Ipe Pia

• Wastewater treatment systems


  • Decentralized
  • Centralized
• Decentralized wastewater treatment systems

  • Septic tank
  • Waste utilization ponds
  • Land treatment
  • Constructed wetland
• Goals of wastewater treatment plants

  • 230 mg/L of BOD5
  • Less than 30 mg/L of suspended solids
  • 200 cfu/1000mL of fecal coliforms
• Typical wastewater treatment system

  1. Preliminary/Pre-treatment

  2. Primary Treatment

  3. Secondary Treatment

  4. Disinfection

  5. Sludge treatment & Disposal
• Preliminary/Pre-treatment


  • Bar Racks - used to remove large objects
  • Grit Chamber - removes small to medium sized objects
• Primary Treatment


  • Primary Sedimentation - to remove settleable solids
• Secondary Treatment


  • To remove suspended solids, nitrogen, phosphate
• Activated sludge process


  • To remove suspended solids, nitrogen, phosphate
• Trickling filter process


  • Same as activated sludge process
• Stabilization Ponds


  • Oldest wastewater treatment systems
  • Used for raw sewage as well as primary treatment
• Facultative Ponds


  • 3 zones: upper photic (aerobic) zone, facultative (aerobic & anaerobic) zone, lower anaerobic zone
  • 1-25m water depth
  • To remove suspended solids, nitrogen, phosphate, pathogens
• Aerated lagoons


  • Biological activity is provided mainly by aerobic bacteria
  • 7-2m water depth
• Sludge Processing


  1. Thickening

  2. Digestion

  3. Dewatering

  4. Disposal
• Sludge Thickening


  To reduce sludge volume, but the concentration of pathogens increases during this process
• Disposal of solid sludge

  • Class A biosolids - home lawn and garden
  • Class B biosolids - agriculture land
• To reduce pathogens for Class A biosolids

  1. Aerobic digestion

  2. Anaerobic digestion

  3. Air drying

  4. Composting

  5. Lime stabilization
• Digestion


  1. To stabilize organic matter, control odors, and destroy pathogens

  2. Aerobic digestion - sludge is agitated with air or oxygen

  3. Anaerobic digestion - sludge is treated in the absence of air
• Dewatering


  1. To concentrate sludge by removing water

  2. Pressure filtration - belt filter press and plate-and-frame filter

  3. Centrifugation

  4. Screw press
• Disposal methods


  • Land Application
  • Landfill
  • Incineration
  • Ocean dumping
• Industrial wastewater treatment


  • Processes used to treat waters that have been contaminated by anthropogenic industrial activities
• Sources of industrial wastewater

  • Iron and Steel Industry
  • Mines and quarries
  • Food Industry
  • Pulp and paper industry
  • Complex organic chemicals Industry
  • Nuclear Industry
• Brine treatment


  Removing dissolved salts from waste stream
• Brine management


  Examines the broader context of brine treatment and may include consideration of government policy
• Solids Removal


  • Most solids can be removed by using simple sedimentation techniques
• Oils and grease removal

  • Many oils can be removed from open surfaces by skimming devices
  • API separator - gravity separation device
  • Parallel plate separators - similar to API but with tilted plate assemblies
• Removal of biodegradable organics

  • Activated sludge process - a biochemical process
  • Trickling filter process - involves absorption of organic compounds
• Treatment of other organics

  • Advanced oxidation processing
  • Distillation
  • Adsorption
  • Vitrification
  • Incineration
  • Chemical immobilization
  • Landfill disposal
• Treatment of acids and alkalis

  • Neutralization of acids
• Wastewater treatment methods


  • Physical
  • Chemical
  • Biological
• Physical treatment methods


  • Sedimentation (Clarification)
  • Screening
  • Aeration
  • Filtration
  • Flotation and skimming
  • Degasification
  • Equalization
• Chemical treatment methods


  • Chlorination
  • Ozonation
  • Neutralization
  • Coagulation
  • Adsorption
  • Ion exchange
• Biological treatment methods


  • Aerobic
  • Activated Sludge Treatment
  • Trickling Filtration
  • Oxidation ponds
  • Lagoons
  • Aerobic Digestion
  • Anaerobic
  • Anaerobic Digestion
  • Septic tanks
  • Lagoons
• Physical methods


  Processes where no gross chemical or biological changes occur
• Chemical treatment


  Involves some chemical reaction(s) to improve the water quality
• Neutralization


  Addition of acid or base to adjust pH levels
• Coagulation


  Addition of chemical to form insoluble product
• Biological treatment methods


  Utilize microorganisms, usually bacteria
• Degrees of wastewater treatment

  • Preliminary Treatment
  • Primary Treatment
  • Secondary Treatment
  • Chlorination
  • Sludge treatment
• Preliminary Treatment


  • Used to protect pumping equipment
  • Removes large suspended solids
  • Includes screens, comminuting devices, grit chambers, re-aeration tanks
• Primary Treatment


  • Most settleable solids are removed
  • Includes septic tanks, settling tanks, two-story tanks, drain sedimentation tanks with mechanical sludge removal, upward flow clarifiers