Figure 4From: Combined sodium hydroxide and ammonium hydroxide pretreatment of post-biogas digestion dairy manure fiber for cost effective cellulosic bioethanol productionScanning electron microscope images of manure fibers before and after treatment at 121°C and 10% alkali loading level. (A) non-pretreated (control), (B) pretreated by NH3 alone, (C) pretreated by NaOH alone, and (D) pretreated by combined NH3 and NaOH.Back to article page