Bioreactor Setup and Operating Costs

Biological nitrate removal systems have two primary costs-  setup and the operating costs.  Setup costs are dominated by the installation of the primary components and amount of nitrate that must be removed daily.   Operating costs are mostly driven by the cost of an external carbon source- a type of "fuel" that our bacteria needs to operate.  The amount of "fuel" needed per day is driven by the amount of nitrate the system has to removed on a daily basis.  This means that higher nitrate loading will require more "fuel".  

Whats the typical cost of a system?  We can look at a basic 50 gallon per minute (GPM) system versus the amount of nitrate that needs to be removed on a daily basis:

  • At 25 mg/l removal,  expect the setup cost to be $20,000- $25,000

  • At 75 mg/l removal,  the setup costs increase to $50,000- $60,000

  • At 125 mg/l removal, the setup costs would be $80,000-85,000.

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Operating costs are primarily driven by the cost of the carbon fuel and insuring the proper ratio of carbon, nitrate, and phosphorus (C:N:P) is maintained.   Carbon sources include acetic acid (vinegar),  alcohols (ethanol and methanol),  and bigger organic molecules like glycerin.  These systems also require some small amount of phosphorus for the denitrifying bacteria to operate at their maximum capacity. A typical C:N:P ratio is  20:5:1.   This requires  that for every one gram of nitrogen (N)  removed we'll need to add about 4 grams of carbon (C) and about 0.2 grams of phosphorus (P).  Keep in mind that these fuels can be mixed- see below.

Can you make your own carbon fuel?  The simple answer is yes!   Contact us for instructions on how to design and operate a specialized anaerobic digester for converting common organic waste into acetic acid and similar compounds that are tasty for our bacteria.