Biofiltration of a styrene/acetone vapor mixture in two reactor types under conditions of styrene overloading

This aim of study was to compare the performance of a biofilter (BF) and trickle bed reactor (TBR) under increased styrene loading with a constant acetone load, 2 gc/m3/h. At styrene loading rates up to 30 gc/m3/h, the BF showed higher styrene removal than TBR. However, the BF efficiency started to drop beyond this threshold loading and could never reach steady state, whereas the TBR continued to yield a 50% styrene removal. The acetone removal remained constant (93-98%) in both the reactors at any styrene loading. Once the overloading was lifted, the BF recovered within 26 min, whereas the TBR efficiency bounced back only to 95%, gradually returning to complete removal only in 10 h.

Respirometry kinetics of phenol oxidation by Comamonas testosteroni Pb50 under various conditions of nutritional stress

Kinetics of phenol biodegradation using suspended biomass of Comamonas testosteroni Pb50 (monoculture) was measured under conditions of nutrient abundance, limitation, and prolonged cell starvation in a fed-batch reactor, with phenol being the sole carbon and energy source. The pre-washed cells were applied for measurement of the phenol and oxygen uptake rates at varied starting phenol concentrations with the kinetic parameters calculated using the Haldane model. The results revealed that nutrient limitation significantly suppressed the maximum value of exogenous respiration rate while the endogenous respiration rate, affinity and tolerance to phenol increased. By contrast, cell starvation resulted in a drop of both the exogenous and endogenous respiration rates by an order of magnitude.

Modelling the steady state and dynamic conditions of a biotrickling filter treating styrene and acetone in air

The aim of this work was the study a trickling biofilter, where water was circulated throughout the bed. In the first steady state experiment, the packing materials used were 25mm Pall rings. The airflow rate was increased gradually and the concentration of styrene in the air stream was held constant. In the second experiment, 15mm Pall rings were used. In this case, the feed contained both styrene and a small amount of acetone. The concentration of acetone and the air flow rate were kept constant, but the styrene inlet concentration was increased. The concentrations were measured at the input, and also at an intermediate and the outlet position in the biotrickling filter to determine the concentration profile along the reactor. Using the values of coefficient of determination (R²) and the coefficient of variation of the fitted constant as criteria, a zero order model with diffusional limitation was chosen as the best representation of the data. Then a further, third, set of experiments were done at unsteady state, using step changes of the inlet concentration levels of both styrene and acetone at a steady air flow-rate . Inlet and outlet concentrations were measured as a function of time and the results were adequately described using a simple first order model.

Start-up and performance characteristics of a trickle bed reactor degrading toluene

The objective of this work was to evaluate toluene degradation in a trickle bed reactor when the loading was carried out by changing the air flow rate. The biofiltration system was inoculated with a mixed microbial population, adapted to degradation of hydrophobic compounds. Polypropylene high flow rings were used as a packing material. The system was operated for a period of 50 days at empty bed residence times ranging from 106s to 13s and with a constant inlet concentration of toluene of 100 mg.m-3. The reactor showed high removal efficiency at higher contact times and increasing elimination capacity with higher air-flow rates. The highest EC value reached was 9.8 gC.m-3.h-1 at EBRT = 13s. During the experiment, the consumption of NaOH solution was also measured. No significant variation of this value was found and an average value of 3.84 mmol of NaOH per gram of consumed carbon was recorded.

Impact of biocatalyst and moisture content on toluene/xylene mixture biofiltration

O objetivo deste trabalho foi determinar a influência da inoculação microbiana na eficiência da degradação. Três biofiltros foram utilizados no tratamento do gás residuais. Uma mistura de composto e perlite na proporção (8:2) serviu como o material de empacotamento dos biofiltros. Um biofiltro foi inoculado com uma população microbial selecionada. O segundo permaneceu inoculado com a população microbiana natural presente no composto. O terceiro biofiltro foi inoculado com microrganismos selecionados com o material de empacotam previamente esterilizado. A capacidade de degradação do biofiltro não inoculado começou a se reduzir após 18 dias, enquanto que a eficiência da remoção do biofiltro se manteve estável. O biofiltro estéril não apresentou nenhuma eficiência na remoção dos compostos tóxicos. O grau de umidade do material e a característica do empacotamento foi avaliado. Os resultados mostraram uma dependência significativa da eficiência de degradação com o teor de umidade do material de empacotamento , a maior elevada remoção foi observada com 70 % de índice de umidade.