Toilet paper replaces chemicalsTheme
Innovation / new techniques, Nutrient Factory
Within the Interreg2Seas project NEREUS (New Energy and Resources from Urban Sanitation), Evides is investigating various techniques for the recovery of raw materials (cellulose, nutrients), water and energy from household wastewater. One of the raw materials recovered is the cellulose from toilet paper, which is removed from the wastewater with a fine sieve. Cellulose is poorly biodegradable in biological purification, but with enzymes the cellulose can be broken down into smaller sugars so that it is available again for the bacteria in the purification. The degraded cellulose can serve as a substitute for the carbon source that is purchased at some wastewater treatment plants. This can save on costs and CO2 footprint.
The enzymatic conversion of cellulose is investigated within NEREUS. In the Delft Blue Innovations research hall at the Harnaschpolder WWTP, screening materials are harvested with a fine sieve and converted. In beaker tests, enzymes from different suppliers were tested for conversion efficiency and a suitable enzyme was selected. In the continuous pilot installation of 200 liters, the selected enzyme achieves the same conversion efficiency and the produced carbon source works at least as well as the commercially available carbon source.
We are currently working hard on optimization of substrate dosing, enzyme dosing, pH and temperature. We also look at the stability of the sieve and the carbon source produced, and this looks good. If we get the business case conclusive, we will implement this process at Schiphol WWTP. A good example of how innovations can help to reduce our CO2 footprint!
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Paula van den Brink