Tertiary treatment of dairy wastewater applying a microalga-fungus consortium.

This paper aimed to apply filamentous fungi (Penicillium oxalicum and Cunninghamella echinulata), the microalga Tetradesmus obliquus and their co-culture in advanced treatment (tertiary treatment) of cheese whey. The bioremediation process was carried out in agitated flasks and bubble column bioreactors with different concentrations of chemical oxygen demand (COD) (223-1663 mg L-1), total nitrogen (TN) (13-61 mg L-1), and total phosphorus (TP) (3-26 mg L-1). The results obtained in shaken flasks showed a superiority of the consortium compared to the systems with separated species. In this sense, the treatment was carried out in a bubble column reactor, and the consortium formed by the microalga and the fungus C. echinulata showed a greater efficiency (at a light intensity of 100 µmol m-2 s-1), promoting by the symbiosis to reach removal efficiencies of up to 93.7, 78.8 and 93.4% for COD, TN and TP, respectively; meeting Brazilian and European standards for discharge into water bodies. In addition, no pH adjustment was required during the co-culture treatment, demonstrating the buffering effect of using these two types of microorganisms. Therefore, the use of the consortium formed by T. obliquus and C. echinulata as a remediator was highly promising to promote the advanced treatment of cheese whey.

Dairy wastewater needs a polishing treatment stage after secondary treatmentThe microalga-fungus consortium met legislation requirementsCOD, nitrogen and phosphorus were efficiently removed by the consortiumNo pH control was applied during the biological treatment by the consortium.

Mass transfer in aerated culture media combining mixed electrolytes and glucose.

The combined effects of mixed electrolyte species and glucose on oxygen transfer were studied in a bubble column with aqueous solutions. Of particular interest was the presence of electrolytes containing ions which are prone to present solute-solute interactions or to crystallize. Without and at low concentration of glucose (≤ 5 g/L), the increasing concentration of electrolytes (nominal ionic strength: 0-0.43 M), up to a critical value, enhanced the volumetric mass transfer coefficient (kLa) and the availability of specific interfacial area (a), due to the inhibition of bubble coalescence. As the glucose concentration increased (10-40 g/L), the enhancing effects of electrolytes were gradually lost. The glucose interacted with electrolytes, reducing their ability to inhibit coalescence and to enhance the kLa. Salt crystallization occurred independently of the addition of glucose; however, it did not have significant effect on mass transfer. Finally, the changes in physicochemical properties were highly collinear with composition variables.

Definition of Liquid and Powder Cellulase Formulations Using Domestic Wastewater in Bubble Column Reactor.

Raw domestic wastewater was used as a culture medium for cellulase production in a bubble column reactor (6.2 UFP/mL, 64.6 U/L h) using the strain Trichoderma harzianum TRIC03-LPBII. Cellulases presented optimum pH and temperature between 4 and 5 and 50 and 70 °C, respectively. Enzymatic extract was concentrated through ultrafiltration and then a cellulolytic formulation was prepared with the addition of sorbitol (50% w/v) and benzoic acid (0.05% w/v). High cellulase stability of around 100% was reached after 30 days at 4 °C. The concentrated extract was also dried in a spray-dryer with the addition of maltodextrin at 20% (w/v), resulting in powder enzymatic formulation with 85% stability after 60 days. With these characteristics, the liquid and powder cellulase products have potential to be used in different industrial applications.

Simultaneous cellulase production using domestic wastewater and bioprocess effluent treatment - A biorefinery approach.

The production of cellulases using domestic wastewater as an alternative culture medium and reducing the pollutant charge of the resultant effluents were assessed for the first time in this study. Cellulase production was carried out in a bubble column, column-packed bed and stirred tank reactors by Trichoderma harzianum. Maximum cellulase activity and productivity of 31 UFP/mL and 645 UFP/mL.h, respectively were achieved in the bubble column bioreactor system without immobilization. The fermented broth was microfiltrated and ultrafiltrated, leading to a cellulase recovery of 73.5% using a 30 kDa membrane and resulting in a 4.23-fold activity concentration. Chemical oxygen demand and nitrogen concentration were reduced 81.37% and 52.9%, respectively, showing great promise in producing cellulases using domestic wastewater with concomitant development of a medium- to-high added-value process and reduced environmental impact. These results contribute to the development of sustainable bioprocesses approaching a biorefinery concept.

Mechanisms of interaction of chromium with Aspergillus niger var tubingensis strain Ed8.

Experiments were conducted to determine the mechanisms of interaction with chromium of Aspergillus niger var tubingensis strain Ed8 in batch culture and in bioreactor experiments. Results obtained in this work showed that the interaction of A. niger var tubingensis Ed8 with Cr(VI) is based mainly in a reduction process and also, secondly, in a sorption process. Using electron microscopy techniques the ultrathin sections obtained from the mycelium biomass produced by the fungus in batch cultures showed the ability to incorporate Cr intracellulary, into low electron-dense inclusions, but not extracellularly. On the other hand, cultures without Cr(VI) of A. niger var tubingensis Ed8, grown in a bubble column bioreactor, reduced Cr(VI) immediately after repeated addition of this oxyanion; after six loads, 460 mg Cr(VI) was reduced to Cr(III) in 60 h, corresponding to a reduction rate of 2.62 mg Cr(VI)g(-1) dry biomass h(-1).