(Source: Author)
Wet air oxidation
This method was initially designed for the paper industry, but it has since been modified for use in sewage treatment facilities, particularly for the treatment of high-toxicity industrial liquid effluent (Li et al., 2020). It is advised, however, when the effluent is too diluted to be burnt and too hazardous to be treated biologically. It is used to oxidize organic material, converting carbon and nitrogen to carbon dioxide and water in most cases (Suarez-Ojeda et al., 2007). The oxidation procedure reduces the amount of sludge while increasing its dewaterability for thermal treatment. The pros and cons are shown in the table below (Table 10).
Table 10 . Principal advantages and disadvantages of wet air oxidation transformation procedure in sludge transformation