Environmental Health Practice Questions

Q: What is the correct order of the steps in the rapid sand filtration process for water purification?

Alum mixing – flocculation – sedimentation – filtration. ***Alum mixing – flocculation – sedimentation – filtration*** - This sequence represents the established steps in conventional **rapid sand filtration**, where each stage plays a crucial role in removing impurities. - **Alum mixing** (coagulation) destabilizes particles, **flocculation** consolidates them, **sedimentation** removes larger flocs, and **filtration** traps remaining fine particles. *Sedimentation – alum mixing – flocculation – filtration* - **Sedimentation** occurs *after* coagulation and flocculation, as these processes are needed to create larger, settleable particles. - Starting with sedimentation before preparing the water for efficient particle removal would be ineffective. *Alum mixing – sedimentation – flocculation – filtration* - **Flocculation** (the gentle stirring to form larger flocs) must happen *after* alum mixing (coagulation) and *before* sedimentation. - Placing sedimentation before flocculation would lead to poor particle removal as the flocs would not have fully formed. *Flocculation – alum mixing – sedimentation – filtration* - **Alum mixing** (coagulation) is the initial step to destabilize particles, which then allows for effective flocculation. - Attempting flocculation before coagulation would be ineffective as the particles would not be prepared to aggregate.

Q: Which of the following tests is NOT used for checking quality of pasteurisation of milk?

Orthotoluidine test. ### ***Orthotoludine test*** * The **Orthotoluidine test** is used to detect residual **chlorine** in drinking water. * It is not employed to assess the quality of pasteurization in milk, which focuses on enzyme inactivation and microbial reduction. ### *Phosphatase test* * The **phosphatase test** is the most widely accepted and reliable method for checking the adequacy of **pasteurization** in milk. * It works by detecting the activity of **alkaline phosphatase**, an enzyme naturally present in raw milk that is destroyed at pasteurization temperatures. ### *Coliform count* * The **coliform count** is an indicator of **post-pasteurization contamination** or inadequate sanitation. * While not a direct measure of the pasteurization process itself, a high coliform count suggests a failure in hygiene after heating, indicating poor overall quality control. ### *Standard Plate count* * The **Standard Plate Count (SPC)**, also known as the **aerobic plate count**, measures the total number of viable microorganisms in milk. * A reduction in SPC after pasteurization indicates the effectiveness of the heat treatment in killing bacteria, making it an indirect measure of pasteurization efficiency and overall microbial quality.

Q: Biomedical waste from a yellow plastic bag is disposed by:

Incineration. ***Incineration*** - **Yellow bags** are designated for **highly infectious waste**, body parts, anatomical waste, and cytotoxic drugs. - **Incineration** is the preferred method for this waste category due to its ability to completely destroy pathogens and reduce waste volume. *Chemical treatment* - This method is typically used for **liquid infectious waste** or for disinfection of certain instruments. - It's not the primary disposal method for the solid, highly infectious waste found in yellow bags. *Microwaving* - **Microwaving** is a thermal disinfection method used for certain types of infectious waste, especially those containing plastics. - It is generally not suitable for **anatomical waste** or large quantities of highly infectious waste like those in yellow bags. *Autoclaving* - **Autoclaving** is a moist heat sterilization method primarily used for items in **red or blue bags**, such as contaminated plastics, cultures, and sharps (after shredding). - It is not the recommended disposal method for anatomical waste or cytotoxic waste collected in yellow bags.

Q: Waste disposal of placenta after delivery is done by

Incineration. ***Incineration*** - **Incineration** is the recommended method for disposing of anatomical waste like the placenta due to its effectiveness in destroying pathogens and reducing waste volume. - This method ensures **safe and complete destruction** of potentially infectious material, preventing environmental contamination. *Disposing it in blue bags* - Blue bags are typically used for **general non-hazardous waste** or specific categories of non-anatomical biomedical waste, not for anatomical waste like the placenta. - Disposing of anatomical waste in blue bags would violate **biomedical waste management guidelines** and pose a risk of infection. *Autoclaving* - **Autoclaving** is a sterilization method that uses steam under pressure, primarily for medical instruments and some types of infectious waste. - While it sterilizes, it does not physically destroy or reduce the volume of anatomical waste like incineration does, making it less suitable for placenta disposal. *Microwaving* - **Microwaving** is not a recognized or safe method for the disposal of anatomical waste due to its inability to reliably sterilize or destroy biological material. - It would not achieve the necessary level of **pathogen destruction** required for waste like the placenta and poses safety risks.

Q: As per biomedical waste management rule 2016 the metallic body implants should be discarded in which of the following?

Separate collection system. ***Separate collection system*** - Metallic body implants, due to their nature and potential for **recycling or specific disposal methods**, are to be segregated into a **separate collection system** as per BMW Rule 2016. - This ensures they do not contaminate other biomedical waste streams and can be handled appropriately, often involving **recovery of precious metals**. *Red colored non-chlorinated plastic bag* - This category is typically for **reusable contaminated waste** such as tubing, catheters, IV sets, and urine bags, which are often plastic. - Metallic implants are not typically suitable for disposal in red bags because they are not meant for incineration or autoclaving in the same manner as these plastic items. *Yellow colored non-chlorinated plastic bag* - Yellow bags are used for **human anatomical waste**, animal anatomical waste, soiled waste, expired or discarded medicines, and **chemical waste**. - Metallic implants do not fall into any of these categories and require a different disposal method due to their material composition and potential for recycling. *Card board box with blue colored marking* - Blue or white translucent boxes/containers are designated for **sharps**, including needles, syringes with fixed needles, and blades, as well as broken or contaminated glass. - While metallic, body implants are not considered "sharps" in the same context, nor are they typically discarded in cardboard, which is unsuitable for their weight and specific disposal requirements.

Q: Orthotolidine (OT) test is done for determining residual free chlorine quantitatively and qualitatively. What is the colour of the solution after adding OT which indicates presence of free chlorine?

Yellow. ***Yellow*** - The **Orthotolidine (OT) test** historically was used to detect and quantify residual **free chlorine** in water. - When Orthotolidine reagent is added to water containing free chlorine, it produces a **yellow color**, with the intensity of the yellow directly proportional to the amount of free chlorine present. - **Important Note:** The OT test has been **discontinued and is no longer recommended** due to orthotolidine being a **suspected carcinogen**. It has been replaced by safer methods like the **DPD (N,N-diethyl-p-phenylenediamine) test**, which also detects free chlorine but uses a safer reagent. *Blue* - A blue color is not associated with the Orthotolidine test for free chlorine. - Other water quality tests or reagents might yield a blue color for different parameters. *Green* - A green color does not indicate the presence of free chlorine in the Orthotolidine test. - It may suggest interference from other substances or mixed reactions. *Red* - A red color is not the characteristic indicator for free chlorine in the Orthotolidine test. - Red or pink colors are associated with the **DPD method** (the current standard test), which produces a pink/red color in the presence of free chlorine.

Q: A vital layer, also known as "Schmutzdecke" is seen in which one of the following ?

Slow sand filter. ***Slow sand filter*** - A vital biological layer known as **"Schmutzdecke"** or **"filter skin"** forms on the surface of slow sand filters. - This layer, composed of **algae, bacteria, fungi**, and protozoa, is crucial for effective water purification by trapping and breaking down organic matter and pathogens. *Air filter* - Air filters primarily remove particulate matter from air, not water, and do not develop a biological layer like **Schmutzdecke**. - Their mechanism involves mechanical filtration, not biological degradation. *Reverse osmosis filter* - Reverse osmosis filters use a **semi-permeable membrane** to remove dissolved solids and contaminants from water under pressure. - They operate on a physical process and do not rely on the formation of a biological "Schmutzdecke" layer for filtration. *Rapid sand filter* - Rapid sand filters primarily rely on **physical straining** and **coagulation/flocculation** for clarification, followed by backwashing to clean the filter media. - While some biological activity may occur, they do not form a distinct, vital **"Schmutzdecke"** layer as seen in slow sand filters, and their primary mechanism is different.

Q: Consider the following stages of modern sewage treatment plants : 1. Use of Grit chamber 2. Use of Primary sedimentation tank 3. Screening 4. Use of Sludge digester What would be the correct sequence of the above stages ?

3→1→2→4. ***3→1→2→4*** - The correct sequence for modern sewage treatment begins with **screening** (3) to remove large debris, followed by **grit chambers** (1) for sand and gravel, then **primary sedimentation tanks** (2) to settle organic solids. Finally, the collected sludge is processed in a **sludge digester** (4). - This order ensures progressive removal of contaminants, from large physical objects to settled organic matter, optimizing the efficiency of each treatment stage. *2→3→4→1* - This sequence incorrectly places the **primary sedimentation tank** (2) as the first step, which would be inefficient as large debris and grit would interfere with its operation. - It also reverses the order of screening and grit removal, which are crucial initial physical processes. *3→2→1→4* - While starting with **screening** (3) is correct, this sequence incorrectly places the **primary sedimentation tank** (2) before the **grit chamber** (1). - Grit removal should precede primary sedimentation to prevent abrasive materials from damaging equipment and accumulating in sedimentation tanks. *4→2→1→3* - This sequence is entirely incorrect, as it begins with the **sludge digester** (4), which is a final step in sludge processing, not the initial treatment of raw sewage. - It also drastically misorders the preliminary physical treatment stages.

Q: Iodine can be used for the disinfection of which of the following? 1. Water 2. Faeces 3. Urine 4. Skin Select the correct answer using the code given below:

1 and 4 only. ***1 and 4 only*** - **Iodine is highly effective for water disinfection**, particularly in emergency and travel situations, killing bacteria, viruses, and protozoa - **Povidone-iodine is a standard antiseptic for skin disinfection** used pre-operatively, for wound care, and before injections due to its broad-spectrum antimicrobial activity - These are the two established and recommended uses of iodine for disinfection in medical and public health practice *1, 3 and 4* - While iodine effectively disinfects water and skin, it is **not used for urine disinfection** - Urine from healthy individuals is typically sterile and does not require routine disinfection - If disinfection of contaminated urine is needed (rare situations), other chemical agents would be preferred *1, 2 and 3* - Iodine is effective for water disinfection but **not suitable for faecal matter disinfection** - Faeces requires stronger disinfection methods: **chlorine-based compounds (sodium hypochlorite/bleach)**, heat treatment, or proper sewage treatment systems - Iodine is impractical and ineffective for the high pathogen load in faecal waste *1 only* - This option incorrectly excludes skin disinfection, which is **one of the most common applications of iodine** in medical practice - Povidone-iodine solutions (Betadine) are standard antiseptics used worldwide for skin preparation before surgical procedures

Q: Which of the following insecticides is not used as a larvicide?

Fenthion. ***Fenthion*** - **Fenthion** is an **organophosphate insecticide** primarily used as an **adulticide** for **mosquitoes** and other flying insects. - While it can target adult mosquitoes, it is **not commonly used or recommended as a larvicide** due to its higher toxicity profile and environmental concerns compared to other dedicated larvicides. *Dichlorvos* - **Dichlorvos** (DDVP) is an organophosphate insecticide that has been used as a **larvicide**, particularly in situations where rapid knockdown of larvae is required. - It is known for its **quick action** and **fumigant properties**, making it effective against early mosquito stages. *Paris green* - **Paris green** (copper(II) acetoarsenite) is historically one of the **earliest larvicides** used to control mosquito larvae. - It acts as a **stomach poison** when ingested by mosquito larvae. *Abate* - **Abate** (temephos) is a widely used **organophosphate larvicide** known for its **low toxicity to mammals** and aquatic organisms at recommended doses. - It is effective against mosquito larvae in various breeding sites, including drinking water, making it a **preferred choice for public health programs**.

Question 1

What is the correct order of the steps in the rapid sand filtration process for water purification?

Accepted Answer

Alum mixing – flocculation – sedimentation – filtration

Answer

Sedimentation – alum mixing – flocculation – filtration

Answer

Alum mixing – sedimentation – flocculation – filtration

Answer

Flocculation – alum mixing – sedimentation – filtration

Question 2

Which of the following tests is NOT used for checking quality of pasteurisation of milk?

Accepted Answer

Orthotoluidine test

Answer

Phosphatase test

Answer

Coliform count

Answer

Standard Plate count

Question 3

Biomedical waste from a yellow plastic bag is disposed by:

Accepted Answer

Incineration

Answer

Chemical treatment

Answer

Microwaving

Answer

Autoclaving

Question 4

Waste disposal of placenta after delivery is done by

Accepted Answer

Incineration

Answer

Disposal in blue bags

Answer

Autoclaving

Answer

Microwaving

Question 5

As per biomedical waste management rule 2016 the metallic body implants should be discarded in which of the following?

Accepted Answer

Separate collection system

Answer

Red colored non-chlorinated plastic bag

Answer

Yellow colored non-chlorinated plastic bag

Answer

Card board box with blue colored marking

Question 6

Orthotolidine (OT) test is done for determining residual free chlorine quantitatively and qualitatively. What is the colour of the solution after adding OT which indicates presence of free chlorine?

Accepted Answer

Yellow

Answer

Blue

Answer

Green

Answer

Red

Question 7

A vital layer, also known as "Schmutzdecke" is seen in which one of the following ?

Accepted Answer

Slow sand filter

Answer

Air filter

Answer

Reverse osmosis filter

Answer

Rapid sand filter

Question 8

Consider the following stages of modern sewage treatment plants :

1. Use of Grit chamber
2. Use of Primary sedimentation tank
3. Screening
4. Use of Sludge digester
What would be the correct sequence of the above stages ?

Accepted Answer

3→1→2→4

Answer

2→3→4→1

Answer

3→2→1→4

Answer

4→2→1→3

Question 9

Iodine can be used for the disinfection of which of the following?

1. Water
2. Faeces
3. Urine
4. Skin
Select the correct answer using the code given below:

Accepted Answer

1 and 4 only

Answer

1, 3 and 4

Answer

1, 2 and 3

Answer

1 only

Question 10

Which of the following insecticides is not used as a larvicide?

Accepted Answer

Fenthion

Answer

Dichlorvos

Answer

Paris green

Answer

Abate

Environmental Health — MCQs

Environmental Health — MCQs

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