REGIONALâIowa farms might start smelling a little better with a new way to make the most of their waste. Anaerobic digesters are becoming popular with the agriculture industry nationwide as hog, cattle and dairy farms look to find uses for the methane they produce. Forrest Carroll is the senior manager of project development at Brightmark, a San Francisco company that is one of several firms selling digesters in Iowa. âWe want to find a way to reduce the odor from our dairy and put this manure to work,â he said. Brightmark is working with at least five farms so far in NâWest Iowa with locations in OâBrien, OsÂÂceola and Sioux counties.