ABSTRACT

This chapter discusses specialized unit processes that are used for specialized wastewaters. These processes include spent caustic treatment systems and amine systems, and are generally used across a spectrum of industries. Spent amines are difficult to biodegrade in wastewater plants and should be recovered by recycling. Spent caustic solutions are produced as a liquid waste stream in a number of industries. They are usually sulphitic, and may contain other materials such as mercaptans, solvents, and phenols. Several technologies are available for the treatment of spent sulphitic caustic. These technologies include neutralization with steam stripping, wet air oxidation (low, medium, and high pressure) with neutralization, and incineration. Spent caustic can be treated by acid neutralization followed by steam stripping. Spent caustic becomes autogenous at much lower chemical oxygen demand values when using a wet air oxidation system as compared to incineration.