Introduction to Waste Water Treatment

An Introduction to Waste Water Treatment

Waste water treatment systems are dependent on the quality of effluent. All waste water treatment systems aim to improve the quality of waste water to a minimum acceptable level. The treatment process aims to reduce the amount of:

Suspended Solids

These are physical particles present in the waste water that settle naturally due to gravity

Biodegradable Organics

These serve as food for microorganisms. Microorganisms thrive and multiply in waste water that is rich in biodegradable organics.

Pathogenic Bacteria

These are disease causing organisms and most relevant when referring to water that is meant for human consumption or close contact with human beings during activities such as bathing or showering.


Nutrients include phosphates and nitrates. Nutrients lead to the growth of algae which in itself causes a heavy load of biodegradable organics in the water.

Waste water treatment is usually conducted in 3 steps

Primary or Mechanical Waste Water Treatment

This is designed to remove floating or suspended solids from waste water. It includes sedimentation by gravity and screening to trap solid objects. Chemicals are sometimes used in primary treatment to accelerate sedimentation. 50 to 60% of total suspended solids in waste water can be removed through primary treatment.

Secondary or Biological Treatment

Secondary treatment removes any organic matter that escaped primary treatment. Microbes are the main workers in biological treatment. They consume organic matter as food and convert it into energy for their growth and reproduction. Secondary treatment also removes suspended solids and includes sludge processing and filtration.

Tertiary Treatment

Tertiary treatment aims to produce effluent that is at least the minimum water quality for discharging to trade waste. This stage of treatment requires technical knowhow and the proper equipment. It will require an Oil Water Separator (OWS) of some sort but may also require other equipment to make the minimum water quality standards.

Waste water treatment is vital to protect the environment by removing all harmful pollutants from waste water before discharging it to the Trade Waste sewage system.  In all cases having water samples prior to designing a waste water treatment system will yield the best results. Depending on the water sample results we will be able to build a custom system that meets all council requirements for discharging waste water to the sewer system.