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Wastewater Management (Part 2) - Coggle Diagram
Wastewater Management (Part 2)
1. Common Wastewater Treatment Methods
Physical Unit Operations - use of physical forces
-Screening; Remove large debris
-Mixing and Flocculation; Promotes aggregation of particles
-Sedimentation; Settles suspended solids
-Flotation; Separates lighter particles
-Filtration; Removes fine particles
-Gas transfer; Introduces gases for treatment
Chemical Unit Processes- uses chemical reaction
-Precipitation; Converts dissolved substances into solids
-Adsorption; Uses activated carbon to remove contaminants
-Disinfection; Destroys harmful microorganisms
Biological Unit Processes- uses microbes
-Removes organic substances(colloidal/dissolved)
-Converts pollutants into gases or biomass for easy removal
2. Mechanical Processes
-Screening; Removes coarse/ fine solids using hand-cleaned or mechanically cleaned screens
Oil Separation;
-API Separator; Uses gravity to separate oil from wastewater ( slow process)
-CPI Separator; Uses plates to increase efficiency but cannot handle shock loads
Flow equalization;
-Balance flow variations
-Prevent sudden surges that disrupt treatment
3. Physical treatment
=Sedimentation; Separates solids via gravity in different tank zones
-Inlet zone
-Settling Zone
-Sludge Zone
-Outlet Zone
=Floatation
-Uses gas bubble to separate particles
-Air floatation: Introduce gas directly
-Vacuum Flotation: Uses air saturation and pressure reduction
4.Chemical Treatment
=Neutralization
-Adjust pH (6-9) for safe discharge
-Acidic wastes - Treated with lime or soda ash
-Alkaline wastes- Treated with sulfuric/hydrochloric acid
=Oxidation/Reduction
-Remove heavy metals, organic contaminants, and odors
-Uses oxidizing agents like chlorine, ozone, or hydrogen peroxide
=Chemical Precipitation
-Uses coagulation & flocculation to enhance solids removal
-Common coagulants: Alum, Ferric Chloride, Lime
5. Physio-Chemical Treatment
-Dissolved Air Flotation (DAF)- Use micron-sized bubbles to remove suspended solids
-DAF with Lamella Flocculation- Uses angled plates for better efficiency
6. Biological treatment
=Aerobic Treatment
-Activated Sludge Process; Use aeration and microorganism to break down organic matter
-Extended Aeration; Increases retention time, reducing sludge production
-Sequential Batch Reactor (SBR): Combines aeration & sedimentation in one tank
-Trickling Filter; Uses biofilm on a bed of media (rock/plastic)for treatment
Anaerobic Treatment
-Converts organic matter to methane gas
-More energy-efficient than aerobic treatment
7. Auxiliary Operation
=Disinfection
-Chemical agents: Chlorine, ozone
Physical agents: UV radiation
Reuse of Treated Effluent
-Used for industrial applications, irrigation
8. Advanced (Tertiary) Treatment
=Filtration
-Removes fine particles using granular media filters
-Types: Two media (sand & anthracite) and three-media filters
=Carbon Adsorption
-Removes resistant organic pollutants
=Membrane Separation
-Ultrafiltration (UF): Removes fine particles
-Reverse Osmosis (RO): Desalinates water
9. Sludge Treatment & Disposal
=Sludge Handling
-Preliminary operations: Grinding, degritting, blending
-Sludge Storage: Prevents degradation before treatment
=Sludge thickening
-Increases solid concentration
-Gravity Thickening: Uses sedimentation tanks
=Sludge Stabilization
-Lime Stabilization; Raises pH to eliminate pathogens
-Heat Treatment; Exposes sludge to high temperatures
-Anaerobic Digestion: Produces methane
-Aerobic Digestion: Lower cost, but energy-intensive
=Sludge Dewatering
-Reduces moisturise using:
-Chemical Conditioning (eg polymers)
-Belt Press & Filter Press (mechanical dewatering)
Drying Beds (sand-based evaporation)
10. Sludge Disposal & Utilization
-Beneficial Uses;
-Fertilizer, soil conditioner (contains nitrogen, phosphorus)
-Landfilling;
-Non-hazardous landfills: Clay-lined
-Hazardous landfills: Double containment to prevent leaks