Open access publications in the SLU publication database

By using the thicker slurry in the top and bottom of the slurry tank for biogas production, the transport costs can be reduced and the methane production in the biogas reactor can be increased. The self-separating ability of the slurry can also be used to optimize the utilization of phosphorus in the manure. This fact sheet describes the results of an experiment in which liquid manure from dairy and pig production has self-separated for at least 6 weeks. The measurements were carried out in two slurry tanks from milk production, a tank from integrated pig production and one from growing-finishing pigs. Manure samples were taken at three sites and three depths in the slurry tanks for the analysis of both methane production and plant nutrients. The manure in slurry tanks had self- separated during the 6 weeks. Floating crust and sediment contained between 20-60% of the phosphorous in the containers. The water-soluble nutrients potassium and ammonium nitrogen was distributed evenly throughout the manure volume. By pumping away 30% of the thinner liquid manure in the middle of the container with integrated pig manure the average methane potential increased by about 15% per ton for remaining slurry.