Biogas Plants


OWS has also developed the BES-Plugflow digestion technology. It is a horizontal plug-flow digester constructed in concrete. Although working at a lower total solids-content than the DRANCO-FARM technology, the DRANCO principle (first-in, first out) and OWS standards can be found in this technology.

Model of a BES-Plugflow digester
Model of a BES-Plugflow digester


The BES-Plugflow technology is a cross-over between the DRANCO-FARM technology and a conventional continuously stirred tank-reactor.

BES-Plugflow characteristics

  • horizontal digester in concrete
  • total solids content between 5 and 15% in the digester
  • plug-flow digestion (first-in, first-out)
  • mesophilic or thermophilic operating temperature
  • intensive recirculation (~ DRANCO-FARM)
  • slow turning paddle stirrers
  • modular concept
BES-Plugflow Plant
BES-Plugflow Plant


The BES-Plugflow process has some significant advantages:

  • minimal retention time for semi-solid feedstocks
  • optimal degassing inside the digester
  • optimal heat- and material distribution inside the digester
  • low electricity consumption
  • limited height (< 11m)
  • short construction period


Mr. Winfried Six
Marketing & Sales Manager

Ms. Norma McDonald
North America Sales Manager


OWS is doing the biological and technological follow-up of several CSTR & Plugflow digesters.

Also check out the references of our Biogas Consulting & Support – division.