There are three main stages of the wastewater treatment process, aptly known as primary, secondary and tertiary water treatment. In some applications, more advanced treatment is required, known as quaternary water treatment. This stage deals with part per million to part per billion levels of contamination and often involves oxidation or fine filtration processes. Each of these stages tackles different pollutants, with water becoming cleaner as it moves through the phases.
What Are the Three Stages of Wastewater Treatment?
What is secondary wastewater treatment?
Secondary treatment of wastewater works on a deeper level than primary and is designed to substantially degrade the biological content of the waste through aerobic biological processes.
Completing secondary wastewater treatment allows for safer release into the local environment, reducing common biodegradable contaminants down to safe levels.
It is done in one of three ways:
Biofiltration uses sand filters, contact filters or trickling filters to ensure that any additional sediment is removed from the wastewater.
Aeration is a lengthy process which increases oxygen saturation by introducing air to wastewater. Typically, the aeration process can last for up to 30 hours, but it is very effective.
Typically used in warmer climates, this method utilises natural bodies of water such as lagoons, allowing wastewater to pass through for a set period before being retained for two to three weeks.