 The concentration of HCO3 -, or Partial Alkalinity, is important since it strongly contributes to the ionic strength, up to 38% for digested streams (Figure ). It is rarely measured (only 4 reference found for digestates), therefore, it was estimated from NH4 + concentration assuming an equimolar mix as discussed in 3.3. HCO3 - concentration is even more rarely measured in non-digested streams, and therefore, had to be determined indirectly. It was deducted from the alkalinity due to VFA and the total alkalinity, since VFA and bicarbonates should represent the major basic compounds in those streams. Even though the ranges proposed are in line with the few experimental data available, it should be taken with care since it was determined indirectly.