Questions regarding alum flocculation
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I heard that the flocculation effect of alum deteriorates in winter; I wonder if this phenomenon really exists If so, is it because alum itself is affected by temperature? Or is it the influence of other factors?
Yes, because the temperatures are low in winter, the hydrolysis rate of alum slows down, the molecular kinetic energy of the flocs decreases, and thus the effectiveness is reduced.
It’s not just alum; other flocculants also see their effectiveness decrease at low water temperatures, and the original poster is absolutely right.
Is there any good solution then? ?
It’s not just alum; other flocculants also see their effectiveness decrease at lower water temperatures. The reason for this is that in winter, when the temperature is low, the molecular kinetic energy of the particles decreases, resulting in fewer collisions between molecules and thus a reduced flocculation effect； On the other hand, in winter the water clarity is too low, resulting in too few particles available for flocculation; thus the chances of particle collisions decrease. It can be considered that adding a small amount of soil increases the clarity of the water. Just as an aside, using alum to treat water was a practice from the 1980s; it’s still being used today – that’s really outdated! ! Polymer flocculants are used these days! ! ! ! :lol :lol
The hydrolysis of alum is endothermic; in winter, when the flocculation effect is poor, coagulants can be added, the dosage can be increased, or another type of coagulant can be used. The specific approach can be determined through experiments based on the characteristics of your water quality.
When the temperature drops below 5 degrees, aluminum salt coagulants have difficulty in causing flocculation and precipitation; as a result, most of the chemicals added are carried away by the water flow. Iron salt coagulants are more tolerant to temperature changes and produce denser flocs, but ferric chloride is highly corrosive, while ferrous sulfate can give color to the treated water. Therefore, in winter, aluminum salts and iron salts can be mixed in certain proportions and used together to overcome their respective shortcomings.
Thank you to my friends for their replies! ! ! :handshake
What era is this that we still use alum? We have inorganic polymer flocculants here, which are not affected by low temperatures. talmh@126.com
Low water temperature in winter is one factor; low turbidity also has an impact； The solution is to heat it or add a little clay.