What is effluent discharge?

Effluent discharge is liquid waste, other than waste from kitchens or toilets, surface water or domestic sewage. It is produced and discharged by any industrial or commercial premises, such as a food processing factory or manufacturing business.

Often referred to as ‘trade effluent’ or ‘wastewater’, effluent discharge usually flows from the premises directly into the main sewer network. It cannot enter a river, reservoir, stream or lake unless it is cleaned and treated first. Only surface water can be released into a natural watercourse.

If the effluent discharge goes straight into a public foul sewer, it will travel via the sewer network to the nearest wastewater treatment works for handling and processing.

The majority of trade effluent is made up of wastewater, water that has been used in a certain process to create a specific product or facilitate production, including cooling machinery or pipes.

wastewater composition

As well as the wastewater itself, trade effluent will often contain one or more contaminants including:

• Fats, oils and greases (FOGs)
• Chemicals
• Detergents
• Heavy metal rinses
• Solids
• Food waste

The trade effluent produced by a factory that manufactures food or beverages, such as a bakery or a brewery, will potentially contain detergents and solids. A company that forges steel bars will use a number of different processes to create the finished product. Its trade effluent may include with heavy metals, oils, greases and chemicals.

Some, usually larger companies however, have an on-site Effluent Treatment Plant (ETP). The effluent produced by a process, or processes, is treated before being discharged, if clean enough, into a nearby watercourse.

It’s also worth noting that, sometimes, trade effluent contains so many pollutants that it must be treated even before it is allowed in the sewer. If this is the case, the company in question will have to comply with whatever is required by the corresponding water company. This makes sure the trade effluent is within the consent license limits and safe to enter the sewer.