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Solum Groups’ Aikan Plant in Holbaek Denmark

During 1999 and 2000 the owner of the Solum Gruppen, Mr Christian Christensen, spent a large amount of time evaluating in-vessel composting technologies with a view to integrating a pre-composting digestion phase. This was undertaken due to the realisation that the whilst existing AD technologies were developed and designed to use a very consistent and easily homogenised feedstock, the processing of ‘municipal waste’ derived organics would prove to be a much tougher challenge. A number of process suppliers showed some interest; however, they were fully concentrated in developing and understanding their own fairly new technologies.

As a consequence, in 2002 Solum raised the funds to build and develop their own ‘dry’ anaerobic digestion and integrated composting (Aikan) plant, in Holbaek, Denmark. The biological process used in the full-scale plant was based on a two-phase digestion process, followed by composting. The principle behind the digestion process is to separate the procedure into two phases: a hydrolysation process and a methane-producing process. Hydrolysation was carried out in concrete modules, and the methane was produced in hermetically-sealed reactor tanks. The products of the biological process are energy, in the form of biogas, and compost.

The five module plant was commissioned in 2003 and shortly afterwards a partnership was entered into, whereby two local waste companies would take a share in ownership, and Solum would be the operating partner. This brought about the immediate diversion of 10,000 tpa of organic material arising across nine municipalities from incineration, producing 80 CuMt of biogas at a 70% methane content and 350 kg of nutrient-rich compost from each tonne.

During this phase of development the process itself was being continually optimised and in 2007 a further five modules were added to the existing plant increasing process capacity to 25,000 tpa.

In 2009 the largest pension fund in Denmark Maj Invest Equity (formerly LD Invest Equity) carried out due diligence on the business model and process dynamics and decided to invest €3.1 million into Solum A/S to make way for further growth.

Some of the investment has been used to update the site with improvements in processing due to the lessons learned and in installing a new reactor tank and CHP unit. Also available on site is a 100th scale model used for optimisation of the process to handle different feedstock’s and processing parameters. A lab scale system that enables determination of biogas potential of differing feedstocks is available.

Today the site is economically viable and processing over 25,000 tpa of municipal organics, selling energy to the grid and heat to neighbouring business as well as producing a top grade agricultural soil improver.

The group has won a handful of awards including the Danish Liberal Party Climate and Environment Award, which was presented by the former Danish Prime Minister, Lars Løkke Rasmussen. The award was given for Solum Gruppen’s ability to successfully combine environmentally friendly waste management with a smarter business model and also received the Gazelle Award from Borsen (Denmark’s leading business newspaper) for outstanding business management and growth in 1999, 2000, 2006 and 2007.

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