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The purpose of this laboratory pilot scale study at the Wastewater Technology Centre (WTC), Environment Canada, Burlington, ON was to investigate the anaerobic biological removal of H2S from biogas under real-time operating conditions. Biogas produced in a 538 litre pilot anaerobic digester was continuously fed into a 12 litre biotrickling filter containing plastic fibres as packing bed media. The process was monitored for several months. The biogas flowrate and H2S concentration ranged between 10 to 70 L/h and 1,000 to 4,000 ppmv respectively over the course of the test period. Nitrate-rich wastewater from a pilot scale sequencing batch reactor effluent was used as the nutritive solution for the biotrickling filter. The paper presents the influence of several operational parameters such as biogas flowrate, hydrogen sulphide concentration and composition of nutrient solution on process performance. To date, our results show H2S removal rates up to 100% without adverse effects on the methane concentration of the biogas. No system deterioration was observed over long term operation. This non-conventional technology is very promising and could be considered for full scale applications.

A biological process for the removal of hydrogen sulphide (H2S) in digester biogas was investigated using nitrified municipal wastewater as a nutrient solution under anoxic conditions. Biogas was continuously fed into a 0.012 m3 biotrickling filter at an H2S loading rate of approximately 1.50 g/d, counter-current to the nutrient solution. A zero-order macro-kinetic process was established on the basis of the degradation and formation rates for N and S species. The process performance was dependent on the presence of nitrate at low concentrations (in the order of 20 mg N-NO3–/L) found to be sufficient to maintain maximum H2S removal efficiency (>99%) under steady-state conditions where nitrate degradation rate was constant. The developed process has the potential to be adopted as an attractive alternative for biogas cleaning and, in some cases, with simultaneous wastewater denitrification. The information contained within this paper may be used as a basis for further research and (or) in the design of a scaled-up process.

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This paper presents the experimental results obtained during the operation of two biotrickling filters packed with 6.7 L of commercially available plastic fibres and lava rocks, respectively. The biotrickling filters were tested under similar operating conditions for hydrogen sulphide (H2S) removal from biogas under anoxic conditions, in order to determine the influence of biogas flow rate and H2S concentration on the process performance and to facilitate process modelling. The biogas flow rate was adjusted to between 25 and 75 L/h, while the input H2S concentration was varied between 500 and 1500 ppmv. The process performance was evaluated by two simultaneous system responses, namely the H2S removal efficiency and H2S loading rate, which were subsequently described by a second-order empirical model and an interaction model, respectively. Good agreement between the experimental results, model prediction and simultaneous dual-response simulation was obtained.