Water is essential for life but limited on Earth. It is important to recycle and purify water to ensure a sustainable supply for human use. Various physical, chemical, and biological processes can be used to purify water through processes like filtration, sedimentation, chlorination, and the use of lagoons and reactors to break down organic pollutants using microorganisms. Proper treatment is needed to remove contaminants and pathogens to provide safe drinking water.

2. Introduction
What is water?
Chemistry: 2 hydrogen atom jointed
to a oxygem atom.
Physics: Polar liquid with boiling
temperature of 100ºC that is solid below 0ºC.
Key point: Water is an essential and
limited element for human life.

3. Introduction Why recycle water?
• Limited recourse of the planet.
Water is recycled by itself but if we
contaminate just one of the step in
the water cycle, all the cycle is
contaminated too.
• So this shows us the importance of recycling water.
freshwater
3%
oceans water
97%
Water on Earth
undergroun
d water
31%
Lakes and
rives
3%
human use
1%
frozen
water
65%
Distribution of Freshwater

4. Introduction Pollution and water purification
• Water pollution affects rainfall, surface water,
groundwater and the resulting degraded
natural ecosystems.
• Since 1900 the population has quadrupled
while water extraction has increased sixfold.
• In addition to sustainable development
policies, purification systems are required to
improve the quality of discharges generated
by human activity.

5. Introduction Residual water purification
• By applying those purification treatments we
remove from water most of the residuals that
are present there and we achieve a reduction
of the negative effect that human activities
have in the nature.
• Treatments:
• Physical treatments
• Chemical treatments
• Biological treatments

6. Introduction Drinking water disinfection
• Each country legally regulates the quality of
water intended for human consumption.
• Water must be treated for human
consumption and may require removal of
dissolved substances, undissolved substances
and microorganisms harmful to health.
• There are different technologies for drinking
water treatment.

7. Introduction Water feautures
There are two important features:
Alkalinity:
Colloids: Particules of 1-100microns. Removed by
coagulation or floculation.

8. Introduction Water feautures
• BOD (Biochemical Oxygen Demand)
 Normally BOD5 is measure -> Oxygent demand
after 5 days
 Used to determine the degree of water pollution
Low leves of BOD does not necessarily imply little
pollution.

9. Water Pollutants Solids
Excepting gases, all substances, either organic or inorganic, which
are diluted in water are called solids
In this sense, solids or total solids (TS) are defined as any substances
which remain as a solid residue in a water sample which has been
heated to a temperature within 100ºC and 105ºC , evaporated and
dried
According to their size we can find to different groups of total solids:

10. Water Pollutants Solids
Excepting gases, all substances, either organic or inorganic, which
are diluted in water are called solids
In this sense, solids or total solids (TS) are defined as any substances
which remain as a solid residue in a water sample which has been
heated to a temperature within 100ºC and 105ºC , evaporated and
dried
According to their size we can find to different groups of total solids:
DISSOLVED SOLIDS
 Can be retained by a 2.0
micron pore filter
 Usually salts or organic
residues
 A filtering and drying
process is carried out to
eliminate it

11. Water Pollutants Solids
Excepting gases, all substances, either organic or inorganic, which
are diluted in water are called solids
In this sense, solids or total solids (TS) are defined as any substances
which remain as a solid residue in a water sample which has been
heated to a temperature within 100ºC and 105ºC , evaporated and
dried
According to their size we can find to different groups of total solids:
DISSOLVED SOLIDS
TOTAL VOLATILED
AND FIXED SOLIDS
 Can be retained by a 2.0
micron pore filter
 Usually salts or organic
residues
 A filtering and drying
process is carried out to
eliminate it
 Are those solids which
volatilize at a
temperature of 550º C
 These organic solids may
be bacteria and viruses
and other organic
substances

12. Water Pollutants Solids
Excepting gases, all substances, either organic or inorganic, which
are diluted in water are called solids
In this sense, solids or total solids (TS) are defined as any substances
which remain as a solid residue in a water sample which has been
heated to a temperature within 100ºC and 105ºC , evaporated and
dried
According to their size we can find to different groups of total solids:
DISSOLVED SOLIDS
TOTAL VOLATILED
AND FIXED SOLIDS
SETTLEABLE SOLIDS
 Can be retained by a 2.0
micron pore filter
 Usually salts or organic
residues
 A filtering and drying
process is carried out to
eliminate it
 Are those solids which
volatilize at a
temperature of 550º C
 These organic solids may
be bacteria and viruses
and other organic
substances
 Solids over 10
micron in size and
which sediment
 These suspended
solids will settle to
the bottom of a
conic shaped
recipient

13. Water Pollutants Organic Residuals
Chemical oxygine demand (COD) is defined as the amount of
diatomic oxygen O2 needed to oxidize that matter which is
susceptible of being oxidized in a liquid sample
Is a good indicator of the amount of organic matter in water
The most common method to determinate COD consists of using
potassium dichromate
Pathogens (pathogenic agents)
Pathogenic agents which cause the transmission of multiple diseases
Bacteria Viruses Protozoa

14. Water Pollutants Minerals
o High concentrations of heavy
metals can occur in some water
bodies
o Zinc, mercury, manganese and lead
are among the most frequently
heavy metals found in water bodies
o Maximum Contaminant Level
(MCL) is the highest level of a
contaminant that is allowed in
drinking water.
PHYSICAL & MINERALS
CHARACTERISTICS CHART
for Calendar Year 2012
Constituent
Annual Range
Detected
Annual
Average
Copper, ppm ND - 0.011 0.002
Hardness,
ppm 10.0 - 29.0 19.6
Iron ND - 0.071 0.018
Magnesium,
ppm 0.70 - 2.00 1.35
Manganese,
ppb ND - 0.010 0.003
Nickel, ppm ND - 0.003 0.000
Phosphate,
ppm 0.37 - 1.38 0.92
Potassium,
ppm 1.10 - 2.70 1.67
Silica, ppm 5.44 - 15.72 10.46
Zinc, ppm 0.074 - 0.252 0.153

15. Water Pollutants Nitrogen & Phosphor
Both, nitrogen and phosphor, are essential nutrients for aquatic life, but
excessive amount s of any of them can produce serious problems.
The main effect of
nitrogen and phosphor
contamination of water is
the so called
Eutrophication.
This process produces an
excessive growth of algae
and aquatic plants
which, after dying,
degrade an decompose
in riverbeds and
reservoir funds.

16. Residual Water Physical Treatments
Clean water
Physical principles No new substances

17. Residual Water Physical Treatments
Hydrocyclone
• Solid-liquid separation
• Centrifugal force
• Sand and particles
heavier than water
• Conical or cylindrical

18. Residual Water Physical Treatments
Dissolved Air Flotation
• Preconoces bassed
on density
• Suspended solid and
contaminant liquids
• Microbubble injection

19. Residual Water Physical Treatments
API oil-water separator
• Oil separation
• Conventional separator:
-Gravimetrical separation
• Parallel plate separator:
-Higher surface
-Less space

20. Residual Water Physical Treatments
Membrane reactors
• Filtration process
through membranes
• Submerged system
• External loop system

21. Residual Water Physical Treatments
Adsorption
• Separating process in which some components of a
liquid phase are transferred to a solid surface.
• Carbon filter
• Residual water
• Pesticides, dissolved organic matter, detergent, etc.

22. Residual Water Physical Treatments
Filtration processes
• Granulated materials: sand
• Improve clarity and desinfect
• Slow filtration
• Fast filtration

23. Residual Water Physical Treatments
Micro, ultra
and
nanofiltration
Nanofiltration:
Ions
0.01 microns
membrane
pores
Microfiltration:
Suspended
solids
0.5 microns
membrane
pores
Ultrafiltration:
Macromolecules
0.1 microns
membrane
pores

24. Residual Water Physical Treatments
Reverse Osmosis
• Filtration through a semi-permeable membrane with
presure
• It can hold particles from 1 to 0.001 microns.

25. Residual Water Biological Treatments
Lagoons
Damming residual water organic matter contained is
degraded by microorganisms
Depending on oxigen level:
 Aerobic
Loop: seaweed in the lagoon (using light) produce high amount of oxygen
aerobic bacteria break organic matter into inorganic compounds
used by seaweed to grow
 Anaerobic
organic charge is higher, so oxygen produced by seaweed is quickly
consumed anaerobic bacteria
 Facultative
Aerobic and anaerobic depending on water deepness
The most used because of highest reduction in BOD (up to 90%)

26. Residual Water Biological Treatments
Lagoons
Usually system composed by an anaerobic and a facultative lagoon
first one reduces solid and organic matter content
second one produces high quality water
Disadvantages
large surface needed
carefully land preparation
located outdoors, and
hence subjected to weather
conditions

27. Residual Water Biological Treatments
Biological Reactors
FIXED FILM SYSTEMS : rotary bio-reactor
•Microorganisms fixed into an inert media, water is passed through it
 Biodiscs
 Biocylinders
Control:
 Speed of the reactor
 Temperature
 Water characteristics (pH, level of
solved oxygen or organic charge).
Advantages:
 Low energy consumption
 Small land needed

28. Residual Water Biological Treatments
Biological Reactors
ANAEROBIC REACTORS
Biogas production
 UASB (Upflow Anaerobic Sludge Blanket)
Cylindrical reactors with an ascendant water flux
 IC ( internal circulation )
Two compartments: the lower one is fed with water with higher organic
charge upper one with less residues
Used for highly contaminated residual water
Advantages:
 high efficiency
 small retention time
 cheap
 energy production due to biogas produced
 easily adapted to seasonal industries

29. Water Desinfection Chlorination
•Cl2 diatomic gas easily solved in water depending on pressure and temperature.
•Highly negative effects on microorganism that that live in water
Types
 Marginal chlorination
 Chloramination
 Breakpoint Chlorination
 Superchlorination and dechlorination
Advantage: long protection time
Carefulness with the doses of Cl added to water to avoid any side effect in human
health or other smaller problems such as bad tastes or smells.

30. Water Desinfection Ozonization
• Ozone (O3) oxidizes organic compounds
• Water is maintained in tanks with different compartments and ozone is
injected there.
• Advantage: production of O3 is very easy (using electrical discharges)
• Disadvantages:
 Ozone very toxic and corrosive
 Cannot be used as method to prevent microorganisms over time
• This method has to be used instead of chlorination when water contains
some determined substances. Example: phenols, which form chlorophenols
that lead to very bad smells and tastes.

31. Water Desinfection UV Radiation
• Removal of organic matter by wet photochemical oxidation
• Nitrogen peroxide (NO2) is added to water, UV light used to start a
reaction between organic compounds that produces their decomposition
•Disadvantages:
 generation of UV light
 energy expenses
 water has to be very clear
 maximum distance to the
UV source
• Advantages:
 minimize chemical compounds added to water
 better water quality