Wastewater is a problem for numerous sectors, particularly as more stringent pollution limits are introduced. Several technologies are used, often in combination, to make wastewater safe for recycling or discharge.

In many situations and sectors, activated carbon is an effective option, reducing costs and providing a reliable, environmentally sound alternative or back-up to technologies such as bioreactors and membranes.

Typical challenges in wastewater purification

Wastewater typically comes from three main sources: industrial wastewater and process water, municipal wastewater or landfill leachate water.

Contaminants depend on the source, with the main ones as follows.

1. Organic components, as measured by Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD). Excessive amounts can cause oxygen depletion in water sources and result in insufficient levels to sustain life.
2. Nitrates and phosphates, often from fertilisers. These can cause eutrophication, where excessive amounts of algae form and starve aquatic organisms of light and oxygen.
3. Adsorbable organic halides (AOX). Organic components containing e.g. chlorine or bromine, many carry environmental risks.
4. Trace components, such as residues from pesticides, hormones, antibiotics, and industrial chemicals. Many are classified as Substances of Very High Concern (SVHC), believed to be harmful even in low concentrations. Others are Persistent Organic Pollutants (POPs) that can accumulate in water, soil and potentially the food chain.
5. Metals, which can damage damage the environment or aquatic life if levels are too high.

Not all contaminants can be removed via adsorption by activated carbon. Nitrates, phosphates and metals are inorganic components and have no affinity with activated carbon and thus require an alternative purification technology. However, for the removal of COD, BOD, AOX and trace components, activated carbon is certainly worth investigation.

Legislation protects the natural watercourses and biodiversity; and reduces risks to human health. Pollution limits vary according to the component, region, and proximity to natural resources or drinking water wells.

Sectors and scenarios

Activated carbon can be used in a wide variety of industries and situations, especially in the treatment of organic contaminants in industrial wastewater.

Petrochemical, chemical and pharmaceutical industries produce wastewater in their production processes, rinsing water and rainwater contaminated with organics such as COD and BOD and trace components. Colour in process water or wastewater can also be removed.

Scrap firms, landfills and waste treatment sites may produce contaminated run-offs when it rains. The composition of the pollution depends on the type of waste on site. Metals from e.g. old car parts and shredded material are often present but cannot be removed via adsorption. Activated carbon typically tackles organic components resulting from leaching of solid waste or spills from gasoline and cooling fluids.

Disasters such as train accidents may result in contaminated water, for example from liquids being transported or from water used to extinguish fires, which typically contains fluorinated components such as PFAS.

Treatment companies can also benefit from activated carbon filtration, as can festivals producing wastewater from kitchens and showers.

Wastewater treatment technologies

Want to know more about the technologies suitable to purify wastewater?

Download our e-book here in which we describe the different stages in wastewater purification, some of the available technologies and how they compare to each other.

At DESOTEC’s facilities, all used carbon is analysed so the right measures can be taken for handling and removing the saturated carbon out of the mobile filters. All molecules that were adsorbed on the activated carbon at the customers’ site, are desorbed inside DESOTEC’s reactivation furnaces. These contaminants are then fully destroyed, in accordance with National and European legislation, by an incineration and neutralisation setup. The entire installation and it's emissions are under continuous on-line monitoring, which guarantees that only harmless water vapour is seen exiting the chimney.