Pilot and full scale applications of floating treatment wetlands for treating diffuse pollution.

Floating treatment wetlands (FTW) are nature-based solutions for the purification of open water systems such as rivers, ponds, and lakes polluted by diffuse sources as untreated or partially treated domestic wastewater and agricultural run-off. Compared with other physicochemical and biological technologies, FTW is a technology with low-cost, simple configuration, easy to operate; has a relatively high efficiency, and is energy-saving, and aesthetic. Water remediation in FTWs is supported by plant uptake and the growth of a biofilm on the water plant roots, so the selection of the macrophyte species is critical, not only to pollutant removal but also to the local ecosystem integrity, especially for full-scale implementation.

Water treatment and reclamation by implementing electrochemical systems with constructed wetlands.

Seasonal or permanent water scarcity in off-grid communities can be alleviated by recycling water in decentralized wastewater treatment systems. Nature-based solutions, such as constructed wetlands (CWs), have become popular solutions for sanitation in remote locations. Although typical CWs can efficiently remove solids and organics to meet water reuse standards, polishing remains necessary for other parameters, such as pathogens, nutrients, and recalcitrant pollutants.

Pyrite-based denitrification combined with electrochemical disinfection to remove nitrate and microbial contamination from groundwater.

Nitrate and microbial contamination of groundwater can occur in countries that face intense urbanization and inadequate sanitation. When groundwater is the main drinking water source, as is often the case in such countries, the need to remove these contaminants becomes acute. The combination of two technologies is proposed here, a biological step to denitrify and an electrochemical step to disinfect the groundwater, thereby aiming to reduce the chemical input and the footprint of groundwater treatment.

Continuous H/CO fermentation for acetic acid production under transient and continuous sulfide inhibition.

Waste gas fermentation powered by renewable H is reaching kiloton scale. The presence of sulfide, inherent to many waste gases, can cause inhibition, requiring additional gas treatment. In this work, acetogenesis and methanogenesis inhibition by sulfide were studied in a 10-L mixed-culture fermenter, supplied with CO and connected with a water electrolysis unit for electricity-powered H supply.

Homoacetogenesis and microbial community composition are shaped by pH and total sulfide concentration.

Biological CO sequestration through acetogenesis with H as electron donor is a promising technology to reduce greenhouse gas emissions. Today, a major issue is the presence of impurities such as hydrogen sulfide (H S) in CO containing gases, as they are known to inhibit acetogenesis in CO -based fermentations. However, exact values of toxicity and inhibition are not well-defined.

Electrochemical treatment of industrial sulfidic spent caustic streams for sulfide removal and caustic recovery.

Alkaline spent caustic streams (SCS) produced in the petrochemical and chemical manufacturing industry, contain high concentrations of reactive sulfide (HS) and caustic soda (NaOH). Common treatment methods entail high operational costs while not recovering the possible resources that SCS contain. Here we studied the electrochemical treatment of SCS from a chemical manufacturing industry in an electrolysis cell, aiming at anodic HS removal and cathodic NaOH, devoid of sulfide, recovery.

Anode materials for sulfide oxidation in alkaline wastewater: An activity and stability performance comparison.

Electrochemical sulfide removal can be attractive as a zero-chemical-input approach for treatment of waste streams such as spent caustics coupled to caustic recovery. A key concern is possible decline in catalytic activity, due to passivation from deposited elemental sulfur (S) on the anode surface and stability limitation, due to sulfide oxidation under highly alkaline conditions. In this study, six commercially available electrode materials (Ir Mixed Metal Oxide (MMO), Ru MMO, Pt/IrOx, Pt, PbOx and TiO/IrTaO coated titanium-based electrodes) were tested to investigate the impact of the electrocatalyst on the process efficiency in terms of sulfide removal and final product of sulfide oxidation, as well as to determine the stability of the electrocatalyst under high sulfide concentrations (50 mM NaS) and high alkalinity (pH > 12).