Examinando por Autor "Rajhi, Hayfa"

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Anaerobic biodegradation of 2,4,6-trichlorophenol in expanded granular sludge bed and fluidized bed biofilm reactors bioaugmented with Desulfitobacterium spp.
(IWA Publishing, 2011-07-01) Puyol, Daniel; Rajhi, Hayfa; Mohedano, Angel F; Rodríguez, Juan José; Sanz, José Luis
The biodegradation of 2,4,6-trichlorophenol (246TCP) was studied using expanded granular sludge bed (EGSB) reactors and a fluidized bed biofilm reactor (FBBR) filled with activated carbon. One of the EGSB reactor and the FBBR were bioaugmented with Desulfitobacterium strains. 246TCP loading rate was gradually incremented from 10 to 250 mg L−1 day−1. The main pathway of dechlorination was in ortho-position, generating 4-chlorophenol and 2,4-dichlorophenol. The maintenance of both COD degradation efficiency (higher than 80%) and methanogenic efficiency (between 0.3 and 0.6 g CH4–COD g−1 COD consumed) in EGSB reactor implies a great stability of the process. Through isotherm studies in FBBR, it could be deduced that around 52% of 246TCP was completely dechlorinated, whereas the adsorption involved around 16%. By means of FISH studies it was proved that the methanogenic Archaea community was maintained in the bioaugmented EGSB reactor, whereas in the FBBR this community was gradually developed until reaching stability. Desulfitobacterium community was also maintained in the reactors, although D. chlororespirans proportion rise in the FBBR at the higher 246TCP loading rates, implying that this species can withstand the 246TCP toxicity better than D. hafniense
Anaerobic treatment of wastewater from used industrial oil recovery
(SCI, 2012-02-24) García-Mancha, Nuria; Puyol Santos, Daniel; Monsalvo García, Víctor Manuel; Rajhi, Hayfa; Fernandez Mohedano, Ángel; Rodríguez Jiménez, Juan José
BACKGROUND: This work is focused on the anaerobic biodegradation of wastewater from used industrial oils (UIO) recovery using a bench-scale expanded granular sludge bed reactor (EGSB) at room temperature. RESULTS: Biodegradability tests showed that this wastewater can be partially biodegraded under anaerobic conditions at mesophilic temperature. Low concentrations of wastewater caused an incremented specific activity of the acetoclastic and the hydrogenotrophic methanogens. Anaerobic biodegradation at room temperature is feasible at organic loading rates (OLR) lower than 5.5 g COD L−1 d−1. A further increase of the OLR to around 10 g COD L−1 d−1 had a detrimental effect on the system performance, making it necessary to work at mesophilic conditions. CONCLUSION: Anaerobic treatment using an EGSB reactor is a feasible option for treating UIO wastewater. Long-term treatment caused a specialization of the granular sludge, modifying substantially its microbial composition. Methane production was even stimulated by the addition of UIO wastewater at low concentrations. Copyright © 2012 Society of Chemical Industry