Screening of resins for use in a biparticle fluidized-bed bioreactor for the continuous fermentation and separation of lactic acid

Recovery of lactic acid from simultaneous saccharification and fermentation media using anion exchange resins

“…A variety of applications have been described for the sodium, potassium, ammonium or calcium lactates [4]. When the objective is the production of lactic acid and the neutralization is carried out with calcium carbonate, the calcium lactate has to be recovered by filtration and reacted with sulphuric acid to give calcium sulphate, adding both new costs in chemicals and additional waste management to the overall process [2,5]. Economic estimates show that the costs of recovery and purification account for about 50% of the overall production costs [5,6], their reduction being one of the most important challenges in the production of lactic acid [7].…”

“…Lactic acid is a commodity chemical with a wide range of applications, mainly in the food industry (which utilizes about 80% of the total production, especially as a microbial preservative or as an agent for acidification or buffering), but also in the production of pharmaceuticals and cosmetics as well as in the polymer industry, where it is used for making biodegradable plastics [1,2]. The industrial production of lactic acid can be carried out by two alternative technologies: chemical synthesis from fossil fuels and biotechnological technologies-the latter being based on the utilization of biomass as raw materials.…”

“…In industrial processes, pH is controlled either by adding a soluble alkali (such as NaOH, KOH, Ca(OH) 2 or NH 4 OH) or by reaction with an excess of calcium carbonate, leading to a salt as the final product [2,3]. A variety of applications have been described for the sodium, potassium, ammonium or calcium lactates [4].…”

Adsorption of lactic acid from fermentation broth and aqueous solutions on Zeolite molecular sieves

“…The presence of extra chemical species in the broth caused Henry's constant to decrease from 2 ± 0.7 L/kg for the pure solution to 1 ± 0.5 L/kg for the broth. This adsorptive capacity is low compared to the amount of 210 g/kg reported for lactic acid adsorption on Amberlite IRA-35 (Kaufman et al, 1994). However, Amberlite's capacity quickly diminished 93% in subsequent loadings after three cycles because of the inability to regenerate the resin and the resins' instability at elevated temperature.…”

Direct capture of products from biotransformations.

“…This pH control must occur in the presence of sugars and products in the enzyme production case and sugars, products, and cell media in the case of whole cell production. This has been shown for lactic acid with solid sorbents (Kaufman et al 1994). The simplest configuration uses a sidestream loop to pass through a separation; however, direct addition and removal of sorbent has been demonstrated using immobilized cells.…”