Use of various chemicals in wastewater slurries processing (chemical treatment) has been known for many years and in many applications. Chemicals are used to improve dewaterability, for odor control, pH modification, pasteurization, disinfection, stabilization, as oxidizing agents in odor control equipment, etc. Chemical reactions take place in many wastewater treatment processes. Chemicals commonly used in wastewater slurries treatment are listed in Table 7-1. Lime and chlorine are the primary chemicals that have been extensively researched and used. Chlorine, a strong oxidant, has been used to inactivate or destroy microorganisms in drinking and wastewater treatment. However, use of chlorine is quite expensive and safety concerns are substantial. Lime or lime containing materials have been widely used to raise pH to inactivate or destroy pathogenic microorganisms. Lime is less effective than chlorine, but it is safer, cheaper and easier to use.