Transcript Water Quality Contamination and Protection

WATER QUALITY:
CONTAMINATION AND
PROTECTION
1. Water Quality
• Microbiological Quality:
Presence of organisms that cannot be seen by the naked
eye – faecal and total coliforms
• Physical Quality
Affecting taste, odour and appearance. pH, Turbidity
etc.
• Chemical Quality
Nature and concentration of dissolved substances. E.g
salts, organics, etc. Most of these are essential, but in
high quantities may cause problems.
2. Common Water Quality
Problems: Surface Water
• Faecal Pollution
High faecal and total coliform counts –near dense
human settlements
• Colour and Stability
Due to organic acids
• Salt Concentrations (TDS)
High sulphate and chloride concentrations. Corrosive
and distinctly salty
2. Common Water Quality
Problems: Surface Water
• Eutrophication
High nutrient concentration (nitrogen,
phosphate) and high algal concentrations.
3. Common Water Quality
Problems: Groundwater
• Salinity
Occurs where the predominant geological formations are
sedimentary rocks of marine origin. Eg. The Karoo
• Fluoride
Especially in the coal bearing regions (central and
western parts of the country)
• Sulphate and Chloride
Especially water with high TDS
3. Common Water Quality
Problems: Groundwater
• Calcium and Magnessium
Especially in dolomitic areas
• Iron and Manganese
While they commonly occur in high concentrations in
groundwater, treatment is easy
4. Water Pollution
• Water Pollution occurs when water is rendered
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less fit for use as a result of human activities
Waste generated by human activity enters the
water environment.
Human Activities
-Intensive Irrigation/Agri.
(Domestic/Indust.)
-Mining activities
-Industrial activity
-Dense human settlements
Waste Streams
-Sewage Waste
-Gray water
-Stormwater
-Solid waste
5. Protection of Water
• Everyone needs to be involved
• National Government must provide a framework (policy) and
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legislation for protecting our water sources
Provincial and local level management measures and actions must
be developed for giving effect to the national water quality
management framework and legislation
Business Owners
Industry
Mines
Farmers
Interest Groups
General Public
6. Water Treatment: Chlorination
• Water-borne diseases are spread by pathogens (disease•
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causing micro-organisms – such as bacteria and viruses)
in water
Pathogenic micro-organisms enter water supplies as
result of pollution by human and animal wastes.
A lot of bacteria and viruses will remain after the First
Barrier and Second Barrier treatment
The final barrier is disinfection – destruction of the
harmful micro-organism – though the use of a chemical
agent.
7. Water Treatment: Chlorination
• Types of possible disinfectants
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Chlorine, Ozone, Chlorine Dioxide, Calcium hypochlorite
(HTH), Sodium hypochlorite (bleach) and
monochloramine
Chlorine is by far the most effective, easy to control, cost
effective and used in over 98% of water treatment
works worldwide.
Side effects and other issues such formation THM’s have
been highlighted – they are all minor and negligible as
compared to the benefits of chlorinating water. Eg.
Cholera epidemic.
5. Water Treatment: Fluoridation
• Water fluoridation involves addition of predetermined
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amounts of a fluoride-containing chemical to the water
during a water treatment process in order to increase
the fluoride concentration to a specific level.
The WRC is currently involved in research to parameters
and control that determines safe and effective
fluoridation of water
On the other side of the coin is defluoridation where
there is also ongoing research to reduce fluoride from
waters with high fluoride concentration, though the use
of modified locally occurring
7. Relevant Research
• Five main fields of research addressed water
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quality and related problems
Over 200 projects have been carried out
Over R150 million has been spent
Over 30 patents have been taken
Over 200 reports, workshops, training session.
At least 5 centres of expertise
Over R40 million invested in on going projects
All major water treatment plants are using one
or more processes or technology developed
through WRC funding
RESEARCH OUTPUTS
• Sewage sludge guidelines and addendum to promote
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safe use of sludge for crop production
Compilation of a guide to assess the magnitude of nonpoint source pollution
With DWAF – Development of methodology to
implement Waste Discharge Charges (Polluter pays
principle)
Models to simulate effect of acid mine water on the
quality of Witbank Dam
Design of soil covers for coal discard dumps that exclude
oxygen formation of acid mine drainage
Use saline mine water to irrigate crops and remove
gypsum
Reduced cost to neutralize acid mine water using
cheaper agents.
RESEARCH OUTPUTS
• Aerobic Digestion (Low cost sanitation) – Almost
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all waste water treatment plants in SA use this
technology
Biosure® Process – Treatment of high sulphate
waters (acid mine water)
Environmental technology and Integrated waste
water beneficiation – treatment of high volume
saline waters
Petro Process
Membrane Technologies