Abstract
In this paper, volumes of storage tanks for digested slurry are calculated by a model for planning transportation and spread of digested slurry to farmlands that was developed by the authors. The model calculated 2 cases for transportation and spread of annual volumes of 10,000 m3 digested slurry to 100 ha of paddy fields and 150 ha of upland fields. Case 1 modeled 1 storage tank in a methane fermentation plant without intermediate tanks. Case 2 modeled 1 storage tank in a plant with 1 intermediate tank.
The Case 1 storage tank required a 4,725.9 m3 volume tank as calculated by the model, whereas Case 2 needed 4,555.6 m3. For Case 2, the intermediate tank required 1,837.9 m3. The intermediate tank volume was reduced to 815.9 m3 by adjustment of capacities for slurry transportation from the storage tank to the intermediate tanks in Case 2 though the storage tank volume was increased to 4,798.3 m3. The storage tank volume was reduced to 3,910.0 m3 by additional manual adjustment of periods for slurry transportation from the storage tank to the intermediate tank in Case 2, but the volume of intermediate tank was 815.9 m3.
The total volume of the two tanks in the additional manual adjustment was the same volume as the storage tank in Case 1. This indicates that construction costs for the intermediate tanks are not absolutely additive. In addition, when plural tanks are planned as storage tanks in a plant, some of the tanks can be moved near the farmlands where the slurry will be applied. These tanks work as intermediate tanks and improve efficiency in transportation and spread of digested slurry to farmlands without large additional construction costs.
