Biogas Produced by Anaerobic Digestion Process and Biodiesel from Date Seeds

Alla Mohammed Alrefai, Raid Alrefai, Khaled Y. Benyounis and Joseph Stokes
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Alla Mohammed Alrefai: School of Mechanical & Manufacturing Engineering, Dublin City University, 9 Dublin, Ireland
Raid Alrefai: School of Mechanical & Manufacturing Engineering, Dublin City University, 9 Dublin, Ireland
Khaled Y. Benyounis: School of Mechanical & Manufacturing Engineering, Dublin City University, 9 Dublin, Ireland
Joseph Stokes: School of Mechanical & Manufacturing Engineering, Dublin City University, 9 Dublin, Ireland

Energies, 2021, vol. 14, issue 16, 1-41

Abstract: Dates are an important food source in many countries that produce different types of dates. Dates have a significant amount of waste, either from planting or eating them. A large amount of seeds are produced from eating it. This study is considered to explore the quantity and the quality of biogas produced from the Sagai date seeds through the anaerobic digestion process (AD) before and after oil extraction and exploitation of oil in biodiesel production. In addition, the study aims to tests the resulted digestate from the AD process. This test was performed to ensure that the digestate contains the three basics elements (N, P and K) to be used in agriculture. In its preparation, the date seeds were ground after washing via a grinding machine without exposure to any other treatment process. Design of Experiments (DOE) was applied in determining the effect of temperature, volatile solid and sludge quantity on the resulted biogas. The energy balance at the optimum results was calculated. The highest biogas volumes from the AD of date seed before and after oil extraction were 4140 cc and 3534 cc, respectively, at 37 °C, 4.2 g-VS and 50% sludge quantity. While the highest methane/g-VS were 1143.8 cc/g-VS and 949.6 cc/g-VS, respectively, at 37 °C, 1.1 g-VS and 50% sludge quantity. The oil obtained using the Soxhlet method at 70 °C, 1:4 ratio of date seeds to n-hexane solvent and 5 h reaction time was 16% of the date seed mass (79% biodiesel and 9% glycerine). Therefore, the resultant effect from the main findings indicated that the study supports the investigation of the possibility of exploiting date seeds in the production of biogas, biodiesel and bio-fertiliser.

Keywords: anaerobic digestion; date seed; date seed oil; biogas; digestate; biodiesel (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
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