water & sanitation · horrock’s apparatus is used for estimating chlorine demand of water....

ENVIRONMENTAL HEALTH

Water & Sanitation

Water purification – large scale

Preliminary processing

Storage and sedimentation

Eliminates suspended matter, organisms, cysts, ova, mollusks and Cyclops

Filtration-

Superior to sedimentation, but clogging of filters can occur

Coagulation • Addition of coagulant

• Addition of alum (aluminium sulphate) or alumino ferric or polyaluminium chloride

• Finely divided clay, Fuller’s earth, bentonites and activated carbon may be used alternatively.

• Rapid mixing is done for rapid and uniform dispersion of coagulant

Flocculation/Clarification

• Gentle and prolonged stirring of coagulated water to aid in flocculation

Sedimentation

• Coagulated water is detained in sedimentation tanks/ settling basin/clarifier for atleast 4 hours.

• Also exposes to sunlight and fresh air and biological effect of aquatic flora and fauna

Filtration Sand Filters

• Process of separating suspended and colloidal impurities from water by passage through a porous media

• Carried out through slow (biological) or rapid (mechanical) sand filters

• The most common type of filter is a rapid sand filter.

• Rapid sand filters are of two types-

• Gravity / Paterson’s type

• Pressure / Candy’s type

• The filter bed of sand filters consists of following layers-

• Supernatant water- 1.5 meter- undergoes sedimentation, oxidation

• Activated carbon or Anthracite Coal- Removes organic compounds which contribute to taste and odor

• Sand bed- 1 meter- undergoes straining, sedimentation, adsorption, biochemical and microbial action.

• Graded gravel – 0.5 meter

• Under drainage system- 0.16 meter

Slow sand filter Rapid sand filter

Simple to construct and operate More difficult

More space required Less space required

Cheaper to construct Expensive

Quality of filtered water is very

high – 99.9%

Quality of filtered water is high-

99%

Preferred for rural or small

community water supply

Preferred for urban water supply

Preliminary sedimentation is

required

Can deal with raw water directly

Filtration is slow Filtration is 50 times faster

Needs 24 hours for vital layer

formation

Filter bed can be used

immediately

Biological layer- Schmutzdecke Chemical layer- alum floc

Washing required only after

several month

Washing required daily or

weekly

Cleaned manually by removal

of top 2-3 cm of sand with vital

layer

Cleaned by backwashing using

water/air.

Effective sand size – 0.2-0.3

mm

Effective sand size- 0.4-0.7 mm

Disinfection/chlorination

Chlorine demand

It is the difference between the amount of chlorine added to water and the amount of residual chlorine after a specified contact period, at a given temperature and pH of water.

Horrock’s apparatus is used for estimating chlorine demand of water

Breakpoint chlorination

• The point at which chlorine demand of water is met

• The point at which free residual chlorine appears after the entire combined chlorine residual has been completely destroyed.

• There must be 0.5 ppm of residual chlorine at treatment plant level with half-an hour of contact period and 0.2 ppm at consumer level.

• Orthotoluidine test/ orthotoluidine Arsenite test – used to test adequacy of chlorination

Chlorination agent Remarks

Chlorine gas Method of choice

Chloramines Useful in large urban water plants as resistant

to contamination

Bleaching powder Useful in rural areas

Up to water supply of 5 lac MLD

Chlorinated lime is used- contains 33%

available chlorine

Water sterilizing

powder

Bleaching powder : quicklime ratio of 80:20

25% available chlorine

Hypochlorites Rarely used

Bleaching Powder reaction

Cl2 + H2O = HCL + HOCL

HOCL = H+ + OCL-

HOCL (Hypochlorous acid)

Not affected by chlorine

• Sporing organisms

• Protozoal cysts

• Helminthes

• Ova

• Molluscs

• Cyclops

• Cercariae

• Hepatitis A

• Poliovirus

WATER QUALITY STANDARDS & CRITERIA

Microbiological / bacteriological aspects-

Coliform:

95% of samples should not contain E. coli in 100 ml of water taken during 12 months period; no 2 consecutive samples should contain E. coli

From wells and springs- up to 10 coliforms per 100 ml are acceptable

Coliforms are selected because

• They are always present in human intestine

• They are foreign to potable water

• They are easy to detect

• They survive longer

• They are more resistant to natural purification.

Ortho-toluidine test is used to determine- (AIIMS 2004)

a) Nitrates in water

b) Nitrites in water

c) Free and combined chlorine in water

d) Ammonia content in water

Which one of the following methods is used for the estimation of chlorine demand of water? (AIIMS 2006, 2007)

a) Chlorometer

b) Horrock’s apparatus

c) Berkefeld filter

d) Double pot method

Which of the following is not true regarding surveillance of water pollution? (AIIMS 2010, 2011)

a) Multiple tube method is used to calculate the number of bacteria

b) E.coli can be tested by Indole test

c) Sodium thiosulfate is used to neutralize chlorine

d) Presence of Clostridium spores indicates recent contamination

Not an indicator of fecal contamination of drinking water is- (AIIMS 2010)

a) E. coli

b) Streptococcus

c) Staphylococcus

d) Clostridium perfringens

All of the following statements are true about break point chlorination, except- (AIIMS 2004)

a) Free chlorine is released in water after break point chlorination

b) Chlorine demand is the amount needed to kill bacteria, oxidize organic matter and neutralize ammonia

c) 1 ppm free chlorine should be present in water after break point chlorination

d) Contact period of 1 hour is necessary

Horrock’s apparatus is used to measure: (UPSC CMS 2013)

a) Free chlorine

b) Combined chlorine

c) Free and combined chlorine

d) Chlorine demand

Minimum level of free chlorine in potable water is (JIPMER-2000)

a) 1mg/dl

b) 0.5mg/dl

c) 0.2 mg/dl

d) 0.7mg/dl

The disinfecting action of chlorine is mainly due to-

a) Chloride atom

b) Hypochlorous acid

c) Chloride ion

d) Hypochlorite ion

A sanitary well should be located at minimum how much distance from likely source of contamination?

a) 10 feet

b) 15 feet

c) 50 feet

d) 100 feet

True about rapid sand filter is-

a) Quality of filtered water is better than slow sand filter

b) Can deal with raw water directly

c) Filtration happens using biological layer

d) Cheaper as compared to slow sand filter

Biomedical Waste

Bio-medical waste

It means any waste, which is generated during the diagnosis, treatment or immunization of human beings or animals or research activities pertaining thereto or in the production or testing of biological or in health camps

Bio-Medical Waste Management Rules, 2016

These rules apply to all persons who generate, collect, receive, store, transport, treat, dispose, or handle bio medical waste in any form.

The rule is not applicable to-

• Radioactive wastes • Municipal Solid Wastes

• Hazardous wastes

• E-waste • Hazardous microorganisms

Hazards of Healthcare waste

• contains potentially harmful microorganisms which can infect hospital patients, health workers and the general public

• radiation burns

• sharps-inflicted injuries

• poisoning and pollution through the release of pharmaceutical products

• poisoning and pollution through waste water; and by toxic elements or compounds such as mercury or dioxins that are released during incineration.

• Of the total amount of waste generated by health-care

activities, about 85% is general, non-hazardous waste

comparable to domestic waste.

• The remaining 15% is considered hazardous material

that may be infectious, toxic or radioactive.

• High-income countries generate on average up to 0.5

kg of hazardous waste per bed per day; while low-

income countries generate on average 0.2 kg.

Biomedical wastes categories

Category Type of Waste Type of Bag Treatment

options

Yellow A. Human Anatomical

Waste

Yellow coloured

non-chlorinated

plastic bags

Incineration or

Plasma

Pyrolysis or

deep burial B. Animal Anatomical

Waste

C. Soiled Waste:

Items contaminated

with blood, body fluids

Category Type of Waste Type of Bag Treatment

options

Yellow D. Expired or Discarded

Medicines: Pharmaceutical

waste

Like cytotoxic including

contaminated cytotoxic drugs

along with glass or plastic

ampoules, vials etc.

Yellow colored

non-chlorinated

plastic bags or

containers

Incineration

E. Chemical Waste:

Chemicals used in production

of biological and used or

discarded disinfectants

Category Type of

Waste

Type of Bag Treatment options

Yellow

F. Chemical

Liquid Waste

Separate

collection system

leading to

effluent

treatment

system

After resource recovery,

the chemical liquid

waste shall be pre-

treated before mixing

with other wastewater.

G. Discarded

linen,

mattresses,

beddings

contaminated

with blood or

body fluid

Non-chlorinated

yellow plastic

bags or suitable

packing material

Non- chlorinated

chemical disinfection

followed by incineration

or Plasma Pyrolysis

Category Type of Waste Type of Bag Treatment options

Yellow

H.

Microbiology,

Biotechnology

and other

clinical

laboratory

waste

Autoclave safe

plastic bags or

containers

Pre-treat to sterilize with

non- chlorinated

chemicals on-site as

per National AIDS

Control Organisation or

World Health

Organisation guidelines

thereafter for

Incineration.

Category Type of Waste Type of Bag Treatment options

Red

Contaminated

Waste

(Recyclable)

Red

coloured

non-

chlorinated

plastic bags

or containers

Autoclaving or micro-

waving/ hydroclaving

followed by shredding

or mutilation. Treated

waste to be sent to

recyclers for energy

recovery.

Category Type of

Waste

Type of Bag Treatment options

White

Waste

sharps

including

Metals

Puncture

proof, Leak

proof, tamper

proof

containers

Autoclaving or Dry Heat

Sterilization followed by

shredding or mutilation or

encapsulation in metal

container or cement concrete;

and sent for final disposal to

iron foundries or sanitary

landfill or designated concrete

waste sharp pit.

Category Type of

Waste

Type of Bag Treatment options

Blue

Glasswa

re:

Metallic

Body

Implants

Cardboard

boxes with

blue colored

marking

Disinfection (by soaking the

washed glass waste after

cleaning with detergent and

Sodium Hypochlorite

treatment) or through

autoclaving or microwaving or

hydroclaving and then sent

for recycling.

What is the color-coding of bag in hospital for disposal of human anatomical wastes such as body parts? (AIPGME 2005)

a) Yellow

b) Black

c) Red

d) Blue

A known HIV positive patient is admitted in an isolation ward after an abdominal surgery following an accident. The resident doctor who changed his dressing the next day found it to be soaked in blood. Which of the following would be right method of choice of discarding the dressing? (AIIMS 2005)

a) Pour 1% hypochlorite on the dressing material and send it for incineration in an appropriate bag

b) Pour 5% hypochlorite on the dressing material and send it for incineration in an appropriate bag

c) Put the dressing material directly in an appropriate bag and send for incineration

d) Pour 2% Lysol on the dressing material and send it for incineration in an appropriate bag

Incineration is not done for (AIIMS-2011)

a) Waste Sharp

b) Cytotoxic drugs

c) Human anatomical waste

d) Animal waste

Expired medical drugs and cytotoxic waste are disposed by (AIIMS 2009)

a) Incineration

b) Are kept for 10 years and then disposed in a land fill

c) Autoclaving

d) In municipal waste

Wrapper of surgical syringe is discarded in which bag? (AIIMS 2008)

a) Red

b) Yellow

c) Blue

d) Black

Biomedical waste from a yellow plastic bag is disposed by: (UPSC CMS 2015)

a) Autoclaving

b) Microwaving

c) Incineration

d) Chemical treatment

Waste disposal of placenta after delivery is done by (UPSC CMS 2015)

a) Disposing it in blue bags

b) Autoclaving

c) Incineration

d) Microwaving

For safe disposal of Biomedical waste, which of the following method is not appropriate?

a) Discarded medicines should be incinerated

b) Liquid waste should be disposed at site by chemical treatment

c) Used and unused sharps should be incinerated

d) Human anatomical waste should be buried deep in rural areas

Healthcare workers involved in handling biomedical waste should be vaccinated against-

a) Hepatitis B alone

b) Hepatitis B and Anthrax

c) Hepatitis B and Tetanus

d) Hepatitis B, Tetanus and Anthrax

Metallic body implants should be disposed off in

a) Cadmium-free red coloured bag

b) Card box with blue coloured marking

c) Puncture-proof and tamper-proof container

d) Doesn’t need special disposal as it is not biomedical waste

Occupational Health

Pneumoconiosis

• It is a general term given to any lung disease caused by dusts that are breathed in and then deposited deep in the lungs causing damage.

• Pneumoconiosis is usually considered an occupational lung disease, and includes asbestosis, silicosis and coal workers' pneumoconiosis (CWP), also known as "Black Lung Disease."

• There is no cure for pneumoconiosis, but it can be prevented with appropriate respiratory protection.

Silicosis

• Caused by breathing air containing silica in its free state, as quartz (SiO2)

• Generalized fibrotic change and development of miliary nodules

• Clinical features- Shortness of breath, decreased chest expansion, a lessened capacity for work and chronic bronchitis with the absence of fever and characteristic X – ray findings

• There is an increased susceptibility to tuberculosis.

• Pulmonary damage is permanent.

• The disease finally produces emphysema and cor pulmonale

Asbestosis

• Asbestos fibers are inhaled and fine dust gets deposited in the alveoli.

• These are insoluble and cause chronic irritation resulting in pulmonary fibrosis of lungs. It can also cause carcinoma of bronchus and mesothelioma of pleura

• Increased risk when exposure is coupled with smoking

• The disease appears after an exposure of 5 to 10 years.

• The fibrosis is peribronchial, diffuse and more near the bases

• Sputum show asbestos fibers coated with fibrin called “asbestos bodies”.

• X - ray chest shows a ground glass appearance in lower parts of lungs.

Anthracosis

• (Synonyms: Coal workers’ pneumoconiosis, Coalminer’s consumption and phthisis melanotica, black spit)

• Due to inhalation of dust in coal mines

• The condition usually occurs after 20 - 30 years in the occupation.

Byssinosis

• Bronchopulmonary diseases caused by exposure to airborne dust of cotton, flax & soft hemp

• Characterized by tightness of the chest & breathlessness at work after the weekend or other absence

• It is also called ‘Monday Fever’.

• This is probably due to a histamine releasing substance.

ESI ACT, 1948

Scope

• Applicable to all non-seasonal factories

• Seasonal factories are those that are operational for less than 7 months.

• Not applicable to Mines and railways

• Applicable to whole of India

• For workers having income of up to Rs. 15000/-

Contribution

• Government gives 2/3rd of administrative expenses

• State government gives 1/8th of expenses of medical treatment and attendance.

• ESI Corporation gives 7/8th of expenses of medical treatment and attendance.

• Employers contribute 4.75% of wages

• Employees contribute 1.75% of wages

Medical providers

• Direct pattern- where 1000 or more employee family units are present, full medical personnel are made available.

• Part-time medical facility is provided where less than 750 employee family units are present.

• Indirect system/ panel system, where few beneficiaries are present.

Benefits

Medical benefit

• All medical care including prosthesis

• Sickness benefit- up to maximum of 91 days / 365 days (around 70% wage)

• Extended sickness benefit- up to a maximum of 2 years.

• 14 days for Tubectomy

• 7 days for vasectomy @ full wage

• Maternity benefit • Confinement for delivery- 26 weeks

• Miscarriage- 6 weeks 2 full wage

• Illness arising out of confinement- 30 days

• Disablement benefit • Permanent disablement – pension throughout life (90% of

wages)

• Temporary disablement- 90% wage till disablement lasts.

Dependent benefit-

• Death due to employment injury, then 90% wages to dependent (wife and children upto 18 years)

Funeral benefit- up to Rs. 10,000/-

Unemployment allowance- Rajiv Gandhi Shramik Kalyan Yojana

• When the person is rendered unemployed due to closure of factory, retrenchment or permanent invalidity due to non-employment injury.

• Provided up to 2 years

• Covers 50% wages and medical benefits

Rehabilitation

• For retired persons and their spouse, after retirement/ permanent disability.

• Continue to medical benefit, after paying Rs. 120/- as annual premium.

For employers employing persons with disabilities-

• Persons with disabilities with payment up to 25,000 get ESI benefits for 3 years.

• Employers’ contribution paid by government

All of the following are suggestive of asbestosis, except- (AIIMS 2003)

a) Occurs within 5 years of exposure

b) The disease progresses even after removal of contact

c) Can lead to pleural mesothelioma

d) Sputum contains asbestos bodies

Nearly 3/4th of occupational cancers are- (AIPGME 2008)

a) Skin cancer

b) Lung cancer

c) Cancer bladder

d) Leukemia

Inhalation of sugarcane dust could cause- (AIIMS 2003)

a) Bagassosis

b) Byssinosis

c) Tobaccossis

d) Farmers’ Lung

The benefits of ESI Act include the following except: (UPSC CMS 2015)

a) Medical benefit

b) Rehabilitation allowance

c) Sickness benefit

d) Nutritional allowance

Sickness benefit in ESI is for how many days (JIPMER 2000)

a) 51

b) 61

c) 91

d) 71

Basophilic stippling of RBSs is a sensitive index of (UPSC CMS 2011)

a) Lead poisoning

b) Arsenic poisoning

c) Asbestosis

d) Silicosis

Benefits under the Employees State Insurance Scheme include all the following except

a) Dependents’ benefit

b) Funeral benefit

c) Dearness allowance

d) Rehabilitation allowance

Which is not true of occupational cancer?

a) History of exposure to carcinogen is present

b) Danger of getting cancer even after exposure has ceased

c) Location and histological pattern are quite common in most occupations

d) Short latent period

In which of the following diseases, the characteristics are of peribronchial fibrosis predominantly near the bases, pleural mesothelioma and ‘ground-glass’ appearance in X-Ray chest.

a) Silicosis

b) Anthracosis

c) Asbestosis

d) Siderosis

METEOROLOGY, POLLUTION AND HOUSING

Dry and wet bulb thermometer

• Mercury thermometers, which measure the air temperature

• The wet bulb is kept wet by a muslin cloth fed by water from a bottle through a wick.

• The evaporation of water from the muslin cloth lowers temperature of the mercury. The wet bulb thermometer therefore shows a lower temperature than the dry bulb thermometer.

• In case both the thermometers record similar readings, then it is presumed that the air is completely saturated with moisture as happens during rains

Maximum Thermometer

• Mercury thermometer with a very fine constriction near the neck of the bulb.

• The capillary stem of the thermometer has a small metal indicator, which is pushed along by the mercury and fits tightly enough to remain behind when the mercury recedes.

• With the rise in temperature, the mercury expands and rushes across the constriction pushing the indicator. Once the temperature falls and the mercury recedes, the indicator, which fits tightly in the capillary, is measured at its lower end to give the maximum temperature reached.

Minimum thermometer

• Minimum thermometer has alcohol inside, in which a dumb-bell shaped index is immersed.

• When the temperature falls the spirit drags the index down towards the bulb end, but when the temperature rises the spirit expands and runs past the index.

• At the end of any period of observation, the position at the end of the index farthest from the bulb is considered as the minimum temperature recorded.

Campbell - Stokes Sunshine Recorder

• The number of hours of sunshine is recorded

• This comprises of a charted paper placed on a concave surface of the recorder.

• A solid glass globe brings to focus the sun’s rays on to this paper, which chars the paper at the point of focus.

With the movement of sun throughout the day, a charred line is created on the paper, which when measured gives the number of hours of sunshine in the day

Black Globe Thermometer

• Measures the radiant heat directly.

• It comprises of a hollow copper globe painted black

• Inserted in it is a calibrated mercury thermometer such that its bulb is placed in the center of the globe.

• The matt-black paint absorbs radiant heat from the surrounding objects.

• The globe thermometer records a higher temperature than the ordinary air temperature thermometer, since it is affected both by the air temperature and the radiant heat.

Whirling or Sling Psychrometer

• Consists of a dry and a wet bulb thermometer mounted side by side on a metal strip, which is fixed on a wooden frame.

• The instrument is whirled

• The readings on the thermometer show a dip due to evaporation of water brought about by the air movement created due to the rotation.

• The two thermometer readings are used to determine the relative humidity of the air using suitable tables and charts.

Kata Thermometer

• Air movement determines the cooling power of air and it influences the comfort levels in an environment

• Consists of dry and wet bulb thermometers, called dry and wet kata, respectively

• The two thermometers are set prior to taking readings by immersing them in hot water to warm them slightly above 130°F

• The bulb of dry kata is wiped dry. Then both the instruments are suspended in air

• The time in seconds is recorded for the alcohol to drop across the cooling range

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