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ARS Home » Southeast Area » Florence, South Carolina » Coastal Plain Soil, Water and Plant Conservation Research » Research » Publications at this Location » Publication #377986
Research Project: Improvement of Soil Management Practices and Manure Treatment/Handling Systems of the Southern Coastal Plain

Location: Coastal Plain Soil, Water and Plant Conservation Research

Title: Improved anaerobic digestion of swine manure by simultaneous ammonia recovery using gas-permeable membranes

Author
item GONZALEZ-GARCIA, ISABEL - Instituto Tecnológico Agrario De Castilla Y León (ITACYL)
item RIANO, BERTA - Instituto Tecnológico Agrario De Castilla Y León (ITACYL)
item MOLINUEVO-SALCES, BEATRIZ - Instituto Tecnológico Agrario De Castilla Y León (ITACYL)
item Vanotti, Matias
item GARCIA-GONZALEZ, MARIA CRUZ - Instituto Tecnológico Agrario De Castilla Y León (ITACYL)

Submitted to: Water Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/25/2020
Publication Date: 2/15/2021
Citation: Gonzalez-Garcia, I., Riano, B., Molinuevo-Salces, B., Vanotti, M.B., Garcia-Gonzalez, M. 2021. Improved anaerobic digestion of swine manure by simultaneous ammonia recovery using gas-permeable membranes. Water Research. 190. Article #116789. https://doi.org/10.1016/j.watres.2020.116789.
DOI: https://doi.org/10.1016/j.watres.2020.116789

Interpretive Summary: Among the alternatives for improving manure management, anaerobic digestion (AD) is considered a solution. However, high ammonia (NH3) concentration in manure reduces the potential production of biogas due to inhibition of the microorganisms (methanogens). In the present study, the effect of NH3 removal using gas-permeable membrane (GPM) technology on AD process performance and biogas production was investigated using swine manure feedstock. Results showed a great potential of gas-permeable membrane technology to improve AD of swine manure while recovering ammonia from the digestate in the form of an ammonium salt. By coupling GPM system in the AD digester, an increase in the methane yield up to 28 percent (%) was detected compared to a control treatment without NH3 recovery. In addition, higher percentages of methane in biogas (8 to 14%) were found during AD with NH3 recovery. Ammonia was recovered and transformed in a concentrated ammonium sulfate solution. Therefore, the AD-GPM configuration produces beneficial results on both biogas quantity and quality while also recovering ammonia nitrogen in marketable ammonium salt.

Technical Abstract: In feedstocks containing high ammonia (NH3) concentration, removal of the NH3 during the anaerobic digestion (AD) process can improve AD process performance. In the present study, the effect of NH3 removal using gas-permeable membrane (GPM) technology on AD process performance and biogas production was investigated using swine manure feedstock. Batch and semi-continuous AD experiments were carried out under mesophilic conditions. The experiment used AD reactors with NH3 recovery and without NH3 recovery (control). In the reactor with NH3 recovery, total ammonia nitrogen (TAN) concentration was reduced up to 28 percent (%) in batch experiments and up to 33% in semi-continuous experiment, compared with the reactor without NH3 recovery. Free ammonia (FA) concentrations were also decreased by 23% and up to 54% in batch and semi-continuous experiments, respectively. These reductions in TAN and FA positively impacted both the quality and quantity of the biogas produced by AD of swine manure using GPM technology. Specifically, the specific methane yield increased of up to 28% in the reactor with NH3 recovery compared with the reactor without NH3 recovery under different operational conditions. Futhermore, higher percentages of methane in biogas (between 8-14%) were obtained during AD retrofitted with GPM system. Simultaneously, a uniform TAN recovery rate of 5.9 grams TAN per square meter of membrane surface per day was obtained for the 205 days of semi-continuous operation. Therefore, the AD-GPM configuration produces beneficial results on both biogas quantity and quality while also recovering ammonia nitrogen in marketable ammonium salt.