Integrated processes for produced water polishing: Enhanced flotation/sedimentation combined with advanced oxidation processes.
In this study, bench scale dissolved air flotation (DAF) and settling processes have been studied and compared to a novel flotation technology based on the use of glass microspheres of limited buoyancy and its combination with conventional DAF, (Enhanced DAF or E-DAF). They were evaluated as pretreatments for advanced oxidation processes (AOPs) to polish produced water (PW) for reuse purposes. Settling and E-DAF without air injection showed adequate turbidity and oil and grease (O&G) removals, with eliminations higher than 87% and 90% respectively, employing 70 mg L-1of FeCl3and 83 min of settling time, and 57.9 mg L-1of FeCl3, 300 mg L-1of microspheres and a flocculation rate of 40 rpm in the E-DAF process. A linear correlation was observed between final O&G concentration and turbidity after E-DAF. In order to polish the O&G content of the effluent even further, to remove soluble compounds as phenol and to take advantage of residual iron after these treatments, Fenton and photo-Fenton reactions were essayed. After 6 h of the Fenton reaction at pH 3, the addition of 1660 mg L-1of H2O2and 133 mg L-1of iron showed a maximum O&G elimination of 57.6% and a phenol removal up to 80%. Photo-Fenton process showed better results after 3 h, adding 600 mg L-1of H2O2and 300 mg L-1of iron, at pH 3, with a higher fraction of elimination of the O&G content (73.7%) and phenol (95%) compared to the conventional Fenton process.
R&D Department, Acciona Agua S.A.U, Parc de Negocis Mas Blau II, Avda. de les Garrigues, 22, 08820, El Prat de Llobregat, Barcelona, Spain; Departament d' Enginyeria Química, Universitat Rovira i Virgili, Av Països Catalans 26, 43007, Tarragona, Spain.
Silvia
S
Jiménez
R&D Department, Acciona Agua S.A.U, Parc de Negocis Mas Blau II, Avda. de les Garrigues, 22, 08820, El Prat de Llobregat, Barcelona, Spain.
María M
MM
Micó
R&D Department, Acciona Agua S.A.U, Parc de Negocis Mas Blau II, Avda. de les Garrigues, 22, 08820, El Prat de Llobregat, Barcelona, Spain.
Marina
M
Arnaldos
R&D Department, Acciona Agua S.A.U, Parc de Negocis Mas Blau II, Avda. de les Garrigues, 22, 08820, El Prat de Llobregat, Barcelona, Spain.
Enrique
E
Ferrero
R&D Department, Acciona Agua S.A.U, Parc de Negocis Mas Blau II, Avda. de les Garrigues, 22, 08820, El Prat de Llobregat, Barcelona, Spain.
Jorge J
JJ
Malfeito
Departament d' Enginyeria Química, Universitat Rovira i Virgili, Av Països Catalans 26, 43007, Tarragona, Spain.
Francisco
F
Medina
Departament d' Enginyeria Química, Universitat Rovira i Virgili, Av Països Catalans 26, 43007, Tarragona, Spain. Electronic address: sandra.contreras@urv.cat.
Sandra
S
Contreras
D002712:Chlorides / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry; D005427:Flocculation; D005898:Glass; D006861:Hydrogen Peroxide / Q000737:chemistry; D008863:Microspheres; D009821:Oils / Q000737:chemistry; D010084:Oxidation-Reduction; D010636:Phenols / Q000302:isolation & purification; D059027:Recycling; D014865:Waste Disposal, Fluid / Q000379:methods; D062065:Wastewater / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis; D018508:Water Purification / Q000379:methods*
D002712:Chlorides; D005290:Ferric Compounds; D006861:Hydrogen Peroxide; D009821:Oils; D010636:Phenols; D062065:Wastewater; D014867:Water; D014874:Water Pollutants, Chemical; C024555:ferric chloride
Fenton; Microspheres; Oil and grease; Phenol; Photo-Fenton; Turbidity