Wastewater treatment is the process of removing contaminants from wastewater which has been received from both domestic and commercial customers. South Gippsland Water’s treatment plants use a number of processes to remove physical, chemical and biological contaminants. The objective is to produce an environmentally safe treated wastewater suitable for disposal or reuse
Wastewater treatment generally involves 3 stages of treatment: primary, secondary and tertiary treatment.
– Primary treatment consists of temporarily holding the sewage in a basin or clarifier where heavy solids can settle to the bottom while oil, grease and lighter solids float to the surface. The settled and floating materials are removed and the remaining liquid is transferred to the next stage of treatment.
– Secondary treatment removes dissolved and suspended biological matter. Secondary treatment is typically performed by water-borne micro-organisms in a managed habitat. Secondary treatment may require a separation process to remove the micro-organisms from the treated water prior to discharge or tertiary treatment.
– Tertiary treatment allows further disinfection either chemically or physically (for example, by lagoons and microfiltration) prior to discharge into a creek or river or it can be used for the irrigation of pastures or sporting fields.
South Gippsland Water currently operates two types of wastewater treatment systems and two different types of wastewater collection system.
Mechanical Wastewater Treatment
South Gippsland Water operates two mechanical wastewater treatment plants at Leongatha and Korumburra. These plants utilise equipment such as clarifiers, digesters and a belt press as part of the treatment processes outlined above.
Lagoon Wastewater Treatment
Most of South Gippsland Water’s wastewater treatment plants are lagoon based systems. These specially designed and constructed wastewater lagoons allow natural biological processes to occur and as a result these processes cleanse the water. The lagoons are designed with shallow bases to allow oxygen and sunlight to filter through the wastewater. In these conditions, micro-organisms thrive and in turn, consume the nutrients in the wastewater. In addition UV sunlight acts as a natural disinfectant.
Some lagoon based treatment systems such as the Meeniyan Lagoons and Wetlands also involve the use of weed and reed beds. The weed bed at Meeniyan is designed to reduce nutrients and improve downstream water quality.
Gravity Sewer Systems
Gravity sewers are also known as conventional sewer systems. Gravity sewers have sewer mains that run to a low point (i.e. use gravity to collect into a central location) and from here water is pumped via large centralised pump stations to the wastewater treatment facility.
Vacuum Sewer Systems
South Gippsland Water only operates one Vacuum Sewer System. This system at Port Albert operates using the differential pressure between atmospheric pressure and a partial vacuum maintained in the piping network and vacuum station collection vessel. This differential pressure allows a central vacuum station to collect the wastewater from homes and businesses. Vacuum sewers take advantage of available natural slope in the terrain and are most economical in flat sandy soils with high ground water.
Pressure Sewer Systems
South Gippsland Water is carrying out a process of connecting properties in Alberton, Poowong, Loch and Nyora to a reticulated pressure sewer system. This infrastructure upgrade tackles public health and environmental problems caused by failing septic systems.
This Pressure Sewer System utilises individual pumps located on each property which transfers wastewater from the property into the sewer main network. Customers who are connected to the system can refer to the homeowner’s guide below for further information.