Production and build-up of sulfide and methane in wastewater collections systems cause several detrimental effects including odour nuisance, health hazards due to its toxicity and corrosion of pipes and inlet structures of sewage treatment plants. On the other hand methane is a greenhouse gas significantly contributing to global warming. Despite these major impacts, sewer-produced sulfide and m...

Mining and metallurgy have negative consequences for the environment [1-3] and lead to changes in geological [4] and climatic conditions [5]. Mining-metallurgy operations include the extraction, preparing of ores (crushing ore and flotation), processing of concentrates, and the disposal of waste rock and by-products. The main waste in mining and metallurgy are waste rocks, flotation tailings an...

The present study addresses the direct flotation route for the concentration of a zinc silicate ore. Flotation of hemimorphite faces some challenges due to the similarity of hemimorphite and quartz surface properties. XRD, and XRF analyses, optical mineralogy and SEM with X-ray mapping were performed for characterization. The results showed that the quartz, hemimorphite, calcite and dolomite ar...

Membrane associated alpha-glucosidase activity was investigated in a methanogenic bioreactor (MR) and a biosulfidogenic bioreactor (SR). Temperature and pH optima studies showed temperature optima of 50 degrees C and pH optima of 8.0 for the alpha-glucosidases from both the MR and SR. Sulfide (at a concentration of 150 mg l(-1)) resulted in the complete loss of all alpha-glucosidase activity in...

Post-treatment of anaerobic wastewater was undertaken to biologically oxidize dissolved methane, with the aim of preventing methane emission. The performance of dissolved methane oxidation and competition for oxygen among methane, ammonium, organic matter, and sulfide oxidizing bacteria were investigated using a lab-scale closed-type down-flow hanging sponge (DHS) reactor. Under the oxygen abun...

Understanding the generation and behaviour of air bubbles in the presence of different reagents is important in the solid/liquid separation processes used to treat mineral and water and wastewater by flocculation–flotation. The presence of large air bubbles in aerated flocs, which have higher up-rising rates, can lead to the development of higher capacity units. The present work evaluated the g...

pH variation in sewers has a significant effect on hydrogen sulfide production and emissions, and hence its accurate prediction is critical for the optimization of mitigation strategies. In this study, the nature and dynamics of pH variation in a sewer system is examined. Three sewer systems collecting domestic wastewater were monitored, with pH in all cases showing large diurnal variations. pH...