night soilReading time:
Night soil properties will vary widely depending on its origins; nightsoil mainly comes from two types of waterproof sumps:
- those described as "water effect" (very little water mixed in with the faecal matter) and usually emptied out once a year. This night soil will be very concentrated (COD ranging from 12 to 30 g·L–1);
- those fitted with a water flush, emptied out more frequently and much more dilute (COD of approximately 2 g·L–1).
The space available in the cesspit will allow the latter to be emptied out at longer or shorter intervals and may or may not provide for a preliminary digestion of this matter. Table 33 provides the properties of these products in some countries.