ENSY AB visits Outreach Location Waterleau New Energy and Demo Plant AM-Power – 2018

Introduction to ENSY AB, Sweden.

ENSY AB is a private technology company in Sweden, active since October 2011, developing solutions for small scale farm-based nutrient recovering systems of manure. The core in ENSYs technology is the Multibox® system, a modularized system of mechanical and chemical de-watering and nutrient recovery modules.

ENSY operates a pilot plant outside Falkenberg in the south of Sweden together with a pig farmer.  For now, they focus on plants that can handle 15-30 000 tonnes manure per year.

ENSY has also an ambition to recover nutrients from digestate from biogas production and have made pilot studies with such input streams. However, for now they focus on manure, as such input material varies less over time than that from biogas plants and therefore easier to treat.

Drivers for nutrient recovery in Sweden

  • Manure and digestate consist of 92-95% water for which spreading and storage has associated risks of losing a large proportion of the nutrients.
  • Traditional spreading of manure, using heavy tankers etc, reduces soil fertility due to soil compacting, especially in clay soils. Soil compaction leads to decreased crop yields, which estimates for a reduced profit of 0,36-3,6 € per ton manure spread.
  • Shortage of land for livestock farmers, typically hampering the transition to more effective large-scale livestock farms.
  • Investment costs of manure storage and handling systems (new manure pits with sealing systems) and costs of transport and distribution of manure (long distance)Shortage of nitrogen fertilizers for organic farmer.

This last point has an impact on the market value of recovered NPK products, because in Sweden, Bio-certified, organic farmers are not allowed to use mineral nitrogen fertilizers. Therefore, the price for certified, organic nitrogen is substantially above that of standard nitrogen products

The Multibox® technology

Manure is separated in several steps. The first dewatering step uses two different types of in-house design self-cleaning filters (patent pending), tailored for the particle size and viscosity of the input stream. The purpose is to reduce all suspended solids in the liquid fraction above a certain size, typically 100-400 micron.  In a second phase of the system, mechanical and chemical treatment steps are combined to further purify the liquid.

The solid phase is further dewatered by ENSY’s in-house squeeze press technology without the use of coagulants or polymers to a dry matter content of 30-35%, comparable to the solid fraction of a decanter centrifuge (with the use of polymers). This product can be dried and pelletized further for better storability and can be used as a soil improver. ENSY plans to add concentrated nutrients from the liquid phase and dry the product further by means of composting, to produce a nutrient rich and hygienized fertilizer product. By composting the C/N ratio is reduced, which makes the nitrogen better accessible for the plants.

The fertilizer product is planned to be packed in big bags and stored and handled as standard mineral fertilizer. The product can also be Bio-certified depending on the origin of manure or digestate.

Contact person: Ulf Orrenius    ulf@ensy.eu    +46709705533

ENSY observations from the AMPower and Waterleau New Energy visits

The situation in Flanders is quite challenging when it comes to manure handling. Due to shortage of land, stringent fertilization limitations (Flanders is a Nitrate Vulnerable Zone according to the Nitrate Directive) and phosphor saturation of land, some farmers are obliged process the manure.

Most popular manure treatment is a separation in liquid and solid phase followed by biological treatment (nitrification-denitrification to reduce the nitrogen content) of the liquid phase. A drawback is loss of nitrogen to the atmosphere which both is a waste of nutrients for the plants and a climate hazard. The solid phase (containing most of the P) is typically transported abroad, often to France, after hygienization in composting tunnels. Nutrient separation/recovery from manure and digestate is only undertaken in a few cases, by pioneers, since the recovered products are still seen as manure by Flemish legislation and therefore the same fertilizing limits apply.

The business case of the biogas plants we visited rests on that the production of electricity is supported by ca 100 € per MWh.

From both plants visited there is an interest for more efficient de-watering technology to replace centrifuge-decanter technology to :

  • reduce the amount of cat-ion polymers applied
  • to reduce the output solid matter content (at present 2-3%).

Such technology could reduce the organic load on the later treatment steps (evaporator, Reversed Osmosis) and thereby reduce the costs of energy and chemicals. The first separation step of ENSYs Multibox® system may be useful here.