Question 1

Which microorganisms are used in sewage water treatment and what is their role?

Accepted Answer

Microorganisms such as bacteria, protozoa, and fungi are used in sewage water treatment. Their role is to decompose organic matter present in sewage by breaking down complex organic compounds into simpler substances, thereby reducing the biological oxygen demand (BOD) and purifying the water. — In sewage treatment, microorganisms metabolize organic pollutants, converting them into carbon dioxide, water, and biomass. Aerobic bacteria consume organic matter in the presence of oxygen during secondary treatment, while anaerobic bacteria break down sludge in the absence of oxygen during sludge digestion.

Question 2

Explain as to how biological oxygen demand represents the condition of sewage water?

Accepted Answer

Biological Oxygen Demand (BOD) is a measure of the amount of oxygen required by aerobic microorganisms to decompose organic matter present in sewage water over a specific period (usually 5 days at 20°C). A high BOD indicates a large amount of organic pollution, meaning the sewage is highly contaminated and requires treatment. Conversely, a low BOD indicates cleaner water with less organic matter. — BOD is an indirect indicator of the organic pollution level in water. When sewage contains a high concentration of biodegradable organic matter, microorganisms consume more oxygen to break it down, increasing BOD. Monitoring BOD helps assess the effectiveness of sewage treatment processes.

Question 3

How does any toxic substance get biomagnified among organisms? Explain in brief.

Accepted Answer

Biomagnification is the process by which toxic substances increase in concentration as they move up the food chain. When a toxic substance is present in the environment, it is absorbed by producers (like plants or algae). Primary consumers eat these producers and accumulate the toxin in their bodies. Secondary consumers then eat the primary consumers, accumulating even higher concentrations of the toxin. This process continues, leading to the highest toxin concentration in top predators. — Toxic substances such as pesticides or heavy metals are not easily broken down or excreted by organisms. As a result, they accumulate in body tissues. Each trophic level consumes many organisms from the lower level, leading to an increased concentration of the toxin at higher levels, which can cause harmful effects on wildlife and humans.

Question 4

What are xenobiotic compounds? How do these compounds affect the productivity of soil?

Accepted Answer

Xenobiotic compounds are synthetic chemicals that are foreign to an ecosystem, such as pesticides, industrial chemicals, and plastics. These compounds are often resistant to natural degradation and can accumulate in the environment. They affect soil productivity by killing beneficial microorganisms, disrupting nutrient cycles, and contaminating the soil, which reduces its fertility and ability to support plant growth. — Because xenobiotic compounds are not naturally occurring, soil microbes may not have the enzymes to degrade them efficiently. Their persistence leads to toxicity in soil biota, reducing microbial diversity and activity essential for nutrient recycling, thus negatively impacting soil health and productivity.

Question 5

Discuss the process of aerobic and anaerobic decomposition of sewage waste water treatment.

Accepted Answer

Aerobic decomposition involves the breakdown of organic matter in sewage by aerobic microorganisms in the presence of oxygen. This process occurs during secondary treatment where bacteria consume organic pollutants, converting them into carbon dioxide, water, and biomass, thus reducing BOD.

Anaerobic decomposition occurs in the absence of oxygen, typically during sludge digestion. Anaerobic bacteria break down organic matter into simpler compounds such as methane, carbon dioxide, and other gases. This process helps reduce sludge volume and produces biogas which can be used as energy. — In aerobic decomposition, oxygen is essential for microbes to metabolize organic compounds efficiently, leading to faster degradation and less odor. Anaerobic decomposition is slower and produces gases like methane, which can be captured for energy. Both processes are complementary in sewage treatment to reduce pollutants and manage waste.

Question 6

What are the different types of solid wastes produced?

Accepted Answer

The different types of solid wastes produced include biodegradable waste (such as food scraps, garden waste), non-biodegradable waste (such as plastics, metals, glass), hazardous waste (such as chemicals, batteries, medical waste), and e-waste (discarded electronic devices). — Solid wastes vary based on their origin and composition. Biodegradable wastes can decompose naturally, while non-biodegradable wastes persist in the environment. Hazardous wastes require special handling due to their toxicity. Proper segregation is essential for effective waste management.

Question 7

Discuss the role of different microorganisms in the process of composting of solid waste.

Accepted Answer

Microorganisms such as bacteria, fungi, and actinomycetes play a crucial role in composting by decomposing organic solid waste into humus. Bacteria initiate the breakdown of simple organic compounds, fungi degrade complex polymers like cellulose and lignin, and actinomycetes help in breaking down tough materials and produce the characteristic earthy smell of compost. Together, they convert waste into nutrient-rich compost useful for soil amendment. — During composting, aerobic microorganisms metabolize organic matter, releasing heat and carbon dioxide. The microbial activity reduces waste volume and transforms it into stable organic matter. Proper aeration and moisture are essential to support microbial growth and efficient composting.

Question 8

How are pesticides harmful for non-target organisms?

Accepted Answer

Pesticides are harmful to non-target organisms because they can be toxic to species other than the pests they are intended to control. They may cause poisoning, disrupt reproductive systems, reduce biodiversity, and lead to the death of beneficial insects, birds, aquatic life, and even humans. Pesticides can also accumulate in the food chain, causing long-term ecological damage. — Non-target organisms may be exposed to pesticides through direct contact, ingestion of contaminated food or water, or through biomagnification. The indiscriminate use of pesticides leads to ecological imbalance and loss of beneficial species that help in natural pest control.

Question 9

Briefly explain as to how microorganisms can bioremediate toxic pesticides into harmless and non-toxic compounds.

Accepted Answer

Microorganisms bioremediate toxic pesticides by enzymatically breaking down the complex pesticide molecules into simpler, non-toxic compounds through processes such as hydrolysis, oxidation, and reduction. These microbes use pesticides as a source of carbon and energy, thereby detoxifying the environment. — Certain bacteria and fungi possess enzymes like esterases, oxygenases, and peroxidases that degrade pesticides. This biodegradation reduces pesticide concentration and toxicity, making the environment safer. Bioremediation is an eco-friendly and cost-effective method for detoxifying contaminated sites.

Question 10

Which of the following compounds can be removed from waste water during treatment using lime?

(a) Organic compound
(b) Phosphorous salts
(c) Ammonia
(d) Urea

Accepted Answer

The correct answer is (b) Phosphorous salts.

Explanation: Lime treatment in wastewater is primarily used to remove phosphorous salts by precipitation as insoluble calcium phosphate compounds. Organic compounds, ammonia, and urea are not effectively removed by lime treatment alone. — Lime raises the pH of wastewater, causing phosphorous salts to precipitate out. This reduces eutrophication potential in receiving water bodies. Other compounds require different treatment methods.

Question 11

Maximum decomposition of water takes place during:
(a) Primary treatment only
(b) Primary and Secondary treatment both
(c) Secondary treatment only
(d) Secondary and tertiary treatment both

Accepted Answer

The correct answer is (c) Secondary treatment only.

Explanation: Primary treatment mainly involves physical removal of solids, while secondary treatment uses biological processes where microorganisms decompose organic matter, leading to maximum decomposition. — Secondary treatment employs aerobic microorganisms to degrade dissolved and suspended organic matter, significantly reducing BOD and organic load in wastewater.

Question 12

Which enzyme is mainly responsible for hydrolytic breakdown of pesticides?
(a) Peroxidase
(b) Oxidare
(c) Cytochrome P/450
(d) Esterase

Accepted Answer

The correct answer is (d) Esterase.

Explanation: Esterase enzymes catalyze the hydrolysis of ester bonds present in many pesticide molecules, leading to their breakdown and detoxification. — Esterases cleave ester linkages in pesticides such as organophosphates and carbamates, facilitating their degradation by microorganisms during bioremediation.

Question 13

Which of the following is not a strategy of bioremediation?
(a) Sludge digestion
(b) Composting
(c) Slury bioreactor
(d) Biopiles

Accepted Answer

The correct answer is (c) Slury bioreactor.

Explanation: 'Slury bioreactor' appears to be a typographical error. The correct term is 'Slurry bioreactor,' which is a bioremediation strategy. Hence, 'Slury bioreactor' is not a recognized strategy. — Sludge digestion, composting, and biopiles are established bioremediation methods. Slurry bioreactors are also used, but the misspelled 'Slury bioreactor' is not valid.

Question 14

Assertion: Bioremediation is a process through which toxic pesticides can be completely removed.
Reason: Microorganisms can be used for bioremediation of toxic chemicals.
(a) Both assertion and reason are true and the reason is correct explanation of assertion.
(b) Both assertion and reason are true but the reason is not the correct explanation of the assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false.

Accepted Answer

The correct answer is (a) Both assertion and reason are true and the reason is correct explanation of assertion.

Explanation: Bioremediation uses microorganisms to degrade and remove toxic pesticides from the environment, effectively detoxifying contaminated sites. — Microorganisms metabolize toxic chemicals, including pesticides, converting them into harmless substances. Thus, bioremediation is a valid and effective process for pesticide removal.

Question 15

On the basis of the colour coding and type of container for disposal of health care waste, choose the correct match:
(a) Yellow — recyclable plastic waste
(b) Red — metallic body
(c) White — sharp metals, needle, syringes
(d) Blue — general health care waste

Accepted Answer

The correct answer is (c) White — sharp metals, needle, syringes.

Explanation: White containers are used for disposal of sharps such as needles and scalpels. Yellow containers are for infectious waste, red for contaminated plastic waste, and blue for glassware and metallic body implants. — Colour coding helps in proper segregation and disposal of health care waste to prevent infection and environmental contamination.

Bioremediation

Bioremediation — Study Notes

Introduction

11.1 Waste Water Treatment

11.1.1 Composition of Sewage

Practice Questions — Bioremediation

All 13 Chapters in Biotechnology