1. The characteristics of municipal sewage
Municipal sewage treatment generally refers to municipal sewage treatment plants, river sewage treatment, sewage treatment plants for large-scale public institutions, etc. The sewage is characterized by large changes in water quality, high COD (chemical oxygen demand), SS (solid suspended solids concentration), and difficult treatment. Sewage treatment processes generally include primary sedimentation tanks, grit sedimentation tanks, secondary sedimentation tanks, biochemical tanks (good nutrition, anaerobic tanks), sludge thickening tanks, sludge dewatering filter presses, etc. Because the sewage before treatment contains high concentrations of organic matter, microorganisms, etc., any product designed to treat reclaimed water must be able to tolerate this variability and contain high concentrations of organic matter and active organisms.
2. Pharmaceuticals selected for municipal sewage treatment
When dealing with municipal sewage, we usually choose polyacrylamide flocculant, generally cationic polyacrylamide, which has a better charge density between 40-50. Sometimes, anionic polyacrylamide is used in the primary or secondary sedimentation tank to accelerate the sedimentation of suspended solids; while the sludge dewatering filter presses are mostly belt filter presses, and medium-strong cations are generally used. Polyacrylamide flocculant, the molecular weight is 9 million-12 million, and the dispensing concentration is 1-2‰.
3. the characteristics of cationic flocculant
Cationic polyacrylamide is a new, high-quality, high-efficiency polymer. It is easy to dissolve in water, has a fast sedimentation rate, and has a good water purification effect. It does not contain harmful substances such as aluminum, chlorine and heavy metal ions, and there is no water phase transfer of iron ions. It is non-toxic, harmless, safe and reliable. Cationic polyacrylamide flocculant can effectively purify municipal sewage, such as turbidity removal, decolorization, deoiling, dehydration, sterilization, deodorization, algae removal, removal of COD, BOD and heavy metal ions in water. Due to the high content of organic matter in municipal sewage, cationic type is generally used. After use, the pH value and total alkalinity of the raw water have a small change range, and the corrosiveness to the treatment equipment is also small; generally the pH value of the water body is 4.0-11.0, so that the effect can reach the pH value of 6.0-9.0.
When using cationic polyacrylamide to treat municipal sewage, at a very low dosage, good results can be achieved, and the cost is low, and the cost of its treatment can be reduced by 20-50%. The dosage of the specific agent depends on the nature of the raw water, and the dosage is different in different situations. If you want to calculate a more accurate dosage, you need to conduct a beaker experiment based on the water sample taken on site to obtain the usage conditions and dosage. Because the water quality of municipal sewage changes greatly, sometimes one or two kinds of chemicals are used in combination. This depends on the actual situation to determine the use of chemicals. Under normal circumstances, we will choose cationic polyacrylamide for treatment.
Post time: Jun-24-2021