GATE Overflow for GATE ESE - Recent activity in Solid and Hazardous Waste Management

Edited: GATE ES 2026 | Question: 52

Thu, 16 Apr 2026 12:22:48 +0000

The characteristics of two types of solid waste are given in the table.

The quantity of sludge to be added to leaves to achieve a $\mathrm{C} / \mathrm{N}$ ratio of $25$ (on dry basis) for the mixed waste is $\_\_\_\_$ $\mathrm{kg}$ of sludge/kg of leaves (rounded off to three decimal places).

Type of solid waste	Characterstics of the solid waste (weight/weight)
Type of solid waste	Moisture content ($\%$)	Nitrogen content ($\%$)	Carbon to Nitrogen (C/N) ratio
Leaves	$50$	$0.7$	$50$
Sludge	$75$	$5.6$	$6.3$

Edited: GATE ES 2026 | Question: 51

Wed, 15 Apr 2026 12:09:30 +0000

An anaerobic digestion system is operated for methane gas generation from organic fraction of municipal solid waste $\text{(OFMSW)}$. The moisture content and volatile solids $\text{(VS)}$ content of $\text{OFMSW}$ are $20 \%$ and $90 \%$, respectively. The biodegradable volatile solids $\text{(BVS)}$ in the $\text{VS}$ is $70 \%$, and the $\text{BVS}$ conversion efficiency to methane gas is $85\%$.

If the methane gas generation in the system is $12 \mathrm{~m}^{3}$ per kg of $\text{BVS}$ converted, the total volume of gas produced from one kilogram of $\text{OFMSW}$ is $\_\_\_\_\_\_$ $\mathrm{m}^{3}$ (rounded off to two decimal places).

Edited: GATE ES 2026 | Question: 21

Wed, 15 Apr 2026 09:52:47 +0000

Which of the following statements is/are CORRECT in the context of hazardous waste management and its risk assessment?

Risk is estimated based on the probability of an action occurring multiplied by the severity of damage.
High octanol water constant ($K_{O W}$) is indicative of lower accumulation of an organic chemical in body tissue.
Pump and treat is an example of contaminated groundwater remediation.
Biological treatment processes are never applied for hazardous waste management.

Edited: GATE ES 2026 | Question: 19

Wed, 15 Apr 2026 09:49:27 +0000

Which of the following processes is/are primarily used to remove the organic matter in sludge?

Digestion
Incineration
Magnetic separation
Wet-oxidation

Edited: GATE ES 2026 | Question: 13

Wed, 15 Apr 2026 09:38:18 +0000

Which ONE of the following options is NOT a parameter as a part of proximate analysis of municipal solid waste?

Volatile matter
Ash content
Carbon to nitrogen ratio
Moisture content

Edited: GATE ES 2025 | Question: 53

Mon, 02 Jun 2025 20:06:00 +0000

A solid waste of composition $\mathrm{C}_{60} \mathrm{H}_{135} \mathrm{O}_{50} \mathrm{~N}_{5}$ is to be composted aerobically in a closed vessel mechanical composting facility. Given: all ammonia generated escapes the facility; air contains $23 \%$ of Oxygen by weight; $100 \%$ excess air requirement for the closed vessel composting facility. The atomic weights: $\mathrm{C}-12$, $\mathrm{H}-1, \mathrm{O}-16, \mathrm{~N}-14$. The actual air required for composting is $\_\_\_\_\_\_$ kg per kg waste. (rounded off to one decimal place).

Edited: GATE ES 2025 | Question: 36

Mon, 02 Jun 2025 19:50:46 +0000

According to the Bio-Medical Waste Management Rules, $2016$, choose the correct option(s) from the following

Bio-medical waste generated should be taken to a common bio-medical waste management facility except for rural areas where common facility is not available.
Bio-medical waste generated should not be taken out of the hospital premise as it may contain dangerous pathogenic organisms.
The red bag containing the human anatomical wastes like amputated body parts, cotton and bandages contaminated with body fluids, etc. should be treated using autoclave or hydroclave to kill the pathogenic organisms.
Increasing operational temperature of an autoclave from $121^{\circ} \mathrm{C}$ (pressure $15$ psi ) to $149{ }^{\circ} \mathrm{C}$ (pressure $52$ psi ), the residence time requirement for treating bio-medical waste will be reduced by $15$ minutes.

Edited: GATE ES 2025 | Question: 32

Mon, 02 Jun 2025 19:44:43 +0000

Which option gives the best control strategies for Dioxins and Furans in the flue gas emitted from waste incineration facilities?

Avoid burning polystyrene (PS) and polyethylene (PE); ensure the furnace temperature above $1000^{\circ} \mathrm{C}$; and use a bag filter for cleaning the flue gas.
Avoid burning polyvinyl chloride (PVC); quickly cool down the flue gas through the temperature range $400-250^{\circ} \mathrm{C}$; and use an activated carbon treatment for the flue gas.
Avoid burning food wastes; ensure the furnace temperature above $900 \pm 50^{\circ} \mathrm{C}$; and use an electrostatic precipitator (ESP) for cleaning the flue gas.
Avoid burning metal bearing waste; ensure the flue gas temperature above $1000^{\circ} \mathrm{C}$; and use a venturi scrubber for cleaning the flue gas.

Edited: GATE ES 2025 | Question: 19

Mon, 02 Jun 2025 16:54:55 +0000

Choose the option(s) giving the correct process flow-sheet for producing refuse derived fuel (RDF) from the segregated waste collected in the dry waste containers (blue coloured containers of the municipal solid waste (MSW) collection scheme).

Edited: GATE ES 2025 | Question: 18

Mon, 02 Jun 2025 16:54:05 +0000

Plastic wastes may be burnt to generate fuel oil and fuel gas.

Plastic wastes along with bitumen may be used for road/pavement construction.
Polyethylene terephthalate (PET) and high density polyethylene (HDPE) are the most common plastics for recycling.
Plastics made of branched monomers can be easily recycled.
Choose the correct option(s) from the following in the plastic waste management

Edited: GATE ES 2025 | Question: 13

Mon, 02 Jun 2025 16:50:43 +0000

Choose the correct option regarding the Basel Convention

Almost all the nations of the world assembled for the first time in the history to discuss and find out the solution for a common environmental problem.
It was for formulating the strategies and guidelines to reduce $\mathrm{CO}_{2}$ and $\mathrm{CH}_{4}$ emissions to control the global warming.
It was for formulating the strategies and guidelines to control the release of acidic gases that can cause acid rains in another country.
It was for formulating the strategies and guidelines for the trans-boundary movement of hazardous wastes.

Edited: GATE ES 2025 | Question: 11

Mon, 02 Jun 2025 16:49:15 +0000

Which option gives the components that are most likely to be present in the segregated combustible fraction (SCF) separated from raw mixed municipal solid waste (MSW)?

plastics, paper, rubber, metals
plastics, paper, leather, glass
plastics, leather, textiles, rubber
plastics, rubber, textiles, food waste

Recategorized: GATE ES 2024 | Question: 13

Mon, 21 Apr 2025 17:04:28 +0000

The costliest functional element in an urban centralized Municipal Solid Waste management infrastructure for a typical Indian Tier $\text{I}$ city is _______.

biological treatment
collection and transport
disposal in a sanitary landfill
thermal treatment

Recategorized: GATE ES 2024 | Question: 12

Mon, 21 Apr 2025 17:04:25 +0000

As per the United Nations Environmental Program (UNEP) guidelines 2004, the maximum size of microplastics is __________.

$10 \mathrm{~mm}$
$5 \mathrm{~mm}$
$10 \mu \mathrm{m}$
$5 \mu \mathrm{m}$

Recategorized: GATE ES 2024 | Question: 21

Mon, 21 Apr 2025 17:03:53 +0000

As per the Hazardous Waste $\text{(Management and Handling)}$ Rules, $2016$, of India, which is/are the characteristic(s) that must be exhibited by a waste to be classified as a
"characteristic" hazardous waste?

Ignitability
Reactivity
Radioactivity
Toxicity

Recategorized: GATE ES 2024 | Question: 24

Mon, 21 Apr 2025 17:03:28 +0000

A municipal solid waste digester generates $1000 \mathrm{~kg}$ of methane gas. The volume of the tank needed to store this gas at $30^{\circ} \mathrm{C}$ and 3 atmospheric pressure is __________ liters $\text{(an integer value)}$.

Use $\mathrm{R}=0.082 \mathrm{~L}-\mathrm{atm} / \mathrm{mole}-\mathrm{K}$, Atomic weights of $\mathrm{C}=12$, and $\mathrm{H}=1$

Recategorized: GATE ES 2024 | Question: 51

Mon, 21 Apr 2025 17:02:23 +0000

Food waste, paper waste and plastic waste have typical densities of $280 \mathrm{~kg} / \mathrm{m}^{3}, 80 \mathrm{~kg} / \mathrm{m}^{3}$, and $50 \mathrm{~kg} / \mathrm{m}^{3}$, respectively. The mixed waste is composed of $70 \%$ food waste, $20 \%$ paper waste and $10 \%$ plastic waste. The density of the mixed waste is __________ $\mathrm{kg} / \mathrm{m}^{3}$ $\text{(rounded off to $2$ decimal places)}$.

Neglect compaction effect.

Recategorized: GATE ES 2023 | Question: 10

Mon, 21 Apr 2025 17:01:07 +0000

Which of the following is NOT a designated waste category under Bio-medical Waste Management Rules, $2016$ of Government of India?

Yellow
Green
Red
Blue

Recategorized: GATE ES 2023 | Question: 11

Mon, 21 Apr 2025 17:01:04 +0000

Consider the following waste categories

i) Domestic Hazardous Waste

ii) Nuclear Waste

iii) Sludge from wet scrubbers of hazardous waste treatment processes

iv) Chromium bearing residue and sludge from leather tanneries

Which one of the options correctly represents the waste categories NOT covered under Hazardous and Other Wastes (Management and Transboundary Movement) Rules, 2016 of Government of India?

(i) and (ii) only
(i) and (iii) only
(ii) and (iv) only
(i),(ii) and (iii) only

Recategorized: GATE ES 2023 | Question: 12

Mon, 21 Apr 2025 17:01:01 +0000

Match the following

Plastic type	Common applications
P. High-density polyethylene (HDPE)	(i) Garbage bags, bubble packaging
Q. Low-density polyethylene (LDPE)	(ii) Pharmaceutical bottles, Styrofoam cups
R. Polyethylene terephthalate (PET)	(iii) Water bottles
S. Polystyrene (PS)	(iv) Geomembrane for landfill liner

$\text{P - (iv), Q - (i), R - (iii), S - (ii)}$
$\text{P - (i), Q - (iii), R - (ii), S - (iv)}$
$\text{P - (iv), Q - (ii), R - (i), S - (iii)}$
$\text{P - (ii), Q - (iii), R - (iv), S - (i)}$

Recategorized: GATE ES 2023 | Question: 35

Mon, 21 Apr 2025 16:59:55 +0000

Read the following statements about aerobic composting of organic fraction of municipal solid waste

The majority of the odour problem in an aerobic composting process is due to the development of anaerobic conditions within the compost pile.
All organic carbon present in the waste will completely biodegrade in $14$ days.
At high $\mathrm{C} / \mathrm{N}$ ratio, ammonia would be released and biological activity may - also be impeded.
Optimum moisture content for aerobic composting process would be $50-60 \%$. Lower moisture would slow down the biological process.Excessive moisture will make it difficult to maintain aerobic conditions.

The correct choice(s) is/are

I and IV are correct
II and III are incorrect
I is correct, IV is incorrect
II is correct; IV is incorrect

Recategorized: GATE ES 2023 | Question: 50

Mon, 21 Apr 2025 16:59:09 +0000

A city generates on average $1000$ metric tonnes/day of municipal solid waste and follows integrated waste management system. $15 \%$ of the total waste is recycled, $40 \%$ of the total waste is used to produce compost. $25 \%$ of the total waste is converted to refuse derived fuel (RDF) with $80 \%$ efficiency. Remaining is disposed of in a sanitary landfill. The calorific value of the RDF is $15 \mathrm{MJ} / \mathrm{kg}$, which is further used to generate electricity. The electrical energy that could be generated from the $\mathrm{RDF}$ with a thermal to electrical energy conversion efficiency of $20 \%$ is __________ (in $\mathrm{MWh} / \mathrm{d}$, $\text{rounded off to two decimal places).}$

Recategorized: GATE ES 2023 | Question: 53

Mon, 21 Apr 2025 16:58:58 +0000

Ultimate analysis of a municipal solid waste sample is given below

\begin{array}{|c|c|c|c|c|}
\hline { Percent by weight } \\
\hline Carbon & Hydrogen & Oxygen & Nitrogen & Ash \\
\hline 48 & 6 & 35 & 6 & 5 \\
\hline
\end{array}

For $1 \mathrm{~kg}$ of the municipal solid waste burnt, assuming that air contains only nitrogen and oxygen, maximum $\mathrm{CO}_2$ emitted is ____________ (in kg, $\text {rounded off to three decimal places}).$

Recategorized: GATE ES 2022 | Question: 14

Mon, 21 Apr 2025 16:47:20 +0000

Leachate generated from a legacy municipal solid waste dumping site has to be collected and managed carefully. Which one of the following statements is correct in the context of treatment of leachate from such a site?

Settling chamber followed by micro-filtration units are required.
Modular treatment units targeting dissolved organic matter and salts are required.
Only biological treatment units like ASP with extended aeration are required.
Only a combination of anaerobic-aerobic treatment units is required.

Recategorized: GATE ES 2022 | Question: 17

Mon, 21 Apr 2025 16:47:12 +0000

Which one of the following statements correctly defines the concept of 'Extended Producer's Responsibility'?

The responsibility of a producer for environmentally sound disposal of the product after the end of its life
The responsibility of a producer for environmentally sound manufacturing process for the product
The responsibility of a producer for environmentally sound management of the product from manufacturing stage until it is sold in the market
The responsibility of a producer for environmentally sound management of the product until the end of its life

Recategorized: GATE ES 2022 | Question: 21

Mon, 21 Apr 2025 16:46:59 +0000

Biodegradable wastes like vegetable peelings from kitchen are usually processed by composting techniques. Which of the following option(s) regarding the processing of biodegradable wastes is/are correct?

Vermi-composting is relatively faster than windrow composting, however vermicomposting is not frequently used on large commercial scale.
The windrow height should be as short as possible as large windrow height may cause compaction due to the self-weight.
The windrow height should be as large as possible as that will help to ensure appropriate temperature within the windrow.
Earthworms facilitate the growth of microorganisms and break down complex organic molecules to simpler ones using enzymatic secretions.

Recategorized: GATE ES 2022 | Question: 22

Mon, 21 Apr 2025 16:46:57 +0000

As per 'Hazardous and Other Wastes (Management and Transboundary Movement) Rules, $2016$ of Govt. of India, the import of hazardous and other wastes from any country shall NOT be permitted for which of the following option(s)?

Recovery, reuse and recycle
Disposal in abandoned mines
Safe disposal in engineered landfills
Utilization, including co-processing

Recategorized: GATE ES 2022 | Question: 39

Mon, 21 Apr 2025 16:46:06 +0000

As per the Solid Waste Management Rules of 2016 (Govt. of India), which of the following statement(s) is/are correct?

Biodegradable wastes should be processed biologically preferably in decentralized facilities at the sources of generation.
Biodegradable wastes should be processed biologically preferably in centralized facilities away from the sources of generation.
Used sanitary pads and napkins should be wrapped and disposed into the domestic hazardous waste containers.
Non-biodegradable components with a heat content more than $1500 \mathrm{kcal} / \mathrm{kg}$ should be used for power generation or Refuse Derived Fuel (RDF) manufacture.

Recategorized: GATE ES 2021 | Question: 6

Mon, 21 Apr 2025 15:42:32 +0000

What is the order of preference of the various elements in integrated waste management hierarchy $\text{(highest preference to lowest preference)}$?

Reduce $>$ Rcuse $>$ recycle $>$ Encrgy recovery $>$ Landfilling.
Reuse $>$ recycle $>$ Reduce $>$ Energy recovery $>$ Landfilling.
Reduce $>$ Energy recovery $>$ Reuse $>$ recycle $>$ Landfilling
Reduce $>$ Reuse $>$ recycle $>$ Landfilling $>$ Energy recovery

Recategorized: GATE ES 2021 | Question: 13

Mon, 21 Apr 2025 15:42:13 +0000

Choose the correct order of biodegradability $\text{(highest to lowest)}$ of the following municipal solid waste components.

Food waste $>$ Newspaper $>$ Polyvinyl Chloride $\text{(PVC)}$
Newspaper $>$ Food waste $>$ Polyvinyl Chloride $\text{(PVC)}$
Food waste $>$ Polyvinyl Chloride $\text{(PVC )}>$ Newspaper
Polyvinyl Chloride $\text{(PVC)}$ $>$ Food waste $>$ Newspaper

Recategorized: GATE ES 2021 | Question: 33

Mon, 21 Apr 2025 15:41:17 +0000

In context of municipal solid waste treatment, match the equipment in List I with their function in List II.

List I	List II
Trommel	Size reduction
Magnetic separator	Aluminium separation
Hammer mill	Screening
Eddy current separator	Ferrous metal recover

$\text{P-(iii), Q-(iv), R-(i), S-(ii)}$
$\text{P-(iii), Q-(ii), R-(iv), S-(i)}$
$\text{P-(i), Q-(iv), R-(iii), S-(ii)}$
$\text{P-(iv), Q-(ii), R-(i), S-(iii)}$

Recategorized: GATE ES 2021 | Question: 47

Mon, 21 Apr 2025 15:40:38 +0000

An underground hazardous waste storage tank is leaking. The contaminant concentration directly beneath the site is $0.5 \mathrm{mg} / \mathrm{L}$. The contaminant is travelling at an effective rate of $0.4 \mathrm{~m}$ per day towards a water well which is $2 \mathbf{~ k m}$ away.

Assume that the degradation of the contaminant follows a first order reaction, and the initial concentration of the contaminant becomes half in $10$ years.

In this case, the contaminant concentration expected at the well under steady state conditions is ____________ $\mathrm{mg} / \mathrm{L}$ $\text{(rounded off to two decimal places)}$.

Recategorized: GATE ES 2021 | Question: 51

Mon, 21 Apr 2025 15:40:27 +0000

The municipal solid waste $\text{(MSW)}$ generated in a community $\text{(population =(100000)}$ is disposed on a $12 \times 10^4 \mathrm{m}^2$ landfill site, which can be filled to a total depth of $25 \mathrm{~m}$ $\text{(including soil cover)}$. Assume that $\text{MSW}$ is generated at a rate of $2.5 \mathrm{kg}$ per person per day and its compacted density is $800 \mathrm{~kg} / \mathrm{m}^3$. If the volumetric ratio of $\text{MSW}$ and soil cover is $5:1$, the useful life of the landfill site is _________ years $\text{(rounded off to the nearest integer)}$.

Recategorized: GATE ES 2021 | Question: 52

Mon, 21 Apr 2025 15:40:22 +0000

A mechanized stationary container system is proposed for waste collection from a commercial area. The container unloading time is $0.1$ hours per container. There are two containers at each location and the drive time between the two locations is $0.2$ hours. The maximum waste 'pick-up time' is $2.4$ hours per trip.
The 'pick-up time' starts at the instant the truck arrives at the first pick-up location and ends when the last container on the route is emptied. The maximum number of locations which can be covered in a trip by the collection vehicle are ________$\text{(answer in integer)}$.