Resource-efficient manure

Livestock manure is a valuable resource, providing soil-improving minerals without the use of chemical fertilisers. Despite this, farmers often get rid of surplus manure waste, consuming energy for treatment and transport and generating air pollution.

The EU-funded project BIOECOSIM (An innovative bio-economy solution to valorise livestock manure into a range of stabilised soil improving materials for environmental sustainability and economic benefit for European agriculture) has developed three innovative technologies to turn manure into mineral nutrients, gas and water.

First, researchers heated the manure to extremely high temperatures in an oxygen-free environment to produce gas, liquid and a carbon-rich solid residue called biochar. To do this, they developed a thermal processing unit that can take up to 100 kg/h of raw pig manure.

After removing the solid biochar, researchers precipitated a mineral phosphate fertiliser mixture from the remaining liquid. Finally, they also recovered ammonia from the liquid using gas permeable membranes.

They have now built lab-scale units that integrate all three technologies, with the resulting products being biochar, gas, phosphorus, ammonia and reclaimed water. In this resource-efficient process, the gas will be used to help power the system while the water will be recycled for livestock or irrigation.

BIOECOSIM's technology should reduce the amount of environmentally toxic surplus nutrients entering water systems in regions with high livestock intensities. It may also generate income for farmers who could sell the project's soil-improving products and generate electricity from the gas.