Inorganic compounds waste treatment

Waste treatment Process chemistry Treatment chemistry Metal compounds Other inorganic compounds... 

Hazardous waste types, which are especially suitable for the pyrolytic treatment, include containerized waste (i.e., barrels) and sludges and liquids that have high ash content, volatile inorganic compounds (NaCl, FeCl2, Zn, and Pb), or high concentrations of chlorine, sulfur, and/or nitrogen. 

The RO process was implemented at the Institute of Atomic Energy, Swierk. The wastes collected there, from all users of nuclear materials in Poland, have to be processed before safe disposal. Until 1990 the wastes were treated by chemical methods that sometimes did not ensure sufficient decontamination. To reach the discharge standards the system of radioactive waste treatment was modernized. A new evaporator integrated with membrane installation replaced old technology based on chemical precipitation with sorption on inorganic sorbents. Two installations, EV and 3RO, can operate simultaneously or separately. The membrane plant is applied for initial concentration of the waste before the evaporator. It may be also used for final cleaning of the distillate, depending on actual needs. The need for additional distillate purification is necessitated due to entrainment of radionuclides with droplets or with the volatile radioactive compounds, which are carried over. 

Even if care is taken to minimize waste, there will still be waste to treat. Currently used wet finishing processes produce waste containing organic as well as inorganic compounds. The efflnents are rich in chemicals of which some are persistent or resistant to water treatment methods. Table 2.1 lists typical examples of finishing waste that resists biodegradation. Removal of these substances from wastewater is expensive and difficult to achieve. Because of this, the effiuent segregation and source reduction methods are preferred as economically attractive alternatives. 

In recent years, titania in general gained a lot of interest in the field of photocatalysis. Here, the titania is not only support but also catalyst. Various review articles with hundreds of references have been published in the last 10 years [56-59]. Mills and Lee [60] reported about a Web-based overview of current commercial applications. One big field of application is the treatment of (waste) water and air by photodegradation of inorganic compounds (like ammonia and nitrates) and organic substances (like chlorinated aliphatic and aromatic compounds) as well as volatile organic compounds (VOCs) in the air. Even 2,4,6,-trinitrotoluene (TNT) can be completely destroyed under aerobic conditions by the use of AEROXIDE TiOj P 25... 

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