.
Polyacrylamide is used as paper-making additive. PAM is widely used in paper-making. It can be used as long fiber paper-making dispersant, wet and dry reinforcing agent, retention aid, filter aid and flocculant of paper-making wastewater.
The latest type of water treatment agent polyacrylamide, when treating sewage and water in many occasions, the combination of anionic polyacrylamide and cationic polyacrylamide has a very significant and synergistic effect than using one kind of ionic polyacrylamide alone. The ability of PAM to reduce surface tension is much greater than the ability of cations or anions existing alone under the same conditions. For the requirement of low surface tension, both anionic and cationic polyacrylamide need to be used at the same time. If they are used improperly, white precipitates will be produced and the effect of using them will be lost. PAM has the characteristics of amphoteric ions. It can complete the coordination of anions and cations. There is no precipitate on the surface. Especially, it is more convenient to use PAM as a flocculant because of the complex water quality or the changeable nature of water.
The sludge used in sewage pretreatment is taken from the sedimentation tank with Qiantang River water as its source of water, and PAC is used as a flocculant in the water plant. The sludge was naturally concentrated to a solid content of 2.7%-2.8%. The organic matter content in the sludge was 12.1%, SJ content was 52.1%, Al content was determined. The content was 20.2%. There are three types of PAM: cationic, anionic and nonionic. Non-ionic PAM dissolves slowly and is generally not used for sludge pretreatment. Therefore, only two representative cationic polyacrylamides and anionic polyacrylamides are selected in the experiment. The molecular weight of cationic PAM was 12 million and the content of
