Power Plant : Practice Questions and Answers

Pressure compounding is also called as Rateau staging.

There are basically 2 ways of compounding steam turbines namely, Rateau staging & Curtis staging.

Laval Turbines are single-stage impulse turbines.

Septic systems are commonly used to treat waste water. There might be one tank that combines all black and grey water or two tanks that divide the black and grey water.

The hydraulic loading rate of a disc filter assumed while designing it is 0.25-0.83 m2/m3/h. This is measured in the units m2/m3/h. This depends on the suspended solids present in the waste water.

The hydraulic loading rate of a cloth disc filter assumed while designing it is 0.1-0. 27 m2/m3/h. This is measured in. This depends on the suspended solids present in the waste water.

The upflow velocity considered for an UASB while treating domestic waste water is 0.8-1. In most cases it is 0.9. This waste water is mixed with the influent biomass from the bottom of the reactor.

There are different types of sewers used based on a type of flow it is designed to carry. Storm sewers are required to transport storm water runoff from roofs, parking lots, streets, and highways to a point of discharge. Storm drainage system helps to minimize flooding and soil erosion.

“Biosolids” is a term often used in waste water engineering publications and public relations efforts by local water authorities when they want to put the focus on reuse of sewage sludge after the sludge has undergone suitable treatment processes.

The waste water coming from bathrooms and kitchens which does not contain fecal matter is known as sullage. Sewer is a pipe carrying sewage from water conduits.

Normally a minimum of 75 mm diameter pipes are used for drainage of waste water. Waste water is from showers, basins, kitchen sinks, washing machines and the like. This is also called grey water.

Gully traps are constructed outside the building to carry waste water discharge from washbasin, sinks, bathroom etc.

The colour of the septic water is black. If the waste water undergoes some degree of decomposition the colour of water is light grey.

The organic matter consists mainly of proteins, carbohydrates and fats. Between 40 and 65 % of the solids in an average waste water are suspended. Usually, about 60 % of the suspended solids in a municipal waste water are 2 settleable (Ron & George, 1998).

The most common indicator organism for waste water evaluation is fecal coliform but there has been discussion regarding the use of Escherichia coli (E. coli) or Total Coliform.

Waste water enters the reactor from the bottom and flows forward. A suspended sludge blanket filters and treats the waste water as the waste water flows through it.

Municipal waste waters may contain from 5 to 20 mg/l of total phosphorous, of which 1-5 mg/l is organic and the rest in inorganic. The individual contribution tends to increase because phosphorous is one of the main constituents of synthetic detergents.

After this kind of treatment that is after physical removal of solids and biological removal of solids, the waste water may be called secondary-treated waste water.

The most commonly used coagulant is alum. A coagulant combines with the impurities in waste water and forms an end product called flocs which is greater in diameter and can be easily removed.

Industrial waste water treatment plants may or may not need the screens. Screens must be provided even for industrial waste water treatment plants to separate labels, stopper, cardboard, and other packing materials.