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Water Treatment• Water Contamination
• Prompt sources of pollution • Linear sources of pollution • Diffuse sources of pollution
• Contaminant substances of the water • Pathogenic micro organisms • Organic dejects • Chemical inorganic substances • Organic composites• Sediments and materials in suspension • Radioactive substances • Thermal contamination
• Water Treatment Processes • Amount
• Quality • Economy
• General aspects on unitary operations• Harrowing
• Straining • Pre-oxidisation • Aeration • Pre-oxidisation by chlorine • Pre-oxidisation by chlorine dioxide
• Pre-oxidisation by ozone
Water Treatment
Water Treatment(Continuing)
• Coagulation/Flocculation• Decantation
• Filtration • Chemical stabilization • Disinfection • Physical disinfection • Mechanical Disinfection • Chemical Disinfection
It is important to relate that the predominant chlorine forms in water are related with pH
Water Treatment• Treatment of the water VERSUS control of pathogenic agents
• Pre-treatment • Coagulation, Flocculation and Sedimentation
Removal of bacteria (E. coli e Clostridium) and protozoa (Giardia e Cryptosporidium) on the optimal coagulation conditions (Le Chevallier, M.W.; Kwok-Keung Au, WHO, 2004)
Water Treatment
Removal of virus (bacteriophage MS-2; phage PRD-1; poliovirus e echovirus) on the optimal conditions of coagulation (Le Chevallier, M.W.; Kwok-Keung Au, WHO, 2004)
•Treatment of the water VERSUS control of pathogenic agents
Water Treatment
• Ionic exchange • Filtration
Type of FilterOperating pressure
(kPa)
Size of do pore (µm)
main application microbiological Removal
MF 30-50 ≥ 0.1 Removal of particles and turbidity
Algae, protozoan and Bacteria
UF 30-50 ≥ 0.01 Removal of non ionic solved solutes
Algae, Protozoan, majority of Bacteria e
Virus
NF 500-1000 ≥ 0.001 Removal of bivalent ion (softening) and
solved organic matter
Algae, Protozoan, majority of Bacteria e Virus
RO 1000-5000 ≥ 0.0001 Removal of ions mono-valents
(desalinization)
Algae, Protozoan, majority of Bacteria e Virus
•Treatment of the water VERSUS control of pathogenic agents
Water Treatment•Treatment of the water VERSUS control of pathogenic agents
Relationship between the size of pores of the filtering layer and the size of the microbiological particles (Le Chevallier, M.W.; Kwok-Keung Au., WHO, 2004)
Disinfection
• Disinfection• Parameters
– Disinfectant concentration– Time of disinfection– pH– Temperature • Agents of Disinfection
• chloride• chloride dioxide• Ozone• U.V. light
Disinfection
• Mechanims of Disinfection• Destruction of the cell• Changes in the metabolism• Interference in the biosynthesis growing
of the cell
• Stages of the Disinfection Process• Oxidation• Disinfection
» Efficient steps means efficient process
Disinfection
• Oxidation• Oxidants are used in a pre-treatment stage
– Reasons for this stage• Improve particle removal of next stage• Control of micro-organisms
Disinfection• By chloride
• chemical oxidation process • Most common process nowadays• reactions are strongly dependent of the pH
• By chloride dioxide • control the amount of iron• Highly soluble in water
• By ozone • inactivates micro-organisms• Reaction with micro-organisms
– Direct– Aqueous solution
Disinfection• By U.V. Light
• U.V.-B and U.V.-C innactivates micro-organisms• Wavelengh 210-300nm• Most eficient at 265nm
– Unwanted activantion of inactive micro-organisms• Solved using a high dose of radiation
• Influence Factor– Suspended organic matter
Disinfection
– Electromagnetic Process• Efficiency is not dependent from the previous factors
• Disinfection is done in few seconds• Tanks are not needed
• By U.V. Light
Distribution systems
• Evaluation of the sanitary risk– Origin of the water – adequate treatment– conditions of storage and transport of treated
water – Protection of the system
Distribution systems
• Evaluation of the sanitary risk– Origin of the water – adequate treatment– conditions of storage and transport of treated water – Protection of the distribution system
• Maintenance of the water quality in all the system– minimizing the microbial growing – preventing the microbial recontamination
Distribution systems • System
– Piping– Connections– Tanks
• How to mantain quality– maintaining a residual part of disinfectant– limiting the organic matter– Controlling the corrosion– temperature, materials of construction, time of
retention
Braga• Geography
– North of Portugal – Minho
– Area 183, 51 km² – Altitude 20 - 572
meters – Between two
rivers: Cávado and Este
– Several hills around the city
– Soil with plenty of water
Braga• Climate
• Maximum temperature average – 19ºC• Minimum temperature average – 10ºC
– Atlantic temperate– four well defined
seasons
– Rainy and wet– Winds from the sea
Braga• Demography
– 931, 1 hab/km² – 170 858 habitants (2004)
• 171000 to 230000 people including temporary citizens
– 70628 houses
Sanitation of Braga Commune Project
• 2 distinct zones– Zones of Intent Population 931, 1 hab/km²
– Zones of Dispersed Population
• Served PopulationYear of entrance in functioning of the
ProjectYear 40
Served Population(Nº Inhabitants)
146184 274913
Floating Population (Nº Inhabitants)
0 0
Industria (Equivalent Inhab.) 7735 14822
Total 153919 289735
Sanitation of Braga Commune Project
Existing ETAR´s
2000 Treatment
Total Population (Equivalent Inhab.) 1009614 ETAR: 1 with treatment by average load
activated-sludge, 1 with treatment physicist-chemistry, 1 with primary and secondary treatment and 1 by lagooning.
Flow (m^3/day) 8512
Organic load - Total CBO5 - (Kg) 6384
Existing Infrastructures
Sanitation of Braga Commune Project
Characteristics of the lift station
1 Lift Station with Substitution of the electro-mechanic equipment
Infrastructures to Renew/Extend/Benefit
Characteristics of the ETAR´s to renew
Year of entrance in functioning of the project
Year 40 Treatment
Total Population (Equivalent Inhab.) 118506 236809
4 ETAR: 1 with tertiary/secondary/ primary treatment, 2 with secondary/ primary treatment and 1 for lagooning
Flow (m^3/day) 9480 18945
Organic load - Total CBO5 - (Kg) 7110 14209
Sanitation of Braga Commune Project
Characteristics of the ETAR´s to build
Year of entrance in functioning of the project
Year 40 Treatment
Total Population (Equivalent Inhab.) 35413 52926
17 ETAR: 5 by lagooning e 12 compactsFlow (m^3/day) 2833 6351
Organic load - Total CBO5 - (Kg) 125 3176
Infrastructures to build
Intercepting and Lifting system
length Diameter Type Lifting Station
71975 300-500 Gravitational -
10823 160-250 Lifting 19
Procedural Description of the Diverse Stages of Treatment
• Preparation stage • First and second aerating lagoon
• Sedimentation lagoon • Maturation Lagoon
Press release
IP/06/1769Brussels, 12 December 2006
Environment: Commission takes Finland, Sweden and Portugal to Court over waste water treatment
The European Commission is taking Finland, Sweden and Portugal to the European Court of Justice (ECJ) for failing to ensure proper treatment of
urban waste water in a significant number of towns and cities. The failure of Finland and Sweden to systematically remove nitrogen when treating the
waste water of their inland cities and towns is contributing to the environmental problems of the Baltic Sea. Portugal has failed to respect a
special decision on urban waste water discharges from Estoril, near Lisbon, and the surrounding area.