Bioethanol Production from Paper Sludge Pretreated by Subcritical Water

Abstract

The depletion of oil reserves, energy dependency and rising greenhouse gas emissions urge for alternatives in all of the affected sectors. The transport sector contributes to 25% of global anthropogenic greenhouse gas emission and its energy dependency is 98%. It has to be emphasised that in the transport sector such a general solution as petrol nowadays is unlikely to be found in the future. The evaluation of alternatives depends on a lot of factors. Biofuels might serve as alternatives if they are produced in a sustainable way. Paper sludge is a waste stream of the paper industry and has a high cellulose content, which makes it appropriate for bioethanol production. The aim of this paper is to show an alternative for bioethanol production from paper sludge. Paper sludge is pre-treated by subcritical water which is followed by an enzymatic hydrolysis and a fermentation step. Optimum condition for the pre-treatment and the enzymatic hydrolysis were determined previously. This paper aims at showing the optimum conditions for the fermentation step. Experiments were performed in shake flasks.