Valorization of date palm waste: A review of thermochemical and biochemical conversion routes for sustainable biorefineries

Mohammed A. Zeinelabdeen (Department of Chemical Engineering, Karary University, Khartoum, 12304, Sudan)
Mohamed Saifeldin Mubarak Mohamed (Department of Chemical Engineering, Karary University, Khartoum, 12304, Sudan)
Ahmed MohamedAlamen Alzain Mohamed (Department of Chemical Engineering, Karary University, Khartoum, 12304, Sudan)
Muzamul MA Siddig (Department of Chemical Engineering, Karary University, Khartoum, 12304, Sudan)
Abubakr Hassan Kheiri (Department of Survey Engineering, Karary University, Khartoum, 12304, Sudan)

Konversi
Vol 15, No 2 (2026): OCTOBER 2026

Date palm cultivation and date processing generate substantial quantities of agricultural and agro-industrial residues, including fronds, leaves, rachis, trunks, leaf sheaths, pedicels, empty fruit bunches, seeds, press cake, pomace, and rejected fruits. These materials are frequently burned, landfilled, or used in low-value applications despite containing cellulose, hemicellulose, lignin, fermentable sugars, lipids, proteins, minerals, and bioactive compounds that can support a diversified biorefinery. This review critically compares thermochemical and biochemical routes for date palm waste valorization, with emphasis on feedstock–process compatibility, product yields, pretreatment requirements, energy integration, scale-up, techno-economic performance, and environmental implications. Pyrolysis can generate biochar, bio-oil, and non-condensable gas from dry lignocellulosic residues; recent studies report biochar yields approaching 45% under slow pyrolysis and bio-oil yields around 26–33% for selected date palm fractions. Gasification offers syngas, hydrogen-rich gas, and methanol opportunities, whereas hydrothermal processing is an underexplored option for wetter residues. Biochemical conversion can recover ethanol, methane, volatile fatty acids, lactic acid, and other products. Recent biorefinery studies have shown that pretreatment followed by fermentation and anaerobic digestion can substantially increase overall energy recovery, while date seeds can support cascade schemes involving oil extraction, biodiesel synthesis, enzymatic hydrolysis, ethanol fermentation, and pyrolysis of the remaining solids. The evidence indicates that no single route maximizes resource efficiency across all date palm residues. Instead, integrated biorefineries that fractionate feedstocks and combine biochemical conversion of carbohydrate-rich fractions with thermochemical processing of lignin-rich residues provide the strongest pathway toward circularity. Key barriers remain feedstock seasonality, logistics, water use, pretreatment cost, product upgrading, catalyst and enzyme expense, tar and inhibitor management, and the scarcity of pilot-scale data. Future work should focus on region-specific feedstock inventories, low-water pretreatments, renewable heat integration, standardized mass and energy balances, and harmonized techno-economic and life-cycle assessments.