Mechanical pretreatment of waste paper for biogas production

Abstract

In the anaerobic digestion of lignocellulosic materials such as waste paper, the accessibility of microorganisms to the fermentable sugars is restricted by their complex structure. A mechanical pretreatment with a Hollander beater was assessed in order to reduce the biomass particle size and to increase the feedstock' specific surface area available to the microorganisms, and therefore improve the biogas yield. Pretreatment of paper waste for 60min improves the methane yield by 21%, from a value of 210ml/gVS corresponding to untreated paper waste to 254ml/gVS. 30min pretreatment have no significant effect on the methane yield. A response surface methodology was used to evaluate the effect of the beating time and feedstock/inoculum ratio on the methane yield. An optimum methane yield of 253ml/gVS was achieved at 55min of beating pretreatment and a F/I ratio of 0.3.

Insight into Pretreatment Methods of Lignocellulosic Biomass to Increase Biogas Yield: Current State, Challenges, and Opportunities

“…Mechanical pretreatment is well-known method to improve biogas production, however it is yet considered to be an expensive method, due its high energy requirements [62]. The size reduction of lignocellulosic biomass is an essential step to increase the accessible surface area and the porosity of the particles, besides reducing the crystallinity of the cellulose and improves the efficiency of the next processing step and global production chain [63]. One advantage of mechanical pretreatment is that it does not produce any secondary inhibitory substances, which suggest that could be suitable for methane production or any other bioprocess [64].…”

“…On the other side, the processing time on particle reduction is not only important in energy terms, but also influence the efficiency of the bioconversion of lignocellulosic biomass [59]. Rodríguez et al [63] compared 30 and 60 min of mechanical pretreatment, and reported a 21% increase in methane yield for 60 min and that 30 min pretreatment did not improve the methane yield. For the cost reduction of the energy involved in mechanical pretreatments, the speed of the milling equipment must be considered [72].…”

Dry Anaerobic Digestion of Food and Paper Industry Wastes at Different Solid Contents

“…Landfilling of these wastes is still the most common practice in the world [2], resulting in pollution of water and soil with leachate, and air with emission of methane and other greenhouse gases [3,4]. Anaerobic digestion to produce biomethane has been a successful treatment option for these wastes; it is effective in solving environmental, health and energy challenges [3][4][5]. Additionally, the digestate residues from biogas plants are rich in macro-and micronutrients and also contain phosphorus and ammonium nitrogen [6], which make them suitable as biofertilizers [7].…”

“…However, the recalcitrant structure of PW makes it difficult for the microorganisms to breakdown this substrate and produce biomethane. Consequently the hydrolysis step is the rate-limiting step in the AD process when treating these lignocellulose-rich wastes [5]. In view of this point, there is a need to determine suitable dry AD process conditions for effective biogas production from PW.…”

Optimization of Pre-Treatment Process Parameters to Generate Biodiesel from Microalga

“…Also, the adequate precession ratio in the ANOVA response surface linear model is above 4, which specifies that the entire model is very adequate and as a sign good model discrimination. However, for a model to be adequate, the model reduction will certifies and significantly accept the essential statistical analysis to carry out an optimization process [49]. The final equation for the experimental parameters and actual factors, as determined by the software is shown in Equation 1 1where: P is the pressure N is the number of passes R is the reaction time As shown in Table 3, there are three interaction terms that have a significant effect on the amount of lipid produced, which are: pressure, number of passes and reaction time.…”