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Integrating the Bottom Ash Residue from Biomass Power Generation into Anaerobic Digestion To Improve Biogas Production from Lignocellulosic Biomass
journal contribution
posted on 2019-09-16, 15:39 authored by Qin Xiao, Wei Chen, Dong Tian, Fei Shen, Jinguang Hu, Lulu Long, Yongmei Zeng, Gang Yang, Shihuai DengThe bottom ash residue
derived from biomass power generation was
characterized by alkalinity and contained about 35 mineral elements,
which offered a possibility to improve anaerobic digestion of lignocellulose
biomass via providing mineral nutrients for microorganisms and alkali
conditions for pretreatment. Technically, bottom ash was mixed with
distilled water to prepare the extracting solution for this investigation.
To check the function as a nutrient provider of bottom ash, the increased
bottom ash loading from 0.37 to 2.96% was employed to achieve the
extracting solutions with different concentrations of mineral elements.
Rice straw was mixed with these extracting solutions for 7 days and
then employed for the anaerobic digestion in batch. Results indicated
that 314.38 mL/g of total solid biogas was achieved by 0.37%
bottom ash, which was 21.2 and 15.8% higher than that of the blank
and 0.12% NaOH (equivalent alkalinity of 0.37% bottom ash), respectively,
proving that bottom ash substantially functioned as a nutrient provider
with the resultant improvement. However, the decreased biogas production
at higher loadings suggested potential inhibitions. Besides, to check
the potential function of alkali pretreatment using bottom ash, the
soaking duration of rice straw in the extracting solution (the calculated
bottom ash loading of 0.37%) was prolonged from 0 to 7 days to achieve
the different intensities, and the results indicated that the lignin
and hemicellulose removal was promoted to 20.1 and 25.3% after 7 days
of pretreatment, respectively, and the corresponding biogas production
and biomethane yield were increased by 63.1 and 28.3%, respectively,
proving that the bottom ash can work as a base provider for alkali-pretreating
rice straw to facilitate anaerobic digestion.