Part B: Advances in gas emission control techniques for anaerobic-based STPs Technical Note 1 - Topics of interest

Abstract

Anaerobic-based sewage treatment plants (STPs) produce various gases that, if not properly managed, can lead to problems such as odor, corrosion, occupational risks, energy losses, or even intensification of the greenhouse effect. The above-mentioned problems are mainly related to the presence of hydrogen sulfide (H2 S) and methane (CH4 ) in the biogas and/or in diffuse emissions from the various units of the STPs. In this sense, this technical note (TN) aimed at addressing the main aspects related to the generation and control of gaseous emissions in anaerobic-based STPs. This contribution is derived from the experience of experts and professionals of the academic and water utility sectors, as well as from the specialized literature. The techniques of interest are summarized in this TN, being individually detailed in the following TN of the collection “Valoration and management of gaseous by-products of sewage treatment. Part B: Advances in gas emission control techniques for anaerobic-based STPs”.

Dissolved methane

“…When a waste gas is too diluted and its CH 4 content is too low (as in simplified and packed desorption chambers with high Q G /Q L ratios, or in the case of gas extraction systems such as in enclosed pretreatment units or UASB reactors with enclosed settlers), the thermal oxidation (burn) of this gas is not feasible (Section 7.4.3.2) and another process for the CH 4 oxidation is required. One option that has been explored in the literature is the biological oxidation in biomass growth reactors, such as biofilters, biotrickling filters and bioscrubbers (Brandt et al, 2016(Brandt et al, , 2019(Brandt et al, , 2021a(Brandt et al, , 2021b(Brandt et al, , 2021c. These units can be used to oxidize the H 2 S and CH 4 in a waste gas.…”

“…In the biofiltration of gas mixtures containing H 2 S and CH 4 , attention should be paid to possible inhibitory effects on the activity of methanotrophic microorganisms (CH 4 oxidizers) due to the acidification of the filter bed caused by the biological oxidation of H 2 S, which can be minimized by a sequential bioreactor system, where the oxidation of H 2 S is carried out in the first Figure 7.11 Content of CH 4 in the recovered gas and gas mixture (biogas + recovered gas) derived from the recovery of dissolved methane from anaerobic reactors for a 'typical' scenario of biogas characteristics. Source: Adapted from Brandt et al (2021aBrandt et al ( , 2021bBrandt et al ( , 2021c.…”

“…Figure 7.2 Principle of dissolved methane desorption from the effluent of an anaerobic reactor. Source: Adapted fromBrandt et al (2021aBrandt et al ( , 2021bBrandt et al ( , 2021c.…”

Anaerobic Treatment of Domestic Wastewater

“…When a waste gas is too diluted and its CH 4 content is too low (as in simplified and packed desorption chambers with high Q G /Q L ratios, or in the case of gas extraction systems such as in enclosed pretreatment units or UASB reactors with enclosed settlers), the thermal oxidation (burn) of this gas is not feasible (Section 7.4.3.2) and another process for the CH 4 oxidation is required. One option that has been explored in the literature is the biological oxidation in biomass growth reactors, such as biofilters, biotrickling filters and bioscrubbers (Brandt et al, 2016(Brandt et al, , 2021a(Brandt et al, , 2021b(Brandt et al, , 2021c. These units can be used to oxidize the H 2 S and CH 4 in a waste gas.…”

Untitled

“…Conforme recomendado por Brandt et al (2018Brandt et al ( , 2019Brandt et al ( , 2021, foi proposta a instalação de uma câmara de dessorção de gases dissolvidos nos efluentes dos reatores UASB, bem como a cobertura e exaustão parcial das canaletas de coleta dos efluentes dos reatores UASB. Considerou-se o tratamento dos gases exauridos em biofiltros.…”