Resource recovery in line with energy generation at an agro-food industry

Highlights

	● Agro-food wastewaters are valuable “raw materials” for resource recovery.
	● Recovery is crucial in bulgur production requiring high amounts of water and energy.
	● Variations of VFAs in fermentation bring advantages in PHA production efficiency.
	● A fermentation period of 7 d is sufficient to maximize PHA production up to 2.6 g/L.
	● In addition to PHA production 47% of the COD can be available for energy recovery.

Abstract

The aim of this study is to investigate the anaerobic treatability and generation of potential valuable by-products of agro-food industry wastewaters where bulgur production is carried out. Among the agro-food products, bulgur which is a wheat product (Triticum spp.) and rich in fibers, is one of the ancient foods of Anatolia. The most critical issue in bulgur production is high energy and water consumption for cooking where wheat starch gelatinizes and results in a considerable amount of high strength wastewater. In the raw bulgur wastewater sample, 81% of total chemical oxygen demand (tCOD) was in soluble form which was readily fermentable and acidic by nature. Batch anaerobic study results indicated almost complete tCOD removal (99%) which decreased from 7820 to100 mg/L. The cumulative methane yield was determined as 275 mL/g tCOD_fed. Hence, for such industrial wastewaters with high level of organic pollution, anaerobic biotechnology stands out as one of the most effective treatment options. Fermented bulgur wastewater was also tested for the production of polyhydroxyalkanoates (PHAs). It was determined that 37% of the tCOD could be recovered as PHAs without hindering the biogas generation. In this context, it was shown that PHAs and biogas production could be simultaneously achievable with a smart organic carbon utilization strategy which will also contribute to reduce energy requirement and carbon footprint of the industrial bulgur production process as well as create environmentally friendly solutions through resource recovery.

Graphical abstract

Keywords

Biogas / Bulgur production / Energy / Polyhydroxyalkanoates / Resource recovery

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Acknowledgements

Authors gratefully acknowledge the Department of Scientific Research Projects of ITU (No. 44477) for their financial support, Res. Ass. Dr. Goksin Ozyildiz for her help during GC biogas analysis, and Env. Eng. Aysenur Cinar for her assistance. The authors would like to thank Armada Foods for their support and guidance throughout the stages of the study.

Conflict of Interests

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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