Effect of Operating Conditions on the Production of Volatile Fatty Acids from Organic Wastes

The five parameters being analyzed are pH, temperature, retention time/organic loading rate, substrate to inoculum ratio, and inhibitors of VFAs. The effect of pH has been shown to produce optimal concentrations of VFAs when outside the optimal range of methanogenesis. Temperature sees different types of VFAs being produced at different concentrations dependant on mesophilic or thermophilic conditions. The organic loading rate (OLR) and retention time (RT) demonstrate similar concepts as longer periods of time allow for more VFAs to be converted from the waste but readily supplying waste to digesters sees higher concentrations produced immediately. The substrate to inoculum ratio (S/I) showed ratios above 1 to be favorable in production as it provided enough inoculum (microorganisms) to convert VFAs effectively. Lastly, the effects of several VFA inhibitors are discussed with regards to their impacts on the anaerobic digestion process and their inhibition of certain VFA’s formation.