Mechanical aeration economics

Scale-up to the industrial scale is only achievable and economical reasonable in stirred or airlift systems. To achieve high cell densities optimal nutrient supply is necessary. Therefore transport limitations have to be avoided by good mixing of cells (microcarrier) and medium. This movement caused by stirrer or aeration leads to mechanical forces evoking severe cell damage or cell death [3,4]. 

The U.S. Army conducted an economic evaluation of windrow composting versus the aerated static pile, and a mechanically agitated invessel composting system (MAIV). 

The results of this economic evaluation show that windrow composting treatment costs are less than aerated static pile or mechanical composting. The MAIV composting system is comparable on a cost-per-ton basis to incineration at 290/ton of soil treated compared to 300/ton for incineration. The greatest cost savings in comparison to incineration are seen by the windrow composting system at 187/ton. The aerated static pile system "treatment only" costs are estimated at 236/ton. All estimates... 

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