The polluted water is one which

Orthotolidine test is used for determination of

The chemical most commonly used to increase speed of sedimentation of sewage is

The disinfection efficiency of chlorine increases by
(i)      Decreasing the time of contact
(ii)     Decreasing the temperature of water
(iii)      Increasing the temperature of water The correct answer is

The layout of distribution system in which water flows towards the outer periphery is

The type of valve which allows water to flow in one direction but prevents its flow in the reverse direction is

The suitable system of sanitation for area of distributed rainfall throughout the year with less intensity is

The main disadvantage of cement concrete sewers is

Settling velocity increases with

Facultative bacteria are able to work in

The suitable layout of distribution system for a city with roads of rectangular pattern is

The slope of sewer shall be

The correct relation between theoretical oxygen demand (TOD), Biochemical oxygen demand (BOD) and Chemical oxygen demand (COD) is given by

The working conditions in imhoff tanks are

The pipe which is used to carry the discharge from sanitary fittings like bath rooms, kitchens etc. is called

If the total hardness of water is greater than its total alkalinity, the carbonate hardness will be equal to

For a given discharge, the efficiency of sedimentation tank can be increased by

Air binding phenomena in rapid sand filters occur due to

The suitable method for disinfection of swimming pool water is

The commonly used material for water supply pipes, which has the properties of being strong, not easily corroded and long life but is heavy and brittle, is

The water carriage system of collection of waste product

The effect of increasing diameter of sewer on the self cleansing velocity is

The rate of BOD exerted at any time is

Generally the detention period for grit chambers is kept as

Sludge volume index is defined as the ratio of

The biochemical treatment of sewage effluents is essentially a process of

Which of the following causes a decrease in per capita consumption?

The suitable method of forecasting population for a young and rapidly increasing city is

Which of the following is not a water borne disease?

Standard EDTA (ethylene diamine tetra acetic acid) solution is used to determine the

The settling velocity of a particle in a sedimentation tank depends on

The detention period in coagulation tanks is usually kept as

Period of cleaning of slow sand filters is about

The process in which the chlorination is done beyond the break point is known as

Disinfection efficiency is

The suitable layout of a distribution system for irregularly growing town is

A sewer that receives the discharge of a number of house sewers is called

The time of concentration is defined as

Most suitable section of sewer in separate sewage system is

The pathogens can be killed by

The minimum dissolved oxygen which should always be present in water in order to save the aquatic life is

If the sewage contains grease and fatty oils, these are removed in

Composting and lagooning are the methods of

The gas from sludge digestion tank is mainly composed of

Assertion A: The consumption of water increases with increase in the distribution pressure. Reason R: Higher distribution pressure causes more loss and waste of water Select your answer according to the coding system given below

The depression of water table in a well due to pumping will be maximum (Where R is the radius of influence)

Ground water is usually free from

On standard silica scale, the turbidity in drinking water should be limited to

The settling velocity of a particle in a sedimentation tank increases if

As compared to rapid sand filters, slow sand filters give
(i)      Slower filtration rate
(ii)     Higher filtration rate
(iii)     Lesser efficiency in removal of bacteria
(iv)      Higher efficiency in removal of bacteria The correct answer is

Chlorine demand of water is equal to

In lime-soda process

Which of the following methods of analysis of water distribution system is most suitable for long and narrow pipe system?

Which of the following sewers is preferred for combined system of sewage?

An egg shaped section of sewer

Sewage treatment units are normally designed for

The means of access for inspection and cleaning of sewer line is known as

The maximum efficiency of BOD removal is achieved in

For the same solid content, if the quantity of sludge with moisture content of 98% is X, then the quantity of sludge with moisture content of 96% will be

The process of lagooning is primarily a means of

The per capital consumption of a locality is affected by
(i)      Climatic conditions
(ii)     Quality of water
(iii)      Distribution pressure The correct answer is

Select the correct relationship between porosity (N), specific yield (y) and specific retention (R)

The maximum permissible limit for fluoride in drinking water is

The dissolved oxygen level in natural unpolluted waters at normal temperature is found to be of the order of

The amount of coagulant needed for coagulation of water increases with
(i)      Increase in turbidity of water
(ii)     Decrease in turbidity of water
(iii)     Increase in temperature of water
(iv)      Decrease in temperature of water The correct answer is

The rate of Alteration of pressure filters is

The treatment of water with bleaching powder is known as

Activated carbon is used for

A pipe conveying sewage from plumbing system of a single building to common sewer or point of immediate disposal is called

The self cleansing velocity for all sewers in India is usually

The type of sewer which is suitable for both combined and separate system is

In a BOD test, 1.0 ml of raw sewage was diluted to 100 ml and the dissolved oxygen concentration of diluted sample at the beginning was 6 ppm and it was 4 ppm at the end of 5 day incubation at 20°C. The BOD of raw sewage will be

Corrosion in concrete sewers is caused by

The main disadvantage of oxidation pond is that

Most of the bacteria in sewage are

The hourly variation factor is usually taken as

The maximum discharge of a tube well is about

Turbidity is measured on

The overflow rate for plain sedimentation tanks is about

Assertion A: Slow sand filters are more efficient in removal of bacteria than rapid sand filters. Reason R: The sand used in slow sand filters is finer than that in rapid sand filters
Select your answer based on the coding system given below:

Which of the following chemical compounds can be used for de-chlorination of water?

Hardy cross method of analysis of distribution system
(i)      Involves successive trials
(ii)     Takes economic aspects into account
(iii)      Is time consuming The correct answer is

Average rate of water consumption per head per day as per Indian Standard is

The hydraulic mean depth (HMD) for an egg-shaped sewer flowing two-third full is

Select the correct statement.

Laying of sewers is usually done with the help of

For normal sludge, the value of sludge index for Indian conditions is

If the average daily consumption of a city is 100,000 m3, the maximum daily consumption on peak hourly demand will be

The most common cause of acidity in water is

The amount of residual chlorine left in public water supply for safety against pathogenic bacteria is about

The detention period and overflow rate respectively for plain sedimentation as compared to sedimentation with coagulation are generally

The effective size of sand particles used in slow sand filters is

In chlorination, with the rise in temperature of water, death rate of bacteria

The method of analysis of distribution system in which the domestic supply is neglected and fire demand is considered is

The specific gravity of sewage is

Which of the following retards the self purification of stream?

Sewerage system is designed for

In facultative stabilization pond, the sewage is treated by

A pipe which is installed in the house drainage to preserve the water seal of traps is called

The distribution mains are designed for

The type of valve, which is provided on the suction pipe in a tube-well, is

Alkalinity in water is expressed as milligrams per litre in terms of equivalent

The length of rectangular sedimentation tank should not be more than( Where B is the width of the tank)

In water treatment, rapid gravity filters are adopted to remove

Disinfection of water results in

The type of valve which is provided to control the flow of water in the distribution system at street corners and where the pipe lines intersect is

The design discharge for the separate sewer system shall be taken as

The most commonly used sewer under culverts is

The relative stability of a sewage sample, whose dissolved oxygen is same as the total oxygen required to satisfy BOD, is

For satisfactory working of a sludge digestion unit, the pH range of digested sludge should be maintained as

As compared to geometrical increase method of forecasting population, arithmetical increase method gives

The phenolic compounds in public water supply should not be more than

Percentage of bacterial load that can be removed from water by the process of plain sedimentation is about

Double filtration is used

The major disadvantage of lime soda process of water softening is that

Scour valves are provided

The velocity of flow does not depend on

The ratio of 5 day BOD to ultimate BOD is about

Septic tank is a
(i)      Settling tank
(ii)     Digestion tank
(iii)      Aeration tank The correct answer is

The population of a town in three consecutive years are 5000, 7000 and 8400 respectively. The population of the town in the fourth consecutive year according to geometrical increase method is

Which of the following values of pH represents a stronger acid?

The alum, when added as a coagulant in water

Cleaning is done by
(i)      Scraping and removal in filters slow sand
(ii)     Back washing in slow sand filters
(iii)     Scraping and removal in filters rapid sand
(iv)      Backwashing in rapid sand filters The correct answer is

As compared to cast iron pipes, steel pipes are

The design discharge for the combined sewer system shall be taken as

If Biochemical oxygen demand (BOD) of a town is 20000 kg/day and BOD per capita per day is 0.05 kg, then population equivalent of town is

The detention period for oxidation ponds is usually kept as

The devices which are installed for drawing water from the sources are called

Residual chlorine in water is determined by

The percentage of chlorine in fresh bleaching powder is about

Sewerage system is usually designed for

The characteristics of fresh and septic sewage respectively are

Which of the following unit works in anaerobic conditions?

As compared to shallow wells, deep wells have

The rate of filtration in slow sand filters in million litres per day per hectare is about

Which of the following compounds is widely used for algae control?

Dissolved oxygen in streams is

If the coli form bacteria is present in a sample of water, then the coli-form test to be conducted is
(i)      Presumptive coli-form test
(ii)     Confirmed coli-form test
(iii)      Completed coli-form test The correct answer is

As compared to higher pH values, the contact period required for efficient chlorination at lower pH values is

Standard BOD is measured at

The velocity of flow of water in a sedimentation tank is about

Alum as a coagulant is found to be most effective when pH range of water is

The percentage of filtered water, which is used for backwashing in rapid sand filters, is about

For a country like India, where rainfall is mainly confined to one season, the suitable sewerage system will be

If the time of concentration is 9 minutes, then the intensity of rainfall according to British Ministry of Health formula will be

The minimum and maximum diameters of sewers shall preferably be

Sewage treatment units are designed for

When there is no recirculation of sewage, then recirculation factor is