Water Treatment Processes Filtration recorded version

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Filtration:

GREPA Health & Environmental Presents Filtration Copyright - GREPA 2010 Do not distribute

Slide 2:

Copyright - GREPA 2010 Do not distribute Filtration & Treatment Technologies Use of treatment chemicals, Settling and Filtration Oxidation , Adsorption Aeration (Air Stripping) Disinfection multiple barriers

Use of treatment chemicals:

Use of treatment chemicals Coagulants : chemicals that cause small particles in water to clump together and settle. Used to clarify water. Example: Alum Polymers : Long chain molecules that enhance particle size and adhesiveness. Used to assist in settling and filtering particles . pH adjustment : To enhance treatment processes or prevent corrosion. Acids or bases. Alkalinity : Buffers pH to prevent corrosion and enhances coagulation. Copyright - GREPA 2010 Do not distribute

Settling & Filtration:

Settling & Filtration Physical removal processes that depend to a large degree on particle size Larger particles settle out faster Larger particles can’t fit between grains of filter media and are screened out. Copyright - GREPA 2010 Do not distribute

Oxidation:

Oxidation Oxidation is a chemical reaction of a substance with an oxidizing chemical that takes electrons from the substance Oxygen, Ozone, Potassium permanganate, and Chlorine. Oxidation performs two main functions in WT: Converts dissolved substances to precipitates Destroys organics and most pathogens. (This is known as chemical disinfection) Copyright - GREPA 2010 Do not distribute

Adsorption:

Adsorption The adhesion of molecules to a surface. Activated Carbon, Zeolites, Activated Alumina, Granular Ferric hydroxide, Specialized Resins Undesirable substances (gases, minerals, etc ) adhere onto treatment media. Example: Ion Exchange is a treatment technique that can be used to remove hardness, nitrates, arsenic, fluoride, and more via the process of adsorption Copyright - GREPA 2010 Do not distribute

Aeration:

Aeration The adding of air to water increases its DO content. Used to increase pH to prevent corrosion. Used to precipitate easily oxidized substances such as iron Used to remove unpleasant or toxic gases such as hydrogen sulfide. (Aeration towers) Copyright - GREPA 2010 Do not distribute

Disinfection:

Disinfection Physical or chemical destruction or inactivation of pathogens in water. Chlorine, Iodine, Ozone UV, ultrasonic waves, boiling Copyright - GREPA 2010 Do not distribute

Multiple Barriers:

Multiple Barriers The multiple barrier approach refers to placing several barriers between undesirable substances and humans drinking and using water. Copyright - GREPA 2010 Do not distribute Source protection Coagulation - Flocculation Sedimentation Filtration Disinfection

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Copyright - GREPA 2010 Do not distribute 200,000 cubic miles

Groundwater Contamination:

Groundwater Contamination Landfills, chemical spills, buried fuel tanks, septics Aquifer: Porous layer of sand or soil that stores water.

Stratification:

Stratification Pic of stratification Algae: Treat with copper sulfate (blue stone) Algae increase DO and pH in the day because they produce oxygen through photosynthesis

Filtration Process:

Filtration Process Copyright - GREPA 2010 Do not distribute

Brief history of filtration:

Brief history of filtration 3000 BC Egyptians using alum to clarify water Water purification and separation of waste from water mentioned in the bible. Invention of the microscope and awareness of water borne pathogens (1650 – 1850) Late 1800’s slow sand filtration and river bank filtration used in Europe Early 1900’s sedimentation used prior to filtration in America along with chemical treatment Copyright - GREPA 2010 Do not distribute

Conventional and Direct Filtration:

Conventional and Direct Filtration Copyright - GREPA 2010 Do not distribute 1-5 sec 10min–1hour 1-4 hrs Used with lower turbidity.

San Diego’s WT process:

San Diego’s WT process Copyright - GREPA 2010 Do not distribute

Treatment Train:

Treatment Train Copyright - GREPA 2010 Do not distribute

Coagulants – How They Work:

Coagulants – How They Work Copyright - GREPA 2010 Do not distribute

Chemical Coagulants:

Chemical Coagulants Chemical Name Chemical Formula Aluminum Sulfate (Alum) - Most Common Al 2 (SO 4 ) 3 Ferrous Sulfate FeSO 4 Ferric Sulfate Fe 2 (SO 4 ) 3 Ferric Chloride FeCl 3 Cationic Polymer various Calcium Hydroxide Ca(OH) 2 Calcium Oxide CaO Sodium Aluminate Na 2 Al 2 O 4 Bentonite Clay Calcium Carbonate CaCO 3 Polyaluminum Sulfate various Nonionic Polymer Various Anionic Polymer various Copyright - GREPA 2010 Do not distribute pH of 5 - 7 May use with oxidizer Adds “stickiness” + charged floc

Settleable vs Nonsettleable Solids:

Settleable vs Nonsettleable Solids Copyright - GREPA 2010 Do not distribute

Slide 21:

Copyright - GREPA 2010 Do not distribute Volume 1mm³ Surface area = 6 mm² Explanation of non-settleable solids Volume 1mm³ Surface area = 6 meters²

Coagulation & Alkalinity:

Coagulation & Alkalinity Lime or soda ash is commonly added if the water does not have sufficient natural alkalinity. Jar testing is done to see how much alkalinity is needed to form good floc. Care must be taken to ensure that sufficient alkalinity remains in the finished water so that a corrosive condition does not develop. Alkalinity consists of bicarbonates, carbonates, and hydroxides which resist change in pH and is also added to prevent corrosion. Copyright - GREPA 2010 Do not distribute

Critical Elements of Coagulation:

Critical Elements of Coagulation Optimal pH : pH effects the solubility of chemicals of water. pH should be adjusted so that chemicals won’t dissolve but remain in precipitate form. Quick and complete mixing : Ideally every particle in the water should come in contact with the coagulation chemical. If not it might not be removed. Complete mixing also reduced the amount of chemical needed. Sufficient Alkalinity : Think of alkalinity as aggregate is to concrete. If you don’t have enough floc won’t form properly and there won’t be enough material for contaminants to adhere to. Copyright - GREPA 2010 Do not distribute

Coagulants and pH:

Coagulants and pH With aluminum sulfate (Alum), optimum coagulation efficiency and minimum floc solubility normally occur at pH 5.0 to 7.0 Iron coagulants can be used successfully over the much broader pH range of 5.0 to 11.0. If ferrous compounds are used, oxidation to ferric iron is needed for complete precipitation. (So they don’t dissolve into solution) Copyright - GREPA 2010 Do not distribute

pH:

pH Acidic Corrosion Leaching of metals Chlorine works better Basic Scale Formation Interference with treatment chemicals

pH: Hydrogen Ion Activity:

pH: Hydrogen Ion Activity pH scale: 0 to 14 Acidic: Below 7 Neutral : 7.0 Basic : Above 7 pH = potentiometric hydrogen ion concentration Measurement of the concentration of hydrogen ions

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Copyright - GREPA 2010 Do not distribute

In Line Mixer:

In Line Mixer Copyright - GREPA 2010 Do not distribute

Venturi mixer:

Venturi mixer Copyright - GREPA 2010 Do not distribute Low pressure, hi-velocity mixing and injection area

Process Control – Jar Testing:

Process Control – Jar Testing Copyright - GREPA 2010 Do not distribute

Slide 31:

Copyright - GREPA 2010 Do not distribute

Horizontal Flocculator :

Horizontal Flocculator Copyright - GREPA 2010 Do not distribute

Circular flocculation basin:

Circular flocculation basin Copyright - GREPA 2010 Do not distribute

Motion paths:

Motion paths Copyright - GREPA 2010 Do not distribute

Slide 35:

Copyright - GREPA 2010 Do not distribute

Sedimentation Basin Example:

Sedimentation Basin Example Copyright - GREPA 2010 Do not distribute

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Copyright - GREPA 2010 Do not distribute

Slide 38:

Circular Clarifier Copyright - GREPA 2010 Do not distribute

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Copyright - GREPA 2010 Do not distribute

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Copyright - GREPA 2010 Do not distribute Tube Settlers: Water flow is forced up through channels. Increases effective surface area of sedimentation basin.

Turbidity:

Turbidity Measurement of the ‘cloudiness’ of water Measured in (Nephelometric Turbidity Units) NTU Most surface water treatment plants are operated based on turbidity.

Turbidity:

Turbidity

Turbidimeter:

Turbidimeter

Filtration:

Filtration Copyright - GREPA 2010 Do not distribute

Multi Media:

Multi Media Copyright - GREPA 2010 Do not distribute

Pressure Filter :

Pressure Filter Copyright - GREPA 2010 Do not distribute

Underdrain Systems:

Underdrain Systems Function To collect filtered water uniformly across bottom of filter. To distribute backwash water evenly so that media will expand, but remain in place Copyright - GREPA 2010 Do not distribute

Backwash:

Backwash Copyright - GREPA 2010 Do not distribute

Backwash – Surface Washers:

Backwash – Surface Washers Copyright - GREPA 2010 Do not distribute

Filtration Options:

Filtration Options Filtration Conventional Direct Gravity Pressure Slow sand Diatomaceous earth Copyright - GREPA 2010 Do not distribute

Slow Sand Filter:

Slow Sand Filter Copyright - GREPA 2010 Do not distribute

Slow Sand Filter:

Slow Sand Filter Copyright - GREPA 2010 Do not distribute

Barrel slow sand filter:

Barrel slow sand filter Media depth Copyright - GREPA 2010 Do not distribute

Diatomaceous Earth:

Diatomaceous Earth Copyright - GREPA 2010 Do not distribute

Slide 55:

Diatomaceous Earth (DE) Copyright - GREPA 2010 Do not distribute

Membrane Process:

Membrane Process Water forced through a porous membrane under pressure while larger molecules are held back. Micro-filtration, nanofiltration, Reverse Osmosis Copyright - GREPA 2010 Do not distribute

Membrane filter:

Membrane filter Copyright - GREPA 2010 Do not distribute

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Copyright - GREPA 2010 Do not distribute

Activated Carbon As A Filter Media:

Activated Carbon As A Filter Media Pros High adsorptive properties Primarily used for taste and odor control Removes some trace organics Granular (GAC) or powder (PAC) A gram of activated carbon can have a surface area up to 1500 m 2 Copyright - GREPA 2010 Do not distribute

Activated Carbon:

Activated Carbon 1.2mm x 0.7 mm Electron Microscope: Molecular level Copyright - GREPA 2010 Do not distribute

Iron and Manganese:

Iron and Manganese Controlled by Oxidation/ Filtration Iron converted to rust & Manganese converted to black compound called manganese dioxide when oxidized Greensand (gluconite) is also used to promote oxidation & adsorption Copyright - GREPA 2010 Do not distribute

Iron & manganese removal:

Iron & manganese removal Copyright - GREPA 2010 Do not distribute

Iron & manganese removal:

Iron & manganese removal Copyright - GREPA 2010 Do not distribute

Iron & Manganese Greensand Filtration:

Iron & Manganese Greensand Filtration Copyright - GREPA 2010 Do not distribute

Water Softening :

Water Softening Hard water is caused by calcium & magnesium ions which come from salts of calcium/magnesium such as sulfate, bicarbonate, carbonate, chloride and nitrate Problems associated with hard water: Scaling on plumbing fixtures Inhibits cleaning action of soap Damages clothing Scaling in boilers and hot water heaters Copyright - GREPA 2010 Do not distribute

Water Softening – Treatment Methods:

Water Softening – Treatment Methods Chemicals used for precipitation: Hydrated lime (slaked) or quicklime ( unslaked ) Ca (OH) 2 Caustic soda (sodium hydroxide) NaOH Soda ash (sodium carbonate) Na 2 CO Copyright - GREPA 2010 Do not distribute

Water Softening – Treatment Methods:

Water Softening – Treatment Methods Ion exchange – Ions are an electrically charged atom or molecule formed by the loss or gain of one or more electrons Similar in design to a filtration unit Media consists of zeolites or other organic polymers Media able to exchange sodium ions with calcium and magnesium ions Copyright - GREPA 2010 Do not distribute

Ion Exchange medias:

Ion Exchange medias Copyright - GREPA 2010 Do not distribute

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Copyright - GREPA 2010 Do not distribute

Operation Of Ion Exchange Unit:

Operation Of Ion Exchange Unit Copyright - GREPA 2010 Do not distribute

Operation Of An Ion Exchange Unit:

Operation Of An Ion Exchange Unit Copyright - GREPA 2010 Do not distribute

Slide 72:

Ion Exchange Copyright - GREPA 2010 Do not distribute

Slide 73:

Adsorption Technology – Arsenic Removal Copyright - GREPA 2010 Do not distribute

Slide 74:

POP QUIZ! Copyright - GREPA 2010 Do not distribute

Which filter system has no back wash cycle?:

Which filter system has no back wash cycle? Multi media Slow sand Diatomaceous earth None of the above Copyright - GREPA 2010 Do not distribute

What is the primary purpose of an under drain system in a filter?:

What is the primary purpose of an under drain system in a filter? Collect filtered water uniformly Distribute back wash water uniformly Prevent confined space entry A and B Copyright - GREPA 2010 Do not distribute

Inadequate backwashing can cause mud balls and filter cracking, which causes::

Inadequate backwashing can cause mud balls and filter cracking, which causes: Shortened filter runs Operators to get fired Water quality problems A and C Copyright - GREPA 2010 Do not distribute

What water quality problem may require the use of PAC or GAC?:

What water quality problem may require the use of PAC or GAC? High turbidity Taste and odors Low pH Water hammer Copyright - GREPA 2010 Do not distribute

What is a definition of pH?:

What is a definition of pH? The measure of reciprocal Hydrogen ion activity There is not one definition None of the above Copyright - GREPA 2010 Do not distribute

What is the usual cause of bluish green stains on plumbing fixtures?:

What is the usual cause of bluish green stains on plumbing fixtures? Turbidity High alkalinity c. Corrosion D. Pathogens Copyright - GREPA 2010 Do not distribute

What standard does taste and odors fall under?:

What standard does taste and odors fall under? Murphys’ standards Primary standards Secondary standards All of the above Copyright - GREPA 2010 Do not distribute

Nitrates cause a condition in infants known as::

Nitrates cause a condition in infants known as: Metronome Blue baby disease Methomoglobonemia B and C Copyright - GREPA 2010 Do not distribute

Corrosion problems can be caused or increased by::

Corrosion problems can be caused or increased by: Low pH Chemistry of the water High flow rates All of the above Copyright - GREPA 2010 Do not distribute

The direct filtration process eliminates what?:

The direct filtration process eliminates what? Coagulation Flocculation Sedimentation Filtration Copyright - GREPA 2010 Do not distribute

What is the most used method for determining the ideal amount of coagulant to use in water treatment?:

What is the most used method for determining the ideal amount of coagulant to use in water treatment? The marble test The jar test A composite test A state test Copyright - GREPA 2010 Do not distribute

What is the primary purpose of flocculation?:

What is the primary purpose of flocculation? To form coagulants Transforms smaller floc into larger floc To allow short circuiting All of the above Copyright - GREPA 2010 Do not distribute

How much time is needed to form good floc?:

How much time is needed to form good floc? 10 min to one hour 30 minute average 2 to 3 hours A and B Copyright - GREPA 2010 Do not distribute

What is the best way to determine if the coagulant chemical is working?:

What is the best way to determine if the coagulant chemical is working? Jar tests several times a day Turbidity of raw water & after sed basin The pH of finished water None of the above Copyright - GREPA 2010 Do not distribute

What usually causes hard water?:

What usually causes hard water ? Iron and manganese Calcium and manganese Calcium and magnesium C and B Copyright - GREPA 2010 Do not distribute

What is the main treatment chemical used in ion exchange?:

What is the main treatment chemical used in ion exchange? Chlorine Salt KMNO4 Polyphosphates Copyright - GREPA 2010 Do not distribute

What else can ion exchange remove from drinking water besides hardness?:

What else can ion exchange remove from drinking water besides hardness? Salt Fluoride Nitrates B and C Copyright - GREPA 2010 Do not distribute

Filtration Worksheet:

Filtration Worksheet Please turn to your handout titled “Filtration Worksheet” and try your hand at applying your water treatment expertise. Compare your answers with the answer key and contact us if you have questions by phone (760) 402-6788 or email grepatrainers@gmail.com In the next presentation we will review and explore E ssential W ater M ath. Copyright - GREPA 2010 Do not distribute

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