{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/44988"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/44988","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"The effect of cation addition on the settling and dewatering properties of an industrial activated sludge","abstract":"The purpose of this research was to examine the impact of cation addition on an industrial activated sludge system and to determine the applicability of the findings of a previous VPI&SU doctoral student (Higgins, 1995) to this industrial sludge. From this research, the implications on the full-scale industrial wastewater treatment system could be postulated. The addition of sodium and potassium to the feed stream of a laboratory-scale activated sludge system improved sludge volume index (SVI), but produced high supernatant solids. Sodium addition resulted in weak flocs and a deterioration in sludge dewatering. Potassium addition also resulted in poor sludge dewatering but did not significantly affect floc stability. The addition of magnesium improved SVI, supernatant solids, and floc stability, but did not significantly affect sludge dewatering. Increasing the monovalent/divalent cation ratio in the reactor feed stream, reduced SVI but produced high supernatant solids. The soluble and bound extracellular protein content was observed to increase with as this ratio increased. No trend was observed with soluble or bound extracellular polysaccharide content. Batch addition of both calcium and magnesium improved sludge settling and dewatering, although this effect was not observed when sludge with low extracellular polymer content was examined. This research confirmed that the effect of cations on activated sludge properties is highly dependent on the feed wastewater composition and starting and operating conditions. This implies the need for laboratory or pilot-scale testing before the effect of cation addition on a given sludge can be determined. For the industrial sludge studied here, the addition of 7 to 12 mM magnesium produced the most desirable sludge characteristics including improved SVI, supernatant solids and floc stability.","abstract_html":"The purpose of this research was to examine the impact of cation addition on an industrial activated sludge system and to determine the applicability of the findings of a previous VPI&SU doctoral student (Higgins, 1995) to this industrial sludge. From this research, the implications on the full-scale industrial wastewater treatment system could be postulated. The addition of sodium and potassium to the feed stream of a laboratory-scale activated sludge system improved sludge volume index (SVI), but produced high supernatant solids. Sodium addition resulted in weak flocs and a deterioration in sludge dewatering. Potassium addition also resulted in poor sludge dewatering but did not significantly affect floc stability. The addition of magnesium improved SVI, supernatant solids, and floc stability, but did not significantly affect sludge dewatering. Increasing the monovalent/divalent cation ratio in the reactor feed stream, reduced SVI but produced high supernatant solids. The soluble and bound extracellular protein content was observed to increase with as this ratio increased. No trend was observed with soluble or bound extracellular polysaccharide content. Batch addition of both calcium and magnesium improved sludge settling and dewatering, although this effect was not observed when sludge with low extracellular polymer content was examined. This research confirmed that the effect of cations on activated sludge properties is highly dependent on the feed wastewater composition and starting and operating conditions. This implies the need for laboratory or pilot-scale testing before the effect of cation addition on a given sludge can be determined. For the industrial sludge studied here, the addition of 7 to 12 mM magnesium produced the most desirable sludge characteristics including improved SVI, supernatant solids and floc stability.","abstract_has_math":false,"creators":["Smith, Michelle L."],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Environmental Planning","degree_department":"Environmental Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":["Novak, John","Love, Nancy G."],"committee_members":["Boardman, Gregory"],"year":1996,"date_issued":"1996","date_published":"1996","updated_at":"2026-07-22T22:19:07Z","subjects":["extracellular polymer"],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-10022008-063331"],"render_values":[{"text":"etd-10022008-063331","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/44988","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","Love, Nancy G."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Boardman, Gregory"]},{"key":"dc:contributor.department","label":"Department","values":["Environmental Engineering"]},{"key":"dc:creator","label":"Author","values":["Smith, Michelle L."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-03-14T21:46:46Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-03-14T21:46:46Z","2008-10-02"]},{"key":"dc:date.issued","label":"Date","values":["1996"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.dcmitype","label":"Dc Type Dcmitype","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Environmental Planning"]},{"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":["extracellular polymer"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"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":["etd-10022008-063331"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/44988"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The purpose of this research was to examine the impact of cation addition on an industrial activated sludge system and to determine the applicability of the findings of a previous VPI&SU doctoral student (Higgins, 1995) to this industrial sludge. From this research, the implications on the full-scale industrial wastewater treatment system could be postulated. The addition of sodium and potassium to the feed stream of a laboratory-scale activated sludge system improved sludge volume index (SVI), but produced high supernatant solids. Sodium addition resulted in weak flocs and a deterioration in sludge dewatering. Potassium addition also resulted in poor sludge dewatering but did not significantly affect floc stability. The addition of magnesium improved SVI, supernatant solids, and floc stability, but did not significantly affect sludge dewatering. Increasing the monovalent/divalent cation ratio in the reactor feed stream, reduced SVI but produced high supernatant solids. The soluble and bound extracellular protein content was observed to increase with as this ratio increased. No trend was observed with soluble or bound extracellular polysaccharide content. Batch addition of both calcium and magnesium improved sludge settling and dewatering, although this effect was not observed when sludge with low extracellular polymer content was examined. This research confirmed that the effect of cations on activated sludge properties is highly dependent on the feed wastewater composition and starting and operating conditions. This implies the need for laboratory or pilot-scale testing before the effect of cation addition on a given sludge can be determined. For the industrial sludge studied here, the addition of 7 to 12 mM magnesium produced the most desirable sludge characteristics including improved SVI, supernatant solids and floc stability."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["BTD"]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["The effect of cation addition on the settling and dewatering properties of an industrial activated sludge"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Novak, John","Love, Nancy G."],"dc:contributor.committeemember":["Boardman, Gregory"],"dc:contributor.department":["Environmental Engineering"],"dc:creator":["Smith, Michelle L."],"dc:date.accessioned":["2014-03-14T21:46:46Z"],"dc:date.available":["2014-03-14T21:46:46Z","2008-10-02"],"dc:date.issued":["1996"],"dc:description.abstract":["The purpose of this research was to examine the impact of cation addition on an industrial activated sludge system and to determine the applicability of the findings of a previous VPI&SU doctoral student (Higgins, 1995) to this industrial sludge. From this research, the implications on the full-scale industrial wastewater treatment system could be postulated. The addition of sodium and potassium to the feed stream of a laboratory-scale activated sludge system improved sludge volume index (SVI), but produced high supernatant solids. Sodium addition resulted in weak flocs and a deterioration in sludge dewatering. Potassium addition also resulted in poor sludge dewatering but did not significantly affect floc stability. The addition of magnesium improved SVI, supernatant solids, and floc stability, but did not significantly affect sludge dewatering. Increasing the monovalent/divalent cation ratio in the reactor feed stream, reduced SVI but produced high supernatant solids. The soluble and bound extracellular protein content was observed to increase with as this ratio increased. No trend was observed with soluble or bound extracellular polysaccharide content. Batch addition of both calcium and magnesium improved sludge settling and dewatering, although this effect was not observed when sludge with low extracellular polymer content was examined. This research confirmed that the effect of cations on activated sludge properties is highly dependent on the feed wastewater composition and starting and operating conditions. This implies the need for laboratory or pilot-scale testing before the effect of cation addition on a given sludge can be determined. For the industrial sludge studied here, the addition of 7 to 12 mM magnesium produced the most desirable sludge characteristics including improved SVI, supernatant solids and floc stability."],"dc:description.degree":["Master of Science"],"dc:format.medium":["BTD"],"dc:format.mimetype":["application/pdf"],"dc:identifier.other":["etd-10022008-063331"],"dc:identifier.uri":["http://hdl.handle.net/10919/44988"],"dc:language.iso":["en"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["extracellular polymer"],"dc:title":["The effect of cation addition on the settling and dewatering properties of an industrial activated sludge"],"dc:type":["Thesis"],"dc:type.dcmitype":["Text"],"thesis:degree_discipline":["Environmental Planning"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:07Z"}