Tiger Worm Toilets (Oxfam Public Health Engineering webinar)
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Transcript of Public Health Engineering
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PUBLIC HEALTH ENGINEERING (CE-355)
Saadat Ali
Phone: 0333-2386630
Email: [email protected]
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Course Introduction Water demand, sources, quality, sampling, analysis,
treatment, distribution network design
Wastewater generation, quality, effects on
environment and health, treatment
Solid waste management
Air and noise pollution control
Environmental Impact Assessments & Environmental
legislations
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Course Objectives
To give students basic concepts about public
health engineering
To give you idea about mitigation of environmental
issues that affect the public health
To make you aware about health and
environmental issues related with civil engineering
To make you aware about present environmental
status of the country and the work going on
To make you aware about legislations
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Recommended Books and Materials
Text Book: Water Supply and Sewerage. By
E.W. Steel, 6th edition.
Reference Book:
All lectures handouts will cover all the topics.
If out of books, reading material would be
provided to students as hard copy.
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Marks Distribution
2 OHTs = 30 (2 x 15)
1 final exam = 30
4 assignments = 10
4 quizzes = 10
Term project = 20 (10 write up + 10 presentation)
Total = 100
Practical
Viva voce= 20
10 Assignments = 50
2 quizzes = 10
Field visit = 20 (10 visits + 10 reports)
Total = 100
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Introduction to Public Health
Engineering
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The Concept
Many diseases are preventable through simple, non-medical methods
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Public Health?
the science of preventing disease, prolonging life and promoting health through the organized efforts of
society, communities and individuals
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History of Public Health From the beginnings of human civilization, it was
recognized that polluted water and lack of proper waste
disposal spread communicable diseases (Moin-ja-darro
and Harrapa civilizations)
Roman times, it was well understood that proper
diversion of human waste was necessary for public
health in urban areas.
During the 14th century Black Death in Europe, it was
believed that removing bodies of the dead would
further prevent the spread of the bacterial infection.
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The Water Water covers 70.9% of the Earth's surface, and is vital for all
known forms of life.
Oceans hold 96.5% of surface water, glaciers and polar ice caps
2.4%, and other land surface water such as rivers, lakes and
ponds 0.6%
Approximately 70% of the fresh water which is actively handled by
humans, is consumed by agriculture.
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The Water
Clean drinking water is essential to humans and
other life forms.
Scientists have estimated that by 2025
more than half of the world population will be
facing water-based vulnerability
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Water Cycle
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The water cycle dynamics does the trick 13
but, H2O is always on the move ...
Instant snap shot:
Ice caps
2.7%
Rivers
0.0002% Lakes
0.007%
Oceans
96.5%
Clouds
0.001%
Groundwater
0.7%
Shortage of freshwater !
A dynamic perspective
gives a better description:
4 600 years 3 000 years
8 days
16 000
years 280
days
Renewable rain gives in 2000 years as
much water as is in the oceans!!!
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Water Chemistry
Water appears in nature in all three common states of matter,
As vapor in clouds;
As solid in glaciers and
As liquid in aquifers in the ground.
Water has high specific heat capacity of 4200 J/(kgK) due to hydrogen bonding between its molecules.
The maximum density of water occurs at 3.98 C (39.16 F).
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This property allows water to moderate Earth's
climate by buffering large fluctuations in temperature.
It has the anomalous property of becoming less dense,
when it is cooled down to its solid form. Ice expands to
occupy 9% greater volume and floats over water.
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Water is miscible with many liquids, such as ethanol, in all proportions, forming a single homogeneous liquid. On the other hand, water and most oils are immiscible usually forming layers according to increasing density from the top.
Water is a universal solvent. Substances that dissolve in water, e.g., salts, sugars, acids, alkalis, gases are known as hydrophilic (water-loving) substances, while those that do not mix well with water (e.g., fats and oils), are known as hydrophobic (water-fearing) substances.
The boiling point of water is dependent on the barometric pressure. On the top of Mt. Everest water boils at 68 C (154 F), compared to 100 C (212 F) at sea level. Conversely, water deep in the ocean near geothermal vents can reach temperatures of hundreds of degrees and remain liquid.
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Water and Human Human body contains from
55% to 78% water. Most
scientists agree that
approximately 2 liters (6 to 7
glasses) of water daily is the
minimum to maintain proper
hydration.
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Potable Water
Water fit for human consumption is called drinking water or
potable water.
Some five million deaths a year are caused by polluted drinking
water. The World Health Organization (WHO) estimates that
safe water could prevent 1.4 million child deaths from diarrhea
each year
It takes around 3,000 liters of water, converted from liquid to
vapour, to produce enough food to satisfy one person's daily
dietary need
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Water Scarcity
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Pakistan available water = 1200 m3/c/year
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Sanitation
Sanitation is the hygienic means of promoting health
through prevention of human contact with the hazards of
wastes. Hazards can be either physical, microbiological,
biological or chemical agents of disease.
These includes human and animal feces, solid wastes,
domestic wastewater (sewage, sullage, greywater),
industrial wastes and agricultural wastes
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Sanitation the silent crises
2.4 billion people (40% of the world's population) lack so called adequate sanitation
18% of the world's population lack safe water supply
10% of all wastewater in developing countries is treated
Malnutrition is a major factor making us more vulnerable to disease and death, thus food security is important
The combined effects of poor personal and domestic
hygiene and lack of safe water and good environmental
sanitation is considered the most important risk factor
for disease and death
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What sanitation is about
Personal and household hygiene
Clean environment incl. water
Solid waste management
Greywater disposal and treatment
Safe excreta disposal
Stormwater handling
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Traditional interpretation:
Additional perspectives:
Acceptance, affordable, convenience and pride
Environmentally sustainable arrangements
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Principle:
Organic other solid waste
Stormwater sewage
Industrial household wastewater
Black toilet water greywater
Strategies for sanitation improvements
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Why do we often act as if we were
only a few hundred million people on
earth?
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v
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What is Wastewater Reuse?
Terminology
Water reuse
The beneficial use of treated wastewater for agriculture, industry, etc.
Water reclamation
Reclamation involves all processes used to treat wastewater so that it can be beneficially reused
Water recycling
Recycling generally means reuse of wastewater back in the same cycle where it is generated.
Hamid Iqbal 24
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What is Wastewater Reuse?
Categories of Water Reuse
Indirect Reuse
Reuse of wastewater within the context of natural water systems (rivers, aquifers, etc.). The ultimate indirect reuse is through the global hydrologic cycle
Other terms: Indirect potable reuse
Direct Reuse
The direct beneficial reuse of treated wastewater for agriculture, industry, etc.
Direct potable reuse: the reuse of reclaimed water for potable uses
Hamid Iqbal 25
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Driving Factors for Water Reuse
Water Availability
Water Consumption
Water Quality
Hamid Iqbal 26
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Benefits of Water Reuse
Important element of integrated water resources utilization and management
Treated effluent is used as a water resource for many possible beneficial purposes
Pollution control e.g. for many Arab coastal cities, wastewater would not be discharged to the sea thus reducing pollution to the marine environment and not creating public health issues
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Public Health and Water Quality
Considerations
Physical water quality considerations
Turbidity, color, etc.
Chemical water quality considerations
Chemical constituents including solids, metals, nitrogen,
phosphorus, etc.
Biological water quality considerations
Pathogens including bacteria, helminths, virus, etc.
Emerging water quality considerations
Pharmaceuticals, hormonal products, personal care
products
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Water Reuse Design Criteria
Water quality requirements
Monitoring requirements
Treatment process requirements
Treatment reliability requirements
Operational requirements
Cross-connection control provisions
Use area controls
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Treatment Reliability
Standby power supply
Multiple or standby unit processes
Emergency storage/disposal provisions
Provisions for continuous disinfection
Non-design features
Qualified personnel
Monitoring
O & M program
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Solid Waste
Waste: Anything which is not useful for a person is called as waste.
However waste is a relative terminology and a useless thing for a person-could be useful for others, e.g. Scavengers collect the solid waste from streets and sell it to waste buyers and earn money.
Solid Waste (SW): Solid waste is the waste arising from all human and animal activities and is normally solid, semi solid or liquid discarded as unwanted material.
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Problems in SWM
The problems associated with the management of solid waste in Pakistan are due to the quantity and diverse nature of waste.
The development of extensive urban areas
The engineering limitations of the impacts of technology, energy and raw materials
So, to achieve a goal of proper solid waste management in an efficient and orderly manner, the fundamental aspects and relationships involved must be identified and understood early.
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Present status in Pakistan It is estimated that presently, 56,000 tons per day of
solid waste is generated in Pakistan.
No weighing facilities are installed at any disposal sites
Open burning of waste or open disposal
Collection 51-69 %
No Disposal facilities
A lot of potential for recycling and involvement of private sector which is overlooked
Hazardous hospital and industrial wastes are being simply treated as ordinary waste
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Air and Noise
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Danger in the air we breathe At rest, human beings breathe in and out at every 4 seconds,
16 times in a minuteand
960 times an hour or
8.5 million times of air intake in a year.
This adds up to I million gallons a year (4 million liters) of oxygen-related air in a year
Hamid Iqbal 36
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Natural sources of air pollution
Ash and smoke from lightning-triggered forest fires
Ash and dust from volcanic eruptions
Salt spray from sea waves
Methane from decaying organic matter
Pollen from plants
Dust from windstorms
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Air Pollution: regional & global problems
Acid rain
Photochemical Smog
Industrial Smog
Greenhouse effect and global warming
Depletion of stratospheric ozone
Eutrophication
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Common health effects of air
indoor pollution
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We never know the worth of water till the well is
dry. ~Thomas Fuller,
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PHE CE 355