Polishing of Anaerobic Secondary Effluent and Symbiotic Bioremediation of Raw Municipal Wastewater by Chlorella Vulgaris

Handle URI:
http://hdl.handle.net/10754/609122
Title:
Polishing of Anaerobic Secondary Effluent and Symbiotic Bioremediation of Raw Municipal Wastewater by Chlorella Vulgaris
Authors:
Cheng, Tuoyuan ( 0000-0001-5170-6546 )
Abstract:
To assess polishing of anaerobic secondary effluent and symbiotic bioremediation of primary effluent by microalgae, bench scale bubbling column reactors were operated in batch modes to test nutrients removal capacity and associated factors. Chemical oxygen demand (COD) together with oil and grease in terms of hexane extractable material (HEM) in the reactors were measured after batch cultivation tests of Chlorella Vulgaris, indicating the releasing algal metabolites were oleaginous (dissolved HEM up to 8.470 mg/L) and might hazard effluent quality. Ultrafiltration adopted as solid-liquid separation step was studied via critical flux and liquid chromatography-organic carbon detection (LC-OCD) analysis. Although nutrients removal was dominated by algal assimilation, nitrogen removal (99.6% maximum) was affected by generation time (2.49 days minimum) instead of specific nitrogen removal rate (sN, 20.72% maximum), while phosphorus removal (49.83% maximum) was related to both generation time and specific phosphorus removal rate (sP, 1.50% maximum). COD increase was affected by cell concentration (370.90 mg/L maximum), specific COD change rate (sCOD, 0.87 maximum) and shading effect. sCOD results implied algal metabolic pathway shift under nutrients stress, generally from lipid accumulation to starch accumulation when phosphorus lower than 5 mg/L, while HEM for batches with initial nitrogen of 10 mg/L implied this threshold around 8 mg/L. HEM and COD results implied algal metabolic pathway shift under nutrients stress. Anaerobic membrane bioreactor effluent polishing showed similar results to synthetic anaerobic secondary effluent with slight inhibition while 4 symbiotic bioremediation of raw municipal wastewater with microalgae and activated sludge showed competition for ammonium together with precipitation or microalgal luxury uptake of phosphorus. Critical flux was governed by algal cell concentration for ultrafiltration membrane with pore size of 30 nm, while ultrafiltration membrane rejected most biopolymers (mainly polysaccharides). Further research would focus on balancing cell growth, specific nutrients removal, and specific COD change by utilizing rotating biological contactor.
Advisors:
Leiknes, TorOve ( 0000-0003-4046-5622 )
Committee Member:
Ghaffour, Noreddine ( 0000-0003-2095-4736 ) ; Wei, Chun-Hai
KAUST Department:
Biological and Environmental Sciences and Engineering (BESE) Division; Environmental Science and Engineering Program
Program:
Environmental Science and Engineering
Issue Date:
May-2016
Type:
Thesis
Appears in Collections:
Environmental Science and Engineering Program; Theses; Biological and Environmental Sciences and Engineering (BESE) Division

Full metadata record

DC FieldValue Language
dc.contributor.advisorLeiknes, TorOveen
dc.contributor.authorCheng, Tuoyuanen
dc.date.accessioned2016-05-12T06:10:34Zen
dc.date.available2016-05-12T06:10:34Zen
dc.date.issued2016-05en
dc.identifier.urihttp://hdl.handle.net/10754/609122en
dc.description.abstractTo assess polishing of anaerobic secondary effluent and symbiotic bioremediation of primary effluent by microalgae, bench scale bubbling column reactors were operated in batch modes to test nutrients removal capacity and associated factors. Chemical oxygen demand (COD) together with oil and grease in terms of hexane extractable material (HEM) in the reactors were measured after batch cultivation tests of Chlorella Vulgaris, indicating the releasing algal metabolites were oleaginous (dissolved HEM up to 8.470 mg/L) and might hazard effluent quality. Ultrafiltration adopted as solid-liquid separation step was studied via critical flux and liquid chromatography-organic carbon detection (LC-OCD) analysis. Although nutrients removal was dominated by algal assimilation, nitrogen removal (99.6% maximum) was affected by generation time (2.49 days minimum) instead of specific nitrogen removal rate (sN, 20.72% maximum), while phosphorus removal (49.83% maximum) was related to both generation time and specific phosphorus removal rate (sP, 1.50% maximum). COD increase was affected by cell concentration (370.90 mg/L maximum), specific COD change rate (sCOD, 0.87 maximum) and shading effect. sCOD results implied algal metabolic pathway shift under nutrients stress, generally from lipid accumulation to starch accumulation when phosphorus lower than 5 mg/L, while HEM for batches with initial nitrogen of 10 mg/L implied this threshold around 8 mg/L. HEM and COD results implied algal metabolic pathway shift under nutrients stress. Anaerobic membrane bioreactor effluent polishing showed similar results to synthetic anaerobic secondary effluent with slight inhibition while 4 symbiotic bioremediation of raw municipal wastewater with microalgae and activated sludge showed competition for ammonium together with precipitation or microalgal luxury uptake of phosphorus. Critical flux was governed by algal cell concentration for ultrafiltration membrane with pore size of 30 nm, while ultrafiltration membrane rejected most biopolymers (mainly polysaccharides). Further research would focus on balancing cell growth, specific nutrients removal, and specific COD change by utilizing rotating biological contactor.en
dc.language.isoenen
dc.subjectEffluent Polishingen
dc.subjectPhycoremediationen
dc.subjectChlorella Vulgarisen
dc.subjectUltrafiltrationen
dc.subjectOil and Greaseen
dc.titlePolishing of Anaerobic Secondary Effluent and Symbiotic Bioremediation of Raw Municipal Wastewater by Chlorella Vulgarisen
dc.typeThesisen
dc.contributor.departmentBiological and Environmental Sciences and Engineering (BESE) Divisionen
dc.contributor.departmentEnvironmental Science and Engineering Programen
thesis.degree.grantorKing Abdullah University of Science and Technologyen_GB
dc.contributor.committeememberGhaffour, Noreddineen
dc.contributor.committeememberWei, Chun-Haien
thesis.degree.disciplineEnvironmental Science and Engineeringen
thesis.degree.nameMaster of Scienceen
dc.person.id132585en
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