A variety of locations are implementing circular economy concepts that promote the reduction of water consumption, reuse of water, and recovery of materials from wastewater.
The linear economy
Our current economic model can be best described as ‘linear’ which typically involves economic actors (people or organisations) harvesting and extracting natural resources, using them to manufacture a product, and selling a product to other economic actors, who then discard it when it no longer serves its purpose.
In the linear economy, following this ‘Take-Make-Dispose’ model, the water sector typically employs the ‘Take-Use-Discharge’ strategy. In this strategy, water is ‘withdrawn’ from streams, rivers, lakes, reservoirs, oceans, and groundwater reservoirs as well as harvested directly as rainwater. Water is then ‘used’ by municipalities, industries, agriculture, the environment, etc. within the water cycle, including for consumptive and non-consumptive uses. Non-consumptive used water is ‘returned’ to the river basin directly or via a municipal treatment facility. Depending on the location within the basin this returned water could then be used downstream or lost to the basin.
Governments around the world are implementing a variety of policies to encourage the transition towards the ‘circular economy’
The circular water economy
While the current linear economic model has generated an unprecedented level of growth, the model has led to constraints on the availability of natural resources in addition to the generation of waste and environmental degradation. In response to climate change, increasing resource scarcity, and environmental degradation, governments around the world are implementing a variety of policies to encourage the transition towards the ‘circular economy’ that focuses on reducing material consumption, reusing materials, and recovering materials from waste.
In the context of water resources management, water utilities are beginning to promote the circular water economy that reduces water consumption, reuses and recycles water and wastewater, and recovers materials, including heat and minerals, from water and wastewater to not only mitigate greenhouse gas emissions but also enhance resilience to climate change.
Reducing water usage with smart meters in Singapore
To meet future demand for water with today’s technologies, Singapore’s Public Utilities Board’s (PUB) energy footprint will need to quadruple from the current 1,000GWh/year to 4,000GWh/year. To reduce this demand, PUB trialled a smart water network that collects detailed data on household water consumption to build customer consumption profiles and identify consumption patterns and trends. The trial enabled customers to set water-saving goals and track their performance. This trial is part of the utility’s wider scheme of installing 300,000 smart meters in new and existing residential, commercial, and industrial premises by 2023.
Reusing water in New York City
New York City’s Department of Environmental Protection has launched its On-Site Water Reuse Grant Pilot Program to provide commercial, mixed-use, and multi-family residential property owners with incentives to install water reuse systems. Grants are available for water reuse systems at the individual building and district level, with district-scale projects involving two or more parcels of land such as a housing development, where the project reduces demand in the shared distribution system.
Recovering biogas in Stockholm
In Stockholm, the two sewage treatment plants, Henriksdal and Bromma, produce around a million tons of sludge per year. When the sludge is digested biogas is formed, providing a steady stream of vehicle fuel: currently, around 17 million cubic meters of crude gas is produced which is sold to Scandinavian Biogas, who then transform the raw gas into vehicle gas. The gas that is not converted to vehicle gas is used for heating and electricity generation.
In conclusion, a range of innovative technologies is available to close the loop and create a circular water economy.