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Lime slippage from sludge contact clarifier

We have a sludge contact clarifier to treat canal water. Alum and poly electrolyte are used as coagulants and flocculants in the clarifier. We are also dosing cold lime, i.e., Ca(OH)2 in the clarifier to remove temporary hardness of water. The flow rate of water is 1200 m3/hr and design flow rate of clarifier is 1450 m3/hr. The clarifier inlet water has about 200 ppm turbidity and outlet of clarifier has turbidity around 10 ppm, and we maintain the pH of clarifier between 9.8 and 10.2.

We have a problem of lime slippage from clarifier. How this problem can be resolved?

Qaiser Mahmood
Operation engineer - Lahore, Punjab, Pakistan
2003

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Sir, in my opinion, to avoid lime slippage adjust a constant flow on clarifier. And if a change in flow is necessary, then change it slowly.
Another thing is the excess dosage of lime. If the lime dosage is controlled than we minimize the lime slippage.

Yasir Shafique
- Multan, Punjab, Pakistan
2007