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Low-cost low-tech approach to Class A Biosolids
Mark Bowman
Posted: Monday, November 28, 2011 11:11 AM
Joined: 10/13/2009
Posts: 1

I've recently taken an interest in low-cost/low-tech processes that use non-proprietary Sludge Process Trains (SPT) that are capable of producing a PFRP product that has been recognized by several State Biosolids Coordinators and the USEPA as Class A. 


Although varied somewhat, each of the SPTs I’m interested in use a batch approach and age either an aerobically or anaerobically digested sludge in either a lagoon or in the case of a cake, separate piles. Once sufficiently aged, (generally about two years) the sludge is then spread onto a paved surface where it is windrowed and periodically agitated until it reaches a TS of ~65%. 


I’ve now read several papers (available upon request) on this SPT and would like to invite further discussion on the process. 


  • Low/moderate capital costs  
  • Low operations and maintenance requirements  
  • Low energy costs  
  • Low noise potential  
  • Beneficial reuse options  


  • Moderate/high land requirements 
  • Moderate odor potential 


Posted: Friday, June 29, 2012 11:46 AM
Joined: 6/29/2012
Posts: 1

I am interested in reading these papers.  Could you please pass them along?  Thanks!