The use of residuals means primary raw materials are preserved. This produces demonstrable environmental and climate benefits. Using life-cycle analysis (LCA) together with sales and transport data, one can calculate the impact of the residuals chain, from the water production process up to and including application by the client.
The benefits of replacing common raw materials by residuals are many times greater than the impact associated with the residuals’ transport, storage and dewatering. On balance, we contribute to a reduction of the drinking water sector’s CO2 footprint. In 2015, the use of residuals lowered emissions by 10.3 million kg CO2 equivalent, which is about 5% of the CO2 emissions from Dutch water production processes.
By far the largest positive contribution comes from recycling aquafer. The use of this residual in the desulphurisation of digesters, or for phosphorus binding in wastewater treatment plants, dispenses with the use of high environmental impact products such as ferric chloride. The environmental benefit of replacing primary lime by lime pellets is smaller, since the environmental impact of lime production is relatively low.