Simulation of composition and mass transfer behaviour of a membrane biofilm reactor using a two dimensional multi-species counter-diffusion model

Adaptive Evolution Laws of Biofilm under Emerging Pollutant-Induced Stress: Community Assembly-Driven Structure Response

The widely used biofilm process in advanced wastewater treatment is currently challenged by numerous exotic emerging pollutants (EPs), and the underlying principle of the challenge is the adaptive evolution laws of biofilm under EP stress. However, there is still a knowledge gap in exploration of the biofilm adaptive evolution theory. Herein, we comprehensively analyzed the morphological variation, community succession, and assembly mechanism of biofilms to report the mechanism underlying their adaptive evolution under sulfamethoxazole and carbamazepine stress for the first time. The ecological role of the dominant species was driven as a pioneer and assembly hub by EP stress, and the deterministic processes indicated the functional basis of the transformation. In addition, the characteristic responses of dispersal limitation and homogenizing dispersal adequately revealed the assembly pathways in adaptive evolution and the resulting structural variation. Therefore, the "interfacial exposure-structural variation-mass transfer feedback" mechanism was inferred to underly the adaptive evolution process of biofilms. Overall, this study highlighted the internal drivers of the adaptive evolution of the biofilm at the phylogenetic level and deepened our understanding of the mechanism of biofilm development under EP stress in advanced wastewater purification.

"Electroactive biofilms: how microbial electron transfer enables bioelectrochemical applications"

Microbial biofilms are ubiquitous. In marine and freshwater ecosystems, microbe–mineral interactions sustain biogeochemical cycles, while biofilms found on plants and animals can range from pathogens to commensals. Moreover, biofouling and biocorrosion represent significant challenges to industry. Bioprocessing is an opportunity to take advantage of biofilms and harness their utility as a chassis for biocommodity production. Electrochemical bioreactors have numerous potential applications, including wastewater treatment and commodity production. The literature examining these applications has demonstrated that the cell–surface interface is vital to facilitating these processes. Therefore, it is necessary to understand the state of knowledge regarding biofilms’ role in bioprocessing. This mini-review discusses bacterial biofilm formation, cell–surface redox interactions, and the role of microbial electron transfer in bioprocesses. It also highlights some current goals and challenges with respect to microbe-mediated bioprocessing and future perspectives.

Study on the effect of new type of suspended carrier on oxygen mass transfer characteristics

Based on the characteristic that the air can form a vortex around the carrier after passing through the suspended carrier, a new layered fan-like carrier and a wave multi-channel carrier were prepared by designing the spatial structure of the suspension carrier and combining 3D printing technology. Compared with commercially available multi-faceted hollow sphere carrier, clear water oxygenation experiment was carried out in a transparent organic glass reactor, and the aeration volumetric flow rate was 0.28, 0.42, 0.56, 0.70, and 0.84 VVM, respectively. The results show that the growth rate of dissolved oxygen, the saturation value of dissolved oxygen, and the oxygen mass transfer coefficient in the new type of carrier reactor are higher than those of commercially available multi-faceted hollow spheres and blank reactors at various aeration intensities. Under the condition of aeration volumetric flow rate at 0.56 VVM, the reactor can reach dissolved oxygen saturation at a faster rate of dissolved oxygen growth. Combined with the FLUENT numerical simulation and sewage treatment experiments, it is proved that changing the spatial structure of the carrier can accelerate the reoxygenation of the water body, increase the value of dissolved oxygen saturated in the water, and create ideal mass transfer conditions for the MBBR (moving bed biofilm reactor).