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Novel biotechnologies to valorize waste emissions are based on the use of specialized microbial groups that produce different compounds of industrial interest. On this scenario, the retention of such specific microorganisms in the system is of critical interest; however, the potential limitations of working with simplified cultures in a competitive open environment are neither fully explored nor well understood. In this work, a series of biofilters treating methanol vapors coupled with heterologous endochitinase production were used to evaluate the performance of a specialized microbial population during a typical open‐to‐environment operation. The biofilters were inoculated with a transformed strain of Pichia pastoris and were operated identically for about 90 days. The results showed that the biofiltration performance became diverse with time in terms of the elimination capacity (EC) shifting from a variation coefficient of 1.5% (EC = 274 ± 24, 279 ± 5, and 281.9 ± 25 g/[m3 h]) at the beginning of the operation to 33% (EC = 297 ± 9, 338 ± 7, and 341 ± 2 g/[m3 h]) at the end of operation. Epifluorescence analysis and cloning‐sequencing suggested that P. pastoris remained as the dominant microorganism of methanol degradation, whereas diverse airborne bacteria, including Ochrobactrum spp. and Klebsiella oxytoca, played a secondary role possibly associated with the consumption of intermediates. Overall, this study found that low diversity systems operated under non‐sterile conditions could be susceptible to contamination with external microorganisms causing a diversifying behavior at the performance and microbial community levels. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2715, 2019

A novel technology was developed for the treatment of a stainless steel wastewater, which contains high nitrate concentration (6.8 g N-NO3 –/L), acidic pH (pH 3.3), and high concentration of metals. Denitrification was performed in an anaerobic swirling fluidized-bed membrane bioreactor (ASFMBR) with synthetic and real wastewater. The treatment concept was also integrated by a precipitation column in which high recirculation of the alkalinity produced from denitrification was introduced to drive the precipitation and recovery of metals present in the wastewater. The novel reactor configuration achieved high nitrate removal (>94%), and the acidic pH was efficiently neutralized in the reactor by recycling the alkalinity produced from denitrification. More than 40% of the metals present in the industrial wastewater was recovered. Membrane fouling was avoided by the hydrodynamic regime established in the ASFMBR. The treatment concept is promising to achieve an efficient removal of nitrate and recovery of metals from metallurgic wastewater.

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