Environment And Health Question And Answers

Environment And Health Definitions

Garbage

• It means discarded vegetable matter from kitchens, canteens, etc.

Sullage – Refers to fluid waste from a kitchen unmixed with excrement

Water sewage – Refers to wastewater from households, industries, etc containing human excreta

Refuse – It is all solid and semi-solid waste matters of a community except excrement

Breakpoint chlorination

• The point where the addition of chlorine to water results in the appearance of free residual chlorine is called break-point chlorination

Environment & Health Important Notes

1. Biological wastes

Categories of biomedical wastes

Color coding

2. Methods of disposal of solid wastes

1. Dumping – Refuse is dumped in low-lying areas
2. Controlled tipping- Material is placed in a trench
3. Incineration- It is the best method for the disposal of healthcare
4. Composting- It is the process of nature where matter breaks down under bacterial action resulting in the formation of humus-like material called compost
5. Manure pits- Manure pits are dug by individual householders to dump the garbage
6. Burial – A trench is excavated and at the end of each day the trench is filled with earth and compacted

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3. Composting is a method wherein sludge is combined with solid wastes to produce manure-quality material

• There are two commercial methods of composting

1. Bangalore method

• It is a natural hot fermentation process in which trenches are dug and filled alternatively with refuse and excreta

2. Mechanical method

• It involves pulverization of raw materials and mixing with sludge.

4. Incineration

• It is a high-temperature dry oxidation process that reduces organic and combustible waste to inorganic, incom- combustible matter resulting in a significant reduction of waste volume and weight
• Types
  • Double-chamber pyrolytic incinerators
  • Single chamber furnaces
  • Rotary kilns
• Incineration is the choice of disposal for the following wastes
  • Human anatomical waste
  • Animal waste
  • Microbiology and biotechnology waste
  • Discarded medicines and cytotoxic drugs
  • Contaminated solid wastes
• Wastes that should never be incinerated are
  • Amalgams
  • Latex gloves
  • Lead wastes
  • PVC plastics

5. Loss of head

• As filtration proceeds, the suspended impurities and bacteria clog the filters and they soon become dirty and
• begin to lose their efficiency
• This is known as loss of head
• When the loss of the head approaches 7-8 feet, filtration is stopped and subjected to backwashing.

Environment & Health Long Essays

Question 1. Describe in detail the small-scale purification.
Answer:

Small-Scale Purification:

Environment & Health Short Essays

Question 1. Principles of chlorination.
Answer:

Principles of chlorination

• The water to be chlorinated should be clear & free from turbidity
• The chlorine demand of the water should be estimated
• The point at which the chlorine demand of the water is met is called the “breakpoint”
• If further chlorine is added, free chlorine begins to appear in the water
• The free residual chlorine should be present for a contest 1 hour to kill bacteria & viruses
• The minimum recommended concentration of free. It is defined as water that is chlorine is 0.5 mg/L for 1 hour
• The correct dose of chlorine to be applied = chlorine de- mand of water + free residual chlorine.

Question 2. Occupational hazards for dentists.
Answer:

Occupational hazards for dentists

Question 3. Potable water.
Answer:

Potable water

• It is defined as water that is
  • Free from pathogens
  • Free from harmful chemicals
  • Pleasant to taste
  • Usable for domestic needs
• Requirements:
  • Must be close to the people as its transportation may lead to pollution
  • The basic requirement at about 2 L/head/day
  • A daily supply of 150-200 L/capita is considered adequate to meet the domestic needs of the urban population
• Uses
  • Domestic purposes: drinking, cooking
  • Public purposes: cleaning streets & fire protection
  • Industrial purposes: factories
  • Agricultural purposes: irrigation

Question 4. Disposable of hospital waste.
Answer:

Hospital Waste Methods:

Hospital Waste Dumping:

• Waste/refuse is dumped in low-lying areas
• It is a suitable method for the reclamation of land
• As a result of bacterial action, refuse decreases consist of each day the erably in volume & is converted gradually into humus

Hospital waste Controlled Tipping:

• Here, the material is placed in a trench or other pared area, adequately compacted & covered with earth at the end of the working day

Hospital Waste Methods:

Hospital Waste Trench Method:

• A long trench is dug out 6-10 feet deep & 12-36 feet wide into which refuse is compacted & covered with caveated earth
• Ramp method
• Moderately sloping terrain is used Area method
• The refuse is deposited & sealed on its exposed face with a mud cover
• Changes occurring in refuse raise the temperature to 60 degrees C within 7 days & kill all the pathogens

Hospital Waste Incineration:

• By it, the refuse is reduced to 1/4th its original weight & the residue is called “clinker” and used for road making
• The incinerator consists of:
• A furnace
• A platform: for tipping refuse
• Baffle plate: to drive out all fumes

Hospital waste Types:

• Double cell Meldrum
• Single-cell destructor

Hospital waste Composting:

• It is a process of nature where matter breaks down under bacterial action resulting in the formation of relatively stable humus-like material called compose
• The compost formed contains few or no disease-producing agents
• The heat produced destroys all pathogens

Hospital waste Manure pits

• Dug by individual householders to dump garbage& other waste & covered with earth after each day’s dumping

Question 5. Rapid sand filtration.
Answer:

Rapid sand filtration

Types:

1. Gravity type
2. Pressure type

Steps:

Coagulation:

• Raw water is first treated with chemical coagulants such as alum

Rapid Mixing:

• The water is then violently agitated in a “mixing chamber” for a few minutes

Flocculation:

• It involves slow & gentle stirring of treated water in a “flocculation chamber” for 30 minutes

Sedimentation:

• The water is then led into sedimentation tanks & kept for 2-6 hours

Filtration:

• The water is then subjected to filtration

Question 6. Composting.
Answer:

Composting

Methods:

Bangalore/Anaerobic/ Hot Fermentation Process:

• Trenches are dug 3 feet deep, 5-8 feet broad, 15-30 feet long & located at least 800 m away from the city limits
• First, a layer of refuse is spread followed by nightsoil
• Similarly, alternate layers of refuse & nightsoil are added till the heap rises 1 foot above the ground level
• The top layer should be of refuse, at least 9 inches in thickness which is covered with excavated earth & compacted
• Within 7 days, considerable heat is generated which persists over 2-3 weeks
• Duration: 4-6 months
• Result
• The resulting material is a well-decomposed, odorless, nocuous material of high-manured value

Mechanical/ Aerobic Method:

• The refuse is first cleared of salvable material
• Then pulverized in pulverizing equipment
• The pulverized refuse is then mixed with sewage, sludge, or night soil in a rotating machine & incubated
• Duration: 4-6 weeks

Question 7. Elements of a slow sand filter.
Answer:

Supernatant Water:

• Depth: 1-1.5 m above the sand bed
• Purposes
  • Provides constant head of water
  • Provides a waiting period of some hours for the raw water

A Bed of Graded Sand:

• Thickness: about 1 m
• The sand bed is supported by a layer of graded gravel
• Water percolates through the sandbed very slowly
• Then it is subjected to mechanical straining, sediments bacterial action

Under Drainage System:

• Consist of porous/ perforated pipes
• Purpose
• Provides an outlet for filtered water
• Support filter medium above

Filter Control:

• It maintains a constant rate of filtration
• The venturi meter is used to measure the loss of head/ bed resistance
• When the resistance builds up the operator opens the regulating valve to maintain a steady rate of filtration

Question 8. Incineration
Answer:

Incineration

• It is a high-temperature dry oxidation process that duces organic and combustible waste to inorganic, combustible matter resulting in a significant reduction of waste volume and weight

Incineration Types

• Double-chamber pyrolytic incinerators
  • Single chamber furnaces
  • Rotary kilns
• Incineration is the choice of disposal for the following wastes
  • Human anatomical waste
  • Animal waste
  • Microbiology and biotechnology waste
  • Discarded medicines and cytotoxic drugs
  • Contaminated solid wastes
• Wastes that should never be incinerated are
  • Amalgams
  • Latex gloves
  • Lead wastes
  • PVC plastics

Environment & Health Short Question And Answers

Question 1. Compositing.
Answer:

Compositing

• It is a process of nature where matter breaks down un- der bacterial action resulting in the formation of relatively stable humus-like material called compose
• The compost formed contains few or no disease-producing agents
• The heat produced destroys all pathogens
• By-products: carbon dioxide, water, heat

Methods: Bangalore method, mechanical composting

Question 2. Backwashing.
Answer:

Backwashing

• Rapid sand filters need frequent washing daily/weekly depending upon the loss of head
• Washing is accomplished by reversing the flow of water through the sand bed-back washing
• Washing is stopped when the wash water is sufficiently clean
• Compressed air is used

Backwashing Effects:

• Dislodges the impurities
• Cleans the sand bed

Duration of Process: 15 minutes

Question 3. Loss of head.
Answer:

Loss of head

• When the filtration proceeds the suspended impurities & bacteria clog the filter
• This results in their reduced efficiency called “loss of head”

Effects:

• Filters soon become dirty
• When “loss of head” approaches 7-8 feet, filtration is stopped
• Filters are subjected to backwashing

Question 4. Vital layer.
Answer:

Vital layer Definition:

• It is the slimy growth covering the surface of the sand bed

Vital layer Synonym:

• Schmutzdecke, zoogleal layer, biological layer

Vital layer Components:

• Threadlike algae
  • Plankton
  • Diatoms
  • Bacteria

Vital layer Formation:

• The formation of the vital layer is known as the “ripening” of Disadvantages: filter
• It takes several days for the formation

Vital layer Significance:

• It is the heart of the slow sand filter
• Removes organic matter
• Holds back bacteria
• Oxidizes ammonical nitrogen into nitrates
• Purifies water

Question 5. Breakpoint chlorination.
Answer:

Breakpoint chlorination

• The fall in residual chlorine continues with a further increase in chlorine dose, until after a stage residual chlorine begins to increase in the proportion
• The point where the addition of chlorine to water results in the appearance of free residual chlorine is called breakpoint chlorination
• When the chlorine dose in the water is increased a reduction in the residual chlorine occurs

Question 6. The hardness of the water.
Answer:

The hardness of the water Definition:

• It is defined as the soap-destroying power of water

Hardness of the water Causes:

• Calcium bicarbonate
• Calcium sulfate
• Magnesium bicarbonate
• Magnesium sulfate

Classification of Hardness of the water:

• Carbonate/temporary hardness
• Non-carbonate/ permanent hardness

Expressed as: milliequivalent/L

The hardness of the water Removed as:

• Temporary hardness
  • Boiling
  • Addition of lime
  • Addition of sodium carbonate
  • Permutit process
• Permanent hardness
  • Addition of sodium carbonate
  • Base exchange process

Hardness of the water Disadvantages:

• Consumes more soap & detergent
• Causes furring of boilers
• Effects cooking
• Fabrics washed do not have a long life
• Results in economic losses
• Shortens the life of pipes & fixtures

Question 7. Sources of water.
Answer:

Sources of water

• Rain-main source
• Surface water
  • It ultimately flows into the sea
  • Impounding reservoirs- artificial lakes/ constructed dams
  • Rivers & streams: grossly polluted & unfit for drinking
  • Ponds & lakes: natural excavation
  • Sea water: contains 35% of salts in solution
• Groundwater: formed by percolated rainwater
  • Shallow wells: above the 1st impervious layer in the ground
  • Deep wells: below the 1st impervious layer in the ground
  • Tube wells: shallow/ deep, costly to construct & operate
  • Springs: shallow/deep, easily contaminated

Question 8. Controlled tipping.
Answer:

Controlled tipping

• Controlled Tipping
  • Here, the material is placed in a trench or other pared area, adequately compacted & covered with earth at the end of a working day
• Methods
• Trench Method
  • A long trench is dug out 6-10 feet deep & 12-36 feet wide into which refuse is compacted & covered with excavated earth
• Ramp method
  • Moderately sloping terrain is used
  • Area method
    • The refuse is deposited & sealed on its exposed surface with a mud cover
    • Changes occurring in refuse raise the temperature to 60 degrees C within 7 days & kill all the pathogens

Question 9. Waterborne diseases.
Answer:

Waterborne diseases

Question 10. Domestic refuse.
Answer:

Domestic refuse

• It consists of ash, rubbish & garbage
• Ash:
• It is the residue from the fire used for cooking & heating Rubbish:
• Comprises of wood bits, paper, clothing, metal, glass, dirt & dust
• Garbage:
• It consists of waste food, vegetable peeling & organic matter
• It needs quick removal & disposal because it ferments on storage

Environment & Health Viva Voce

1. The slimy growth covering the surface of the sand bed
2. Rapid sand filter is an earlier method of filtration where 99.9% of impurities are filtered out.
3. Clinical wastes are disposed of in yellow bags and non-clinical wastes are disposed of in black bags
4. Incinerators are used to burn all the combustibles at a temperature of 1300-1500 degrees C
5. Bangalore’s method of composting is anaerobic.
6. Occupational hazards to dentists result from accidental infection
7. Residual chlorine of water should be 0.5 mg/ltr after 1 hour
8. The temporary hardness of water is due to the presence of salts of calcium and phosphorous bicarbonates
9. Dumping is considered as most unsanitary method of waste disposal.
10. Waste sharps from hospitals should be discarded in
11. The heat produced over 60 degrees C in composting kills
12. Composting is a combined method of disposal of re-fuse and nightsoil.
13. Dumping is the most commonly used method of waste disposal posing a health hazard in India.
14. The hardness of water is expressed in terms of oil- equivalent per liter
15. The permanent hardness of water can be removed by base blue/white translucent bins. exchange process
16. Chlorination of water acts by killing pathogenic bacteria the pathogenic organisms.
17. Rainwater is the purest form of water