Question

Imagine you need to design a jar test experiment to determine the most efficient removal of phosphate from

water, e.g., precipitation from a treated wastewater. For each of the following potential wastewater effluent

phosphate requirements, recommend a chemical dose to achieve these requirements. Be sure to explain why

you are recommending these doses.

a.1 mg P/L

b.0.5 mg P/L

c.0.1 mg P/L

Answer 1

SOLUTION :---->>>>>

ANS. (a) :- For 1mg P/L :--- In this the quantity of phosphate is too much hence for less sludge formation used boilogical phosphorus removal method.

Over the past 20 years, several biological suspended growth process configurations have been used to accomplish biological phosphorous removal. The principal advantages of biological phosphorous removal are reduced chemical costs and less sludge production as compared to chemical precipitation.

ANS. (b) :- For 0.5mg P/L :--- In this the quantity of phosphate is medium that is not too much high and not too much low. Hence for this the postprecipitation is a standard treatment of a secondary effluent, usually using only metallic reagents. It is the process that gives the highest efficiency in phosphorous removal. Efficiency can reach 95%, and P concentration in the effluent can be lower than 0.5 mg/l. Postprecipitation gives also a good removal of the SS that escape the final sedimentation of the secondary process.

ANS. (c) :- For 0.1mg P/L :--- Here the quantity of phosphate is very low hence sludge formation in wate water due yo this we use chemical precipitation to remove the inorganic forms of phosphate by the addition of a coagulant and a mixing of wastewater and coagulant. The multivalent metal ions most commonly used are calcium, aluminium and iron.

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