Water Treatment

Prague , January of 2007

By :

Julio Costa n. 384657

Pedro Vasconcelos n. 384394

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

Treatment Processes • Lagooning

Procedural Description of the Diverse Stages of Treatment

• Preparation stage • First and second aerating lagoon

• Sedimentation lagoon • Maturation Lagoon

Braga Commune Map Sanitation Net

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.

The end.

(Thank you for your attention)