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Reasons for foam floating with PAC

During the phosphorus removal process of PAC, PAC is added at the end of the sedimentation tank and the biochemical tank respectively. However, yellow foams float on the water after use, and these foams usually take three or four days to eliminate. What is the reason? What should I do?

The added polyaluminium chloride reacts with volatile fatty acid salts in wastewater from the biochemical tank to produce volatile fatty acids which float on the liquid surface through aeration. Due to the high surface tension of such foams, they are not easy to break down and can be maintained for two to three days in the natural state.

Another point is that if the above described phenomena occur, it is necessary to determine whether the dosing is intermittent or not. If the dosing is intermittent, it is very likely to cause local excessive situation. The local excessive formation is aluminium hydroxide colloid, which absorbs part of activated sludge and forms yellow foam on the surface during aeration.

Polyaluminium chloride added affects the alkalinity balance of biochemical system, affects the metabolism of microorganisms and secretes some extracellular products, most of which are monosaccharides and colloidal substances, so foams can also be formed by aeration.

The latter point is to consider the quality of PAC products used, such as: whether the content of active ingredients and elemental substances meet the requirements of national standards. To sum up, it is recommended to dilute the addition of polyaluminium chloride at multiple points while paying attention to the influence of pH value before and after the addition. Yellow foam floating on the surface can be broken by spraying clean water if the effect is apparent.

Thank you for your attentionHenan aierfuke Chemical Co., Ltd：Focus on water treatment, only for the healthy world! Our company is committed toPolyaluminium chloride、Polyferric sulfateThe R & D, manufacturing and sales of series of water purification materials are willing to create success with our customers and friends.