Background and Objective: Iran is one of the countries with abundant palm groves, and we must look for appropriate solutions to use palm tree lignocellulosic waste. In this regard, the potential for biogas production from palm tree leaf waste is very important as an accessible and indigenous source in the country.

Materials and methods: The combined effects of sulfuric acid percentage were studied at four levels, and the pretreatment time at two levels. Also, the combined impact of ozonation time was studied at three levels, and the moisture content of palm tree leaves was studied at two levels. All experiments on the amount of biogas and methane produced were conducted based on a factorial design. The main and interaction effects of the factors were analyzed using SPSS 22 software and Duncan's test.

Results: The maximum daily biogas production reached 540 ml/L with 1% acid concentration and 440 ml/L with 4 hours of ozonation. Based on the cumulative methane produced and the amount of volatile solids (VS) reduced, the best acid pretreatment can yield approximately 374 ml/gr VS of biogas and 173 ml/gr VS of pure methane. In comparison, the best ozone pretreatment can produce around 175 ml/gr VS of biogas and 64 ml/gr VS of pure methane.
 
Conclusion: The lignocellulosic biomass of palm tree leaves can be effectively used for energy production with appropriate pretreatment. Further research is essential to evaluate alternative pretreatment methods to determine the best approach to maximize biogas yield from this affordable and readily available resource.
 
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