Succession of microorganisms in a plate-type air treatment biofilter during filtration of various volatile compounds

A review on biofiltration techniques: Recent advancements in the removal of volatile organic compounds and heavy metals in the treatment of polluted water

Good quality of water determines the healthy life of living beings on this earth. The cleanliness of water was interrupted by the pollutants emerging out of several human activities. Industrialization, urbanization, heavy population, and improper disposal of wastes are found to be the major reasons for the contamination of water. Globally, the inclusion of volatile organic compounds (VOCs) and heavy metals released by manufacturing industries, pharmaceuticals, and petrochemical processes have created environmental issues. The toxic nature of these pollutants has led researchers, scientists, and industries to exhibit concern towards the complete eradication of them. In this scenario, the development of wastewater treatment methodologies at low cost and in an eco-friendly way had gained importance at the international level. Recently, bio-based technologies were considered for environmental remedies. Biofiltration based works have shown a significant result for the removal of volatile organic compounds and heavy metals in the treatment of wastewater. This was done with several biological sources such as bacteria, fungi, algae, plants, yeasts, etc. The biofiltration technique is cost-effective, simple, biocompatible, sustainable, and eco-friendly compared to conventional techniques. This review article provides deep insight into biofiltration technologies engaged in the removal of volatile organic compounds and heavy metals in the wastewater treatment process.

Performance and fungal diversity of bio-trickling filters packed with composite media of polydimethylsiloxane and foam ceramics for hydrophobic VOC removal

Bio-trickling filters (BTFs) can be used for the treatment of hydrophobic VOC-contaminated air. To improve treatment performance, two novel polydimethylsiloxane (PDMS) packing media were produced and trialled in BTFs inoculated with Cladophialophora fungus. The BTF packed with PDMS/foam ceramic composite filler showed superior performance: rapid start-up within 3 days, rapid restart within 7 days after starvation for 1 month, a maximum toluene elimination capacity (EC) of 264.4 g m^-3·h^-1 at an empty bed residence time of 10 s, and a pressure drop that was controllable by adjusting the nutrient supply regime. High-throughput sequencing was used to analyse the effect of spatial position on the microbial communities in the top and bottom filler layers. Meanwhile, by investigating the EC in the vertical direction of the BTF, spatial heterogeneity in the fungal degradation of a hydrophobic VOC was preliminarily explored.

Evaluation of Immobilization of Selected Peat-Isolated Yeast Strains of the Species Candida albicans and Candida subhashii on the Surface of Artificial Support Materials Used for Biotrickling Filtration

The paper describes the process of n-butanol abatement by unicellular fungi, able to deplete n-butanol content in gas, by using n-butanol as source of carbon. Isolated and identified fungi species Candida albicans and Candida subhashii were subjected to a viability process via assimilation of carbon from hydrophilic and hydrophobic compounds. The isolates, which exhibited the ability to assimilate carbon, were immobilized on four different types of artificial support materials used for biotrickling filtration. Application of optical microscopy, flow cytometry and the tests employing propidium iodide and annexin V revealed viability of the fungi isolated on support materials’ surfaces at the average level of 95%. The proposed method of immobilization and its evaluation appeared to be effective, cheap and fast. Based on performed comparative analyses, it was shown that polyurethane foam and Bialecki rings (25 × 25) could be attractive support materials in biotrickling filtration.

Performance and microbial community evolution of toluene degradation using a fungi-based bio-trickling filter

Fungi have their unique advantages in capturing and degrading hydrophobic VOCs. To study the performance of fungi-based bio-trickling filters (BTFs) with respect to the degradation of toluene, and the succession process of the fungal colony under different operating conditions, a three-layer BTF packed by dominant Fusarium oxysporum immobilized with ceramic particles were set up. The fungal BTF started quickly within 7 days and restarted less than 7 days after starvation; its average RE was higher than 92.5% when the toluene inlet loading rate (ILR) ranging from 7.0 to 100.9 g m^-3 h^-1 at steady state. Moreover, the maximum elimination capacity (EC) of 98.1 g m^-3 h^-1 was obtained at a toluene ILR of 100.3 g m^-3 h^-1. The microorganism analysis of time and space revealed that the dominant fungi Fusarium were replaced by Paramicrosporidium saccamoebae after a certain evolutionary period. The intermediate layer had more microbes and a more complex community than the other two layers, and was more suitable for the survival of the varieties of microbes.

Recent progress and perspectives in biotrickling filters for VOCs and odorous gases treatment

Pollution caused by volatile organic compounds (VOCs) and odorous pollutants in the air can produce severe environmental problems. In recent years, the emission control of VOCs and odorous pollutants has become a crucial issue owing to the adverse effect on humans and the environment. For treating these compounds, biotrickling filter (BTF) technology acts as an environment friendly and cost-effective alternative to conventional air pollution control technologies. Besides, low concentration of VOCs and odorous pollutants can also be effectively removed using BTF systems. However, the VOCs and odorants removal performance by BTF may be limited by the hydrophobicity, toxicity, and low bioavailability of these pollutants. To solve these problems, this review summarizes the design, mechanism, and common analytical methods of recent BTF advances. In addition, the operating conditions, mass transfer, packing materials and microorganisms (which are the critical parameters in a BTF system) were evaluated and discussed in view of improving the removal performance of BTFs. Further research on these specific topics, together with the combination of BTF technology with other technologies, should improve the removal performance of BTFs.