Recent questions tagged environmental-engineering

For wastewater coming from a wood pulping industry, Chemical Oxygen Demand $\text{(COD)}$ and $5$-day Biochemical Oxygen Demand $\text{(BOD}_{5})$ were determined. For th...

A wastewater sample contains two nitrogen species, namely ammonia and nitrate. Consider the atomic weight of $\text{N, H, and O}$ as $14\:g/mol$, $1\:g/mol$, and $16\:g/m...

The relationship between oxygen consumption and equivalent biodegradable organic removal (i.e.,BOD) in a closed container with respect to time is shown in the figureAssum...

Consider a rigid retaining wall with partially submerged cohesionless backfill with a surcharge. Which one of the following diagrams closely represents the Rankine’s acti...

As per Noise Pollution (Regulation and Control) Rules $2000$ of India, the day time noise limit for a residential zone, expressed in dB(A)L$_{eq}$, is$55$$65$$75$$85$

Following observations have ben made for the elevation and temperature to ascertain the stability of the atmosphere:$$\begin{array}{|c|c|} \hline \text{Elevation (in m) }...

The most important type of species involved in the degradation of organic matter in the case of activated sludge process isautotrophsheterotrophsprototrophsphoto-autotrop...

The composition of a municipal solid waste sample is given below:$\begin{array}{|l|c|c|c|} \hline \text{Component} & \text{Percent by} & \text{Moisture Content} & \text{E...

For a given water sample, the ratio between BOD$_{\text{5-day, 20}^{\circ} C}$ and the ultimate BOD is $0.68$. The value of the reaction rate constant $k$ (on base $e$) (...

A municipal corporation is required to treat $1000 \: m^3/day$ of water. It is found that an overflow rate of $20 m/day$ will produce a satisfactory removal of the discre...

Which one of the following is a secondary pollutant?OzoneCarbon MonoxideHydrocarbonVolatile Organic Carbon (VOC)

Sedimentation basin in a water treatment plant is designed for a flow rate of $0.2 \: m^3/s$. The basin is rectangular with a length of $32 \: m$, width of $8 \:m $, and ...

A sample of air analysed at $0^{\circ} C$ and $1 \: atm$ pressure is reported to contain $0.02 \: ppm$ (parts per million) of $NO_2$. Assume the gram molecular mass of $N...

A wastewater is to be disinfected with $35 \: mg/L$ of chlorine to obtain $99 \%$ kill of micro-organisms. The number of micro-organisms remaining alive $(N_t)$ at time $...

Which one of the following options contains ONLY primary air pollutants?Hydrocarbons and nitrogen oxidesHydrocarbons and ozoneOzone and peroxyacetyl nitrateNitrogen oxide...

Analysis of a water sample revealed that the sample contains the following species.$CO_3^{2-}, Na^+, H^+, PO_4^{3-}, Al^{3+}, H_2CO_3, Cl^-, Ca^{2+}, Mg^{2+}, HCO_3^-, Fe...

Chlorine is used as the disinfectant in a municipal water treatment plant. It achieves $50$ percent of disinfection efficiency measured in terms of killing the indicator ...

A water treatment plant treats $6000 \: m^3$ of water per day. As a part of the treatment process, discrete particles are required to be settled in a clarifier. A column ...

Raw municipal solid waste (MSW) collected from a city contains $70 \%$ decomposable material that can be converted to methane. The water content of the decomposable mater...

Consider the reactor shown in the figure. The flow rate through the reactor is $Q \: m^3/h$. The concentrations (in $mg/L$) of a compound in the influent and effluent are...

A water supply board is responsible for treating $1500 \:m^3/day$ of water. A settling column analysis indicates that an overflow rate of $20 \: m/day$ will produce satis...

The hardness of a ground water sample was found to be $420 \: mg/L$ as $CaCO_3$. A softener containing ion exchange resins was installed to reduce the total hardness to $...

The sound pressure (expressed in $\mu P a$) of the faintest sound that a normal healthy individual can hear is$0.2$$2$$20$$55$

A sample of water has been analyzed for common ions and results are presented in the form of a bar diagram as shown.The non-carbonate hardness (expressed in mg/L as $CaCO...

A noise meter located at a distance of $30 \: m$ from a point source recorded $74 \: dB$. The reading at a distance of $60 \: m$ from the point source would be __________

For a wastewater sample, the three-day biochemical oxygen demand at incubation temperature of $20^{\circ}C$ (BOD$_{\text{3day}, 20^{\circ}C}$) is estimated as $200 mg/L$....

Pre-cursors to photochemical oxidants are$NO_X, \: VOC$s and sunlight$SO_2, \: CO_2$ and sunlight$H_2S, \: CO$ and sunlight$SO_2, \: NH_3$ and sunlight

It was decided to construct a fabric filter, using bags of $0.45$ m diameter and $7.5$ m long, for removing industrial stack gas containing particulates. The expected rat...

Match the items in Group – I with those in Group – II and choose the right combination.$$\begin{array}{llll} {} & \underline{\text{Group – I}} & {} & \underline{\text{G...

Effluent from an industry ‘A’ has a pH of $4.2$. The effluent from another industry ‘B’ has double the hydroxyl (OH) ion concentration than the effluent from industry ‘A’...

An electrostatic precipitator (ESP) with $5600\:m^2$ of collector plate area is $96$ percent efficient in treating $185\:m^3/s$ of flue gas from a $200$ MW thermal power ...

The $2$-day and $4$-day BOD values of a sewage sample are $100$ mg/L and $155$ mg/L, respectively. The value of BOD rate constant (expressed in per day) is __________

The wastewater from a city, containing a high concentration of biodegradable organics, is being steadily discharged into a flowing river at a location S. If the rate of a...

The equivalent sound power level (in dB) of the four sources with the noise levels of $60$ dB, $69$ dB, $70$ dB and $79$ dB is ______

Two wastewater streams A and B, having an identical ultimate BOD are getting mixed to form the stream C. The temperature of the stream A is $20^{\circ}C$ and the temperat...