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Enhancement of Methane Production from Solid-state Anaerobic Digestion of Yard Trimmings by Biological Pretreatment

Zhao, Jia
http://rave.ohiolink.edu/etdc/view?acc_num=osu1374240087

Abstract Details

2013, Master of Science, Ohio State University, Food, Agricultural and Biological Engineering.
Anaerobic digestion (AD) is a biological process in which organic matter is decomposed by an assortment of microbes under oxygen-free conditions to produce biogas (about 40-70% CH4 and 30-60% CO2). AD is an efficient and mature waste treatment technology that can can not only achieve the goal of waste disposal, but also generates biomethane, a renewable energy source. Based on its total solids percent (TS), AD can be classified as liquid AD (L-AD) or solid-state AD (SS-AD). Even though L-AD has a faster reaction rate and shorter retention time, SS-AD is generally thought to be advantageous over L-AD due to the smaller volume reactor equipment required, less energy input for heating, and because the solid byproduct weighs less, is more conductive to transportation and storage as compared to typical liquid AD effluents. Yard trimmings are one of the main components of municipal solid waste. They are traditionally recycled by composting or disposed of by landfilling. In both process, energy is lost as heat. SS-AD could provide an alternative solution for the treatment of yard trimmings and the recovery of energy as biogas. The challenge of utilizing lignocellulosic biomass such as yard trimmings for SS-AD, however, is its recalcitrant structure, which impedes the hydrolysis of cellulose and hemicellulose. Lignin is believed to be one of the major factors inhibiting lignocellulose hydrolysis. Therefore, pretreatment aimed at removing lignin from yard trimmings prior to SS-AD may improve the degradability of this feedstock. In this study, two biological pretreatment methods for the enhancement of methane production during SS-AD were evaluated. These included fungal pretreatment by Ceriporiopsis subvermispora and composting. The fungal pretreatment study focused on the effect of moisture content (45%, 60% and 75%) and aeration mode (natural aeration, mechanical aeration for 15 min every 12 h and mechanical aeration for 30 min every 24 h) on the holocellulose and lignin loss and on methane yield during SS-AD. It was found that both aeration mode and moisture content had significant effects on the loss of hemicellulose and lignin. The highest lignin loss (20.9%) was obtained from naturally aerated yard trimmings with 60% moisture content as was the highest methane yield (44.6 L/kg VS(original yard trimmings)). Methane yield was positively linearly correlated with lignin degradation. Compared with the methane yield from original yard trimmings (without fungal pretreatment), fungal pretreatment increased the methane yield by up to154%. In addition, a simulated composting was used to pretreat a mixture of yard trimmings and AD effluent. The composting pretreatment was conducted at 45 °C with moisture content of 55% under natural aeration (no extra mechanical aeration) for 30 days. Composted yard trimmings and additional AD effluent were mixed and then fed into SS-AD reactors and placed at 37 °C for 30 days. The results showed no remarkable lignin loss during the composting process. The methane yield from the composted yard trimmings was not improved compared with the methane yield from original yard trimmings (without composting pretreatment). Therefore composting pretreatment did not appear to be a promising approach to improvement of methane yield of yard trimmings during SS-AD.
Yebo Li (Advisor)
Jay Martin (Committee Member)
Frederick Michel (Committee Member)
98 p.
Agricultural Engineering; Alternative Energy
Solid-state anaerobic digestion; Methane; Yard Trimmings; Fungal Pretreatment; Composting

Recommended Citations

Citations

  • Zhao, J. (2013). Enhancement of Methane Production from Solid-state Anaerobic Digestion of Yard Trimmings by Biological Pretreatment [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1374240087

    APA Style (7th edition)

  • Zhao, Jia. Enhancement of Methane Production from Solid-state Anaerobic Digestion of Yard Trimmings by Biological Pretreatment. 2013. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1374240087.

    MLA Style (8th edition)

  • Zhao, Jia. "Enhancement of Methane Production from Solid-state Anaerobic Digestion of Yard Trimmings by Biological Pretreatment." Master's thesis, Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1374240087

    Chicago Manual of Style (17th edition)

osu1374240087
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This open access ETD is published by The Ohio State University and OhioLINK.