Comparison of sodium hydroxide and calcium hydroxide pretreatments of giant reed for enhanced enzymatic digestibility and methane production.

NaOH pretreatment with leachate reuse and Ca(OH)2 pretreatment were compared for improved enzymatic digestibility and biogas production from giant reed, a promising energy crop. The NaOH pretreatment with leachate reuse increased glucose yields during enzymatic hydrolysis by 2.6-fold, and methane yields during anaerobic digestion by 1.4- to 1.6-fold. However, NaOH pretreatment had a negative net benefit (i.e., revenue from increased energy production minus chemical cost). Pretreatment with 7-20% Ca(OH)2 not only improved glucose yield and methane yield by up to 2.3-fold and 1.4-fold, respectively, but also obtained a net benefit of $1.1-5.8/tonne dry biomass. Thus, Ca(OH)2 pretreatment was shown to be more feasible than NaOH pretreatment for biogas production from giant reed.