Performance of a combined system of biotrickling filter and photocatalytic reactor in treating waste gases from a paint-manufacturing plant

A comprehensive review and perspective research in technology integration for the treatment of gaseous volatile organic compounds

Volatile organic compounds (VOCs) are harmful pollutants emitted from industrial processes. They pose a risk to human health and ecosystems, even at low concentrations. Controlling VOCs is crucial for good air quality. This review aims to provide a comprehensive understanding of the various methods used for controlling VOC abatement. The advancement of mono-functional treatment techniques, including recovery such as absorption, adsorption, condensation, and membrane separation, and destruction-based methods such as natural degradation methods, advanced oxidation processes, and reduction methods were discussed. Among these methods, advanced oxidation processes are considered the most effective for removing toxic VOCs, despite some drawbacks such as costly chemicals, rigorous reaction conditions, and the formation of secondary chemicals. Standalone technologies are generally not sufficient and do not perform satisfactorily for the removal of hazardous air pollutants due to the generation of innocuous end products. However, every integration technique complements superiority and overcomes the challenges of standalone technologies. For instance, by using catalytic oxidation, catalytic ozonation, non-thermal plasma, and photocatalysis pretreatments, the amount of bioaerosols released from the bioreactor can be significantly reduced, leading to effective conversion rates for non-polar compounds, and opening new perspectives towards promising techniques with countless benefits. Interestingly, the three-stage processes have shown efficient decomposition performance for polar VOCs, excellent recoverability for nonpolar VOCs, and promising potential applications in atmospheric purification. Furthermore, the review also reports on the evolution of mathematical and artificial neural network modeling for VOC removal performance. The article critically analyzes the synergistic effects and advantages of integration. The authors hope that this article will be helpful in deciding on the appropriate strategy for controlling interested VOCs.

Removal of Volatile Organic Compounds (VOCs) from Air: Focus on Biotrickling Filtration and Process Modeling

Biotrickling filtration is a well-established technology for the treatment of air polluted with odorous and volatile organic compounds (VOCs). Besides dozens of successful industrial applications of this technology, there are still gaps in a full understanding and description of the mechanisms of biotrickling filtration. This review focuses on recent research results on biotrickling filtration of air polluted with single and multiple VOCs, as well as process modeling. The modeling offers optimization of a process design and performance, as well as allows deeper understanding of process mechanisms. An overview of the developments of models describing biotrickling filtration and conventional biofiltration, as primarily developed and in many aspects through similar processes, is presented in this paper.

Treatment of gaseous emissions from tire manufacturing industry using lab-scale biofiltration pilot units

Continuously seeking the improvement of environmental protection, the limitation of exhaust emissions is of significance for the tire manufacturing industry. The aim of this study is to assess the potential of biofiltration for the treatment of such gaseous emissions. This work highlights that biofiltration is able to remove both hydrophilic and hydrophobic compounds within a single pilot unit of biofiltration. Due to Ethanol/Alkanes ratios (95/5 and 80/20), high performance levels were observed for low EBRT (16 and 12 s). After twenty days of stable running, the dynamic of stratification patterns could be explained as a result of species coexistence mechanisms. While its impact on performance has not been observed under stable operating conditions, the use of an adsorbent support such as granular activated carbon (GAC) could be relevant to promote system stability in the face of further perturbations, such as transient regimes, that are problematic in full-scale industrial applications.

Screening and study of the degradation characteristics of efficient toluene degrading bacteria combinations

In this paper, three effective toluene-degrading bacteria were obtained through acclimation and screening by using landfill leachate as the initial liquid strain. The three obtained bacteria were denoted as J1, J2 and J3, and identified as Pseudomonas, Bacillus and Staphylococcus, respectively. We then identified the optimal combination of these toluene-degrading bacteria in the laboratory. The combination of J1 + J3 (1:1) exhibited the highest toluene removal efficiency (RE). A vertical bio-trickling filter (BTF) packed with ceramsite was started by inoculation with the effective combination. The performance of the BTF in treating toluene under various operating conditions was investigated. After 17 days of operation, the toluene RE reached about 90% and the maximum elimination capacity reached 42.0 g m^-3 h^-1. The scanning electron microscope (SEM) showed that after the successful start-up of the BTF, the biofilm on the packing surface primarily consisted of Bacillus and Staphylococcus. During the stable state, the RE of the BTF was maintained above 80%, the shortest empty bed residence time was 34 s and toluene concentrations ranged between 300 and 800 mg m^-3. The results indicate that the BTF started using the effective combination of bacteria described here is robust. This paper also provides a preliminary analysis of the mechanism of microbial degradation of pollutants in the BTF.

Biological Waste Air and Waste Gas Treatment: Overview, Challenges, Operational Efficiency, and Current Trends

International contracts to restrict emissions of climate-relevant gases, and thus global warming, also require a critical reconsideration of technologies for treating municipal, commercial, industrial, and agricultural waste gas emissions. A change from energy- and resource-intensive technologies, such as thermal post-combustion and adsorption, as well to low-emission technologies with high energy and resource efficiency, becomes mandatory. Biological processes already meet these requirements, but show restrictions in case of treatment of complex volatile organic compound (VOC) mixtures and space demand. Innovative approaches combining advanced oxidation and biofiltration processes seem to be a solution. In this review, biological processes, both as stand-alone technology and in combination with advanced oxidation processes, were critically evaluated in regard to technical, economical, and climate policy aspects, as well as present limitations and corresponding solutions to overcome these restrictions.

Significance of a Non-Thermal Plasma Treatment on LDPE Biodegradation with Pseudomonas Aeruginosa

The use of plastics has spanned across almost all aspects of day to day life. Although their uses are invaluable, they contribute to the generation of a lot of waste products that end up in the environment and end up polluting natural habitats such as forests and the ocean. By treating low-density polyethylene (LDPE) samples with non-thermal plasma in ambient air and with an addition of ≈4% CO₂, the biodegradation of the samples can be increased due to an increase in oxidative species causing better cell adhesion and acceptance on the polymer sample surface. It was, however, found that the use of this slight addition of CO₂ aided in the biodegradation of the LDPE samples more than with solely ambient air as the carbon bonds measured from Raman spectroscopy were seen to decrease even more with this change in gas composition and chemistry. The results show that the largest increase of polymer degradation occurs when a voltage of 32 kV is applied over 300 s and with a mixture of ambient air and CO₂ in the ratio 25:1.

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.