Pilot-scale study on dehydration effect of water hyacinth with different pulverization degree

The dehydration technology of water hyacinth has been the choke point to achieve the utilization of its resources, so it was very important for developing the dewatering equipment with high efficiency and low cost. The selfmade equipment of SHJ-400 including solid-liquid separator and special vertical sewage pump was tested under different pulverization degree of water hyacinth through adjusting motor frequency or number of layers with blade on the vertical grinder. Firstly, influence of dehydration effect of water hyacinth under different degree of pulverization was tested in the laboratory, then the new grinder of horizontal and flail were designed based on requirements for pulverization efficiency of dewatering equipment, and a pilot test on operational effect of the whole equipment (including pulverization and dehydration) was carried out. The results showed that the dehydration rate increased with the pulverization degree of water hyacinth, but excessive pulverization caused more energy consumption of pulverization and more contents loss of dry matter as while as more proportion outflow of nitrogen, phosphorus, potassium and other nutrients of residue. The best operating condition was at pulverization degree of 32.92, i.e. 88% proportion of the remnant body length of water hyacinth was smaller than 5 cm after smashed, where moisture content of residue decreased to 83.65%, the lowest total energy consumption of 6.39 kW·h/t was obtained. In addition, the pilot test had the similar effect to laboratory test, particularly the efficiency of pulverization and dehydration were higher than that of laboratory test, the total energy consumption (including pulverization and dehydration) was reduced to 2.28-2.72 kW·h/t. According to 200 t/d processing capacity, the processing cost was 4.5 Yuan/t (the other costs including equipment depreciation was neglected). So the equipment and engineering technology are applicable for industrialization of comprehensive utilization of water hyacinth.