| Parameter |
Range |
Information |
| Temperature |
95-105°F Mesophilic
125-140°F Thermophilic |
The higher end of the mesophilic range is ideal for
maximum biogas production |
| pH |
6.5 – 7.5 |
Ideal pH is neutral at 7.0. Self-regulating by anaerobic
microbes; methanogens unlikely to grow with pH < 6.5 |
| Alkalinity |
0.133 ounce/gallon |
Self-regulating by hydrogen in waste converting to
Biocarbonate |
| Acidity to Alkalinity Ratio |
0.3 to 0.5 |
Easier to measure than VFA or alkalinity |
| Volatile Fatty Acids (VFA) |
<0.013 ounce/gallon |
Higher concentrations will inhibit acetate and biogas
production |
Carbon to Nitrogen Ratio
. |
20 to 30 |
Higher C:N ratios result in methogens consuming
nitrogen; lowering biogas production |
| Organic Loading Rate |
3-5 kg of Volatile Solids per
cubic meter of digester
volume per day |
Microbes are generally inhibited if loading rate exceeds
6.4 kg/m3 day |
| Residence Time |
9 – 95 days |
Varies widely based on feedstock, temperature, and system design |
