Q. Alum precipitation occurs at which pH?

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Q. Iron precipitation occurs at which pH?

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Q. Out of these which is not used as a chemical coagulant?

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Q. What is the one disadvantage of adding chemicals to bring about precipitation?

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Q. When alum is added to the waste water containing calcium ions which compound is formed as a precipitate?

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Q. Along with ferrous sulphate what other chemical is added in order to bring about precipitation?

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Q. Why is Ferric ammonium sulfate generally not used as a coagulant?

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Q. What is the recommended surface loading rate in case of alum floc suspension?

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Q. In percentage what is the amount of TSS removed by chemical clarification?

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Q. In percentage what is the amount of BOD removed by chemical clarification?

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Q. In percentage, how much does the chemical sludge contribute to the total sludge formed?

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Q. Assume in a sample of waste water around 60% TSS is removed by primary sedimentation without chemical addition. Calculate the mass of TSS removed for the following data.

Amount of TSS present initially: 220 mg/L
Waste water flow: 1000 m³/d

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Q. Determine the sludge formed from the following set of data.

Specific gravity of sludge: 1.05
Moisture content: 92.5%
Total dry solids: 213.4 kg/1000 m³

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Q. At what pH is phosphate precipitated out?

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Q. Name the compound formed when lime is added in order to precipitate phosphate.

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Q. At which point, chemical addition for phosphorous removal can’t be carried out?

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Q. Calculate the dosage rate for the following data.

Flow rate: 2200m³/hr
Dosage: 100 ppm

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Q. Calculate the volume of lime to be dosed for the below given data. Round it off to the nearest digit.

Flow rate: 2200m³/hr
Dosage: 25 ppm
Specific gravity: 1.12
Concentration: 10%

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Q. Calculate the size of the tank for the below given data. Round off to the nearest 1000 digit.

Flow rate: 440lph
Retention time: 17 hrs

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Q. What is the detention time assumed while designing a flash mixer?

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