Losses in nitrogen,phosphorus and potassium of water hyacinth dehydrated by mechanical press

An experiment was carried out to investigate the effect of dehydration by mechanical press on water removal and NPK losses.The results showed that when the pressure increased from 0 MPa to 12MPa,the moisture content was reduced from 94.72% to 68.90%.The dehydration rate was up to 91.27% and the dry matter loss was up to 29.31%.The leached NPK increased as the pressure increased.Under a pressure up to 12MPa,the maximum losses in NPK were 52.28%,47.83% and 84.83%,respectively.The rates of loss on different nutrients were: total N(Kjeldahl nitrogen)(71.00%)> inorganic nitrogen(42.97%),water-soluble P(68.90%) > organic P(45.03%) and water-soluble K(84.75%).The nutrient losses in water hyacinth under the mechanical press were closely related to the nutrients' water solubility.