Utilization of cast seaweed and waste from pectin production for anaerobic digestion

The paper describes a preliminary study on the environmental consequences of realizing a biogas plant using locally available biomass fractions in Solrød, Denmark. The biomass, which will be used at the plant, will consist of: cast seaweed (app. 20,000 tons year-1), waste from pectin production (app. 80,000 tons year-1) and manure (app. 50,000 tons year-1) and other materials in lesser amounts. Methane potentials of the two “new” biomass fractions were measured to predict their contribution to the biogas production. Measured methane potentials were: Pectin waste: 370 to 460 ml CH4 g VS-1 and cast seaweed (winter sample): 118 ml CH4 g VS-1. The predicted annual biogas production of the plant was 5.4 million m3 CH4. An environmental assessment concluded that a biogas plant using the aforementioned organic materials will reduce greenhouse gas emissions between 25,000 tons CO2 year-1 and 40,000 tons CO2 year-1 depending on the type of energy utilization. Reduction of nutrients in the coastal zone by removal of seaweed was found to be of high value.