Polyhydroxyalkanoate production using waste vegetable oil and filtered digestate liquor of chicken manure

Abstract

The production of polyhydroxyalkanoates (PHA) using digestate of chicken manure combined with waste sunflower oil as no-cost feedstocks in a multi-stage process was investigated. Using Cupriavidus necator H16 in combined culture media, a maximum PHA accumulation of 4.6 ± 0.2 g/L at 75.1 ± 1.4% of cell dry matter and a residual cell matter yield of 1.5 ± 0.1 g/L were obtained after 96 hr of cultivation (30 °C, 160 rpm, pH 7.0) in flask-based experiments. Manure was acidogenically fermented in a continuous stirring tank reactor in fed-batch mode. The bioreactor was operated at varying organic loading rates (OLR) and hydraulic retention times (HRT) ranging from 1–4 g volatile solids (VS)/L/d and 4–8 days, respectively. Optimal operation was observed at an OLR of 4 g VS/L/d and an HRT of 4 days. Analysis showed the presence of significant amounts of ammonia, potassium, magnesium, calcium, and trace elements, i.e. Fe, Cu, Ni, Mn, Co, Zn, Cr in the digestate. The micro-filtered digestate was utilized as a complex culture media base while waste oil served as an additional carbon source and supplemented for effective PHA production. The total volatile fatty acid content of digestate greatly affected the growth performance of the PHA-producing microorganism Cupriavidus necator H16.

Keywords:

• Chicken manure
• Cupriavidus necator
• Digestate liquors
• Polyhydroxyalkanoate
• Waste vegetable oil

Acknowledgments

This work has been funded by the Adiyaman University Scientific Research Projects Foundation (Project Number; MÜFBAP/2014-0009). The author would like to thank Prof. Dr. Alexander STEINBUCHEL (Institut für molekulare Mikrobiologie und Biotechnologie, Münster, GERMANY) for providing the strain of C. necator H16.

Disclosure statement

No potential conflict of interest was reported by the author.

Additional information

Funding

This work has been funded by the Adıyaman University Scientific Research Projects Foundation (Adiyaman Üniversitesi) (Project Number; MÜFBAP/2014-0009).