Lactic acid production
is highly affected by the fermentation pH.
The need for neutralizing agents and the salts produced during fermentation
have a significant impact on the overall process performance. Changing
the neutralizing agent and allowing lower pH fermentation can improve
the process profitability. This work investigates the impact of fermentation
parameters and evaluates the process economics of alternative downstream
processing designs to produce lactic acid. The results show that low-pH
fermentation (pH = 3.86) was profitable (internal rate of return,
IRR > 10%) at a fermentation yield of 0.97 g/g sucrose. Decomposing
the salt subproduct to reduce the environmental burden associated
with gypsum disposal has a significant impact on the economic performance,
resulting in a lower IRR than the other designs. Although the salt
decomposition process has a high energy demand, it is compensated
by the savings obtained in the downstream processing, thus resulting
in a similar overall energy demand when compared to conventional reactive
distillation. A novel process configuration with ammonium sulfate
subproduct shows potential for 3 p.p. higher IRR and up to 30% lower
fuel demand in comparison with the conventional process. Therefore,
alternative downstream processes could drive low-pH fermentation to
outperform the conventional process without any neutralizing agent.