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Alanco Questions with Answers on Water Treatment

Q1. The maximum desirable limit (BIS) of total hardness (as CaCo3) in drinking water is

A. 600 ppm

B. 300 ppm

C. 500 ppm

D. 1000 ppm


Q2. Hardness of water does not

A. have any bad effect in boiler

B. make cooking of foods difficult

C. make it unfit for drinking

D. cause difficulty in the washing of clothes with soaps


Q3. Zeolite used in zeolite softening process for the treatment of hard water gets exhausted after certain time of usage but can be regenerated by flushing it with

A. 10% calcium chloride solution

B. 10% magnesium sulfate solution

C. 10% magnesium chloride solution

D. 10% sodium chloride solution


Q4. Secondary treatment uses __________ to consume wastes.

A. micro-organisms

B. chemicals

C. filtration

D. none of these


Q5. Permanent hardness of water is caused by the presence of

A. bicarbonates of calcium and magnesium

B. carbonates of sodium and potassium

C. chlorides and sulfates of calcium and magnesium

D. phosphates of sodium and potassium


Q6. According to BIS the maximum permissible limit of dissolved solids in drinking water is

A. 1000 mg/l

B. 500 mg/l

C. 2000 mg/l

D. 1500 mg/l


Q7. Which of the following physical method is used as germicidal in modern time for the treatment of drinking water?

A. Chlorination

B. Treating with potassium permagnate

C. UV radiation

D. Treating with bleaching powder


Q8. The common methods used for disinfection in waste water treatment plants are

A. chlorination

B. UV light

C. both (a) and (b)

D. Phenolic solvent


Q9. Which of the following substances are commonly used in a filter?

A. Charcoal

B. Sand

C. Both (a) and (b)

D. Aluminum chloride


Q10. The maximum permissible limit (BIS) of turbidity in drinking water is

A. 5 NTU

B. 10 NTU

C. 15 NTU

D. 20 NTU


Q11. The ultimate source of water is

A. rivers and lakes

B. dew and forest

C. rain and snow

D. underground and surface


Q12. Permanent hardness of water may be removed by the addition of

A. lime

B. soda ash

C. potassium permagnate

D. sodium bicarbonate


Q13. Lagoons may be characterized as

A. anaerobic

B. facultative

C. aerated

D. all of these


Q14. The maximum desirable limit (BIS of mercury in the drinking water is

A. 0.05 mg/l

B. 0.9 mg/l

C. 0.1 mg/l

D. 0.001 mg/l


Q15. The purest form of naturally occurring water is

A. rain water

B. river water

C. pond water

D. well water


Q16. Calgon is used for removal of

A. sodium carbonate

B. permanent hardness of water

C. potassium carbonate

D. none of these


Q17. The water being used in dairy industry should contain not more than

A. 5 proteolytic and/or lipolytic organisms per ml

B. 10 proteolytic and/or lipolytic organisms per ml

C. 15 proteolytic and/or lipolytic organisms per ml

D. 20 proteolytic and/or lipolytic organisms/ml


Q18. Coliform bacteria in water is an indication of the presence of

A. radioactive wastes

B. excess fertilizer

C. decaying animals and plants

D. human feces


Q19. Both temporary and permanent hardness of water can be removed by

A. boiling

B. distillation

C. filtration

D. decantation


Q20. Zeolite softening process removes both temporary and permanent hardness of water. In this process the calcium and magnesium present in water are precipitated as

A. insoluble carbonates

B. insoluble zeolites

C. insoluble chlorides

D. insoluble sulfates


Q21. BOD stands for

A. biochemical oxygen demand

B. british oxygen demand

C. british oxygen depletion

D. biological oxygen depletion


Q22. The activated sludge process is sometime referred as

A. fluid bed biological oxidation system

B. fixed bed biological oxidation system

C. turning bed biological oxidation system

D. none of the above


Q23. The activated sludge process consists of returning a portion of the clarifier

A. effluent water entering the reactor

B. influent water coming out of the reactor

C. influent water entering the reactor

D. effluent water coming out of the reactor


Q24. If the depletion of oxygen is found to be 2.5 mg/litre after incubating 2.5 ml of sewage diluted to 250 ml for 5 days at 20°C, B.O.D. of the sewage is

A. 50 mg/l

B. 100 mg/l

C. 150 mg/l

D. 200 mg/l

E. 250 mg/l.


Q25. The pH value of fresh sewage is usually

A. equal to 7

B. more than 7

C. less than 7

D. equal to zero.



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