Selection Of Polyacrylamide For Papermaking Wasterwater
【characteristics of Papermaking Wasterwater】
Paper mill to produce the main characteristics of sewage water big and high chromaticity, high suspended solids content, high concentration of organic matter, the wastewater treatment in general the main problem is to remove SS and COD, and the current relatively popular in the papermaking wastewater treatment methods have spirit float and precipitation, physicochemical and biochemical treatment, etc., the combination of using air floatation or precipitation method, by adding coagulant (polyaluminium chloride) and coagulant aid, it can remove most of the SS, at the same time also can remove most of the soluble COD and part of soluble COD and BOD5.The polyacrylamide used for paper mill is generally more than 15 million molecular weight anion polyacrylamide effect is relatively ideal (do test type selection, see your sewage water quality is suitable what degree of hydrolysis polyacrylamide PAM product).If the combination of physicochemical and biochemical treatment is adopted, the process of general physicochemical and biochemical treatment is that waste water, screen, regulation, precipitation or air floatation, A/O or contact oxidation, secondary sedimentation and discharge. Cationic polyacrylamide is generally used in this treatment process.
【different ion polyacrylamide for different papermaking wasterwater】
There are two types of polyacrylamide used in papermaking
Cationic and anionic polyacrylamide. Among them, anionic polyacrylamide or cationic polyacrylamide is mostly used in the air flotation link, while cationic polyacrylamide is mostly used in the sludge dewatering link.
As for the type of polyacrylamide used in the air flotation of paper making, we need to choose the suitable polyacrylamide products according to the actual water quality.
Paper mill gas float link, when choosing polyacrylamide type, need to be carried out on the water quality test, and then do small, select multiple types of polyacrylamide products, and multiple sets of the same water quality, water quantity of waste water, then add an equal amount of PAC solution, polyacrylamide solution, after joining, mixing wastewater at the same time, the observation condition of waste water flocculation precipitation, precipitation rate, the effects of precipitation, and the clarity of water quality, etc., and then, according to the dosing quantity data, such as to select the best type of polyacrylamide products.
In the air flotation process, anion polyacrylamide products with a molecular weight of 10 million to 18 million are mostly used. As the water PH value of the air flotation wastewater is more than 7, it is suitable to be treated with quansen anion polyacrylamide.However, the waste water at this time is white water, mainly containing fine fiber, filler, paint and dissolved wood components.
As well as the added adhesive, wet strong agent and preservative, insoluble COD is the main part, with low biodegradability. The added preservative has certain toxicity.The amount of white water is larger, but the organic pollution load is much lower than that of black liquor and waste water.When this kind of white water is treated, the choice is mostly low - Yang chuansen cationic polyacrylamide, the treatment effect will be better.The cationic polyacrylamide used is mostly 10, 15, 20 ionic low-yang products.