Environment in health and disease (Water)

Presented by,Dr. Shivashankar.KP.G., Dept of Public Health Dentistry

CONTENTS

INTRODUCTION

ENVIRONMENTAL FACTORS

WATER REQUIREMENT

USES OF WATER

SOURCES OF WATER SUPPLY

WATER POLLUTION

PURIFICATION OF WATER

WATER QUALITY-CRITERIA AND STANDARDS

SURVEILLANCE OF DRINKING WATER QUALITY

HARDNESS OF WATER

CONCLUSION

REFERENCES

Introduction

• The study of disease is really the study of man and his

environment.

• All external factors--- living+ non-living+ non-material

• Social and economic conditions

Components of environment

Physical

Social

Biological

Sanitation

Environmental sanitation: “the control of all those factors in man’s physical environment which exercise or may exercise a deleterious effect on his physical development, health and survival”.

(WHO)

Environmental factors influencing the spread of communicable diseases

Water

Safe and wholesome water

Free of Pathogenic agents

Free of harmful Chemical substance

Pleasant to taste

Useable

Requirements

2 liters per head per day

The consumption of water – climatic conditions

A daily supply of 150-200l iters per capita

In rural India 40 liters per day is the target

USES OF WATER

a) Domestic

b) Public

c) Industrial

d) Agricultural

e) Power production

f) Carrying away

SOURCES OF WATER

3 main sources:

Rain

Surface water

Ground water

RAIN

Physically- clear, bright and sparkling

Chemically- soft

Bacteriologically- free of pathogens

SURFACE WATER IMPOUNDING RESERVOIRS Artificial lakes

Dams built across rivers and mountain

streams.

RIVERS AND STREAMS

TANKS, LAKES AND PONDS

Large excavations in which surface water is

stored

• SEA WATER

GROUND WATER

• Rain water percolating into ground

• Cheapest & most practical way of

providing water to small communities

Advantages:

• Likely to be free from pathogenic agents

• Usually requires no treatment

• Supply likely to be certain even during

dry season

• Less subjected to contamination

Ground water

wells springs

Shallow and Deep

Dugand Tube

Dug

Katcha well (sanitary)

Pucca well

Characteristics SHALLOW WELLS DEEP WELLS

Definition Taps the water from above the first impervious layer

Taps the water from below the first impervious layer

Chemical quality Moderately hard Much hard

Bacteriological qualityOften grossly contaminated Taps purer water

Yield Usually goes dry in summer Provides a source of constant supply

SANITARY WELL A sanitary well is one which is

properly located, well-constructed and protected against contamination with a view to yield a supply of safe water.

Points to be taken into consideration:

1. Location- 15m2. Lining-6m3. Parapet-70cms4. Platform-1m5. Drain6. Covering7. Hand pump8. Consumer responsibility9. Quality

SPRINGS

When ground water comes to the surface and flows freely under natural

pressure, it is called a ‘spring’.

WATER POLLUTION

Natural impurities

Dissolved gases

Microscopic organisms

Suspended impurities

Dissolved minerals

Man made impurities

Sewage Industrial and trade wastes

Agricultural pollutants

Physical polutants

Indicators of water pollution

• Amount of total suspended solids

• Biochemical oxygen demand (BOD) at 20 deg. C

• Concentration of chlorides

• Nitrogen and phosphorus

• Absence of dissolved oxygen.

Water related diseases

Water related diseases

b) CHEMICAL:• Chemical pollutants of diverse nature

• may affect man’s health directly and indirectly

Other associated ...Dental health

Cyanosis in infant

Cardiovascular diseases

inadequate use of water

Some diseases are related to the disease carrying insects

Water Pollution Law

• In India, water pollution is becoming a serious problem.

• Parliament in 1974-Water (Prevention and Control of Pollution)

Act.

• Seeks to provide legal deterrent against the spread of water

pollution.

• The Act is a comprehensive piece of legislation.

• It provides for the constitution of State and Central Water

Boards and Joint Water Boards endowed with wide powers for

controlling pollution.

Purification of water

Purification on large scaleStorage :

Water is drawn out from the source and impounded in

natural or artificial reservoirs.

Due to storage, purification occurs:

I. Physical

II. Chemical

III. Biological

Optimum period of storage 10-14 days.

Purification on large scale

Filtration

Second stage in water purification

98-99% of bacteria are removed by filtration

Types of filters

Slow sand filter/ biological

Rapid sand filter/ mechanical

Slow sand filters

a) Supernatant (raw) water: Above sand bed; depth varies

from 1 to 1.5M (always kept constant).

b). Sand bed

• Most important part of the filter. Thickness of 1 Meter

• Sand grains are carefully chosen - round and have "effective

diameter" of 0.2-0.3 mm

VITAL LAYER: ‘Schmutzdecke’ layer, Zoogleal layer, Biological layer

• Slimmy gelatinous layer - Algae, planktons, diatoms & bacteria.

• Formation of vital layer – ‘Ripening’ of the filter.

• When fully formed -extends for 2-3 cm into the top portion of the sand

bed.

• Heart of slow sand filter.

c) UNDER DRAINAGE SYSTEM

• FILTER BOX

• Supernatant water- 1 to 1.5m

• Sand bed-1.2m

• Gravel support-0.30m

• Filter bottom-0.16m

d) FILTER CONTROL

• Venturi meter- measures loss of head

• Loss of head 1.3meter- uneconomical

Cleaning:

Scraping of the top portion by 1 or 2 cms

Advantages:

• Simple to construct and operate.

• The cost of construction is cheaper

• quality of water is very high.

• reduce bacterial counts by 99.9 to 99.99 per cent and E. coli

by 99 to 99.9 per cent.

Rapid sand filters

Gravity type Pressure type (Candy 's filter)

• Coagulation• Rapid mixing • Flocculation • Sedimentation • Filtration

1.COAGULATION:

• Raw water+Alum (5-40mg/L) chemical coagulant

2.RAPID MIXING:

• Violent agitations in mixing chamber (few min)

3.FLOCCULATION:

• Slow & gentle stirring of treated water(30 min.)

• Mechanical type of flocculator

• Thick, copious, white floccules precipitate Of aluminum

hydroxide.

4. SEDIMENTATION

• Detained here for 2-6 hrs

5. FILTRATION:

Filter bed

• Surface area: 80-90 sq.M

• Media: sand

• Particle size: 0.4-0.7mm

• Depth: 1M

• Depth of water on sand bed is 1-1.5mm

Slimmy layer: Absorbs bacteria - purification

Cleaning:

Advantages:1.No preliminary storage is needed.

2.The filter beds occupy less space.

3.Filtration is rapid

4.washing is easy.

5.Flexibility in operation.

Properties Rapid sand filter Slow sand filter

Area Small Large

Rate of filtration (L/m2/hr)

4000-7500 100-400

Sand size (diameter) 0.4-0.7 mm 0.2-0.3 mm

pretreatment Coagulation and sedimentation

Sedimentation

Filter cleaning Back washing Scraping

Operation More skilled Less skilled

Removal of bacteria 98-99% 99.9-99.99%

Prior water storage Storage needed No need

DISINFECTIONCHLORINATION:

Mechanism of action:

H2O + CL2 -- HCL + HOCL

HCL is neutralized by alkalinity of water

HOCL (Hypochlorus acid) Ionises into H + OCL (Hydrogen & Hypochlorite

ion)

Methods of chlorination1. Chlorine gas

2. Chloromine

3. Perchloron

Superchlorination

Orthotolidine (OT) test

Orthotolidine-arsenite (OAT) test

Other agents a)Ozone oxidizing agent

b)U-V radiation

PURIFICATION OF WATER ON A SMALL SCALE

a. HOUSEHOLD PURIFICATION OF WATER:

• Boiling

• Chemical disinfection

• filtration

• Ultra violet irradiation

• Multistage reverse osmosis purification of water.

PURIFICATION OF WATER ON A SMALL SCALE

b. Disinfection of wells

WATER QUALITY - CRITERIA & STANDARDS

WHO guidelines for drinking water quality. 1. Acceptability aspects2. Microbiological aspects3. Chemical aspects4. Radiological aspects

Microbiological aspectsPresence of fecal streptococci, sulfite reducing clostridia- primary

bacteriological indicator.

Acceptability aspects

Radiological aspects

Chemical aspects

NATIONAL WATER SUPPLY AND SANITATION PROGRAM

• The National Water Supply and Sanitation Program was launched

in 1954 by the Govt. of India …

• Provision has been made in the successive 5-year Plans to improve

the water supply.

• HEALTH EDUCATION…The provision of merely good water supply

does not in itself secure freedom from water-borne diseases.

…….important weapon in creating among people a desire for

higher standards of life.

CONCLUSION

REFERENCES

• Textbook of preventive and social medicine – K.Park 20TH Edition

• Environmental Health In Emergencies. WHO practical guide 2002

• The International Water and Sanitation Decade (1981-90) “Water for

All” by 1990

• WHO 1972.Health hazards of human environment, WHO, Geneva

• WHO 1995. The World health report 1995, Bridging the gaps, p-41

• WHO 2012, World health statistics 2012• Water and sanitation interlinkages across the 2030 Agenda for

Sustainable Development. WHO