the afc process n.
Skip this Video
Loading SlideShow in 5 Seconds..
The AFC Process PowerPoint Presentation
Download Presentation
The AFC Process

Loading in 2 Seconds...

  share
play fullscreen
1 / 10
Download Presentation

The AFC Process - PowerPoint PPT Presentation

ranit
114 Views
Download Presentation

The AFC Process

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. The AFC Process

  2. What Is AFC? UF System Permeate Effluent Balance Tank Feed AFC Reactor Retentate Concentrate Return Inert Blowdown Chemical Treatment • Key Operations are • Balancing of incoming waste streams • Thermophilic activated sludge (AFC) to oxidise the organic load • Ultrafiltration to separate the biomass from the treated effluent • Chemical treatment to hydrolyse excess biomass and make it biodegradable 2003

  3. The advantages of AFC technology • Simple, robust and flexible process • Able to treat high strength wastes (COD 20,000 – 200,000 mg.l-1) • Thermophilic process which generates its own heat • Able to digest biological solids • Complete retention of biomass within the system • Complete destruction of excess biomass generated or biomass added in feed stream • No sludge disposal off-site • Conversion of nitrogenous compounds to ammonia • Conversion of phosphorus compounds to phopshate • Flexible plant with small footprint • Potential for heat, ammonia, phosphate and carbon dioxide recovery 2003

  4. Ultrafiltration - principles 2003

  5. Ultrafiltration – key points • Ultrafiltration using ceramic membranes to remove biological solids from the treated effluent • Complete retention of solids; permeate solids level at <50 mg.l-1 • Independent of physical form of the biomass • Does not require a flocculant sludge • Ceramic membranes used because • Stable at operating temperatures employed • Resistant to biological fouling • Resistant to aggressive cleaning regimes • Unit sized on basis of permeate flow through a unit membrane area • Membranes arranged into four filtration units, each skid containing four membrane assemblies • Circulation flow around the UF system is designed at 6 times the permeate flow • Provided with Clean In Place (CIP) skid to allow any one membrane skid to be cleaned at a time 2003

  6. Ultrafiltration – ceramic membrane module 2003

  7. Chemical Treatment – key points • Continuous chemical process to partially solubilise and oxidise • the excess biomass generated in the AFC process • the non-degradable portion of the biological fermentation solids input • any other recalcitrant COD • biosurfactants that could cause foaming • Treated material returned to AFC system for further treatment • Uses concentrated biomass returned from UF as feedstock • Process uses • Hydrogen peroxide (oxidant) at dose of 1 part per 4 parts VSS • Acidic conditions (pH 3-5) using sulphuric acid • High temperature (>65C) • Minimum 8 hour retention time • Or use ferrous sulphate as catalyst to accelerate hydrolysis and oxidation reactions • Raw materials fed in proportion fo feed flow to chemical tank • Vents to atmosphere • Blowdown from AFC system • To control build up of inorganics (principally struvite - magnesium ammonium phosphate) • Based on magnesium feed to AFC system • Blowdown from ultrafilter concentrate return line to existing WWTP 2003

  8. AFC Operating Conditions • Principle operating conditions for the AFC bioreactor are • Loading rate • 200-400 mg COD per litre per hour (4.8 – 9.6 kg COD/m3/d) • Dissolved Oxygen Concentration • Maintained in the range 1-3 mg per litre • Mixed Liquor Suspended Solids • Contains both active thermophilic biomass and waste fermentation biomass for destruction • In the range 25-35,000 mg per litre • pH • In the range 6.5-8.5 • Temperature • 45C- 70C 2003

  9. AFC Plant at GSK 2003

  10. Ultrafiltration Plant at GSK 2003