Impact of Date Palm Seed Size on Biogas Production from Date Seeds/Wastewater Treatment Sludge Mixtures

Abstract

Biogas in the form of methane can be produced from wastewater treatment sludge mixed with a variety of biodegradable organic feedstocks through anaerobic digestion. In this study, biogas was produced from date palm seeds, which are locally available, and wastewater treatment sludge mixtures. The objective of the study was to assess the effect of date palm seed additives with different sizes on biogas production from the mixtures. In the study, two locally available types of date seeds, Khalas and Khudari, were anaerobically co-digested with wastewater treatment sludge in 50 mL serum bottles under mesophilic conditions. Date seeds with three different sizes; 1.18– 3.75 mm, 0.6 –1.18 mm; and 0.425 – 0.6 mm, were added to the sludge at date seeds to sludge total solids (TS) weight ratios of 0%, 2.5%, 5%, 7.5%, and 10%. The experimental results confirmed that the addition of date seeds significantly enhanced biogas production up to 20% to 30%. The results indicated that the date seed size slightly affected biogas production, with the order of cumulative biogas production and biogas production rates, expressed in terms of date seed sizes, being as follows: 0.425 – 0.6 mm > 0.6 – 1.18 mm > 1.18 – 3.75 mm. However, the results showed no major difference in biogas production between the two different date seed types.