Anaerobic EGSB System


Anaerobic EGSB System

Expanded Granular Sludge Bed Reactor System for Secondary Wastewater Treatment

The Clean Water Technology (CWT) Expanded Granular Sludge Bed Reactor (EGSB) is a sophisticated modification of the UASB technology, operating at high up-flow velocities while promoting better mass transfer.  The EGSB removes high levels of organic material in a small volume.  


Expanded Granular Sludge Bed Reactors Installed
Expanded Granular Sludge Blanket Reactor Design
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Patent Pending Internal Settler

For the secondary treatment of wastewater, the Expanded Granular Sludge Bed Reactor (EGSB) is a sophisticated modification of the Upflow Anaerobic Sludge Bed (UASB) Reactor.  The EGSB operates at high up-flow velocities while promoting better mass transfer.  It removes high levels of organic material in a small volume.

The EGSB by Clean Water Technology is sustainably focused in design.  The footprint of the reactor is small but effective.  The patent pending internal settler is effective with an exclusive design to remove high levels of organic material within a short hydraulic retention time (HRT.)

The sealed reactor provides total emission control and eliminates odor. 


EGSB Stages produce methane as a byproduct
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The EGSB works through a number of stages in a vertical flow series whereby chemical oxygen demand and biological oxygen demand (COD/BOD) are broken down to reduce high concentrations of contaminants,  odor and byproduct collection.

Chemical reaction stages of the EGSB (Anaerobic) System include:
  1. Complex organic materials are subjected to hydrolysis of lipids, cellulose and proteins where materials hydrolyze and ferment into fatty acids. This process can take place in an aerobic or anaerobic environment.
  2. The acid genesis fatty acids (large chains as propionic, acetic and butyric acid) are oxidized by β-oxidation to produce hydrogen (H2) and acetate. These processes are termed – Acetogenesis & Dehydrogenation respectively.
  3. The last stage is methanogenesis (generation of methane) which combines the hydrogen (H2) with carbon dioxide (CO2) to form methane and splits acetic acid into carbon dioxide (CO2) and methane (CH4).

The production of methane gas is the slowest and most sensitive step of the anaerobic digestion process because it requires specific environmental conditions for the growth of methanogenic bacteria. These bacteria digest most effectively at a pH of 6.6-7.6, and if the growth of the acid forming bacteria is excessive, there will be an overproduction of acid leading to a decrease in the pH level which may cause problems. Also, the methanogenic bacteria have a limited temperature range for optimum performance, usually in the mesophilic range of 90 – 105 °F. CWT’s EGSB
manages these steps with proven reliability and performance.

  • Internal settler is effective and exclusive – patent pending
  • High organic removal
  • Short hydraulic retention time (HRT)
  • Low energy demand
  • Total emission and odor control in a sealed reactor
  • Methane biogas byproduct
  • Usable sludge for agricultural purposes
  • Reliable

Industries producing products with high levels of dissolved chemical/biological oxygen demand (COD/BOD) benefit most from using EGSB technology for the treatment of wastewater.  EGSB ‘s rapidly tanform contminant to biogas, allowing loading rates up to 30,000 ppm of chemical oxygen demand (COD) with typical reduxtion rates grater then 80% before the streem is sent to the aerobic and clarification processes.  

Some example industrues include:

  • Breweries, distilleries, wineries, fruit juice and soft drinks
  • Yogurt, ice cream, milk, snack foods and health bars
  • Pharmaceuticals
  • Wheat, grain and ethanol
  • Cane suger, yeast and starches
  • High fructose waste streams
  • Condiments
  • More…

EGSB Advantages Include

  • Byproduct production of usable methane and fertilizers
  • Reduced or eliminated compliance fees
  • Small footprint
  • Good environmental stewardship
  • High organic contaminant removal
  • Short hydraulic retention time (HRT)
  • Low energy usage
EGSB Anaerobic Wastewater Treatment System

Questions about CWT’s Biological EGSB System?

Talk to an expert about our Expanded Granular Sludge Bed Reactor (EGSB) system, for secondary treatment of wastewater.