Activation of persulfate (PS) and peroxymonosulfate (PMS) and application for the degradation of emerging contaminants

The science of the total environment

Physical Review B

Sulfate radical-based advanced oxidation processes (SR-AOPs) employing heterogeneous catalysts to generate sulfate radical (SO4 −) from peroxymonosulfate (PMS) and persulfate (PS) have been extensively employed for organic contaminant removal in water. This article aims to provide a state–of–the–art review on the recent development in heterogeneous catalysts including single metal, mixed metal, and nonmetal carbon catalysts for organic contaminants removal, with particular focus on PMS activation. The hybrid heterogeneous catalyst/PMS systems integrated with other advanced oxidation technologies is also discussed. Several strategies for the identification of principal reactive radicals in SO4 −–oxidation systems are evaluated, namely (i) use of chemical probe or spin trapping agent coupled with analytical tools, and (ii) competitive kinetic approach using selective radical scavengers. The main challenges and mitigation strategies pertinent to the SR-AOPs are identified, which include (i) possible formation of oxyanions and disinfection byproducts, and (ii) dealing with sulfate produced and residual PMS. Potential future applications and research direction of SR-AOPs are proposed. These include (i) novel reactor design for heterogeneous catalytic system based on batch or continuous flow (e.g. completely mixed or plug flow) reactor configuration with catalyst recovery, and (ii) catalytic ceramic membrane incorporating SR-AOPs.

Generation of sulfate radical through heterogeneous catalysis for organic contaminants removal: Current development, challenges and prospects

Evaluation of advanced oxidation processes for water and wastewater treatment - A critical review.

This invention discloses a material for removing pollutants difficult to be degradated in waste-water. First, iron, such as: iron-shavings, ferrous powder or iron scurf, is immersed into silver nitrate solution with its weight concentration of 0.1-1%, keeping the solution flowing continuously, to plate silver onto the iron surface, with the ratio of silver/iron of 0.1-2%. The material thus produced is filled into catalyst iron reactor or catalyst iron reaction pond. The wastewater containing pollutants difficult to be degradated is pumped into the same, keeping flowing circulation, controlling reaction time and pH value, under ambient temperature and pressure, to achieve wastewater treatment. This invention has advantages of: available raw materials, low cost, no pollution to environment, excellent ability for removing pollutant being of difficult to be degradated.

Method for manufacturing and using material for removing pollutant difficult to be degraded in water

A modification of granular activated carbon (GAC) by Fe–Mn–O was proposed to improve the catalytic activity of GAC for the enhanced mineralization of aqueous RB5. The efficiency, kinetics, and possible mechanism of ozonation of aqueous RB5 catalyzed by GAC and mGAC have been investigated. mGAC exerted enhanced catalytic activity in the mineralization of aqueous RB5 and a slight promotion in decoloration. An additional 18% TOC removal efficiency was observed in the degradation of RB5 by O3/mGAC compared with O3/GAC under identical experimental conditions within 1 h. The pH exerted an evident impact on the degradation of RB5, with maximal mineralization achieved at pH 7. mGAC showed stable catalytic activity in the ozonation of aqueous RB5. Reaction kinetics showed that the TOC removal rate constant of RB5 degradation by O3/mGAC was 5.4 times higher than that by O3 alone. The reaction mechanism involved the enhanced mineralization of aqueous RB5 at the catalyst–solution interface via hydroxyl radica...

Enhanced mineralization of aqueous Reactive Black 5 by catalytic ozonation in the presence of modified GAC

The invention belongs to the water treatment technical field, in particular relating to an integrated denitrogenation and dephosphorization method of iron internal electrolysis and biological coupling. The method comprises the following steps that: an iron internal electrolysis bed is prepared; activated sludge of an iron internal electrolysis-SBR denitrogenation and dephosphorization system is acclimatized; the iron internal electrolysis-SBR denitrogenation and dephosphorization system is operated formally; acclimatized sludge is added with wastewater to be treated, and the addition of the wastewater is 30 to 50 percent of the volume of an SBR reactor; the feeding time is between 0.3 and 0.6 hour according to the properties of the wastewater; the mass concentration (MLSS) of the sludge is controlled between 3 and 5 grams per liter; after the feeding is over, aeration reaction is performed, and the aeration time is controlled to between 2 and 4 hours and the concentration of dissolved oxygen is controlled to between 3 and 4 micrograms per liter according to the properties of the wastewater; after the aeration is over, a mixing plant is started for denitrification reaction, and the stirring time is controlled to between 1 and 2 hours according to the concentration of ammonia nitrogen in the inlet water; the mixing plant is closed and the sedimentation stage is started, with a sedimentation time between 50 and 70 minutes; supernatant is exhausted from a water outlet and the water displacement is the same as the inflow of mixture; and outlet water obtained reaches the primary emission standard. The method has small floor area, low cost and convenient use.

Integration denitrification and dephosphorization method of iron inner electrolysis and bio-coupling

Sequestration of free and chelated Ni(II) by structural Fe(II): Performance and mechanisms

The invention relates to a maintaining method of a sewage treatment device, in particular to a method for back washing electrolysis filler in catalytic iron by air and water. The method comprises thefollowing steps: inserting back washing air pipes connected with a compressed air pipeline and back washing water pipes connected with a high-pressure water supply pipeline into electrolysis filler incatalytic iron in a catalytic iron reactor; setting distributed planes of the back washing water pipes to be parallel to the bottom plane of the filler and have a distance of 30-50 mm with the bottomplane of the filler, wherein the spraying directions of back washing water outlet holes on the back washing water pipes is downward; setting the distributed planes of the back washing air pipes to beparallel to the outer plane of the filler facing water flows and have a distance of 30-50 mm with the outer plane, wherein the spraying direction of back washing air holes on the back washing air pipes is opposite to the directions of the water flows; and after the catalytic iron reactor is operated for a period of time, back washing the filler by the back washing air pipes and the back washing water pipes. The invention can conveniently and efficiently clear the electrolysis filler in the catalytic iron so as to improve the sewage treatment effect.

Deli Wu

Papers

Method for manufacturing and using material for removing pollutant difficult to be degraded in water

Enhanced mineralization of aqueous Reactive Black 5 by catalytic ozonation in the presence of modified GAC

Integration denitrification and dephosphorization method of iron inner electrolysis and bio-coupling

Sequestration of free and chelated Ni(II) by structural Fe(II): Performance and mechanisms

Method for back washing electrolysis filler in catalytic iron by air and water