The circular economy can bring vast efficiencies

Using the byproducts of wastewater treatment

Advanced anaerobic digestion of wastewater sludge produces energy-rich biogas. Nutrients and nitrogen recovered from wastewater treatment are used by farmers as fertilizer for their crops. Nitrogen, ammonia, and other compounds are sold to chemicals and manufacturing companies.

Large amounts of heat energy left over from the advanced anaerobic digestion process have been harnessed by other industries, particularly horticulture, and by municipal authorities to meet their own heating needs. In cooler climates, complexes of greenhouses, growing vegetables year-round, are a common sight alongside anaerobic digestion plants, with pipeline networks transferring heat between them. In warmer climates, effluent is disinfected and used for irrigation to promote greener cities.

In water-stressed locations, wastewater treatment is used to supplement other sources of potable water. It has become increasingly common for water to be treated to a nonpotable standard for other uses: municipal watering, crop irrigation, and industrial cooling, for example.

A no-waste approach to construction and decommissioning

The circular economy has taken root in construction and asset management too. Design for manufacture and assembly (DfMA) is used whenever possible to create new assets. It minimizes the consumption of materials, all but eliminates construction waste, and enables components to be recovered and reused when assets are retired or need to be reconfigured.

When old water assets are decommissioned, demolition materials are provided to the construction industry. Mechanical equipment is returned to suppliers to be reconditioned or disassembled for recycling.

Commercializing this process has provided the industry with revenue to reinvest in the development of new, greener infrastructure.