Wastewater
Household wastewater can be in the form of blackwater (generated from the toilet), greywater (from hand basins, shower, laundry and kitchen) and sewage (a combination of both blackwater and greywater). Wastewater from manufacturing and industrial operations such as food processing or metal refining is industrial or trade waste. This includes liquid waste from any process (e.g. water used to cool machinery or clean equipment).
Wastewater contains many polluting substances including:
- organic matter, capable of reducing the amount of oxygen in the water needed by marine animals and plants
- suspended solids capable of increasing the turbidity in receiving coastal waters
- micro-organisms (bacteria, viruses, fungi, protozoa, parasitic worms), which may be dangerous to humans and marine animals
- nutrients, particularly nitrogen and phosphorus
- toxic organic substances such as pesticides and solvents
- oil
- detergents
- biologically active drug residues from the medicines humans take
- litter.
The nutrients, nitrogen and phosphorus, are the pollutants that most threaten the Adelaide coastline. Most other substances are reduced to low levels by secondary and tertiary sewage treatment or by prevention of industrial waste entering the sewage system.
In Adelaide, most wastewater is treated at the three main sewage plants; Port Adelaide, Glenelg and Bolivar.
Do you know what happens to your wastewater and what it does to the marine environment when you flush the toilet, empty the bath, or drain the washing machine? It’s worth finding out!!!!
The main concerns of wastewater (household and industrial) discharge into the coastal environment are:
- Elevated loads of nutrients, mainly nitrogen and phosphorus, causing algal blooms, which may prevent light from reaching seagrasses and seaweeds. Algal blooms can also produce toxins harmful to animals and human health, and when they decay, they reduce the amount of oxygen available to marine life.
- Contaminants such as heavy metals are present in treated sewage and can accumulate in the floors of the ocean and in living marine organisms. Organisms accumulate heavy metals in their tissues and this contamination is concentrated in organisms higher up the food chain ('bioaccumulation'). Heavy metal contamination can affect marine animals, fisheries and human consumers of seafood.
- Dangerous microorganisms in sewage can enter coastal waters via sewage system overflows after heavy rains or poor treatment . This can affect human health if you swim in contaminated water or eat seafood that has been affected.