Advantages and disadvantages of mechanical manure dewatering

Abstract

The article provides an analysis of the performed experiments on mechanical dewatering of manure by a press and a centrifuge. It was determined that 2.5-3.5 tons of liquid can be removed from 10 tons of manure with 70% moisture. It is known that the mechanical method of removing moisture from manure saves a significant amount of thermal energy in comparison with the thermal method, which is moisture evaporation. However, along with water, nutrients dissolved in it, especially nitrogen, are removed from the manure. The subsequent use of nitrogen-depleted manure as fuel is beneficial because less nitrogen oxide is released into the atmosphere. Moreover, when coal is added to the manure, it is possible to intensify this process. Up to 44% of nitrogen, up to 41% of phosphorus and up to 35% of potassium pass into the liquid fraction. Such liquid can be used for foliar feeding of plants with a close arrangement of sowing crops. When using manure as a fertilizer, it is more expedient not to use mechanical dewatering, but to perform thermal drying with simultaneous disinfection from pathogenic microflora and weed seeds. To exclude formation of manure lumps with an outside crust and some droppings that didn’t undergo disinfection, it must be pre-mixed with dry droppings or sawdust.