دانلود رایگان مقاله چالش و راه حل برای بیوفیلتراسیون ترکیبات آلی فرار آبگریزی

Abstract

Volatile organic compounds (VOCs) emitted to the environment highly probably result in ecological and health risks. Many biotechnologies for waste gases containing hydrophobic VOCs have been developed in recent years. However, these biological processes usually exhibit poor removal performances for hydrophobic VOCs due to the low bioavailability. This review presents an overview of enhanced removal of hydrophobic VOCs in biofilters. Mechanisms and problems relevant to the biological removal of hydrophobic VOCs are reviewed, and then solutions including the addition of surfactants, application of fungal biocatalysts, biofiltration with pretreatment, innovative bioreactors and utilization of hydrophilic compounds are discussed in detail. Future research needs are also proposed. This review provides new insights into hydrophobic VOC removal by biofiltration.

5. Conclusions

Biological technologies for air pollution control offer advantages over physicochemical methods. One of the main drawbacks of biological technologies is the low bioavailability or slow biological oxidation of hydrophobic VOCs, making the biofilter very large and uncompetitive. Hydrophobic VOC removal in biofilters is affected by many factors including VOC mass transfer, microbial populations, packing media and moisture. Surfactants can increase the biodegradation rate of hydrophobic organic compounds by increasing the total aqueous solubility of these compounds. However, the biodegradation intermediates of surfactants by microorganisms and the distribution of surfactants on the packing material are often overlooked. Moreover, the application of mixed anionic-nonionic surfactants in gas biofiltration and the process mechanism of surfactants for biofilm growth control are rarely studied. Fungal-based biocatalysts have shown some potential but are limited by their growth conditions. Some innovative technologies such as physicochemical-biological methods or innovative bioreactors (TPPBs or RDB) have been developed to overcome the poorly soluble or recalcitrant substances. Nevertheless, further research is still needed in order to eliminate potential nuisances from these new techniques. It will help to move these new techniques from innovative to mature. There is an experimental evidence that the removal efficiency of hydrophobic compounds can be improved in the presence of the hydrophilic compounds. Further investigations on the precise mechanisms are necessary as well. A model for hydrophobic and hydrophilic VOC biofiltration is imperative to predict the effect between hydrophobic and hydrophilic VOCs removal.