The Effects Of Pulp And Paper Industry Wastewater Treatment Sludge Composts On Soil Properties And Lignin Degradation

摘要

The aim of this study was to investigate the effects of pulp and paper wastewater sludge composts on soil and crops. The objective was to study how easily lignin containing sludges can be composted and how lignin degradation affects the soil characteristics. Five different sludges were composted for four months in piles. Then the composts were moved to a field for agricultural experiments. Test plants were barley and oats. The composting process was monitored weekly and samples were taken before andduring composting. In agricultural experiments the crop yield was measured and the chemical and microbiological properties of the soil were analysed. The results showed that the forest industry sludges were suitable for composting and for soil improvement in agricultural plant production. The amendment of compost increased both the lignin concentration (2–24 %) and the quantity of fungi in soil. Lignin degradation increased humus content and the quantity of microorganisms in soil. Also the porosity increased in compost plots compared to the plots with no compost addition. The barley grain yield was as good with composted sludges as with mineral fertilisers (NPK-fertilisers).