Freeze Dry Unit - The story

The Freeze Dry Unit is the machine that can revolutionize sludge dewatering and drying. By freezing and drying, the Freeze Dry Unit achieves a dry solids content of above 95 percent - without the use of polymer. The Freeze Dry Unit is more environmentally friendly and has lower energy consumption than today’s drying methods. The Freeze Dry Unit is here to stay.

In the autumn of 2019, the world will for the first time finally see the Freeze Dry Unit. The machine and process that has received praise such as “Dewatering without polymers is completely revolutionizing” and “If what you say is accurate you have found the Holy Grail of sludge dewatering. This is the machine we are looking for”. The first public showing of the Freeze Dry Unit takes place in November at Europe’s biggest exhibition for water solutions, Aquatech in Amsterdam. Here the market, competition, future partners, customers and many more get to see the machine which not only can dewater sludge without polymers, but also dries the sludge with less energy and is more environmentally friendly than today’s methods.

The vast knowledge of Elajo behind its development

The development of the Freeze Dry Unit has taken several years and builds on the Elajo Groups technical knowledge and expertise. Elajo has decided to work with the big global trends: Digitalisation, Climate Change and Urbanisation. In these areas, innovation should be implemented and achieved. The strategy has already borne fruit as it has led to the development of Elajos digital platform and process control programme, SystemOne.

Elajo knew about the problem of waste with radioactive particles in sludge from the development of nuclear power. Today, this waste is stored in pools around the world. The connection from this can be made to the global challenges with sludge treatment as additives are banned and restrictions on disposal ways are made. The results from the work with nuclear sludge could apply to different applications such as wastewater sludge. So, the idea for the Freeze Dry Unit was formed.

Market research praise

Before the development of the Freeze Dry Unit, market research was conducted, both in Sweden and internationally. The reception was overwhelmingly positive. Praise such as “It is a paradigm shift to be able to control the DS content, without polymers, to a completely dry product” was received.

Elajo realised that the Freeze Dry Unit could be a solution to a global environmental challenge.

The market research showed that the market is very big and global.


Under strict secrecy, the development of the Freeze Dry Unit started during the first part of 2018. Twenty of Elajos experts in process control, mechanical manufacturing, SystemOne, design and construction as well as cooling and ventilation began the development. An application to the Swedish Environmental Protection Agency was sent to gain financial support from the agency’s project City Innovations. The development of the Freeze Dry Unit received support to perform pilot testing at the wastewater treatment plant in Oxelösund.

Clear results

The results from the pilot testing was clear. Sludge with a dry solids content of only one percent could, in the Freeze Dry Unit, achieve a dryness of above 95 percent. Sludge from biogas production, the food industry, paper pulp and sludge with and without polymers was tested. The results speak for themselves – wet sludge is transformed to a dry product as well as a particle free reject water.

The Freeze Dry Unit lives up to all the praise. This is a potential paradigm shift for sludge treatment. This enables a circular economy regarding sludge. The Freeze Dry Unit can support solutions already existing on the market, among others, effective mono incineration for further extraction of phosphorus. The Freeze Dry Unit is all and all a solution that works now and is a solution for future applications.