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DatoValore
TitleIMPROVING PRIMARY TREATMENT OF URBAN WASTEWATER WITH LIME-INDUCED COAGULATION
AbstractThe enhancement of primary treatment efficiency through the coagulation process may yield several advantages, including lower aeration energy in the subsequent biological unit and higher recovery of biogas from sludge digestion. In this work sewage coagulation with lime was studied at pilot plant level, using degritted sewage from the city of Rome. The work aimed at optimising the operating conditions (coagulant dosage or treatment pH, and mixing conditions in the coagulation and flocculation tanks), in order to maximise the efficiency of suspended Chemical Oxygen Demand (COD) removal and to minimise sludge production. Lime dosage optimisation resulted in an optimal treatment pH of 9. Lime addition up to pH 9 may increase COD removal rate in the primary treatment from typical 30-35% of plain sedimentation up to 55-70%. Within the velocity gradients experimented in this work (314-795 s(-1) for the coagulation tank and 13-46 s(-1) for the flocculation tank), mixing conditions did not significantly affect the lime-enhanced process, which seems to be controlled by slow lime dissolution. Sludge produced in the lime-enhanced process settled and compacted easily, inducing an average 36% decrease in sludge volume with respect to plain settling. However excess sludge was produced, which was not accounted for by the amount of suspended solids removed. This is probably due to incomplete dissolution of lime, which may be partially incorporated in the sludge.
SourceAnnali di chimica (Testo stamp.) 94, pp. 399–408
JournalAnnali di chimica (Testo stamp.)
EditorSocieta chimica italiana, Roma, Italia
Year2004
TypeArticolo in rivista
DOI10.1002/adic.200490049
AuthorsMARANI D., RAMADORI R., BRAGUGLIA C.M.
Text42236 2004 10.1002/adic.200490049 ISI Web of Science WOS 000222977400005 IMPROVING PRIMARY TREATMENT OF URBAN WASTEWATER WITH LIME INDUCED COAGULATION MARANI D., RAMADORI R., BRAGUGLIA C.M. CNR IRSA The enhancement of primary treatment efficiency through the coagulation process may yield several advantages, including lower aeration energy in the subsequent biological unit and higher recovery of biogas from sludge digestion. In this work sewage coagulation with lime was studied at pilot plant level, using degritted sewage from the city of Rome. The work aimed at optimising the operating conditions coagulant dosage or treatment pH, and mixing conditions in the coagulation and flocculation tanks , in order to maximise the efficiency of suspended Chemical Oxygen Demand COD removal and to minimise sludge production. Lime dosage optimisation resulted in an optimal treatment pH of 9. Lime addition up to pH 9 may increase COD removal rate in the primary treatment from typical 30 35% of plain sedimentation up to 55 70%. Within the velocity gradients experimented in this work 314 795 s 1 for the coagulation tank and 13 46 s 1 for the flocculation tank , mixing conditions did not significantly affect the lime enhanced process, which seems to be controlled by slow lime dissolution. Sludge produced in the lime enhanced process settled and compacted easily, inducing an average 36% decrease in sludge volume with respect to plain settling. However excess sludge was produced, which was not accounted for by the amount of suspended solids removed. This is probably due to incomplete dissolution of lime, which may be partially incorporated in the sludge. 94 Articolo pubblicato AdC_in_PDF.pdf Articolo in rivista Societa chimica italiana 0003 4592 Annali di chimica Testo stamp. Annali di chimica Testo stamp. Ann. chim. Testo stamp. Annali di chimica. Testo stamp. camillamaria.braguglia BRAGUGLIA CAMILLA MARIA dario.marani MARANI DARIO roberto.ramadori RAMADORI ROBERTO