Study of dehydration of organic sapropel by compression method

In the Polissya part of the Volyn region of Ukraine there are mainly sod-podzolic soils, which are characterized by low natural fertility, so the application of fertilizers, especially organic ones, is a determining factor in obtaining high yields. For this region, a great reserve for increasing soil fertility is the use of sapropels as organic fertilizers. The potential of sapropels as an alternative source of organic matter for the preservation and reproduction of soil fertility in Ukraine as a whole is 140 million tons when converted to 60% moisture. In its natural state, sapropel is a colloidal system with a moisture content of 92...98%. Therefore, the main and most energy-intensive operation of its processing is dehydration. Studies have shown that free (capillary) moisture is the least energetically bound, it is held in the material mechanically due to its porous structure and can be extracted by compression. Known studies of this process are based on discrete measurements. Therefore, an automated system for measuring the amount of water released from sapropel in the process of its compression in a closed volume with information processing using computer technology was developed. To build an automated measuring device we used a strain gauge (SBR-1); analog to digital converter (NX 711); water flow sensor (YF-S401). As a controller Arduino UNO ATmega 328P-PU was used, and for signal processing on a computer – LabVIEW environment. To obtain a mathematical model of the studied process in the form of a regression equation, a symmetric non-compositional plan of the Box-Behnkin experiment of the second order was used. According to the obtained regression equation, the response surface was constructed. Based on the analysis of the response surface, it was found that it is possible to reduce the water content in the studied samples of organic sapropel from 94% to a minimum value of 72–74% at a sample pressure of 80–100 kPa and a holding time under load of 22–26 s.