Drinks based on juice are an ...

Drinks based on juice are an issue because they will contain soluble sugars, organic and citric acids.  Unless you have pulp to remove, there is no point in sending this through a DAF unit.  Dairy waste will depend on the process you have afterwards and how effective the biology is.  If the material is based on cheese, then you may have to dose between 500-1000 ppm of ferric chloride and use a high dose of caustic to correct the acidity of the ferric chloride.  There is an organic coagulant produced by Suez Water Technologies (Old Betz Dearborn, GE Water) Klaraid 4000 which only needed 20-30 ppm with the correct pH correction which works well with cheese.  It was found that a different coagulant was needed for milk Klaraid 2700.  Dose rates were much lower. Also the ferric chloride produces 30-40 % sludge generated by its own solid content, which does not occur with organic coagulants.  There is no substitute for tests being carried out on your actual waste using different coagulants and most reputable companies will carry this work out for you.  The critical factor is the pH and each coagulant will work at an optimum pH.  Ferric chloride depresses the pH considerably.  Aluminium-based products are also pH sensitive and produce a lighter floc than ferric.  If PAC or ACH is used, then it is also pH sensitive and extremes of pH can cause the coagulant to break down before it has reacted with the material.

If the dairy is liquid milk, then the pH can be dropped to pH 3, which causes the milk solids to coagulate.  In this case the pH needs to be corrected with caustic or lime after solids removal.

On all plants, I have worked with, there has been a balance tank before the DAF plant.  If this does not occur, the dose rate constantly changes, so the only way forward is to provide a dose rate which always works and this will be higher than necessary.  A balance tank will cause a reduction in coagulant dosing by balancing flows and pH levels.