title: Response surface optimization of the thermal acid pretreatment of sugar beet pulp for bioethanol production using Trichoderma viride and Saccharomyces cerevisiae.
abstract: BACKGROUND
  Worldwide nowadays, relying on the second generation bioethanol from the lignocellulosic feedstock is a mandatory aim. However, one of the major drawbacks for high ethanol yield is the physical and chemical pretreatment of this kind of feedstock. As the pretreatment is a crucial process operation that modifies the lignocellulosic structure and enhances its accessibility for the high cost hydrolytic enzymes in an attempt to maximize the yield of the fermentable sugars. The objective of this work was to optimize and integrate a physicochemical pretreatment of one of the major agricultural wastes in Egypt; the sugar beet pulp (SBP) and the enzymatic saccharification of the pretreated SBP using a whole fungal cells with a separate bioethanol fermentation batch processes to maximize the bioethanol yield.
  
  
  RESULTS
  The response surface methodology was employed in this study to statistically evaluate and optimize the conditions for a thermal acid pretreatment of SBP. The signiﬁcance and the interaction effects of the concentrations of HCl and SBP and the reaction temperature and time were studied using a three-level central composite design of experiments. A quadratic model equation was obtained to maximize the production of the total reducing sugars. The validity of the predicted model was conﬁrmed. The thermally acid pretreated SBP was further subjected to a solid state fermentation batch process using Trichoderma viride F94. The thermal acid pretreatment and fungal hydrolyzes were integrated with two parallel batch fermentation processes of the produced hydrolyzates using Saccharomyces cerevisiae Y39, that yielded a total of ≈ 48 g/L bioethanol, at a conversion rate of ≈ 0.32 g bioethanol/ g SBP.
  
  
  CONCLUSIONS
  Applying the proposed integrated process, approximately 97.5 gallon of ethanol would be produced from a ton (dry weight) of SBP.
authors.affiliation: Egyptian Petroleum Research Institute, Nasr City, Cairo, PO Box 11727, Egypt.
authors.forename: Nour Sh
authors.initials: NS
authors.lastname: El-Gendy
authors.forename: Hekmat R
authors.initials: HR
authors.lastname: Madian
authors.forename: Hussein N
authors.initials: HN
authors.lastname: Nassar
authors.forename: Salem S Abu
authors.initials: SS
authors.lastname: Amr