title: 2,4-Dichlorophenol removal in a solid-liquid two phase partitioning bioreactor (TPPB): kinetics of absorption, desorption and biodegradation.
abstract: The applicability of a sequencing batch two phase partitioning bioreactor (TPPB) to the biodegradation of a highly toxic compound, 2,4-dichlorophenol (DCP) (EC(50)=2.3-40 mgL(-1)) was investigated. A kinetic study of the individual process steps (DCP absorption into the polymer, desorption and biodegradation) was performed and, based on favourable absorption/desorption characteristics (DCP diffusivity of 6.6×10(-8)cm(2)s(-1)), the commercial polymer Tone P787 (Dow Chemical), was utilized as the sequestering phase for TPPB operation. Batch kinetic biodegradation tests were performed in both single- and two-phase modes, and the Haldane equation kinetic parameters were estimated (k=1.3×10(-2) mgDCP mgVSS(-1)h(-1), K(I)=35 mgDCPL(-1) and K(s)=18 mgDCPL(-1)), confirming the highly toxic nature of DCP. Consistent with these findings, operation of the single-phase system showed that for an initial DCP concentration of 130 mg L(-1) the biomass was completely inhibited and DCP was not degraded, while the two-phase system achieved near-complete DCP removal. In sequencing batch mode the TPPB had a removal efficiency of 91% within 500 min for a feed of 320 mg L(-1), which exceeds the highest concentration previously degraded. These results have confirmed the effectiveness of the use of small amounts (5%, v/v) of inexpensive commercial polymers as the partitioning phase in TPPB reactors for the treatment of a highly toxic substrate at influent loads that are prohibitive for conventional single-phase operation, and suggest that similar detoxification of wastewater influents is achievable for other target cytotoxic substrates.
authors.affiliation: Water Research Institute, C.N.R., Via Salaria km 29, 300 C.P. 10, 00015 Monterotondo Stazione, Rome, Italy. tomei@irsa.cnr.it
authors.forename: M Concetta
authors.initials: MC
authors.lastname: Tomei
authors.forename: M Cristina
authors.initials: MC
authors.lastname: Annesini
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Daugulis
mesh_terms: D000042:Absorption; D061249:Batch Cell Culture Techniques; D001673:Biodegradation, Environmental; D018533:Biomass; D019149:Bioreactors; D002733:Chlorophenols / Q000302:isolation & purification*; D007700:Kinetics; D010100:Oxygen / Q000378:metabolism; D044367:Phase Transition; D012995:Solubility
chemical_list: D002733:Chlorophenols; C004762:2,4-dichlorophenol; D010100:Oxygen