Recent questions and answers in Water and Waste Water Quality and Treatment

One-third of the solid matter in a sludge containing $90 \%$ water is composed of fixed mineral solids with specific gravity $2.5$, and two-third is composed of volatile ...

The grown algae are useful in the operation ofoxidation pond.slow sand filter.cyclone separator.septic tank.

The $2.4$ ml of raw sewage is diluted to $240$ ml. The Dissolved Oxygen (DO) of the diluted sample at the beginning of Biochemical Oxygen Demand (BOD) test was $8 \mathrm...

The analysis of major cations and anions in a water sample collected from a city's water supply is given below. Ions present in minor concentrations are not given.\[\begi...

Anaerobic bacteria are being utilized for the destruction of biodegradable organic content of wastewater measured in terms of Chemical Oxygen Demand (COD). The yield coef...

A rapid sand filter bed of depth $0.8$ m has $40 \%$ porosity during service cycle. It is recommended that during backwash operation, the expanded filter bed should have ...

The settling velocity of inorganic particles in the sedimentation tank of a water treatment plant is governed byDarcy's lawStokes' lawDupuit's lawBernoulli's law

Which of the following components is/are NOT removed in the secondary treatment of sewage?Suspended settleable organic solidsColloids including dissolved organic matterPa...

The average sewage from a city is $90$ million litres per day and the average $5$-day Biochemical Oxygen Demand ($\text{BOD5}$) is $300 ~\mathrm{mg} / \mathrm{l}$. Averag...

An Activated Sludge Process $\text{(ASP)}$ has an inlet wastewater flowrate of $20000 \mathrm{~m}^{3} /$ day with a Biochemical Oxygen Demand $\text{(BOD)}$ concentration...

The maximum demand at a water purification plant has been estimated as $12$ million litres per day. For the raw supplies, a rectangular sedimentation tank is to be design...

Free residual chlorine concentration in water was measured to be $2 \mathrm{mg} / 1\left(\right.$ as $\left.\mathrm{Cl}_{2}\right)$. The pH of water is $8.5$. By using th...

A compound has a general formula $\mathrm{C}_{\mathrm{a}} \mathrm{H}_{\mathrm{b}} \mathrm{O}_{\mathrm{c}} \mathrm{N}_{\mathrm{d}}$ and molecular weight $187$. A $935 \: \...

​​​​​$\mathrm{MgCl}_{2}$ and $\mathrm{CaSO}_{4}$ salts are added to $1$ litre of distilled deionized water and mixed until completely dissolved. Total Dissolved Solids (T...

A hypothetical multimedia filter, consisting of anthracite particles (specific gravity: $1.50$), silica sand (specific gravity: $2.60$), and ilmenite sand (specific gravi...

A circular settling tank is to be designed for primary treatment of sewage at a flow rate of $10$ million liters/day. Assume a detention period of $2.0$ hours and surface...

Activated carbon is used to remove a pollutant from wastewater in a mixed batch reactor, which follows first-order reaction kinetics.At a reaction rate of $0.38 /$ day, t...

Which of the following is/are NOT active disinfectant(s) in water treatment? $\cdot \mathrm{OH}$ (hydroxyl radical)$\mathrm{O}_{3}$ (ozone) $\mathrm{OCl}^{-}$(hypochlorit...

In the context of water and wastewater treatments, the correct statements are:particulate matter may shield microorganisms during disinfectionammonia decreases chlorine d...

The theoretical aerobic oxidation of biomass $\left(\mathrm{C}_5 \mathrm{H}_7 \mathrm{O}_2 \mathrm{~N}\right)$ is given below:$\mathrm{C}_5 \mathrm{H}_7 \mathrm{O}_2 \mat...

A system of seven river segments is shown in the schematic diagram. The $\mathrm{R}_{\mathrm{i}}$ 's, $\mathrm{Q}_{\mathrm{i}}$ 's, and $\mathrm{C}_{\mathrm{i}}$ 's $(\ma...

Identify the waterborne diseases caused by viral pathogens: Acute anterior poliomyelitisCholera Infectious hepatitis Typhoid fever

In the following table, identify the correct set of associations between the entries in Column-$1$ and Column-$2.$$$\begin{array}{|l|l|}\hline {\qquad \text{Column-1} } &...

A flocculator tank has a volume of $2800 \mathrm{~m}^{3 .}$ The temperature of water in the tank is $15^{\circ} \mathrm{C}$, and the average velocity gradient maintained ...