Bioconversion of Crude Glycerol into 1,3-Propanediol(1,3-PDO) with Bioelectrochemical System and Zero-Valent Iron Using Klebsiella pneumoniae L17

Da Seul Kong,Yunchul Cho,Sang Eun Oh,Minsoo Kim,Sakuntala Mutyala,Jung Rae Kim,Eun Joo Park,Changman Kim

doi:10.3390/en14206806

Abstract

Crude glycerol is a major byproduct in the production of biodiesel and contains a large number of impurities. The transformation of crude glycerol into valuable compounds such as 1,3-propanediol (1,3-PDO) using clean and renewable processes, like bioconversion, is an important task for the future of the chemical industry. In this study, 1,3-PDO bioproductions from crude and pure glycerol were estimated as 15.4 ± 0.8 and 11.4 ± 0.1 mmol/L, respectively. Because 1,3-PDO is a reductive metabolite that requires additional reducing energy, external supplements of electron for further improvement of 1,3-PDO biosynthesis were attempted using a bioelectrochemical system (BES) or zero-valent iron (ZVI). The conversions of crude and pure glycerol under electrode and iron-based cultivation were investigated for 1,3-PDO production accompanied by metabolic shift and cell growth. The BES-based conversion produced 32.6 ± 0.6 mmol/L of 1,3-PDO with ZVI implementation.

Highlights

Crude glycerol, a major byproduct of the biodiesel process in the transesterification of animal fats and vegetable oils, has been widely examined for waste conversion to produce value-added chemicals [1,2]
Previous reports determined that oxygen can strongly interrupt glycerol dehydratase and coenzyme B12 synthesis, which is utilized as an essential co-factor for DhaB in the K. pneumoniae strain
Fermentation results indicated that significantly higher 1,3-PDO production was identified with crude glycerol (15.4 ± 0.8 mM) compared to pure glycerol (11.4 ± 0.1 mM)

Summary

Introduction

A major byproduct of the biodiesel process in the transesterification of animal fats and vegetable oils, has been widely examined for waste conversion to produce value-added chemicals [1,2]. Several successful glycerol conversion studies have been reported, further improvement is still required because of the relatively high purification cost [4]. Pure glycerol costs 7.5 times more than its crude counterpart at the current market price (Table 1) [2,5]; this implies that the additional glycerol purification process is complicated and expensive. Several studies have reported direct bioconversion of nonpurified crude glycerol to value-added products, such as hydrogen, methane, fatty acids, and 1,3-propanediol [6,7,8,9,10,11]

Methods

Results

Conclusion