Importance of thermodynamics dependent kinetic parameters in nitrate-based souring mitigation studies

Alternating current-powered bioelectrode for enhanced sulfide removal from sulfide-rich organic effluent

Conventional biological wastewater treatments often struggle with efficient sulfide removal. This study presents an innovative and sustainable approach using an alternating current (AC)-powered bioelectrode to facilitate periodic microbial oxidation and reduction for sulfide removal from sulfide-rich organic effluents. The AC bioelectrode addressed the drawbacks of conventional direct current (DC) systems, demonstrating 93.2 % sulfide removal, 64.5 % elemental sulfur production and 75.8 % chemical oxygen demand removal, coupled with a 25 % decrease in energy consumption. AC stimulation mitigated elemental sulfur accumulation on the electrode surface, promoted biofilm colonization, and enhanced bidirectional electrocatalytic activity, thereby elevating active biomass and electron utilization efficiency. Additionally, AC bioelectrode enriched functional microbiomes capable of sulfur-oxidizing, sulfur-reducing, and electron-transport capacities, as confirmed by enzyme gene expression profiling. This study offers an efficient, resource-efficient, and sustainable solution to treating sulfide-rich organic effluents.

Inhibitory Effects of the Addition of KNO3 on Volatile Sulfur Compound Emissions during Sewage Sludge Composting

Odor released from the sewage sludge composting process often has a negative impact on the sewage sludge treatment facility and becomes a hindrance to promoting compost technology. This study investigated the effect of adding KNO₃ on the emissions of volatile sulfur compounds, such as hydrogen sulfide (H₂S), dimethyl sulfide (DMS), and carbon disulfide (CS₂), during sewage sludge composting and on the physicochemical properties of compost products, such as arylsulfatase activity, available sulfur, total sulfur, moisture content, and germination index. The results showed that the addition of KNO₃ could inhibit the emissions of volatile sulfur compounds during composting. KNO₃ can also increase the heating rate and peak temperature of the compost pile and reduce the available sulfur loss. The addition of 4% and 8% KNO₃ had the best effect on H₂S emissions, and it reduced the emissions of H₂S during composting by 19.5% and 20.0%, respectively. The addition of 4% KNO₃ had the best effect on DMS and CS₂ emissions, and it reduced the emissions of DMS and CS₂ by 75.8% and 63.0%, respectively. Furthermore, adding 4% KNO₃ had the best effect from the perspective of improving the germination index of the compost.