Optimization of Two-Stage Anaerobic Digestion of Lignocellulosic Straw

Author(s):

Nithish Mani , Sahasrara Earth Services & Resources Ltd.; Muhammad Waseem, Faculty of agriculture and environmental sciences, Universität Rostock, Germany; George Andiego, Water resources and environmental services department, Nairobi, Kenya; Muhammad Usman, Institute of water resources and water supply, TUHH Hamburg, Germany

Keywords:

Acidogenesis, Biogas, Hydrolysis, Methane Yield, Rumen Biocoenosis

Abstract:

Biogas production using anaerobic digestion (AD) is an alternative energy source that allows the use of organic, agricultural and energy crops as a fuel. In this work, the mono-digestion approach was used with lignocellulosic straw and rumen content as inoculum. The main problem with lignocellulosic straw is its long digestion time, low biogas yield and low biodegradability. Therefore, an alternate degradation technique using rumen biocoenosis for cellulosic straw was investigated to determine the Chemical Oxygen Demand (COD) balance and upscale gas production. The hydrolysis and acidification process of anaerobic digestion in Continuous Stirred Tank Reactor (CSTR) was operated at 33 -38˚C with 20 days Hydraulic Retention Time (HRT). Buffer solutions were added to maintain the pH in the range of 7.2-7.8. The methanogenesis reactor used in this study was the Up-Flow Anaerobic Sludge Blanket Reactor (UASB). The working volume and recirculation rate in the reactors were 4.2 cubic meters (m3) and 750 liters per day (l/d) respectively. Methane (CH4) concentration in CSTR was found to be 30% and UASB reactor was 70%. The samples taken from the reactors were tested for total solids (TS) and COD. Additionally, methane production from the substrate, digesters and recirculation liquid was determined using a laboratory batch test according to the VDI4630 guideline. The average specific methane yield during the three phases of experiment with loading rates of 1.07, 2.14 & 3.21-kilogram (kg) VS/ m3d were 433.21, 216.47 & 359.98 L CH4/kg VS respectively. Futuristic studies should focus on improving the mixing capacity of the mixing pump and existing UASB system to function efficiently and the gas yield can be increased by using pretreatment strategies.

Other Details:

Manuscript Id	:	IJSTEV4I6026
Published in	:	Volume : 4, Issue : 6
Publication Date	:	01/01/2018
Page(s)	:	55-67

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