The role of polymers in sludge treatment
One of the most important steps in the sludge treatment process is the separation of water from the liquid sludge. To do that, it is necessary to coagulate suspended colloids, flocculate suspended solids, and precipitate dissolved substances to separate them from water.
During water separation, coagulants, flocculating agents, and precipitates are used to facilitate water separation. In many situations, water separation would not be possible without them.
Inorganic coagulants are usually Iron, Aluminum, Calcium or Magnesium based electrolytes. Precipitation chemicals have many types, often with sodium, potassium, calcium or magnesium bases. (The role of polymer for sludge press)
Since the 1960s, polymeric compounds have been used in wastewater treatment and they are rapidly becoming an essential tool. Linear or branched polymers are most commonly used.
Mechanism of action of polymer in sludge treatment lý
Polymer applications for sludge dewatering: low-content sludge is mixed with polymers and various inorganic chemicals to aid in water removal. Cationic polymers of medium molecular weight are often used in this situation. The degree of charge of the polymer will depend on the type of sludge and will vary widely, from a medium charge for sludge from a paper mill to a very high charge for a municipal sludge.
The polymer mechanism for slurry presses is based on the fact that slurries usually carry a negative charge. As the polymer cations are attracted towards the sludge mass, they gradually shrink into a coating that surrounds the sludge while allowing the water to drain. The medium-weight polymer molecules seem to be able to squeeze the sludge, making it easy to separate water on the membrane, in the screw…
Some types of biological sludge such as activated sludge or sludge from anaerobic wastewater treatment systems are difficult to handle. In this case, inorganic compounds such as ferric chloride or lime are used to aid in the dehydration process.
Selection of Polymer for the sludge press
There are many types of polymers, from dry powders to solutions and emulsions, with different charge compositions and degrees of charge, as well as very different molecular weights. Each type of polymer has a different role in the wastewater and sludge treatment cycles, and each type of sludge has a corresponding polymer.
There are three main types of Cationic Polymer, Anionic Polymer, and Nonionic Polymer with specific uses:
Suitable for wastewater with high organic matter content.
Wastewater has a high concentration of suspended matter. Cationic polymers are well suited in acidic or alkaline media for very high precipitation efficiency.
Specific examples are: Industrial wastewater in beer and wine production, dairy factories, aquatic products factories, wastewater from centralized wastewater treatment plants, wastewater from monosodium glutamate and potato starch factories. noodles, wastewater from sugar factories, wastewater from slaughterhouses, wastewater from beverage factories, wastewater from textile printing and dyeing factories.
Anionic polymer products are suitable and highly effective for wastewater with high inorganic content.
Treatment of wastewater with neutral or alkaline pH value arising from iron, steel, plating, metallurgy industries. Using anionic polymers in the physico-chemical treatment of the wastewater treatment process (flotation and flocculation – flocculation), the effect of anionic polymer is to bind the waste to form a mass of large weight and settle it ( for the process of coagulation – flocculation), for the flotation process, Anion polymers are used to bind the wastes together with the effect of the gas flow into the adhered waste blocks that will float. to the top, helping the wastewater treatment process achieve high efficiency.
Besides, Polymer anion also treats water from rivers, sediments and minerals, and wastewater with high turbidity, and filters water after rain.
The non-ionic polymer product is more suitable for strongly acidic wastewater because the Nonionic polymer non-ionic polymer better adsorbs suspended particles in the wastewater and results in very high treatment efficiency. Besides, NPAM is also an additive for the textile industry or a very good soil humectant.
CHARACTERISTICS AND APPLICATIONS OF POLYMER FOR MINING MACHINE
Through the mechanism of action of the polymer presented, users need to choose the appropriate type of polymer. Choosing the wrong type of polymer not only reduces the efficiency of wastewater treatment, the efficiency of water separation from sludge, in many cases also leads to the treatment process not being performed. In particular, severe cases can cause system bottlenecks.
Coagulation principle: Polymer is used at low concentration (0.1-0.5%) to break the stability of colloidal particles in water and make them clump together by polymer. The broken colloidal particles will stick together into small clumps, then into larger clusters and settle, called the flocculation process.
Because polymers are corrosive, the types of materials used to store these products are usually: stainless steel, fiberglass, plastic, epoxy.
Application of polymer for slurry press:
Improve concentration, sedimentation aid, water absorption and increase concentrate quality. Depending on the field of water to be treated, we use different anionic polymers and cationic polymers:
– Surface water: The best polymer is an anion or has very few cations, because in water there are many positive ions such as Fe, Mn, etc.
Industrial wastewater: for treatment, anionic polymers are often used in combination with inorganic coagulants.
– Urban wastewater: Using inorganic coagulant polymer combined with anionic flocculant.
In addition, polymers are also used as additives and binders in aquatic feed.
– Drying sludge after treatment: Sludge with inorganic properties needs anionic flocculant, cationic flocculant suitable for organic sludge treatment.
The amount of polymer for the sludge press required when treating water is very small, only about a thousandth. If too much polymer is used, the water will become very viscous, hindering further processing steps. In addition, excess polymer in water will increase COD. Therefore, when applying polymers, it is necessary to carry out practical tests to choose the appropriate dosage.
REFERENCES FIRE Press:
Multi-Disc Screw Slurry Press