Design and Optimization of a Pilot-Scale Digester for Biogas Production

In many industrial situations, wastes are produced that can be harmful to the environment.  Many of these organic wastes can be digested anaerobically to produce a methanogenic biogas rich in energy.  Treatment of such wastes through digestion can reduce BOD below allowable limits for discharge.  Preliminary results utilizing lab-scale bioreactors for digestion of sewage sludge and shrimp processing waste were very promising in regard to methane content and total gas production.  However, little to no data exists on larger reactors for many suitable feedstocks.  A pilot-scale 250 gallon, jacketed reactor was purchased an set up on a trailer for mobile operation, with the intent to process multiple sources of local waste.  These wastes include sewage sludge, shrimp and crab wastes, beer wastes, wood chips, and other food processing plants’ wastes.

Considerations in the design and operation of the digester will be presented, as well as optimization and production data from various waste sources.