There are two types of wastewater - domestic and industrial. Wastewater is also commonly referred to as sewage. Wastewater contains approximately 99% of water and 1% of mostly biodegradable products such as detergents, food scraps and human waste. The average household generates between 200-250 litres of wastewater daily.

Domestic wastewater

Domestic wastewater is the used water from the toilet, drains, baths, showers, sinks and washing machines from homes and industry. Domestic wastewater does not include the rain that falls on the roof of your house and travels down the downpipe, or the water that runs into the gutters at the front of your house. This water enters the stormwater system and is discharged untreated into waterways or the sea. The stormwater system operates independently of Gippsland Water's wastewater system and is the responsibility of the local council.

Industrial wastewater

Industrial wastewater is any liquid waste generated by businesses, industries, or manufacturing processes and is often defined as 'trade waste'. Examples of trade waste are fats, oils, grease, pulp and paper waste and food manufacturing waste. Businesses like restaurants, fish and chip shops and service stations, are required to install grease/oil inceptor traps to store their trade waste. These traps capture the solid waste in order to prevent blockages in our wastewater systems and treatment plants. Some larger industries are required to partially treat their wastewater before Gippsland Water will accept it into the system for further treatment and eventual disposal.

Wastewater quality standards

Gippsland Water's main objective is to ensure our discharges from our Wastewater Treatment Plants (WWTP) comply with Environment Protection Authority (EPA) discharge licence requirements.

The EPA is charged with the responsibility of monitoring Gippsland Water’s discharges and treatment processes. This discharge licence is to ensure our environmental resources are maintained through compliance with the State Environment Protection Policy (SEPP) for Victoria, which provides a legal framework for State and Local government agencies, businesses and communities to work together to protect and rehabilitate Victoria’s surface water environment.

The results of our annual wastewater monitoring program are reported to the EPA under the terms of our wastewater discharge licence agreements as part of our Annual Regulatory Reporting framework.

Overview of wastewater treatment processes

To ensure compliance with the EPA discharge licences, Gippsland Water employs physical, chemical and biological treatment of its wastewaters, since the role of a wastewater treatment plant is to reduce harmful contaminants and strength of the wastewater collected from homes and industry before it is released into the environment. There are several processes that can be employed to treat wastewater and many rely on nature’s bugs (ie: bacteria, protozoa, algae) to breakdown the solids and organic products in our wastewater.

Primary Treatment – is the removal of large solids, grit and oils from the wastewater entering the treatment plant by use of screens and gravity separation.

Secondary Treatment – is the biological process whereby a large population of microorganisms help convert organic material into other forms which can be easily separated into solids and clear liquid. These solids are settled out in settling tanks.

Tertiary Treatment – is the use of filters and /or disinfection of the clear liquid to reduce the other contaminants as well as pathogens, which are microorganisms that pose a risk to public health.

Due to the variety of treatment plants across the Gippsland Water region the treatment process may vary from plant to plant. To produce wastewater compliant with the EPA discharge licence, during the treatment process, wastewater passes through a number of stages that may include:

• pre- treatment
• secondary treatment/nutrient removal (biological)
• sludge removal
• tertiary filtration
• disinfection