DEPARTAMENTO DE ENGENHARIA CIVIL E ARQUITECTURA

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1 DEPARTAMENTO DE ENGENHARIA CIVIL E ARQUITECTURA MESTRADO INTEGRADO EM ENGENHARIA DO AMBIENTE PROJECTO DE INSTALAÇÕES DE TRATAMENTO PART 1 WATER TREATMENT (CONTINUATION) PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 1

2 SCHEME OF TREATMENT The treatment scheme is the set of actions which must be carried out in various unit operations and processes in order to optimize the treatment of water, technically and economically, taking into account the physical, chemical and bacteriological raw water characteristics (in accordance with the provisions laid out in Decree-Law 236/98 of 1 August) and the corresponding treated water quality (in accordance with the provisions laid out in Decree-Law 306/2007 of 27 August). PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 2

3 WATER TREATMENT PLANT (WTP) PROCESS DIAGRAM PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 3

4 RAW WATER PARAMETERS TREATMENT PROCESSES OR UNIT OPERATIONS RAW WATER PARAMETERS Iron / manganese Turbidity Microbiological parameters Total suspended solids Calcium-carbonic equilibrium Oxidation of organic matter Residual in treated water Synthetic organic compounds (pesticides and herbicides) PROCESSES OR UNIT OPERATIONS Oxidation + removal by chemical precipitation Clarification Oxidation + clarification+ disinfection (chlorine) Clarification Addition of lime, crushed limestone chambers Ozone, potassium permanganate, chlorine (but not as the first treatment operation) Chlorine addition GAC (granular activated carbon) adsorption CAP (powered activated carbon) adsorption PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 4

5 RAW WATER SOLIDS AND GRIT REMOVAL SOLIDS REMOVAL The removal of solids is operated almost exclusively when you want to treat surface water source (water intakes from rivers, reservoirs, ponds, etc.); GRIT REMOVAL The removal of sand is operated when you want to treat surface water source lotic systems (flowing water - rivers, springs, creeks and streams); is not normally required in lentic systems (calm waters: lakes, ponds, etc.) PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 5

6 AREIAS DO VILAR (BARCELOS) WTP ÁGUAS DO NOROESTE, S.A. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 6

7 WATER INTAKE ATLL - AIGÜES TER LLOBREGAT (SPAIN / BARCELONA) PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 7

8 WATER INTAKE ATLL - AIGÜES TER LLOBREGAT (SPAIN / BARCELONA) PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 8

9 RESERVOIR WATER INTAKE PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 9

10 PRE-OXIDATION PRE-OXIDATION Ozonation Potassium permanganate Chlorine should not be used as pre-oxidant PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 10

11 PRE-OXIDATION Chlorine should not be used as a pre-oxidant, since it can enhance the formation of organochlorine products, especially trihalomethanes THM (cancer precursors). The THMs are a group of organic compounds that are considered derivatives of methane (CH 4 ) in the molecules of which three of its four hydrogen atoms have been replaced by an equal number of atoms of the halogen elements (chlorine, bromine and iodine). The formation of THMs during the pre-oxidation of water with free chlorine, follows a complex mechanism by which chemical species, the halogens form with water, react with humic and fulvic substances that normally contained in raw water. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 11

12 POTASSIUM PERMANGANATE PRE-OXIDATION ATLL - AIGÜES TER LLOBREGAT (SPAIN / BARCELONA) PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 12

13 POTASSIUM PERMANGANATE PREPARATION ATLL - AIGÜES TER LLOBREGAT (SPAIN / BARCELONA) PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 13

14 PRE-OXIDATION / OZONATORS ASSEISSEIRA WTP / EPAL - PORTUGUESA DAS ÁGUAS LIVRES, S.A. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 14

15 PRE-OXIDATION / OZONATION CHAMBERS ASSEISSEIRA WTP / EPAL - PORTUGUESA DAS ÁGUAS LIVRES, S.A. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 15

16 CLARIFICATION The clarification is an essential step in a WTP, including, usually, four sub-steps: RAPID MIXING FLOCCULATION FLOTATION SEDIMENTATION FILTRATION PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 16

17 CLARIFICATION / COAGULATION PROCESSES MIXING DESTABILIZATION - FLOCCULATION Coagulation processes are commonly included in WTP to promote aggregation of small particles into larger particles that can be subsequently removed by sedimentation and/or filtration processes. Particulate suspensions commonly removed with coagulation processes include clay and silt-based turbidity, natural organic matter and other associated constituents, such as microbial contaminants, toxic metals, synthetic organic chemicals, iron, and manganese. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 17

18 CLARIFICATION / COAGULATION PROCESSES MIXING DESTABILIZATION - FLOCCULATION The coagulation process is comprised of three sequential steps. These steps include coagulation formation, particle destabilization, and particle aggregation. Coagulation formation and particle destabilization are promoted in a rapidmixing stage where treatment chemicals are added, hydrolyzed, and dispersed throughout the particulate suspension to cause destabilization. Particle aggregation is then promoted in a flocculation stage where inter-particle collisions create larger amenable to separation from the treated water. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 18

19 CLARIFICATION / RAPID MIXING Chemical storage. RAPID MIXING Most common chemicals used: aluminum sulfate Al 2 (SO 4 ) 3 14H 2 O, ferric chloride FeCl 3, among others); synthetic organic polymers (cationic polymers) are sometimes used in addition to or in place of metal salt coagulants when jar tests demonstrate acceptable performance. Solution or suspension preparation. Chemical dosages (jar tests are generally performed to select coagulation process chemical dosages). Rapid mixing chambers or other devices themselves (high velocity gradients G value between 600 a 1000 s -1 - concept developed by Camp and Stein in 1943). PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 19

20 CLARIFICATION / RAPID MIXING / EXAMPLE PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 20

21 CLARIFICATION / RAPID MIXING / EXAMPLE ASSEISSEIRA WTP / EPAL - PORTUGUESA DAS ÁGUAS LIVRES, S.A. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 21

22 CLARIFICATION / FLOCCULATION FLOCCULATION Flocculation is typically performed in a basin baffled into three or more compartments with mechanical mixing (G value between 20 a 70 s -1 ) provided in each stage to promote inter-particle collisions and aggregation. In an effort to reduce the capital and operating costs associated with traditional form of flocculation, contact flocculation performed within up-flow sludge blanket clarifiers, buoyant media roughing clarifiers, and granular media filters are gaining increased application. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 22

23 CLARIFICATION / FLOCCULATION CHAMBER / EXAMPLE PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 23

24 CLARIFICATION / FLOCCULATION CHAMBER/ EXAMPLE ASSEISSEIRA WTP / EPAL - PORTUGUESA DAS ÁGUAS LIVRES, S.A. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 24

25 CLARIFICAÇÃO CLARIFICATION / FLOCULAÇÃO FLOTATION - COAGULAÇÃO Flotation is a solid-liquid gravity separation process, mostly used for algae removal. FLOTATION Flotation processes introduce gas bubbles into the water that attach to solid particles and create bubblesolid agglomerates that float to the top of the water column where accumulated solids are removed. Flotation is not generally used in place of sedimentation in water treatment. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 25

26 CLARIFICATION / FLOTATION / EXAMPLE ASSEISSEIRA WTP / EPAL - PORTUGUESA DAS ÁGUAS LIVRES, S.A. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 26

27 CLARIFICATION / SEDIMENTATION Sedimentation is a solid-liquid gravity separation process that promote gravity settling of solid particles to the bottom of the water column where accumulated solids are removed. SEDIMENTATION Sedimentation is generally used in combination with coagulation and flocculation to remove flock particles and improve subsequent filtration efficiency. Sedimentation is particularly necessary for high turbidity and highly colored waters that generate substantial solids during the coagulation and flocculation processes. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 27

28 CLARIFICATION / SEDIMENTATION SEDIMENTATION Sedimentation is sometimes unnecessary prior to filtration (direct filtration / water turbidity between15 a 20 mg/l) in instances where flocculation solids production is low and filtration can effectively handle the solids loading. Sedimentation is also sometimes used at the head of a WTP in the form of a pre-sedimentation basin to allow gravity settling of denser solids that do not require coagulation and flocculation for promotion of solids separation. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 28

29 CLARIFICATION / SEDIMENTATION SEDIMENTATION Sedimentation is most effective when hydraulic approach plug and laminar flow so that short circuiting and turbulence are minimized. Poor inlet flow distribution and effluent collection, wind or rising bubbles, and density differences caused by temperature or concentration all can contribute to flow instability. Therefore, design of an effective sedimentation process is dependent on proper consideration of physical design factor such as surface loading rate, size and shape of proper tankage, inlet and outlet flow arrangements, baffling, and solids removal methods. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 29

30 CLARIFICATION / SEDIMENTATION Types of conventional sedimentation tanks: Horizontal-flow rectangular tank; Circular radial-flow tanks; Square radial-flow tank. SEDIMENTATION Types of high-rate sedimentation (increase the available area for solids settling, decrease the solids settling depth, promote the flow stability, and decrease land requirements in comparison to more traditional tanks): Tube settlers; Plate settlers. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 30

31 CLARIFICATION / SEDIMENTATION HORIZONTAL-FLOW RECTANGULAR TANK PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 31

32 CLARIFICATION / SEDIMENTATION CIRCULAR RADIAL-FLOW TANK PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 32

33 CLARIFICATION / SEDIMENTATION TUBE SETTLER PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 33

34 CLARIFICATION / SEDIMENTATION PLATE SETTLER PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 34

35 CLARIFICATION / FILTRATION Filtration, as it applies to water treatment, is the passage of water through a porous medium to remove suspended solids. FILTRATION The granular media type, size, gradation, shape, and depth determine pore volume, pore size, and pore tortuosity that affect solids holding capacity, head loss, filtrate quality, and backwash requirements. The most common materials used in granular media filters are sand, crushed anthracite coal, and granular activated carbon (GAC). PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 35

36 CLARIFICATION / RAPID FILTRATION / NORMAL OPERATION ASSEISSEIRA WTP / EPAL - PORTUGUESA DAS ÁGUAS LIVRES, S.A. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 36

37 CLARIFICATION / RAPID FILTRATION / BACKWASH OPERATION ASSEISSEIRA WTP / EPAL - PORTUGUESA DAS ÁGUAS LIVRES, S.A. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 37

38 CLARIFICATION / RAPID FILTRATION / BACKWASH OPERATION ASSEISSEIRA WTP / EPAL - PORTUGUESA DAS ÁGUAS LIVRES, S.A. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 38

39 CLARIFICATION / RAPID FILTRATION / CONTROL EQUIPMENT ASSEISSEIRA WTP / EPAL - PORTUGUESA DAS ÁGUAS LIVRES, S.A. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 39

40 DISINFECTION Disinfection is provided in water treatment to assure the production of a microbiologically safe finished water quality. DESINFECTION Disinfectants include free and combined chlorine (calcium hypochlorite Ca(ClO) 2 or sodium hypochlorite NaClO), chlorine dioxide ClO 2, ozone, ultraviolet (UV) irradiation, and other disinfectants. Free chorine and combined chlorine are excellent biocides and provide a persistent residual to maintain the microbiological safety of the finished water as it passes through the transmission and distribution system. Ozone is the most powerful disinfectant of those used in water treatment; however, ozone is highly unstable in water and lacks persistent residual. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 40

41 DISINFECTION / CHLORINE STORAGE ASSEISSEIRA WTP / EPAL - PORTUGUESA DAS ÁGUAS LIVRES, S.A. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 41

42 TREATED WATER CISTERN ASSEISSEIRA WTP / EPAL - PORTUGUESA DAS ÁGUAS LIVRES, S.A. PROJECTO DE INSTALAÇÕES DE TRATAMENTO / PROF. EDUARDO RIBEIRO DE SOUSA 42