Evaluation of lactic acid purification from fermentation broth by hybrid short path evaporation using factorial experimental design Andrea Komesu a,⇑ , Patrícia Fazzio Martins a,b , Betânia Hoss Lunelli a , Johnatt Oliveira a , Rubens Maciel Filho a , Maria Regina Wolf Maciel a a School of Chemical Engineering, University of Campinas (UNICAMP), 13083-970 Campinas, SP, Brazil b Departamento de Ciências Exatas e da Terra, Universidade Federal de São Paulo (UNIFESP), 09972-270 Diadema, SP, Brazil article info Article history: Received 9 January 2014 Received in revised form 13 August 2014 Accepted 9 September 2014 Available online 17 September 2014 Keywords: Lactic acid Purification Fermentation Evaporation system abstract This work describes the evaluation of lactic acid purification from fermentation broth by hybrid short path evaporation. The proposed hybrid purification process consists of an evaporation system composed by a cylindrical wiped film evaporator with two condensers, one located internally and other externally to the evaporator. Through factorial experimental design, the influence of operation conditions as feed flow rate, agitation, condenser and evaporator temperature on residue and distilled percentages, lactic acid purity and recovery were studied. Models were developed in order to describe the response of inter- est as function of operating conditions. The results showed that with a high operating pressure (in terms of short path evaporation), with a pressure of 1000 Pa, and one step of separation, lactic acid purity around 89.7% was obtained which was about 18 times lactic acid concentration higher than the initial content in raw material. Ó 2014 Elsevier B.V. All rights reserved. 1. Introduction An increasing interest for discovering new environment- friendly sources of chemicals has been observed due to the current concerns related to the cost and environmental impact of using tra- ditional petrochemical processes. One important technological bio- mass-based platform is the biotechnological process for lactic acid production by fermentation that potentially offers several advanta- ges: low substrate costs, production temperature and energy con- sumption [1]. Lactic acid has a wide variety of applications such as cosmetics, pharmaceutical products, chemistry, food and more recently in the medical area. The presence of two adjacent functional groups in the lactic acid (hydroxyl and carboxyl) in a small molecule with only three carbon atoms shows its high reactivity, as well as their tendency to decompose at high temperatures. The development of an efficient method of lactic acid separation and purification from fermentation broth is very important, because, these steps can reach up to 50% of the total costs [1,2] and it is still difficult to recover it with high purity for the reasons: high affinity with water, decomposition at elevated temperatures and complex and energy intensive recovery technology [3]. A con- siderable number of methods for the recovery of lactic acid from fermentation broth, such as solvent extraction [4–7], separation with membranes [8–10], reactive distillation [11–13] and others have been studied. Conventional molecular distillation (or short path evaporation) had been used to recovery lactic acid with purity up to 95–96% [14–16]. The operating pressure is usually below 0.1 Pa and two or more steps of refining are required. To keep the high-vacuum a mechanical force-pump and diffusion pump should be used simultaneously [14], which is in direct conflict with energy-saving. Each additional step in the downstream represents an increase in the total operating costs. Hybrid short path evaporation [17–19] is an alternative separa- tion process with potential for the recovery and concentration of thermally unstable molecules such as lactic acid. It has been recog- nized as a promising technology mainly because of its low evapo- ration temperature and short residence time, which minimize problems with thermal decomposition [20]. In previous work, our research group studied the technical fea- sibility of lactic acid concentration from synthetic mixture of water: lactic acid (36 wt% of lactic acid) using hybrid short path evaporation system [20]. The experimental results showed that carrying out the lactic acid concentration by using evaporative system is technically feasible and advantageous. Based on the http://dx.doi.org/10.1016/j.seppur.2014.09.010 1383-5866/Ó 2014 Elsevier B.V. All rights reserved. ⇑ Corresponding author. Tel.: +55 19 35213971, +55 19 983764925; fax: +55 19 35213910. E-mail address: andrea_komesu@hotmail.com (A. Komesu). Separation and Purification Technology 136 (2014) 233–240 Contents lists available at ScienceDirect Separation and Purification Technology journal homepage: www.elsevier.com/locate/seppur