Management of hydrogen sulphide generation at a Kraft mill effluent plant

Communities surrounding an integrated Kraft mill noticed odours from the mill’s effluent treatment plant. A project was therefore commissioned by the mill to proactively manage the odours from both the pulp-processing operations and the effluent treatment plant. This project formed part of a co-ordinated study that was implemented by the mill to limit emissions of the total reduced sulphur (TRS) components from the pulp mill operations. It was found that sulphate-reducing bacteria (SRB) converted the sulphates present in the effluent to hydrogen sulphide (H2S) by dissimilatory respiration. The combined use of a nitrate-releasing biomodifier (Bulab® 9518) and an anthraquinone sulphate-reduction inhibitor (Busperse® 2432) was effective in reducing both SRB activity and H2S levels. The average aqueous H2S levels (40 mg/ℓ) were reduced to between 92% and 99%.Keywords: biomodifiers, hydrogen sulphide, Kraft mill effluent plant, sulphate-reducing bacteria (SRB), anthraquinone, sulphate reduction inhibition, sodium nitrat

Production and properties of hemicellulases by a Thermomyces lanuginosus strain

Thermophilic fungi producing extremely high β-xylanase and their associated hemicellulases have attracted considerable attention because of potential industrial applications. Thermomyces lanuginosus strain SSBP isolated from soil, produced β-xylanase activity of 59 600 nkat ml-1 when cultivated on a medium containing corn cobs as substrate and yeast extract as nitrogen source. Lower β-xylanase activities were produced after growth on other xylan substrates, sugars and soluble starch. Other hemicellulases were produced extracellularly at significantly lower levels than the β-xylanase activity produced on corn cobs. No cellulase activity was observed. The optimal conditions for β-xylanase production were 50 °C and pH 6.5, whereas 70 °C and between pH 5.5 and 9.5 were optimal for β-xylanase activity. The temperature optima for other hemicellulases were less than the xylanase with the exception of β-mannosidase. The pH optima of the other hemicellulases were between 5.0 and 6.5. Xylanase was stable up to 70 °C and between pH 5.5 and 9.0 for 30 min whereas the other hemicellulase were less stable. These results suggest that the most suitable conditions for hydrolysis of hemicellulose by these enzymes would be at 50 °C and pH 6.0.Articl

Management of hydrogen sulphide generation at a Kraft mill effluent plant

Communities surrounding an integrated Kraft mill noticed odours from the mill’s effluent treatment plant. A project was therefore commissioned by the mill to proactively manage the odours from both the pulp-processing operations and the effluent treatment plant. This project formed part of a co-ordinated study that was implemented by the mill to limit emissions of the total reduced sulphur (TRS) components from the pulp mill operations. It was found that sulphate-reducing bacteria(SRB) converted the sulphates present in the effluent to hydrogen sulphide (H2S) by dissimilatory respiration. The combined use of a nitrate-releasing biomodifier (Bulab® 9518) and an anthraquinone sulphate-reduction inhibitor (Busperse® 2432) was effective in reducing both SRB activity and H2S levels. The average aqueous H2S levels (40 mg/ℓ) were reduced to between 92% and 99%

Management of hydrogen sulphide generation at a Kraft mill effluent plant

Please refer to abstract in articl