This thesis is made by Carl Persson and Alejandro Saavedra for Gryaab. Gryaab is Gothenburg?s water processing plant and produces about 60 GWh biogas annually with a flow around 1150 Nm3/h. Gryaab wants to research their possibilities to become independent with electrical energy and the possibilities to enrich, upgrade biogas. The use of methane rich gases like biogas and natural gas is today low in Sweden compared to major parts of the world.

Urinsten, urolithiasis, är en relativt vanlig åkomma i hundens urinvägar. Stenarna är uppbyggda av olika mineraler och salter av vilka kalciumoxalat och struvit (magnesiumammoniumfosfat) är de vanligaste, ensamma eller i kombination med andra ämnen. Stenarna återfinns framförallt i de nedre urinvägarna, det vill säga i urinblåsa och urinrör. De kan ställa till stora problem genom obstruktion och svår smärta. De upptäcks vanligtvis genom röntgen och måste ofta avlägsnas kirurgiskt men risken för att nya stenar utvecklas är stor.

During whole-tree harvesting, there is a risk that the soil will become impoverished of nutrients. To prevent this, nutrients are returned to the harvested site as wood ash. This action also reduces the risk of soil acidification. Nevertheless, the ash does not result in any increase of tree growth if it is added on mineral soils, which is where the measure is most commonly used in Sweden. Due to the lack of growth response, the interest from landowners is small, which is why ash amendment today is not done enough to compensate for the need.

Distillers? grain is a by-product of ethanol production. Corn, wheat and barley are the grains that are generally used in the distillery process. Distillers? grain is rich in protein and phosphorus.

1. Reaction on burial depth and nitrogen availability and placement in competition with a crop In this trial it was investigated how couch grass (Elymus repens) changes its ability to compete in stands of wheat and barley with different burial depth and different amounts and placement of nitrogen. More knowledge in this area can be valuable in the attempt to decrease the use of herbicides and still keep the weeds under control. The trial was carried out in the summer of 2004 as an outdoor pot experiment. The pots contained 15 litres of soil with a surface of 0,06 m2.