4.2.3 Biological characteristics of liquid wastes
Liquid wastes contain many different types of bacteria and other micro-organisms originating from human wastes and other sources. Many of these bacteria are beneficial and are responsible for the biodegradation of organic components of the wastes; others may be pathogenic. The presence of bacteria in wastewater is normal and expected, but it becomes a problem if the waste is not kept separate from people or if it contaminates clean water or food. The safe management and disposal of any waste containing human excreta is the most critical aspect of sanitation and hygiene and is essential to prevent the spread of infectious disease.