SCREENSScreening is normally the first unit operationused at wastewater treatment plant.The screen is a device with openings,generally of uniform size, that is used to retainlarge objects and solids such as rags, paper,plastics, metals, and the like.WHY:To avoid any damages and blockage tosubsequent process equipment.
SCREENS SCREENS Classification Coarse Microscreens Fine screens < 0.5 mm screens 6 to 150 mm < 6 mm Hand Mechanically Static Drum Stepcleaned cleaned Wedgewire Chain Reciprocating Catenary Continuous driven rake belt
SCREENSCharacteristics & quantities removed from WW with COARSE screens Size of opening Volume of Screenings Moisture between bars Specific L/1000 m3 content mm weight Kg/m3 Range Typical % 12.5 60-90 700-1100 37 - 74 50 25 50-80 600-1000 15 - 37 22 37.5 50-80 600-1000 07 - 15 11 50 50-80 600-1000 04 - 11 06 Characteristics & quantities removed from WW with FINE screens Volume of Screenings Size of opening Moisture Specific weight L/1000 m3 between bars content Kg/m3 Range Typical mm % 6 80-90 900-1100 44 - 110 75 Fine Screens are substitute for Primary treatment (I.e. primary clarifier)
EQUALIZATION TANKThe main function of the equalization/buffering tankis to obtain equalisation of the wastewater quality(BOD, COD, TSS, nitrogen,...) and quantity (flow).The tank also buffers the wastewater during nonfeeding phases.The wastewater is kept in a continuous state ofsuspension and anaerobic conditions are avoided.
Aeration and Mixing in Equalization TankAeration and mixing equipment should be sized toblend the contents of the tank and preventdeposition of solids in the basin.For WW with TSS in the range of 200 PPM:Mixing Requirements: 0.004 to 0.008 KW/m3Air requirements to prevent septic & odour: 0.01to 0.015 m3/m3/minNote: In equalization basin that follows primarysedimentation and have a short retention timeaeration may not be required.
AERATION AND MIXING EQUIPMENT IN EQUALIZATION TANKSurface aerators Coarse bubblePump Ejector Submersible aerators
IBAC Integrated Bio Active ClarifierIBAC Treatment ZonesUpper Concentric zones: Aerobic Zone Anoxic Zone Clarification Zone Clarification Clarification ANOXIC ANOXIC AerationLower Zones: Facultative Zone Anaerobic Zone Facultative Sludge Treatment Zone Anaerobic Sludge Treatment Ideal , compact and economical solution for Municipal & Industrial Wastewater treatment and reuse
IBAC ADVANTAGES Innovative, evaluated, tested and in use. The technology serves a wide range of applications Typical plant size is more than 50% smaller in footprint Typical plant maintenance and operator costs are 50% less Municipal and industrial discharges can be co-treated Typically 70% less sludge is produced - low hauling costs Sludge is stabilized and does not need dewatering Harmful nutrients are removed to preserve water bodies Automated compact plants are easy to manage and secure Global remote monitoring and remote control option Operator friendly and doesn’t require operator presence 24/7
IBAC CONSTRUCTION1. IBAC CYLINDRICAL VESSEL ALTERNATIVES: Concrete vessel for permanent sites Vessel with steel panels for movable and permanent sites Prefab reinforced fiberglass vessel for small systems
SLUDGE GENERATION COMPARISON Conventional IBAC IBAC Activated Sludge Advantage0.7 to 1Kg. Dry Solids 0.2 to 0.3 Kg. Dry 57% – 80% Per Kg. BOD Solids Per Kg. BOD Removal Removal< 1% of Dry Sludge 3% of Dry Solid in 300% + in Sludge Water Sludge Water
Typical Municipal Footprint 2,000 m3/ Day Flow Traditional System IBACPrimary ClarifierAnoxic Tank Single VesselAeration TankSecondary ClarifierAnaerobic Digester Total 1000 m2 Total 225 m2
IBAC Vs Conventional System IBACSludge SecondaryDigester Clarifier Anoxic Tank Aeration tank Pump stationPrimary Recycle SludgeClarifier Thickener
SELECTOR TANKFilamentous Bulking is a problem affecting the biosolids settling and thickeningproperties caused by filamentous micro organisms if present in large number.The problem will lead to high effluent suspended solids and poor treatmentperformance.The Solution to this problem is to have a SELECTOR TANK prior to the aeration tankwhere the growth of floc-forming bacteria is favored over filamentous bacteria.The Selector is a tank or series of tanks in which incoming wastewater is mixed withreturn sludge under Aerobic Or Anoxic Or Anaerobic condition , and classified intotwo types: - Kinetics based selector (With high reactor substrate concentration) - Metabolic based selector (With high reactor substrate concentration & biological nutrient removal) The IBAC doesn’t require a selector Tank as it includes an Anoxic zone
IBAC AERATION EQUIPMENT Fine bubble diffusersBubble size : 1 – 3 mm DiaKla (Oxygen Mass transfer Rate):max. at 1.5 – 2.5 mm Dia
IBAC Process Treatment Range From Municipal To High-Strength Industrial Wastewater Note: Wastewater Strength is measured in BOD-5 mg/liter WASTEWATER STRENGTH IBAC Treatment Range100 22,000mg/l. BOD-5 mg/l. BOD-5 LOW MEDIUM HIGH HIGHERMunicipal Slaughterhouse Pulp & Paper Hog wasteHousehold Food Processing Rendering DistilleriesGrey Water Breweries Cosmetics Fisheries Dairy Farms
IBAC VERSIONS OF PRODUCT LINE IBAC I - For general municipal or industrial applications IBAC II - Same as IBAC I but for very unstable flows IBAC III - For wastewater with very high suspended solids IBAC IV - For solar-powered applications
FILTRATION (TERTIARY TREATMENT) MULTI MEDIA PRESSURE FILTERS
FILTRATION (TERTIARY TREATMENT) MULTI MEDIA GRAVITY FILTERS
FILTRATION (TERTIARY TREATMENT) Depth (or deep-bed) filtration, in which the particles are removed throughout the filter bed or in a significant portion of it (e.g., sand filters); Media: Anthracite: ES1.1 to 1.2 mm, D 30 – 60 cm Fine Sand: ES 0.5 to 0.6 mm, D 25 – 50 cm Coarse Sand: ES 1.5 to 3 mm, D 5 – 10 cm Gravel : Support media ES : Effective size D : Depth
PROCESS VARIABLES AFFECTING FILTRATION• Flow rate “Q”• Type of solid particles: - Particle Size distribution. - Shape of particle. - Particle surface charge.• Liquid viscosity• Liquid density• Solid concentration
DISINFECTION (TERTIARY TREATMENT) As Wastewater contains many types of humans enteric organisms that are associated with various waterborne diseases, here come the importance of disinfection , which is the destruction of these organism for safe use of the reclaimed water.Physical Radiation ChemicalPatronization Gama Ray Halogens (Cl , Br & I)UV Alcohols Phenol Soaps & Synthetic detergents Ozone Hydrogen Peroxide Etc.
CHARACTERISTICS OF AN IDEAL DISINFECTANT CHARACTERISTIC PROPERTIES / RESPONSEAvailability Should be available in large quantities and reasonably pricedDeodorizing Should deodorize while disinfectingHomogeneity Solution must be uniform in compositionInteraction with extraneous Should not be absorbed by organic matter othermaterial than bacterial cellsNoncorrosive and nonstaining Should not disfigure metals or stain clothingNontoxic to higher forms of life Should be toxic to microorganisms and nontoxic to humans and other animalsPenetration Should have the capacity to penetrate through surfacesSafety Should be safe to transport, store, handle, and useSolubility Must be soluble in water or cell tissueStability Should have low loss of germicidal action with time on standingToxicity to Microorganisms Should be effective at high dilutionsToxicity at ambient Should be effective in ambient temperature rangetemperatures
MOST USED DISINFECTANTS Chlorine Gas Sodium Hypochlorite Ultra Violet Cl2 NaOClSupplied as liquefied gasunder high pressure incontainers vary in size from - Only available as Liquid. - Open channel45kg , 68 kg (cylinders) & - 12 to 15% active chlorine - Closed Pipe908 containers (1 ton). - Decompose with heat & - Different types of lamps light especially at high concentration.
MECHANISM OF DISINFECTION CHLORINE UV RADIATION1.oxidation 1.Photochemical damage to RNA and2.Reactions with available DNA (e.g., formation of double bonds) chlorine within the cells of an organism. 2.The nucleic acids in microorganisms3.Protein precipitation are the most important absorbers of4.Modification of cell wall the energy of light in the wavelength permeability range of 240---280 nm.5.Hydrolysis and mechanical 3.Because DNA and RNA carry genetic disruption information for reproduction, damage of these substances can effectively inactivate the cell
TYPICAL CHLORINE DOSAGE Initial Coliform Chlorine dose ,mg/L TYPE OF count, Effluent standard ,MPN /100 mL WASTEWATER MPN / 100 ml 1000 200 23 <2.2Raw wastewater 107-109 15-40Primary effluent 107-109 10-30 20-40Trickling filter effluent 105-106 3-10 5-20 10-40Activated-sludgeeffluent 105-106 2-10 5-15 10-30Filtered activated-sludge effluent 104-106 4-8 5-15 6-20 8-30Nitrified effluent 104-106 4-12 6-16 8-18 8-20Filtered nitrified effluent 104-106 4-10 6-12 8-14 8-16Microfiltration effluent 101-103 1-3 2-4 2-6 4-10Reverse osmosisb ̃0 0 0 0 0-2Septic tank effluent 107-109 20-40 40-60Intermittent sand filtereffluent 102-104 1-5 2-8 5-10 8-18a Adapted in part from U.S. EPA (1986); White (1999).b Based on free chlorine.
BIOSOLIDS TREATMENT (Excess Sludge Or Waste Sludge)Sludge out of the Belt Press Direct to mechanicalIBAC (Stabilized) Filter Press dewatering2 -3 % Dry Solids Decanter (centrifuge) Sludge out of Convectional Aerobic/Anaerobic systems Digestion Max. 1 % Thickening(Non-stabilized) Dry Solids Max. 0.8 % Dry Solids Gravity/mechanical Belt Press Thickener Filter Press To Dewatering 2-3 % Decanter (centrifuge) Dry Solids
BIOSOLIDS TREATMENT (Excess Sludge Or Waste Sludge)Belt filter press filter press The target DS after dewatering is 20 – 40% Decanter centrifuge
BIOSOLIDS TREATMENT (ACCESSORIES)Polymer Preparation unit Conveyors
AUTOMATION & CONTROL Alarms Operator PC Notifications Engineering PC TelephoneUniversity Admin Access from Home Field PLC Instruments Programming Laptop On the Road IBAC
FIELD INSTRUMENTSMixed liquor concentration IBAC TankDissolved Oxygen meter IBAC TankTurbidity Meter Final Treated WaterFlow Meter Inlet Main HeadersDelta Pressure Transmitters Multimedia FilterspH & Temperature IBAC TankChlorine residual Final Treated WaterVFD Control Room
IBAC VS. TRADITIONAL ACTIVATED SLUDGE Traditional activated sludge Headwork (screen+ pump Primary Anoxic station) clarifier Tank Pressure Effluent Sec. Aeration Tank Filters Tank clarifier Recycle Chlorine For Irrigation Pump contactChlorination Station building Tank Holding StabilizationDewatering tank Thickener Tank Polymer Station
IBAC VS. TRADITIONAL ACTIVATED SLUDGE IBAC Headwork (screen+ pump Effluent IBAC station) Tank Holding Chlorine PressureDewatering contact tank Filters Tank Polymer Station Chlorination building For Irrigation