Comparison between conventional biofilters and biotrickling filters applied to waste bio-drying in terms of atmospheric dispersion and air quality

Abstract

Biofiltration has been widely applied to remove odours and volatile organic compounds (VOCs) from industrial off-gas and mechanical-biological waste treatments. However, conventional open biofilters cannot guarantee an efficient dispersion of air pollutants emitted into the atmosphere. The aim of this paper is to compare conventional open biofilters with biotrickling filters (BTFs) in terms of VOC dispersion in the atmosphere and air quality in the vicinity of a hypothetical municipal solid waste bio-drying plant. Simulations of dispersion were carried out regarding two VOCs of interest due to their impact in terms of odours and cancer risk: dimethyl disulphide and benzene, respectively. The use of BTFs, instead of conventional biofilters, led to significant improvements in the odour impact and the cancer risk: when adopting BTFs instead of an open biofilter, the area with an odour concentration > 1 OU m(-3) and a cancer risk > 10(-6) was reduced by 91.6% and 95.2%, respectively. When replacing the biofilter with BTFs, the annual mean concentrations of odorants and benzene decreased by more than 90% in the vicinity of the plant. These improvements are achieved above all because of the higher release height of BTFs and the higher velocity of the outgoing air flow.

Desulphurisation of Biogas: A Systematic Qualitative and Economic-Based Quantitative Review of Alternative Strategies

“…It is important to note that there is a simpler configuration of the BTF called the biofilter [109]. Simple block diagrams to highlight the difference between the BTF and the simpler biofilter are presented in Figure 2.…”

“…Generally speaking, biofilters constitute an interesting technology that has been explored in previous studies as bench scale [111] and pilot scale operations [112], with large-scale biofilters expected to lead to further improvements in the economic performance [41]. Although Figure 2 highlights the configurational simplicity of the biofilter compared to the BTF, biofilters have the major drawback of presenting poor performances, largely due to poor microbial density in the filter beds [109]. Poor microbial density may be a result of reduced access to nutrients by the microbes.…”

“…Poor microbial density may be a result of reduced access to nutrients by the microbes. Issues of filter bed clogging are, however, common in biofilters and BTFs, suggesting the need for regular cleaning operations [109]. In an attempt to mitigate the aforementioned limitations, biofilter technologies have been developed that exhibit properties similar to biotrickling filters such that water nutrient solution addition, although not continuously available, is supplied intermittently at a higher frequency [113].…”

“…The incorporation of these two stages of H 2 S absorption and biological sulphide oxidation is highlighted in Figure 3. Although Figure 2 highlights the configurational simplicity of the biofilter compared to the BTF, biofilters have the major drawback of presenting poor performances, largely due to poor microbial density in the filter beds [109]. Poor microbial density may be a result of reduced access to nutrients by the microbes.…”

Technical Aspects of Upgrading Composting to Anaerobic Digestion and Post-Composting

“…Benefits are also achievable in terms of space reduction, mainly thanks to the generally lower empty-bed residence time required by BTFs and to the less stringent requirements on the superficial gas velocity, which make BTFs more compact and developed in the vertical dimension. According to a recent work [24], the replacement of a biofilter with an equivalent air treatment system based on BTFs would reduce the area for air treatment by about 85%, value significant in the frame of waste treatment plant enhancement [25].…”