{"id":{"repo_id":"cape-town","oai_identifier":"oai:open.uct.ac.za:11427/15664"},"canonical_url":"https://search.dev.ndltd.org/etd/cape-town/oai:open.uct.ac.za:11427/15664","repository":{"repo_id":"cape-town","name":"University of Cape Town","base_url":"https://open.uct.ac.za/oai/request"},"display":{"title":"Nitrification and denitrification kinetics in the activated sludge process","abstract":"The bi-substrate active-site death regeneration model, developed by Dold, Ekama and Marais (1980), to describe the aerobic activated sludge process, was extended to provide a reliable description of the behaviour of the nitrification-denitrification single sludge activated sludge process under constant, cyclic or unsteady conditions of flow and load. The extended model applies to series reactor systems containing aerated and non-aerated reactors and to single reactor systems having alternating aerated and non-aerated periods. The extension describing the behaviour in the anoxic state required no change in the basic equations describing the aerobic state. The numerical values of the kinetic constants in the anoxic state equations were found to be the same as those in the aerobic state equations, except for one: The value of the utilization rate constant for slowly biodegradable material in an anoxic environment is a fraction of approximately 0,38 of the value of this constant in an aerobic environment. Nitrification is affected in so far that growth of nitrifiers takes place in an aerobic environment, whereas death of nitrifiers takes place in both aerobic and anoxic environments. The existing empirical denitrification models (valid for constant flow and load conditions) could be deduced from the solutions of the basic equations. The empirical denitrification rate constants could be interpreted in terms of the expressions for utilization of easily and slowly biodegradable organic substrates in an anoxic environment. These constants were shown to have no fundamental kinetic significance; they are only apparent constants, the result of kinetic reactions which, fortuitously, show little variation under normal operational conditions.","abstract_html":"The bi-substrate active-site death regeneration model, developed by Dold, Ekama and Marais (1980), to describe the aerobic activated sludge process, was extended to provide a reliable description of the behaviour of the nitrification-denitrification single sludge activated sludge process under constant, cyclic or unsteady conditions of flow and load. The extended model applies to series reactor systems containing aerated and non-aerated reactors and to single reactor systems having alternating aerated and non-aerated periods. The extension describing the behaviour in the anoxic state required no change in the basic equations describing the aerobic state. The numerical values of the kinetic constants in the anoxic state equations were found to be the same as those in the aerobic state equations, except for one: The value of the utilization rate constant for slowly biodegradable material in an anoxic environment is a fraction of approximately 0,38 of the value of this constant in an aerobic environment. Nitrification is affected in so far that growth of nitrifiers takes place in an aerobic environment, whereas death of nitrifiers takes place in both aerobic and anoxic environments. The existing empirical denitrification models (valid for constant flow and load conditions) could be deduced from the solutions of the basic equations. The empirical denitrification rate constants could be interpreted in terms of the expressions for utilization of easily and slowly biodegradable organic substrates in an anoxic environment. These constants were shown to have no fundamental kinetic significance; they are only apparent constants, the result of kinetic reactions which, fortuitously, show little variation under normal operational conditions.","abstract_has_math":false,"creators":["Van Haandel, Adrianus Cornelius"],"institution":"Department of Civil Engineering","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Marais, Gerrit van Rooyen"],"committee_chairs":[],"committee_members":[],"year":1981,"date_issued":"1981","date_published":"1981","updated_at":"2026-07-22T22:23:14Z","subjects":[],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/11427/15664","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Marais, Gerrit van Rooyen"]},{"key":"dc:creator","label":"Author","values":["Van Haandel, Adrianus Cornelius"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2015-12-08T06:53:45Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2015-12-08T06:53:45Z"]},{"key":"dc:date.issued","label":"Date","values":["1981"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["Department of Civil Engineering"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["University of Cape Town"]},{"key":"dc:type","label":"Dc Type","values":["Doctoral Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["Doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["PhD"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["eng"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/11427/15664"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Includes bibliography."]},{"key":"dc:description.abstract","label":"Abstract","values":["The bi-substrate active-site death regeneration model, developed by Dold, Ekama and Marais (1980), to describe the aerobic activated sludge process, was extended to provide a reliable description of the behaviour of the nitrification-denitrification single sludge activated sludge process under constant, cyclic or unsteady conditions of flow and load. The extended model applies to series reactor systems containing aerated and non-aerated reactors and to single reactor systems having alternating aerated and non-aerated periods. The extension describing the behaviour in the anoxic state required no change in the basic equations describing the aerobic state. The numerical values of the kinetic constants in the anoxic state equations were found to be the same as those in the aerobic state equations, except for one: The value of the utilization rate constant for slowly biodegradable material in an anoxic environment is a fraction of approximately 0,38 of the value of this constant in an aerobic environment. Nitrification is affected in so far that growth of nitrifiers takes place in an aerobic environment, whereas death of nitrifiers takes place in both aerobic and anoxic environments. The existing empirical denitrification models (valid for constant flow and load conditions) could be deduced from the solutions of the basic equations. The empirical denitrification rate constants could be interpreted in terms of the expressions for utilization of easily and slowly biodegradable organic substrates in an anoxic environment. These constants were shown to have no fundamental kinetic significance; they are only apparent constants, the result of kinetic reactions which, fortuitously, show little variation under normal operational conditions."]},{"key":"dc:title","label":"Title","values":["Nitrification and denitrification kinetics in the activated sludge process"]}]}],"canonical_facts":{"dc:contributor.advisor":["Marais, Gerrit van Rooyen"],"dc:creator":["Van Haandel, Adrianus Cornelius"],"dc:date.accessioned":["2015-12-08T06:53:45Z"],"dc:date.available":["2015-12-08T06:53:45Z"],"dc:date.issued":["1981"],"dc:description":["Includes bibliography."],"dc:description.abstract":["The bi-substrate active-site death regeneration model, developed by Dold, Ekama and Marais (1980), to describe the aerobic activated sludge process, was extended to provide a reliable description of the behaviour of the nitrification-denitrification single sludge activated sludge process under constant, cyclic or unsteady conditions of flow and load. The extended model applies to series reactor systems containing aerated and non-aerated reactors and to single reactor systems having alternating aerated and non-aerated periods. The extension describing the behaviour in the anoxic state required no change in the basic equations describing the aerobic state. The numerical values of the kinetic constants in the anoxic state equations were found to be the same as those in the aerobic state equations, except for one: The value of the utilization rate constant for slowly biodegradable material in an anoxic environment is a fraction of approximately 0,38 of the value of this constant in an aerobic environment. Nitrification is affected in so far that growth of nitrifiers takes place in an aerobic environment, whereas death of nitrifiers takes place in both aerobic and anoxic environments. The existing empirical denitrification models (valid for constant flow and load conditions) could be deduced from the solutions of the basic equations. The empirical denitrification rate constants could be interpreted in terms of the expressions for utilization of easily and slowly biodegradable organic substrates in an anoxic environment. These constants were shown to have no fundamental kinetic significance; they are only apparent constants, the result of kinetic reactions which, fortuitously, show little variation under normal operational conditions."],"dc:identifier.uri":["http://hdl.handle.net/11427/15664"],"dc:language.iso":["eng"],"dc:publisher.department":["Department of Civil Engineering"],"dc:publisher.institution":["University of Cape Town"],"dc:title":["Nitrification and denitrification kinetics in the activated sludge process"],"dc:type":["Doctoral Thesis"],"dc:type.qualificationlevel":["Doctoral"],"dc:type.qualificationname":["PhD"]},"updated_at":"2026-07-22T22:23:14Z"}