Fractionation of baker's yeast vinasse via ultrafiltration: assessment of feasibility

Design of a sustainable biorefinery for the valorization of waste from the baker's yeast industry through process simulation: A case study for the production of animal feed, fertilizers, and biofuels from vinasse

The present work deals with the biotechnological valorization of the vinasse through a sustainable biorefinery. The aim was to design and analyze, through process simulation, a biorefinery for the valorization of vinasse in products such as organo-mineral fertilizers, supplements for animal feed, and biogas. For this purpose, the SuperPro Designer software was used, and a modified hierarchical decomposition method was applied. One base case and three scenarios were techno-economically assessed, and the net present value was used as a selection criterion. The technological configuration with the best techno-economic criterion was analyzed socially and environmentally. The results suggest that the best configuration of the biorefinery corresponded to scenario 3, with a net present value of USD$73,364,000, a number of direct employees of 38, and a blue water footprint of 16.16 m3/h. These findings highlight the potential of the design of biorefineries to address the valorization of vinasses in Colombia and worldwide.

Developing a sustainable process for the cleaner production of baker's yeast: An approach towards waste management by an integrated fermentation and membrane separation process

Baker's yeast industries generate highly polluted effluents, especially the cell free broth (i.e., vinasse) characterized by high chemical oxygen demand, nitrogen, and salts. In this work, it was found that the residual by-products (i.e., ethanol and acetic acid) and salts in the vinasse severely inhibited the cell growth, which hindered the reuse of the vinasse for the production of Saccharomyces cerevisiae. Through optimizing a suitable control strategy, the productions of ethanol and acetic acid were eliminated. Then, a nanofiltration membrane (i.e., NF5) was preferred for preliminarily and simultaneously separating and concentrating valuable molecules (i.e., invertase, food grade proteins and pigments) in the vinasse, and the main fouling mechanism was cake layer formation. Subsequently, a reverse osmosis membrane (RO) was suitable to separate and concentrate salts in the NF5 permeate, where the membrane fouling was negligible. Finally, the RO permeate was successfully reused for the production of S. cerevisiae. In addition, without calculating the benefit from the recovery of the valuable molecules, the cost of the integrated process can be decreased by 59.8% compared with the sole triple effect evaporation. Meanwhile, the volume of the fresh water used in the fermentation process can be decreased by 68.8%. Thus, it is a sustainable process for the cleaner production of baker's yeast using the integrated fermentation and membrane separation process.

Treatment technologies for bakers' yeast production wastewater

Researchers in recent years have utilized a broad spectrum of treatment technologies in treating bakers' yeast production wastewater. This paper aims to review the treatment technologies for the wastewater, compare the process technologies, discuss recent innovations, and propose future perspectives in the research area. The review observed that nanofiltration was the most effective membrane process for the treatment of the effluent (at >95% pollutant rejection). Other separation processes like adsorption and distillation had technical challenges of desorption, a poor fit for high pollutant load and cost limitations. Chemical treatment processes have varying levels of success but they are expensive and produce toxic sludge. Sludge production would be a hurdle when product recovery and reuse are targeted. It is difficult to make an outright choice of the best process for treating the effluent because each has its merits and demerits and an appropriate choice can be made when all factors are duly considered. The process intensification of the industrial-scale production of the bakers' yeast process will be a very direct approach, where the process optimisation, zero effluent discharge, and enhanced recovery of value-added product from the waste streams are important approaches that need to be taken into account.