Modeling polyhydroxyalkanoates production from sugarcane vinasse by mixed microbial cultures

Sugarcane vinasse is wastewater suitable for polyhydroxyalkanoates (PHA) production by mixed cultures in a three-stage process. In this work, models representing the selection of PHA-producing microorganisms in a sequencing batch reactor (SBR) submitted to a feast-famine process and uncoupled carbon/nitrogen feeding, as well as an accumulation of PHA in a fed-batch reactor from sugarcane vinasse were developed. Sensitivity analysis of the models allowed to rank the influence of parameters and calibration was carried out applying the Box-Draper method in conjunction with the Markov Chain Monte Carlo optimization method. The optimized selection model was able to describe the SBR under different operational conditions. Optimization for each condition of the accumulation showed that higher CODt/Nitrogen ratios in the SBR induced the selection of a culture with a growth response rather than storage, contributing to elucidate the impact that the CODt/Nitrogen ratio in the SBR has on PHA accumulation.