Enhanced Biogas Production of Cassava Wastewater Using Zeolite and Biochar Additives and Manure Co-Digestion

Chibueze G. Achi, Amro Hassanein and Stephanie Lansing
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Chibueze G. Achi: Department of Environmental Science & Technology, University of Maryland, College Park, MD 20742, USA
Amro Hassanein: Department of Environmental Science & Technology, University of Maryland, College Park, MD 20742, USA
Stephanie Lansing: Department of Environmental Science & Technology, University of Maryland, College Park, MD 20742, USA

Energies, 2020, vol. 13, issue 2, 1-13

Abstract: Currently, there are challenges with proper disposal of cassava processing wastewater, and a need for sustainable energy in the cassava industry. This study investigated the impact of co-digestion of cassava wastewater (CW) with livestock manure (poultry litter (PL) and dairy manure (DM)), and porous adsorbents (biochar (B-Char) and zeolite (ZEO)) on energy production and treatment efficiency. Batch anaerobic digestion experiments were conducted, with 16 treatments of CW combined with manure and/or porous adsorbents using triplicate reactors for 48 days. The results showed that CW combined with ZEO (3 g/g total solids (TS)) produced the highest cumulative CH 4 (653 mL CH 4 /g VS), while CW:PL (1:1) produced the most CH 4 on a mass basis (17.9 mL CH 4 /g substrate). The largest reduction in lag phase was observed in the mixture containing CW (1:1), PL (1:1), and B-Char (3 g/g TS), yielding 400 mL CH 4 /g volatile solids (VS) after 15 days of digestion, which was 84.8% of the total cumulative CH 4 from the 48-day trial. Co-digesting CW with ZEO, B-Char, or PL provided the necessary buffer needed for digestion of CW, which improved the process stability and resulted in a significant reduction in chemical oxygen demand (COD). Co-digestion could provide a sustainable strategy for treating and valorizing CW. Scale-up calculations showed that a CW input of 1000–2000 L/d co-digested with PL (1:1) could produce 9403 m 3 CH 4 /yr using a 50 m 3 digester, equivalent to 373,327 MJ/yr or 24.9 tons of firewood/year. This system would have a profit of $5642/yr and a $47,805 net present value.

Keywords: methane; fermentation; dairy; poultry; absorbent (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (4)

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