Potassium Hydroxyde Pre-Treatment Enhances Methane Yield from Giant Reed (Arundo donax L.)

Abstract

The biogas production through the anaerobic digestion (AD) of giant reed (Arundo donax L.) biomass has received increasing attention. However, due to the presence of lignin, a low CH4 yield can be obtained. Aiming to improve the CH4 yield from giant reed biomass, the effectiveness of a thermo-chemical pre-treatment based on KOH was evaluated in this paper. The usefulness of a washing step before the AD was also assessed. The pre-treatment led to a specific CH4 yield up to 232 mL CH4 g−1 VS which was 21% higher than that from untreated biomass; the maximum daily rate of production was improved by 42%, AD duration was reduced by 10%, and CH4 concentration in the biogas was increased by 23%. On the contrary, the washing step did not improve the AD process. Besides, washing away the liquid fraction led to biomass losses, reducing the overall CH4 production. The use of a KOH-based pre-treatment appears as a good option for enhancing the AD of giant reed, also presenting potential environmental and agronomical benefits, like the avoidance of salty wastewater production and the likely improvement of the digestate quality, due to its enriched K content.

Biogas Production from Coffee Pulp and Chicken Feathers Using Liquid- and Solid-State Anaerobic Digestions

“…Delignification 1 TS, total solid; A, potential biogas production; U, maximum biogas production rate; λ, minimum time for biogas production; R 2 , the correlation coefficient. This study's modified Gompertz method can determine the estimated flow rate of biogas production [54,55]. Actual and predicted volumes were similar when viewed through the comparison graphs.…”

Model-Based Assessment of Giant Reed (Arundo donax L.) Energy Yield in the Form of Diverse Biofuels in Marginal Areas of Italy

“…The outputs of 30-year spatially explicit simulations were used to describe the overall variability of CAAB, biomethane (Nm 3 ha −1 ), and bioethanol (L ha −1 ) productions in the form of a table, as well as the energy yield that may be achieved from the combustion of these substrates in the baseline and 2030 via the use of boxplots. Biomethane, bioethanol, and energy yields were derived combining simulated values of above ground biomass (Mg ha −1 ) and potential biomethane (275.6 Nm 3 CH 4 Mg −1 DM, computed by averaging experimental data reported by Di Girolamo et al [53,54]; Corno et al [24]; Yang and Li [55], Liu et al [56]; Jiang et al [57]; Shilpi et al [58] Ceotto et al [25]; Vasmara et al [28]) and bioethanol (217.7 L Mg −1 DM, computed by averaging experimental data reported by Bura et al [59]; Scordia et al, [60]; Corno et al [24]; and Viola et al [61]). The efficiency with which the crop biomass is converted to biomethane is referred to as specific methane yield (SMY) and expressed as mL CH 4 g −1 VS (volatile solids, i.e., DM minus ash content), in standard conditions (STP) of temperature (273.15 K) and pressure (101.3 kPa).…”

“…Climate change impact studies carried out on the same crop in lowlands [27] and wet areas around the river banks [10,28,32] in Northern Italy, provided more optimistic projections compared to those herein presented, because they considered potential growth conditions for water and nutrient availability. As a consequence, relative yield changes expected in the future were always positive, or at most did not show any noticeable change, due to increasingly favorable thermal regimes for this macrothermal species and the absence of possible water stress along crop season, especially in the driest areas.…”

“…Nevertheless, the high biomass productivity allows to obtain higher biomethane production per hectare compared to other energy crops, especially when a single annual harvest at the end of the growing season is adopted [25]. Although the crop biomass does not require any fermentation pretreatment when it is harvested within a range of dry matter content between 30 and 38% [27], a recent study showed that a thermo-chemical pre-treatment with KOH at 120 • C was able to increase the methane yield by about 20%, while reducing the anaerobic digestion duration by about 10 days [28]. Given the high biomass productivity and the high heating value (HHV; 18.7 MJ kg −1 according to Danelli et al [29]), the crop also shows a promising potential for direct combustion, even though it has high ash content, coming from leaf tissues, which can reduce thermal conversion efficiency especially in the early season harvesting.…”

Impact of Attrition Ball-Mill on Characteristics and Biochemical Methane Potential of Food Waste

“…Often activated sludge is added to improve the AD of food waste [17]. In chemical pretreatment, alkalis (e.g., NaOH, KOH) or oxidants (e.g., ozone) are used [16,18,19]. Usually, alkali treatment is used with thermal or mechanical treatment [20].…”