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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
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