Study of effective drying method of sludge from livestock digestion tank using a wire mesh screen

Sun drying bed, one of a drying method for sludge overproduced from livestock-waste-water treatment system, was developed with a wire mesh screen. We examined the effectiveness and the condition of early sludge-separation from filter bed. 1. A container installed with stainless-steel wire mesh at the bottom was placed on the sawdust filter bed, and sludge was spread on it. 1day later, sludge cake with wire mesh was easily removed from the filter bed. 2. Experimental sludge was dried after separation, and control sludge was dried by the common method (left on the bed directly). Drying rate of experimental sludge was faster than that of control sludge, and days to decrease the moisture content of the sludge below 80% were shortened 12days at average temperature 18.9 degrees (17days in control sludge and 5days in experimental sludge) and 4days at average temperature 6.1 degrees (18days in control sludge and 14days in experimental sludge) respectively. 3. Open areas (30-70%) or openings (1-10mm) little affected drying rate. Considering the inflow prevention of the filter, the strength of wire mesh, and the ease of setting, appropriate specifications of wire mesh for this method were 0.3-0.5mm for wire diameter, and 1-2.5mm for opening. Drying rate was accelerated by removing the sawdust on the underside of wire mesh.