MCQ Bank

Sludge lagoons are among the less commonly used methods for sludge dewatering compared with drying beds and mechanical processes. They require substantial land and relatively long retention times.

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Q29

Facultative ponds require how much time for sludge removal from liquid phase?

A) Decades
B) Weeks
C) Days
D) Months

AI Explanation

Facultative ponds can retain sludge for very long periods because solids accumulate gradually at the bottom. Consequently, sludge removal may be required only after many years or even decades.

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Q30

Time required for the accumulation of discarded sludge from WWTPs is------------.

A) 2 years
B) 4 years
C) 3-5 years
D) 3 years

AI Explanation

Discarded sludge from wastewater treatment plants may accumulate over several years before removal or further management is required. A typical period given for accumulation is about 3–5 years.

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Q31

In UASB + polishing pond dry solid level ranges between?

A) 4-5%
B) 2-3%
C) 3-4%
D) 1-2%

AI Explanation

In UASB treatment followed by polishing ponds, the sludge generally has a relatively low dry-solids concentration. The dry solid level is typically around 1–2%.

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Q32

In a dewatering process the dry solid level in the dewaterd sludge of filter press ------------------.

A) 20-30%
B) 30-45%
C) 25-40%
D) 80-90%

AI Explanation

Filter presses are effective mechanical dewatering devices that can produce sludge cakes with relatively high solids content. A typical dry-solids concentration for filter-press dewatered sludge is approximately 20–30%.

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Q33

Thermal decomposition process by oxidation is known as _______.

A) Sanitary landfill
B) Land reclamation
C) Land farming
D) Incineration

AI Explanation

Incineration is a thermal treatment process in which sludge is subjected to high temperatures and organic matter is oxidized. This substantially reduces the volume and destroys combustible organic components.

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Q34

Time period required to carry out compositing through in-vessel biological reactors is normally-----------.

A) 14-21 hours
B) 14-21 days
C) 30-60 days
D) 50-90 days

AI Explanation

In-vessel composting uses controlled biological reactors to accelerate decomposition under managed conditions. The composting period is commonly around 14–21 days, depending on operating conditions.

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Q35

--------is a land disposal process, in which the organic substrate is biologically degraded in the upper layer of the soil and the inorganic fraction is transformed or fixed into this layer.

A) Ocean disposal
B) Land farming
C) Sanitary Landfill
D) Maturation ponds

AI Explanation

Land farming is a land disposal and treatment method in which organic contaminants are biologically degraded in the upper soil layer. Inorganic components may be transformed or immobilized within the soil.

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Q36

The process in which decomposition of aerobic organic matter is achieved through controlled conditions of temperature, water content and nutrients is known as --------

A) Percolation
B) Filterable assembly
C) Lime stabilization
D) Compositing

AI Explanation

Compositing refers to the controlled biological decomposition of organic matter under aerobic conditions. Temperature, moisture, oxygen, and nutrients are managed to support effective decomposition.

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Q37

Microbes capable of utilizing a variety of carbon sources and degrading a number of typical contaminants are commonly found in_______.

A) Sewage
B) Air
C) Water
D) Soil

AI Explanation

Soil contains diverse microbial communities capable of using many carbon sources and degrading various contaminants. These microorganisms are important in natural biodegradation and bioremediation processes.

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Q38

The underlying relevnt processes for the biological mechanisms is/are -------------.

A) All of the above
B) biosorption
C) demethylation
D) methylation

AI Explanation

Biosorption, demethylation, and methylation are biological processes that can contribute to contaminant transformation or removal. Therefore, all of the listed processes are relevant biological mechanisms.

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Q39

---------------method is more sophisticated and refined used normally in bioremediation.

A) Biosparging
B) Bioventing
C) Injection Recovery
D) All

AI Explanation

Biosparging, bioventing, and injection-recovery approaches can be applied in engineered bioremediation systems. These methods provide controlled treatment of contaminated environments and can be more sophisticated than simple natural attenuation.

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Q40

Bioventing is not generally suitable for remediating sites with a water table within _____of the surface.

A) 2.2m
B) 1.0 m
C) 2.0 m
D) 0.1 m

AI Explanation

Bioventing is generally less suitable when the water table is very close to the ground surface because limited unsaturated soil remains available for air movement. A water table within about 2.0 m of the surface can significantly restrict effective bioventing.

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Q41

In----------technique air extraction rate is adjusted to maximize underground decomposition.

A) Biosparging
B) Injection Recovery
C) All of the above
D) Bioventing

AI Explanation

Bioventing controls the rate of air extraction or injection to optimise oxygen supply and stimulate microbial degradation in the unsaturated soil zone. The airflow is adjusted to promote underground biodegradation.

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Q42

----------technique is used to remediate contamination above the boundary of the water table.

A) All of the above
B) Biosparging
C) Injection Recovery
D) Bioventing

AI Explanation

Bioventing is primarily used to remediate contamination in the unsaturated zone above the water table. It supplies oxygen to stimulate aerobic microorganisms that degrade contaminants.

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Q43

Some plants act as pumps or siphons, removing contaminants from the----------.

A) Air
B) Soil
C) All of the above
D) Water

AI Explanation

Certain plants can act as biological pumps, taking up contaminants from contaminated soil through their roots. This phytoremediation process can accumulate or transform contaminants within plant tissues.

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Q44

---------method makes use of the movement of ground water through the zone of contamination to assist the remediation process.

A) Bioventing
B) Injection Recovery
C) All of the above
D) Biosparging

AI Explanation

Injection-recovery methods use the movement of groundwater through a contaminated zone to assist in transporting and recovering contaminants. This controlled groundwater flow can enhance the remediation process.

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Q45

Pteris vittata, accumulates -------percentage of arsenic.

A) 4.5%
B) 2.3%
C) 3.4%
D) 1.2%

AI Explanation

Pteris vittata is a well-known arsenic hyperaccumulator and can accumulate about 2.3% arsenic in its frond biomass. This exceptional accumulation ability makes it useful for phytoremediation of arsenic-contaminated soils.

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Q46

Hyperaccumulators have ability to absorb large amounts of metals typically______more as compared to most ordinary plants.

A) 30-50 times
B) 100-150 times
C) 50–100 times
D) 20-30 times

AI Explanation

Hyperaccumulator plants can absorb and concentrate metals at levels far exceeding those of ordinary plants. In many educational references, this capacity is described as roughly 100–150 times greater.

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Q47

The technique which choose and permit plants to grow for a suitable length of time.

A) Rhizofiltration
B) Phytoextraction
C) Bioaccumulation
D) All of the above

AI Explanation

Phytoextraction involves growing selected plants for a suitable period so they absorb contaminants from soil and accumulate them in harvestable tissues. The plants are then harvested to remove the contaminants from the site.