Biofilter for generation of concentrated sulphuric acid from H2S

Abstract

Biofilters are used for the conversion of odorous hydrogen sulphide to odourless sulphate in wastewater treatment plants under the right conditions of moisture and pH. One of the consequences of maintaining the suitable pH and moisture content is the production of large volumes of weakly acidic leachate. This paper presents a biofilter with a maximum H2S elimination capacity of 16.3 g m −3 h −1 and removal efficiency greater than 95 % which produces small volumes (1 mL of solution L −1 of reactor day −1 ) of sulphuric acid with a concentration greater than 5.5 M after 150 days of continuous operation. The concentrated sulphuric acid was produced by intermittently trickling a minimum amount of nutrient solution down the upflow biofilter which created a moisture and pH gradient within the biofilter resulting in an environment at the top for the bacterial conversion of H2S, while sulphuric acid was accumulated at the base. Genetic diversity profiling of samples taken from different sections of the biofilter confirms that the upper sections of the biofilter had the best environment for the bacteria to convert H2S to sulphate. The formation of concentrated sulphuric acid presents an opportunity for the recovery of sulphur from the waste stream as a usable product.

Hydrogen sulfide capture and removal technologies: A comprehensive review of recent developments and emerging trends

“…Deposition of a large amount of sulfur (yellow deposits) and sulfate in high inlet sulfide loading rates or inlet concentration (e.g. critical concentration of 380 ppm/min reported by [46]) may result in the accumulation of deposits on the bed, reducing H 2 S mass transfer and, as a result, deteriorating the removal efficiency [47,48].…”

“…The increased acidity by forming sulfuric acid can limit the bacterial function and propagation and, subsequently, reduce the H 2 S mass transfer into the biofilm, adversely affecting the removal efficiency. Here, acidophilic species like Thiobacillus genus have been recommended as they can efficiently function also in these conditions, i.e., at pH values as low as 0.2 [46,51,52]. Ben Jaber et al, [53] reported a removal efficiency higher than 96% at pH of 1.2 for an inlet H 2 S concentration of 250 ppm.…”

Trivalent Metal Ions (Al, Ga, In)-Doped TiO2 for Enhanced Photocatalytic Desulfurization of H2S: Band Structure Regulation, Performance, and Mechanism

“…Hydrogen sulfide (H 2 S) is a highly toxic and odorous pollutant that can cause nausea and vomiting at very low concentrations (<50 ppm) in human daily life . Moreover, H 2 S has unique chemical properties that can result in metal equipment corrosion, acid rain, and ecosystem destruction. , In response to these hazards, various conventional treatments have been developed to remove H 2 S, including adsorption, chemical scrubbing, biological scrubbing, membrane separation, and selective thermal catalytic oxidation. − However, these techniques have limitations in efficiently removing H 2 S at low concentrations. − For instance, although biological scrubbing is well-known for its effectiveness in removing H 2 S, it requires time-consuming adjustments to ensure optimal survival conditions for the strains, such as pH values and temperature . Meanwhile, selective thermal catalytic oxidation has been considered as an attractive desulfurization alternative due to its high performance and durability .…”