Enrichment of a K-strategist microbial population able to biodegrade p-nitrophenol in a sequencing batch reactor.
The biological treatment of a high-strength p-nitrophenol (PNP) wastewater in an aerobic Sequencing Batch Reactor (SBR) has been studied. A specific operational strategy was applied with the main aim of developing a K-strategist PNP-degrading activated sludge. The enrichment of a K-strategist microbial population was performed using a non-acclimated biomass coming from a municipal WWTP as inoculum, and following a feeding strategy in which the PNP-degrading biomass was under endogenous conditions during more than 50% of the aerobic reaction phase. Hundred per cent of PNP removal was achieved in the whole operating period with a maximum specific PNP loading rate of 0.26 g PNP g(-1)VSS d(-1). A kinetic characterization of the obtained PNP-degrading population was carried out using respirometry assays in specifically designed batch tests. With the experimental data obtained a kinetic model including substrate inhibition has been used to describe the time-course of the PNP concentration and specific oxygen uptake rate (SOUR), simultaneously. The kinetic parameters obtained through optimization, validated with an additional respirometric test, were k(max)=1.02 mg PNP mg(-1) COD d(-1), K(s)=1.6 mg PNP L(-1) and K(i)=54 mg PNP L(-1). The values obtained for the K(s) and k(max) are lower than those reported in the literature for mixed populations, meaning that the biomass is a K-strategist type, and therefore demonstrating the success of the operational strategy imposed to obtain such a K-strategist population. Moreover, our measured K(i) value is higher than those reported by most of the bibliographic references; therefore the acclimated activated sludge used in this work was evidently more adapted to PNP inhibition than the other reported cultures.
Martín-Hernández
Mariángel
M
Department of Chemical Engineering, Escola Tècnica Superior d'Enginyeria (ETSE), Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain.
Carrera
Julián
J
Pérez
Julio
J
Suárez-Ojeda
María Eugenia
ME
D001419:Bacteria / Q000378:metabolism*; D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology; D008954:Models, Biological; D009596:Nitrophenols / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*; D018508:Water Purification / Q000295:instrumentation* / Q000379:methods
D009596:Nitrophenols; D014874:Water Pollutants, Chemical; C024836:4-nitrophenol