{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/23192"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/23192","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Effect of Long Chain Fatty Acids on Anaerobic Digestion of Municiapal Sewage Sludge in Completely Mixed Reactors","abstract":"Fats, oil and grease (FOG) are generated in large amounts by cooking and food processing. Anaerobic co-digestion with municipal sewage sludge has proven to be one of best alternatives for FOG disposal due to its high potential for biogas production. However, excessive addition of long chain fatty acid, the major content of FOG, has been reported to have inhibitory effects on the anaerobic digestion process and to cause operational challenges. In this study, high purity long chain fatty acids (LCFAs) including linoleic acid, oleic acid, and a mixture of oleic acid and stearic acid were added to laboratory completed mixed anaerobic digesters. The performance of the digesters in terms of solids destruction, COD degradation, LCFAs accumulation and gas production was investigated. After reaching steady state, a large amount of palmitic acid was found in the reactors with oleic acid addition and mixture of stearic and oleic acid addition. In the meantime, no palmitic acid increase was observed in reactors where linoleic acid was added. A better solids and COD reduction and a higher biogas production were observed in reactors with higher LCFAs addition. For reactors with the same dosage of LCFAs addition, linoleic acid addition resulted in the greatest improvement in digester performance; the mixture of stearic acid and oleic acid achieved the least increase in biogas production and solids and COD reduction. A high concentration of both palmitic and stearic acid in the reactors with oleic acid addition and with 20% mixed acid addition was observed. In contrast, linoleic acid and 30% mixed acid addition did not lead to a greater palmitic or stearic acid concentrations. Up to 30% of pure linoleic acid, oleic acid and mixed acid addition are able to enhance the performance of anaerobic digesters. It is recommended that the dosage of oleic acid be below 30% to avoid LCFAs accumulation and to increase reactor stability.","abstract_html":"Fats, oil and grease (FOG) are generated in large amounts by cooking and food processing. Anaerobic co-digestion with municipal sewage sludge has proven to be one of best alternatives for FOG disposal due to its high potential for biogas production. However, excessive addition of long chain fatty acid, the major content of FOG, has been reported to have inhibitory effects on the anaerobic digestion process and to cause operational challenges. In this study, high purity long chain fatty acids (LCFAs) including linoleic acid, oleic acid, and a mixture of oleic acid and stearic acid were added to laboratory completed mixed anaerobic digesters. The performance of the digesters in terms of solids destruction, COD degradation, LCFAs accumulation and gas production was investigated. After reaching steady state, a large amount of palmitic acid was found in the reactors with oleic acid addition and mixture of stearic and oleic acid addition. In the meantime, no palmitic acid increase was observed in reactors where linoleic acid was added. A better solids and COD reduction and a higher biogas production were observed in reactors with higher LCFAs addition. For reactors with the same dosage of LCFAs addition, linoleic acid addition resulted in the greatest improvement in digester performance; the mixture of stearic acid and oleic acid achieved the least increase in biogas production and solids and COD reduction. A high concentration of both palmitic and stearic acid in the reactors with oleic acid addition and with 20% mixed acid addition was observed. In contrast, linoleic acid and 30% mixed acid addition did not lead to a greater palmitic or stearic acid concentrations. Up to 30% of pure linoleic acid, oleic acid and mixed acid addition are able to enhance the performance of anaerobic digesters. It is recommended that the dosage of oleic acid be below 30% to avoid LCFAs accumulation and to increase reactor stability.","abstract_has_math":false,"creators":["Zhu, Kuang"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Civil Engineering","degree_department":"Civil and Environmental Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":["Novak, John T."],"committee_members":["Little, John C.","Boardman, Gregory D."],"year":2013,"date_issued":"2013-06-10","date_published":"2013-06-10","updated_at":"2026-07-22T22:19:06Z","subjects":["Anaerobic digestion","Fats","oil and grease","Long chain fatty acids","biogas production","Energy Recovery"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:1271"],"render_values":[{"text":"vt_gsexam:1271","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/23192","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Novak, John T."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Little, John C.","Boardman, Gregory D."]},{"key":"dc:contributor.department","label":"Department","values":["Civil and Environmental Engineering"]},{"key":"dc:creator","label":"Author","values":["Zhu, Kuang"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2013-06-11T08:00:24Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2013-06-11T08:00:24Z"]},{"key":"dc:date.issued","label":"Date","values":["2013-06-10"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Civil Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Anaerobic digestion","Fats","oil and grease","Long chain fatty acids","biogas production","Energy Recovery"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:1271"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/23192"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Fats, oil and grease (FOG) are generated in large amounts by cooking and food processing. Anaerobic co-digestion with municipal sewage sludge has proven to be one of best alternatives for FOG disposal due to its high potential for biogas production. However, excessive addition of long chain fatty acid, the major content of FOG, has been reported to have inhibitory effects on the anaerobic digestion process and to cause operational challenges. In this study, high purity long chain fatty acids (LCFAs) including linoleic acid, oleic acid, and a mixture of oleic acid and stearic acid were added to laboratory completed mixed anaerobic digesters. The performance of the digesters in terms of solids destruction, COD degradation, LCFAs accumulation and gas production was investigated. After reaching steady state, a large amount of palmitic acid was found in the reactors with oleic acid addition and mixture of stearic and oleic acid addition. In the meantime, no palmitic acid increase was observed in reactors where linoleic acid was added. A better solids and COD reduction and a higher biogas production were observed in reactors with higher LCFAs addition. For reactors with the same dosage of LCFAs addition, linoleic acid addition resulted in the greatest improvement in digester performance; the mixture of stearic acid and oleic acid achieved the least increase in biogas production and solids and COD reduction. A high concentration of both palmitic and stearic acid in the reactors with oleic acid addition and with 20% mixed acid addition was observed. In contrast, linoleic acid and 30% mixed acid addition did not lead to a greater palmitic or stearic acid concentrations. Up to 30% of pure linoleic acid, oleic acid and mixed acid addition are able to enhance the performance of anaerobic digesters. It is recommended that the dosage of oleic acid be below 30% to avoid LCFAs accumulation and to increase reactor stability."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:title","label":"Title","values":["Effect of Long Chain Fatty Acids on Anaerobic Digestion of Municiapal Sewage Sludge in Completely Mixed Reactors"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Novak, John T."],"dc:contributor.committeemember":["Little, John C.","Boardman, Gregory D."],"dc:contributor.department":["Civil and Environmental Engineering"],"dc:creator":["Zhu, Kuang"],"dc:date.accessioned":["2013-06-11T08:00:24Z"],"dc:date.available":["2013-06-11T08:00:24Z"],"dc:date.issued":["2013-06-10"],"dc:description.abstract":["Fats, oil and grease (FOG) are generated in large amounts by cooking and food processing. Anaerobic co-digestion with municipal sewage sludge has proven to be one of best alternatives for FOG disposal due to its high potential for biogas production. However, excessive addition of long chain fatty acid, the major content of FOG, has been reported to have inhibitory effects on the anaerobic digestion process and to cause operational challenges. In this study, high purity long chain fatty acids (LCFAs) including linoleic acid, oleic acid, and a mixture of oleic acid and stearic acid were added to laboratory completed mixed anaerobic digesters. The performance of the digesters in terms of solids destruction, COD degradation, LCFAs accumulation and gas production was investigated. After reaching steady state, a large amount of palmitic acid was found in the reactors with oleic acid addition and mixture of stearic and oleic acid addition. In the meantime, no palmitic acid increase was observed in reactors where linoleic acid was added. A better solids and COD reduction and a higher biogas production were observed in reactors with higher LCFAs addition. For reactors with the same dosage of LCFAs addition, linoleic acid addition resulted in the greatest improvement in digester performance; the mixture of stearic acid and oleic acid achieved the least increase in biogas production and solids and COD reduction. A high concentration of both palmitic and stearic acid in the reactors with oleic acid addition and with 20% mixed acid addition was observed. In contrast, linoleic acid and 30% mixed acid addition did not lead to a greater palmitic or stearic acid concentrations. Up to 30% of pure linoleic acid, oleic acid and mixed acid addition are able to enhance the performance of anaerobic digesters. It is recommended that the dosage of oleic acid be below 30% to avoid LCFAs accumulation and to increase reactor stability."],"dc:description.degree":["Master of Science"],"dc:format.medium":["ETD"],"dc:identifier.other":["vt_gsexam:1271"],"dc:identifier.uri":["http://hdl.handle.net/10919/23192"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["Anaerobic digestion","Fats","oil and grease","Long chain fatty acids","biogas production","Energy Recovery"],"dc:title":["Effect of Long Chain Fatty Acids on Anaerobic Digestion of Municiapal Sewage Sludge in Completely Mixed Reactors"],"dc:type":["Thesis"],"thesis:degree_discipline":["Civil Engineering"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:06Z"}