Sewage is liquid waste. Biodegradable liquid waste is the organic portion. We convert from a volume of sewage to a mass of liquid waste using the density of liquid waste.
Biodegradable liquid waste = liquid waste * organic proportion of liquid waste
Used to calculate: non-biodegradable liquid waste
Depends upon:
—Parameters: density of liquid waste and organic proportion of liquid waste
—Other metrics: ecosystem area and sewage from people