Final answer:
Liquid waste should be treated at a sewage treatment plant, where it undergoes various processes to remove contaminants before it is discharged into environments such as rivers or the ocean. If such facilities are not available, natural treatment methods like constructed wetlands could be used as an alternative.
Step-by-step explanation:
When disposing of liquid waste that includes chemicals, it is paramount that such waste is treated before being discharged. The chemical content should be unused and in the form of a commercial chemical product. Globally, it's estimated that half of all wastewater is discharged without proper treatment, which has significant environmental impacts. Wastewater treatment plants are critical for cleaning sewage and industrial waste to make water suitable for reuse or for safely returning it to the environment. The treated water, or effluent, is usually released into a local river or the ocean. Some applications of this treated water include landscaping and irrigation, though it is generally not used for drinking.
In the absence of wastewater treatment facilities, alternative methods such as the creation of wetlands can sometimes serve to naturally treat wastewater by filtering pollutants through plant roots and soil microbes. However, ideally, liquid waste should be directed to a sewage treatment plant, where it undergoes several stages including pretreatment, primary treatment, secondary treatment, tertiary treatment, and disinfection before it is considered safe to discharge.