Patrícia Angélica Vieira

Biodegradation of diesel oil and gasoline contaminated effluent employing intermittent aeration.

We examined the effects of aeration interval and agitation speed in an effort to optimize the biodegradation of effluent contaminated with diesel oil and gasoline. The biodegradation process employed a C(1) mixed culture and intermittent aeration. Optimization was performed using central composite design (CCD). The independent variables were aeration interval (X(1)) and agitation speed (X(2)) and the dependent variable was the degree of removal of total petroleum hydrocarbons (TPH). The optimum aeration interval (33h) and agitation speed (110rpm) resulted in TPH removal of 75.9% after 3 days. Five hydrocarbons classes were identified using gas chromatography: paraffins, isoparaffins, olefins, naphthenics, and aromatics. The following reductions were observed: 91.8% for the paraffins, 83.3% for the isoparaffins, 80.9% for the olefins, 39.3% for the naphthenics, and 80.9% for the aromatics. In comparative studies performed under constant aeration (CA), without aeration (WA), and intermittent aeration (IA) conditions, intermittent aeration resulted in the highest TPH removals, with 90% reduction after 22 days. Under the IA condition, the degradation percentages were 99.6% for the paraffins, 94% for the isoparaffins, 95.4% for the olefins, 70.8 for the naphthenics, and 83.4% for the aromatics.

Sedimentation of mixed cultures using natural coagulants for the treatment of effluents generated in terrestrial fuel distribution terminals.

This study evaluated the use of natural coagulants (Moringa oleifera and chitosan) under different conditions with a mixed culture (C1 mixed culture). This culture was used for the biodegradation of hydrocarbons present in the effluent from fuel distribution terminals contaminated with diesel oil and gasoline. The biodegradation was evaluated by two central composite design (CCD) experiments: the first with varying concentrations of Moringa oleifera (MO), drying temperatures (TE) and seed drying times (TI); the second with varying concentrations of chitosan and the hydrochloric acid in which chitosan had been solubilized. The responses monitored in the CCD experiments included the sludge volume index (SVI), the turbidity removal (TR) and the specific rate of oxygen uptake (SOUR). Subsequently, the biodegradation was monitored in a sequencing batch reactor (SBR) under the optimal conditions obtained for each CCD experiment. The results indicated that the best coagulant was chitosan solubilized in 0.25 N HCl at a concentration of 50mg/L. Within five cycles with chitosan as a coagulant, the total organic carbon (TOC) removal increased from 77±1.0% to 82±0.5%, the volatile suspended solids (VSS) increased from 1.4±0.3 to 2.25±0.3 g/L and the total petroleum hydrocarbon (TPH) removal increased from 75±1.0% to 81±0.5%.

The sedimentation of mixed cultures used in the treatment of effluents generated from terrestrial fuel distribution terminals.

This study evaluated the use of coagulants (ferric chloride and aluminium sulphate) and an anionic polyelectrolyte (polyacrylamide) in the settling of a mixed culture (C(1)), which was used for the biodegradation of hydrocarbons present in effluent of fuel distribution terminals contaminated with diesel oil and gasoline. In preliminary investigations conducted in jar tests, the optimal concentrations of coagulant were obtained for further studies. After preliminary tests, biodegradation was evaluated in a central composite design (CCD) with varying concentrations of ferric chloride and polyelectrolyte. Ferric chloride and polyelectrolyte concentrations ranged from 77.9 to 422.12 mg/L and 0.0 to 3.2mg/L, respectively. The responses monitored in CCD experiments included the sludge volume index (SVI), turbidity, and specific rate of oxygen uptake (SOUR), where values of 100mL/g, 840 nephelometric turbidity unit (NTU) and 58 mg O(2)/gh, respectively, were obtained. Subsequently, biodegradation was monitored in a sequencing batch reactor (SBR). The results indicated that within five cycles, total petroleum hydrocarbon (TPH) removal increased from 75 ± 1.0% to 79 ± 0.5%, while the volatile suspended solids (VSS) increased from 1300 to 2500 mg/L.

Biopolymer production using fungus Mucor racemosus Fresenius and glycerol as substrate

This study evaluated extracellular production of biopolymer using fungus Mucor racemosus Fresenius and glycerol as a carbon source. Initially employing conical flasks of 500 mL containing 100 mL of cultive medium with 0.18 ± 0.03 g.L–1 of microorganisms, the results showed that the best conditions of the variables studied were: initial concentration of glycerol 50 g.L–1, fermentation time of 96 h, inoculum cultivation time of 120 h, and aeration in two stages–the first 24 hours without aeration and 72 hours fermentation with aeration of 2 vvm and 2 g.L–1 of yeast extract. The experiments conducted in a Biostat B fermenter with a 2.0 L capacity that contained 1.0 L of medium showed production of 16.35 g.L–1 gum formed and 75% glycerol consumption. These conditions produced a biopolymer with the molecular weight and total sugar content of 4.607×106 g.mol–1 (Da) and 89.5%, respectively.

Experimental Investigation about Rinse Water Consumption of a CIP Process Applied to a Shell and Tube Exchanger

This paper focused the CIP (clean in place) rinse stage, typically applied to the food industry. The dynamic behavior of residuals removal kinetics was studied, to obtain mathematical models that describe adequately the system. The optimization of water, detergent, etc., is the next goal. The obtained results show that the temperature influence can be neglected in comparison with the rinse water flow rate considering the cleaning process. The systems dynamics are non linear and were adequately represented by 1st order plus dead time transfer functions. The flow models obtained with this paper were validated versus experimental data and the results were close with respect to the last ones.