Effluent and Wastewater

November 2021

The terms effluent and wastewater are sometimes confused, largely because there is actually an overlap in their meaning. Additionally, the terms are used slightly differently within various industries and have been adopted into everyday conversation to mean different things.

For example, sewage is commonly referred to as both effluent and wastewater.

What is effluent?

When defining effluent it is helpful to think about the direction of flow. Effluent flows away from either a man-made structure or from a natural water body. Conversely, influent refers to water going in. While typically we think about effluent as being a liquid, it can also be an outflowing of gas.

Water is the most common type of effluent, either in treated or untreated form. In engineering, effluent is the stream exiting a chemical reactor.

What is wastewater?

Wastewater refers to water after it has been used for a specific purpose. More specifically, this could include water that has been used in domestic, agricultural, industrial or commercial applications. It can also include stormwater, surface run-off and sewer inflow.

More generally, the term wastewater is commonly used interchangeably with the terms industrial wastewater, cooling water, leachate, return flow, surface run-off, stormwater, urban run-off, liquid wastewater and agricultural wastewater.

What is the difference?

The difference between effluent and wastewater really lies in the definition. In practice, there is sometimes very little difference between the two. For example, let’s look at sewage. All sewage is wastewater having been used for its purpose. On leaving the home, sewage is also referred to as effluent. When the sewage enters the water treatment plant, it is referred to as influent. After it has been treated and the treated wastewater leaves the treatment plan, this wastewater is again referred to as effluent.

The terms really do overlap, so it is useful to think about the direction of flow and if and how the water has been used when adopting the terms effluent or wastewater.

How do the terms effluent and wastewater relate to farming?

Farming uses a lot of water, so consequently, large amounts of wastewater and consequent effluent are generated.

Common sources of wastewater in farming settings include storm and groundwater, run-off and overflow from irrigation or buildings. Further wastewater is generated from vehicle wash downs, plant and shed wash downs and food processing by-products and waste.

The term Agricultural Effluent is commonly used to refer to wastewater generated from settings such as dairy sheds or piggeries.

Responsible farming practice requires all wastewater to be managed carefully with strong consideration given to the potential damage from contaminated effluent. Wastewater from any of the above processes will most likely contain organic matter, nutrients, dissolved inorganic matter, toxic chemicals or pathogens. Wastewater treatment is required to remove these contaminants.

Various filtration systems are available to effectively treat effluent and wastewater. Our team at Think Water can help you develop an effective filtration system that allows you to safely manage wastewater, sometimes even recycling the wastewater after it has been treated.

How do effluent and wastewater relate to factories?

Wastewater and effluent are common products in commercial and industrial activities. Water is used in a range of processes in nearly all phases of production for heating, cooling, cleaning and more. Food and beverage processing is heavily reliant on water in their production. Likewise, mining and chemical manufacturing companies are also highly dependant.

Industry must comply with heavy regulations before discharging wastewater as effluent into water bodies, onto the land, into sewage treatment plants or even before recycling. Industrial wastewater will often contain contaminants. In the food industry, this may take the form of pesticides, insecticides, animal waste or fertilisers. In the resource sector contaminants can include significant levels of metals, industrial chemicals and petroleum products.

Therefore, industries are faced with the continual challenge of treating wastewater before discharging it. Industries have the choice of wastewater and effluent treatment onsite, offsite or a combination of both. Water filtration systems are integral to any on-site solution. With targeted water filtration, wastewater can be effectively treated to help industries achieve their wastewater objectives while being sensitive to the environment and complying with regulations. Regular wastewater testing is key to the success of any water filtration system, giving companies confidence before discharging wastewater into the natural environment or outsourcing wastewater for further treatment.

A variety of strategies are usually required for effluent treatment and to remove contamination from wastewater, ensuring effluent is safe on release. Talk to our team at Think Water about possible wastewater treatment solutions for you.