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González, D.; Gabriel, D.; Sánchez, A. Odors Abatement. Encyclopedia. Available online: https://encyclopedia.pub/entry/23274 (accessed on 22 July 2024).
González D, Gabriel D, Sánchez A. Odors Abatement. Encyclopedia. Available at: https://encyclopedia.pub/entry/23274. Accessed July 22, 2024.
González, Daniel, David Gabriel, Antoni Sánchez. "Odors Abatement" Encyclopedia, https://encyclopedia.pub/entry/23274 (accessed July 22, 2024).
González, D., Gabriel, D., & Sánchez, A. (2022, May 24). Odors Abatement. In Encyclopedia. https://encyclopedia.pub/entry/23274
González, Daniel, et al. "Odors Abatement." Encyclopedia. Web. 24 May, 2022.
Odors Abatement
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This entry is adapted from the peer-reviewed paper 10.3390/atmos13050798

Traditionally, odor abatement has been carried out using physical–chemical technologies such as chemical absorption (scrubbing) and adsorption. However, biological technologies for odor treatment such as biofilters or biotrickling filters have become more relevant in the last years for many reasons, such as their high odor removal performances and the low operational costs associated.

odor organic waste composting biofiltration biotrickling filter VOC

1. Introduction

Traditionally, odor abatement has been carried out using physical–chemical technologies such as chemical absorption (scrubbing) and adsorption. The former is the most widespread technology at industrial scale, mostly favorable for medium- to highly-soluble compounds (dimensionless Henry coefficient lower than 1). Adsorption is a technology favorable for poorly soluble compounds, such as many hydrophobic VOC (dimensionless Henry coefficient above 1). In both cases, either chemicals’ consumption in scrubbing or adsorbent replacement or regeneration make such technologies much more expensive than biological processes in terms of operational expenditures (OPEX). Although other common gas treatment technologies such as incineration or condensation could be used, they are also not economical in practice. Incineration needs natural gas to be added due to the low concentrations of odorant flows, whereas condensation costs either by pressure increase or cooling are not justified unless valuable chemicals can be recovered. However, practitioners still need to be convinced that emerging biological processes are a real alternative for odor abatement.
Biological gas treatment can be carried out with a range of configurations of bioreactors in practice. In all cases, the catalyst for odor stabilization is a microbial culture able to grow under the operating conditions in the bioreactor. However, mainly biofilters and biotrickling filters are used at full-scale for odor abatement. The reasons for that are essentially the higher construction costs of bioscrubbers compared to biofilters or biotrickling filters, as bioscrubbers are constituted by an absorption unit for pollutant capture followed by a reaction unit were biodegradation of pollutants takes place. Additionally, the odor is mainly made of very low concentrations of often poorly soluble compounds, which are not suitable to be treated in bioscrubbers where the absorption unit operates under larger L/G ratios (ca. 5–10 times larger) compared to biofilters and biotrickling filters. Thus, out of the large list of factors affecting the biofiltration performance in biofilters and biotrickling filters such as pH, temperature, or nutrient availability; the watering rate, in combination with an adequate gas contact time, is the most critical factor for a proper performance in the removal of odorants [1], as mass transport from the gas to the biofilm (biofilters) or liquid phase (biotrickling filters) is directly dependent on the thickness of the water layer over the biofilm. Selection of the most appropriate configuration is still challenging, but only a few works have systematically addressed that topic. Shammay et al. (2019) proposed a selection flowchart for the treatment of sewer network emissions [2]. Although H2S removal is properly accomplished by biofilters, biotrickling filters, and activated carbon adsorbers, fluctuating loads and the presence of other odorants make selection complex. Often a combination of different configurations in-series is an appropriate alternative [3][4].

2. Biofilters

Biofilters are packed bed type bioreactors in which a complex microbiota grows as a biofilm on the surface of a packing material, which is simply continuously wetted through water humidity condensation or intermittently watered in case of evaporation. Most applications use one single or a combination of organic packing materials such as peat, compost, or wood chips [5], even though some authors have proven that the use of sole plastic materials such as polyethylene films may be also effective for inorganic odorants such as H2S and NH3 [6]. The packing material exerts an influence on the performance of biofilters [7]. Gas contact times below 10–15 s are enough for medium-to-highly soluble odorants such as H2S, NH3, or alcohols, whereas gas contact times above 25–30 s are required to remove odorant VOCs. However, determining an appropriate watering rate is challenging and often depends on the optimum results in adhoc field testing. As a proper starting point for testing, watering rates in the order of 0.1–0.3 m3·m−2d−1 are suggested for odor removal in biofilters. Further research is needed to establish the potential correlations of the impact of the watering frequency and rate over biofilters’ performance.
Application of biofilters as an alternative for odor abatement has been extensively reviewed in the past [8]; however, novel applications and opportunities are still arising [9]. Liu et al. (2021) proposed recently a novel three-stage integrated biofilter combining an acidophilic bacterial-based section for S and N removal and fungal-based and heterotrophic bacteria-based sections for the treatment of organic odorants such as VOCs from MSW treatment facilities [10]. Stratification of the bed in different sections was demonstrated as a compact efficient alternative as previously proposed by other authors from a modeling point of view [11]. New opportunities from knowledge findings in the biofiltration field can still be explored. Yao et al. (2019) showed that methanethiol removal in a biofilter was increased when methane was present [12], which may be useful for properly designing and exploiting the performance in odor mitigation of biocovers of landfills [13], which share many similarities with odor-abatement biofilters from other waste treatment facilities such as MSWTF.

3. Biotrickling Filters

Biotrickling filters (BTFs) are conceptually similar to biofilters except for the packing materials used, usually inert materials such as plastic or polyurethane foam fillings, and for the fact that a liquid phase is continuously trickled over the bed. Consequently, BTFs are more suitable for medium-to-high solubility compounds, such as H2S, NH3, or soluble VOCs such as alcohols and some carboxylic acids or ketones. Their main advantage over biofilters is that they can be built with a taller bed (4–6 m in height), opposite to biofilters often built with 1–1.5 m in height to avoid bed compaction that leads to channeling. Together with the shortest gas contact time needed for relatively soluble compounds (often below 5–10 s), this make BTFs a much more compact technology.
In recent decades, BTFs have gained much more interest since Gabriel and Deshusses demonstrated in 2003 the outstanding performance of a polyurethane packed BTF for the removal of H2S as the main target odorant in WWTPs at gas contact times around 2 s [14]. A range of applications have been developed since then targeting the design of more compact units able to deal with larger pollutant concentrations and gas flow rates including the treatment of odorant concentration levels of VOCs. Strategies such as intermittent trickling of water in the removal of H2S [15], the effect of natural stratification in multilayer BTFs for simultaneous H2S and VOCs removal [16], or the optimization of the process parameters such as the packing material configuration and liquid recirculation [17] and the usage of additives, microbial inoculation, and pretreatment techniques to lower odor emission during the process have been recently explored with successful results [18].
Despite BTFs’ benefits in terms of controllability and footprint amongst others, still, biofilters are the preferred configuration at industrial scale, as they are the less expensive configuration among biofiltration technologies [19]. This is particularly important when large gas flowrates, above 40,000–60,000 m3·h−1, have to be treated. Such high flow rates require the use of parallel BTF units, thus leading to much less competitive installations as BTFs present 30–50% larger capital expenditures (CAPEX) than biofilters. However, at the low-end of the range of gas flowrates BTFs offer much more appealing benefits both technically and economically.

4. Odor Abatement in In-Series Configurations

Because of the complexity of the emissions in many waste treatment facilities and despite recent advances, single-type configurations are usually not able to cope with the more and more restrictive limits in terms of odorant emissions. If bioprocesses are considered, the most widespread combination of technologies for odor treatment at full-scale is the use of in-series chemical scrubbers for VICs’ (volatile inorganic compounds) removal (mainly NH3 and H2S) followed by biofilter for VOCs’ removal. Alternatives such as the use of plasma systems [20] or the combination of adsorption and biotrickling filtration [21] have been also explored with interesting results.
However, several authors have shown that either converting chemical scrubbers to BTFs for VICs’ removal [14][22], combining a BTF followed by a biofilter for complex odorants abatement at WWTP [3], or even using in-series BTFs for S-compounds’ removal may be also effective for biobased-only odor abatement, while, at the same time, a much more sustainable and economical alternative [23].

References

  1. Lee, S.-H.; Kurade, M.B.; Jeon, B.-H.; Kim, J.; Zheng, Y.; Salama, E.-S. Water condition in biotrickling filtration for the efficient removal of gaseous contaminants. Crit. Rev. Biotechnol. 2021, 41, 1279–1296.
  2. Shammay, A.; Evanson, I.E.J.; Stuetz, R.W. Selection framework for the treatment of sewer network emissions. J. Environ. Manag. 2019, 249, 109305.
  3. González, D.; Colón, J.; Sánchez, A.; Gabriel, D. Multipoint characterization of the emission of odour, volatile organic compounds and greenhouse gases from a full-scale membrane-based municipal WWTP. J. Environ. Manag. 2022, 313, 115002.
  4. Beniwal, D.; Taylor-Edmonds, L.; Armour, J.; Andrews, R.C. Ozone/peroxide advanced oxidation in combination with biofiltration for taste and odour control and organics removal. Chemosphere 2018, 212, 272–281.
  5. Viswanathan, S.; Neerackal, G.; Buyuksonmez, F. Removal of beta-pinene and limonene using compost biofilter. J. Air Waste Manag. Assoc. 2013, 63, 237–245.
  6. Zheng, T.; Li, L.; Chai, F.; Wang, Y. Factors impacting the performance and microbial populations of three biofilters for co-treatment of H2S and NH3 in a domestic waste landfill site. Process Saf. Environ. Prot. 2021, 149, 410–421.
  7. Márquez, P.; Herruzo-Ruiz, A.M.; Siles, J.A.; Alham, J.; Michán, C.; Martín, M.A. Influence of packing material on the biofiltration of butyric acid: A comparative study from a physico-chemical, olfactometric and microbiological perspective. J. Environ. Manag. 2021, 294, 113044.
  8. Barbusinski, K.; Kalemba, K.; Kasperczyk, D.; Urbaniec, K.; Kozik, V. Biological methods for odor treatment—A review. J. Clean. Prod. 2017, 152, 223–241.
  9. Marycz, M.; Brillowska-Dąbrowska, A.; Muñoz, R.; Gębicki, J. A state of the art review on the use of fungi in biofiltration to remove volatile hydrophobic pollutants. Rev. Environ. Sci. Biotechnol. 2022, 21, 225–246.
  10. Liu, J.; Yue, P.; Zang, N.; Lu, C.; Chen, X. Removal of odors and VOCs in municipal solid waste comprehensive treatment plants using a novel three-stage integrated biofilter: Performance and bioaerosol emissions. Front. Environ. Sci. Eng. 2021, 15, 48.
  11. López, M.E.; Rene, E.R.; Boger, Z.; Veiga, M.C.; Kennes, C. Modelling the removal of volatile pollutants under transient conditions in a two-stage bioreactor using artificial neural networks. J. Hazard. Mater. 2017, 324, 100–109.
  12. Yao, X.-Z.; Chu, Y.-X.; Wang, C.; Li, H.J.; Kang, Y.-R.; He, R. Enhanced removal of methanethiol and its conversion products in the presence of methane in biofilters. J. Clean. Prod. 2019, 215, 75–83.
  13. Yun, J.; Jung, H.; Ryu, H.W.; Oh, K.-C.; Jeon, J.-M.; Cho, K.-S. Odor mitigation and bacterial community dynamics in on-site biocovers at a sanitary landfill in South Korea. Environ. Res. 2018, 166, 516–528.
  14. Gabriel, D.; Deshusses, M.A. Retrofitting existing chemical scrubbers to biotrickling filters for H2S emission control. Proc. Natl. Acad. Sci. USA 2003, 100, 6308–6312.
  15. Bua, H.; Carvalho, G.; Huang, C.; Sharma, K.R.; Yuan, Z.; Song, Y.; Bond, P.; Keller, J.; Yu, M.; Jiang, G. Evaluation of continuous and intermittent trickling strategies for the removal of hydrogen sulfide in a biotrickling filter. Chemosphere 2022, 291, 132723.
  16. You, J.; Chen, J.; Sun, Y.; Fang, J.; Cheng, Z.; Ye, J.; Chen, D. Treatment of mixed waste-gas containing H2S, dichloromethane and tetrahydrofuran by a multi-layer biotrickling filter. J. Clean. Prod. 2021, 319, 128630.
  17. Caicedo, F.; Estrada, J.M.; Silva, J.P.; Muñoz, R.; Lebrero, R. Effect of packing material configuration and liquid recirculation rate on the performance of a biotrickling filter treating VOCs. J. Chem. Technol. Biotechnol. 2018, 93, 2299–2306.
  18. Andraskar, J.; Yadav, S.; Kapley, A. Challenges and Control Strategies of Odor Emission from Composting Operation. Appl. Biochem. Biotechnol. 2021, 193, 2331–2356.
  19. Prado, O.J.; Gabriel, D.; Lafuente, J. Economical assessment of the design, construction and operation of open-bed biofilters for waste gas treatment. J. Environ. Manag. 2009, 90, 2515–2523.
  20. Helbich, S.; Dobslaw, D.; Schulz, A.; Engesser, K.-H. Styrene and Bioaerosol Removal from Waste Air with a Combined Biotrickling Filter and DBD-Plasma System. Sustainability 2020, 12, 9240.
  21. Santos-Clotas, E.; Cabrera-Codony, A.; Martin, M.J. Coupling adsorption with biotechnologies for siloxane abatement from biogas. Renew. Energy 2020, 153, 314–323.
  22. Prado, O.J.; Redondo, R.M.; Lafuente, J.; Gabriel, D. Retrofitting of an Industrial Chemical Scrubber into a Biotrickling Filter: Performance at a Gas Contact Time below 1 s. J. Environ. Eng. 2009, 135, 359–366.
  23. Sun, S.; Jia, T.; Chen, K.; Peng, Y.; Zhang, L. Simultaneous removal of hydrogen sulfide and volatile organic sulfur compounds in off-gas mixture from a wastewater treatment plant using a two-stage bio-trickling filter system. Front. Environ. Sci. Eng. 2019, 13, 60.
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Subjects: Engineering, Environmental; Environmental Sciences
Contributors MDPI registered users' name will be linked to their SciProfiles pages. To register with us, please refer to https://encyclopedia.pub/register :
Daniel González
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David Gabriel
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Antoni Sánchez
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Entry Collection: Environmental Sciences
Revisions: 3 times (View History)
Update Date: 27 May 2022
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