Oxygen enhanced water treatment

Water Treatment. Sodium sulfite is an agent in the reduction of chlorine or oxygen in water. Dissolved oxygen in boiler water tends to enhance pitting and other types of corrosion. In boilers operated at below 4.82 MPa (700 psi), a residual concentration of 30 ppm of sodium sulfite is generally effective. Catalytic amounts of cobalt are often added to accelerate the reaction of oxygen with sulfite (321,322) (see Water, industrial water treatment). 

The formation of gas bubbles in a porous medium affects, e.g., the performance of anaerobic granular sludge particles containing entrapped gas (waste-water treatment), or the performance of electrochemical reactors where a gas (hydrogen, oxygen, chlorine) evolves inside a porous electrode. A related problem is that of bubble nucleation on structure surfaces, which can be as varied as specially designed surfaces for enhanced nucleate boiling heat transfer, or the... 

Tertiary treatment processes remove specific pollutants, including traces of benzene and other partially soluble hydrocarbons. Tertiary water treatment can include ion exchange, chlorination, ozonation, reverse osmosis, or adsorption onto activated carbon. Compressed oxygen may be used to enhance oxidation. Spraying the water into the air or bubbling air through the water removes remaining traces of volatile chemicals such as phenol and ammonia. 

The various routes that have been examined to enhance the corrosion resistance of anodized aluminium using cerium compounds, such as nitrates or sulphates, include pre- and post-treatments and anodizing with cerium species added to the bath formulation (the addition of cerium to commercial alloys for corrosion protection has not been reported). Each of these approaches has revealed some benefits in short-term laboratory corrosion tests. However, the imderlying mechanisms of corrosion protection are imclear. Corrosion inhibition of aluminium alloys caused by cerium species is well-established, with cerium acting as a cathodic inhibitor at intermetallic particles (Amott et al, 1987). Cerium oxide/ Itydroxide precipitates in response to the increase of pH at cathodic particles as the alloy briefly corrodes following its immersion in the environment. The precipitates stifle further corrosion by hindering the reduction of oxygen and water. 

---