Billund BioRefinery - How WWTPs Can Contribute to a Circular Economy

Case studies

“…The Billund BioRefinery is Public Private Partnership (PPP) between Krüger-Veolia, the municipality of Billund, and its utility company Billund Vand A/S, and is an extension of the wastewater treatment plant at Grinsdstead in Denmark. In 2013, a competition was organized and requested ideas on the 'Wastewater Treatment Plant of the Future' specifically to showcase Danish skills in wastewater treatment (Bro et al, 2017). The PPP was set in co-operation with Danva (the Danish National Environmental Agency) and was supported by federal grants and 12 million USD.…”

“…This was with the aim of improving water and nutrient reclamation while simultaneously reducing energy consumption and increasing the generation of energy. The plant treats 6,500 m 3 /d of flow containing 0.65 and 0.1 t of nitrogen and phosphorous, respectively (Bro et al, 2017). The biorefinery had defined two major ambitions.…”

“…The second ambition was related to the digestion of sludge and other waste materials (Figure 6.8). Table 6.3 shows the quantity and types of materials processed (adapted from Bro et al, 2017). The total flow to the plantcomprising both site-generated sludge and importsis approximately 50,000 wet t per year, equivalent to 5,800 dry t.…”

“…Sludge is held in the hydrolysis unit for 30 min, after which it is diluted and digested in a second mesophilic digester along with other materials which have been pretreated with pasteurization rather than thermal hydrolysis. The pasteurization process is based on heating the material at 70°C in batches for 1 hr to enable compliance with Danish Regulations for organic fertilizers (Bro et al, 2017).…”

“…From Table 6.3, the typical input into the hydrolysis process is approximately 8 t DS/d (2,920 t DS annually), although the design capacity is 15.3 t DS/d, or 5,600 t DS per year (Bro et al, 2017). In total, 350 m 3 of ammonia-rich digestate derived from the digestion process with average concentrations of 1,000-1,500 mg/l (equivalent to load of 350-525 kg/d ammonia) are processed in an AnitaMox ® deammonification-based system.…”