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Bioflocculation: Implications for Activated Sludge Properties and Wastewater Treatment

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dc.contributor.authorMurthy, Sudhir N.en
dc.contributor.committeechairNovak, John T.en
dc.contributor.committeememberRandall, Clifford W.en
dc.contributor.committeememberLove, Nancy G.en
dc.contributor.committeememberKnocke, William R.en
dc.contributor.committeememberGregory, Eugene M.en
dc.contributor.departmentCivil Engineeringen
dc.date.accessioned2014-03-14T20:22:20Zen
dc.date.adate1998-08-10en
dc.date.available2014-03-14T20:22:20Zen
dc.date.issued1998-07-23en
dc.date.rdate1999-08-10en
dc.date.sdate1998-07-23en
dc.description.abstractStudies were conducted to determine the role of bioflocculation in the activated sludge unit processes. Laboratory and full-scale studies revealed that bioflocculation is important in determining settling, dewatering, effluent and digested sludge properties (activated sludge properties) and may be vital to the function of all processes related to the above properties. In these studies, it was shown that divalent cations such as calcium and magnesium improved activated sludge properties, whereas monovalent cations such as sodium, potassium and ammonium ions were detrimental to these properties. The divalent cations promoted bioflocculation through charge bridging mechanisms with negatively charged biopolymers (mainly protein and polysaccharide). It was found that oxidized iron plays a major role in bioflocculation and determination of activated sludge properties through surface interactions between iron and biopolymers. Oxidized iron was effective in removing colloidal biopolymers from solution in coagulation and conditioning studies. The research included experiments evaluating effects of potassium and ammonium ions on settling and dewatering properties; effects of magnesium on settling properties; effects of sodium, potassium, calcium and magnesium on effluent quality; effect of solids retention time on effluent quality; and evaluation of floc properties during aerobic and thermophilic digestion. A floc model is proposed in which calcium, magnesium and iron are important to bioflocculation and the functionality of aeration tanks, settling tanks, dewatering equipment and aerobic or anaerobic digesters. It is shown that activated sludge floc properties affect wastewater treatment efficiency.en
dc.description.degreePh. D.en
dc.identifier.otheretd-63098-18036en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-63098-18036/en
dc.identifier.urihttp://hdl.handle.net/10919/30647en
dc.publisherVirginia Techen
dc.relation.haspartetd.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectbioflocculationen
dc.subjectcationen
dc.subjectbiopolymeren
dc.subjectsoluble microbial producten
dc.subjectproteinen
dc.subjectpolysaccharideen
dc.subjecteffluenten
dc.subjectsettlingen
dc.subjectdewateringen
dc.subjectdigestionen
dc.subjectthermophilicen
dc.titleBioflocculation: Implications for Activated Sludge Properties and Wastewater Treatmenten
dc.typeDissertationen
thesis.degree.disciplineCivil Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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