1
Alternative water treatment
Lecture 01
Introduction
Stanisław M. Rybicki, Ph.D. (Eng); PE; KM; IWA
Chair of Water and Wastewater Treatment
(Zakład Oczyszczania Wody i Ścieków)
Room 311
stan@venus.pk.edu.pl
2
Standards
of finished (tap) water quality
• WHO (World Health Organisation)
• Regional objectives
– European Union Directives
– US EPA Standards
• Local Standards
– National Standards (EU)
– State Standards (US)
The WHO guidelines summarize world-wide knowledge
regarding potable water impact on consumers.
Guidelines are being updated due to development of
measurement techniques, better understanding of an impact
mechanisms also due to changing aesthetic requirements of
consumers.
3
Treatment process choice
• Apply only necessary processes
• Follow processes that take place in nature
• Minimize chemicals’ use
• More complicated process costs more
• Check by-products formation and handling
4
Treatment process development
(last 100 years)
• 19
th
Century – slow sand filtration, infiltration
• 19
th
/20
th
Century – disinfection
• 20’s – sand rapid filtration
• 30’s –chemical treatment
• 50’s – sorption for taste improvement
• 70’s – by-product formation control
• 80’s - minimize chemical use
• 90’s – biological treatment, quality within the network
5
Follow processes that take place in
nature – basic examples
• Sand filtration – natural infiltration using porous media
• Sedimentation – self-purification of an ambient water in
reservoirs
• Sorption – sorption of organics on clay particles
• Ozone generation - lightning
• Disinfection – UV/solar radiation
• Biological nitrification/denitrification
• QUIZ : Coagulation - ??????
6
Surface water treatment
Complexed layouts, more processes applied
Seasonal changes in raw water quality, impact of weather
conditions, impact of wastewater
Typical processes applied
– Colour removal
→
coagulation
– Turbidity removal
→
coagulation
– Organic matter removal →
oxidation
– Suspended solids removal
→
filtration
– Disinfection
coagulation followed by sedimentation
7
Process scheme
Process scheme (layout) is ‘tailor made’ for specific raw
water quality
Set of treatment units (facilities) create Water Treatment
Plant (WTP)
EU Directive 440/75/EEC requires WTP layout to be
adopted to the raw water characteristics – categories of
equipment
Level of treatment for each of category
– Category A1 – simple treatment: filtration / disinfection;
– Category A2 – full treatment:
coagulation/sedimentation/filtration/disinfection/
– Category A3 – advanced treatment : as A2 plus oxidation and
sorption
8
Process
scheme
category
A1
Chlorination
Disinfection
TREATED WATER
Contact chamber
Treated water reservoir
Sand rapid filter
(Filtration)
Water intake
Raw water
9
Process
scheme
category
A2
Chemical
Coagulants
Flocculants
Chlorination
Disinfection
TREATED WATER
Contact chamber
Treated water reservoir
Sand rapid filter
(Filtration)
Clarifier
(Post-coagulation sedimentation)
Rapid mixing
Flocculation chamber
Water intake
Raw water
10
Process
scheme
category
A3
Chemical
Coagulants
Flocculants
Chlorination
Disinfection
TREATED WATER
Contact chamber
Treated water reservoir
GAC Filter
Adsorption
Ozonization
(Oxidation)
Sand rapid filter
(Filtration)
Clarifier
(Post-coagulation sedimentation)
Rapid mixing
Flocculation chamber
Water intake
Raw water
11
Typical groundwater treatment scheme
Chlorination
Treated water - to consumers
Treated water
reservoir
Contact chamber
Sand rapid filters
Aeration
Well
raw water intake
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Alternative treatment
• Conventional treatment (e.g.: sedimentation,
coagulation, filtration, disinfection) A1, A2
• Advanced treatment (e.g.: GAC filtration/adsorption,
advanced oxidation/ozonization) A3
• Industrial water treatment (e.g.:ion exchange, softening)
• Alternative treatment:
– Membrane technologies
– Non-chemical coagulants
– In-situ treatment
– Solar radiation applied in disinfection
– Changes in quality within a network
– Biological processes in water treatment
– Wastewater reuse/reclamation
13
Application of
an alternative treatment
Membrane technologies:
• Effective removal of solid particles and colloids
without chemicals’ addition;
• Minimization of disinfectants’ use by removal of
‘large size’ pathogens (protozoa, bacteria even
viruses);
• Effective prevention against contamination within a
network;
• Recommended especially in remote areas without
and energy deficit;
• Efficient in emergency WTPs e.g. Container WTPs
applied by relief units of the UN
14
MF
UF
NF
RO
MF
UF
NF
RO
Membrane application
15
Application of
an alternative treatment
Non-chemical coagulants dual advantage:
– Developed countries:
• Minimization of heavy metals’ traces from hydrolysis
of amphoteric metals’ salts (e.g. Al
3+
);
• Avoidance of chemicals in treatment processes while
continuous coagulation is a must;
– Developing countries:
• Minimization of heavy metals’ traces from hydrolysis
of amphoteric metals’ salts (e.g. Al
3+
);
• Avoidance of chemicals in treatment processes while
continuous coagulation is a must;
16
Application of
an alternative treatment
In-situ treatment:
• Improvement of quality of groundwater;
• Creation of an ‘artificial groundwater’;
• Increase of an operational capacity of
groundwater intakes (wells);
• Recovery from contamination e.g. oil spills;
17
Application of
an alternative treatment
Solar radiation applied in disinfection:
Direct use of an ultraviolet radiation for
disinfection;
Advantages:
• Lack of chemical by-products;
• Use of ‘cheap energy’;
• BAT for remote areas in warm climate
18
Application of
an alternative treatment
Changes in quality within a network:
• Bacterial growth;
• Chemical corrosion;
• I/I control;
• Countermeasures
Wastewater reclamation:
• Production of water from wastewater (mainly
municipal);
• Typical applications:
– Cooling citcuits;
– Agriculture (the ‘fruit rule’);
– Groundwater supplementaion
19
Application of
an alternative treatment
Biological processes in water treatment
• Nitrification/denitrification for nitrogen
compounds’ removal mainly from
groundwater;
• In-situ denitrification;
• This group of processes is under dynamic
development due to enormous contamination
of groundwater in rural areas of Europe;
• Technologies may be applied also in marshes
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