title: Improvement of municipal wastewater pretreatment by direct membrane filtration.
abstract: The high content of particulate matter in municipal wastewater hinders the conventional anaerobic treatments at psychrophilic temperatures. The hydrolysis of the particulate chemical oxygen demand (pCOD) could be the limiting step under these conditions. Therefore, new pretreatments or improved conventional pretreatments are needed in order to separate pCOD. In this work, direct membrane filtration of municipal wastewater, using an ultrafiltration membrane, was investigated. This intensive pretreatment, which aims to separate soluble chemical oxygen demand (sCOD) and to concentrate pCOD, together with anaerobic treatments of both streams at psychrophilic and mesophilic conditions respectively, could be an alternative to the conventional activated sludge process. The obtained results show a removal yield of 24.9% of the total solids (TS) and 45% of total chemical oxygen demand (tCOD), obtaining a permeate free of suspended solids. This physical removal implies the accumulation of solids inside the membrane tank, reaching the values of 45.4 and 4.4 g/L of TS in the sedimentation and filtration sections, respectively. The membrane operated with filtration, backwashing cycles and continuous gas sparging, with a permeate flux predominantly around 10 L/(m2h). The results show the viability of the technology to concentrate pCOD and so to improve energy recovery from municipal wastewater.
authors.affiliation: a Department of Chemical Engineering and Environmental Technology , University of Valladolid , Valladolid , Spain.
authors.forename: Thiago A
authors.identifier: http://orcid.org/0000-0002-3367-2255
authors.initials: TA
authors.lastname: Nascimento
authors.affiliation: a Department of Chemical Engineering and Environmental Technology , University of Valladolid , Valladolid , Spain.
authors.forename: Fanny R
authors.identifier: http://orcid.org/0000-0002-2289-3618
authors.initials: FR
authors.lastname: Mejía
authors.affiliation: a Department of Chemical Engineering and Environmental Technology , University of Valladolid , Valladolid , Spain.
authors.forename: Fernando
authors.identifier: http://orcid.org/0000-0003-1972-3244
authors.initials: F
authors.lastname: Fdz-Polanco
authors.affiliation: a Department of Chemical Engineering and Environmental Technology , University of Valladolid , Valladolid , Spain.
authors.forename: Mar
authors.identifier: http://orcid.org/0000-0002-8176-4381
authors.initials: M
authors.lastname: Peña Miranda
mesh_terms: D000693:Anaerobiosis; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D005374:Filtration; D012722:Sewage; D014865:Waste Disposal, Fluid; D062065:Wastewater; D018508:Water Purification / Q000379:methods*
chemical_list: D012722:Sewage; D062065:Wastewater
keywords: Direct membrane filtration; anaerobic digestion; gas sparging; membrane cleaning; wastewater solids concentration