Billund biorefinery – advancing the recycle circle
Gilbert, A.B – Veolia Water Technologies, UK
(free)
Abstract
The development of the wastewater treatment plant at Grindsted is a strong example of local circular economy and sustainable resource recovery. Resource recovery is the main focus of the upgrading of the plant and realized by implementation of energy efficient and state-of- the-art technologies.
The transformation into a BioRefinery is ongoing and when completed the energy demand of the facility is reduced by circa 60-70% and the phosphorus removal is converted from a chemical to a biological process, facilitating the phosphorus recovery on local agricultural land.
The energy and heat production from the digestion processes is significantly increased resulting in both excess electricity and heat exports to the local grid infrastructures. The heat produced is in excess of the plant’s demand, due to the efficiency of the Veolia ExelysTM continuous thermal hydrolysis system.
Further activities will bring the resource recovery to the next level by evaluating the feasibility of phosphorus recovery by struvite precipitation and of co-digestion of manure from farming.
Keywords
ExelysTM Continuous Thermal Hydrolysis, Energy, Recycle, Co-Digestion, BioRefinery
Introduction
Circular economy is the buzzword of our time, but it is also a business model that pays off. Currently the wastewater treatment plant (WWTP) of Grindsted in Denmark is rebuilt as a private-public partnership into Billund BioRefinery [BBR] also known as “The Wastewater Treatment Plant of the Future”. At this facility, resource recovery is the main focus and apart from being an investment in a better environment, it is a good business for the utility company in terms of investment savings, operation stability, lower operational costs and a significantly higher net energy production.
To achieve a circular business model the WWTP with a capacity of 100,000 EP is upgraded with state-of-the-art technologies to control the wastewater treatment processes, to treat the effluent and reject water and to generate significantly more methane gas from the wastewater sludge, organic household waste and organic industrial waste. Moreover, the energy use of the WWTP is minimized by advanced online control of the wastewater treatment and biogas processes and by introducing energy efficient technologies.
The Billund BioRefinery [BBR] has been established and developed to meet the Danish and global political goals of focusing on substantial processes. The development towards a BioRefinery follows the initial operation of the plant at Grindsted in the Municipality of Billund as a co-digestion facility where Municipal organic waste was co-digested with the wastewater plant’s indigenous sludge, with both feedstocks being combined for Pasteurisation prior to the thermophilic anaerobic digestion process.
