Patent KR-100822378-B1 (KR)
Title: Method for fertilization treatment of byproduct accompanying digestion treatability of livestock excretion and device for using the same
Inventor: KIM BU YEOUN
IPC: C05F3/00
Filed: 2007-08-23
Granted: 2008-04-16
Abstract: A composting method accompanying aerobic or anaerobic digestion of livestock excretion and a composting device employing the method are provided to utilize a liquid fertilizer which is byproduct of livestock excretion treatment as useful resources, to fix nitrogen in soil for time-release fertilizer and to transform liquid fertilizer into solid fertilizer which is transported or stored more easily by adjusting pH of liquid fertilizer before concentration to 4-7 with strong acid. A composting method accompanying aerobic or anaerobic digestion of livestock excretion comprises: acidity control process which adjusts pH of liquid fertilizer to 4-7 with strong acid; and liquid fertilizer concentration process which concentrates the liquid fertilizer of pH 4-7 to 55-90% through pressure evaporation. The acidity is controlled by the amount of strong acid in the process. The composting method optionally comprises: water content control process by mixing the concentrated liquid fertilizer with absorptive material; and solidifying process for the mixture from the water content control process. A composting device employing the method comprises: a pH control part(1) which controls initial pH of liquid fertilizer; a pressure evaporation part(2) which concentrates the liquid fertilizer from the pH control part(1); an absorptive material mixing part(310) for mixing the concentrated liquid from the pressure evaporation part(2) with absorptive material; solidifying treatment part(3) which solidifies the mixture from the absorptive material mixing part(310) to produce particulate solid fertilizer; and an energy supplying part(4) comprising a gas boiler(410) and a control valve(420), which controls steam generated from the gas boiler(410) to be supplied for the pressure evaporation part(2). The pH control part(1) comprises a liquid fertilizer retention tank(110) for storing liquid fertilizer from an anaerobic treatment system(5), a storing tank(120) for strong acid, a control valve(130) to control the amount of strong acid for pH control, a liquid fertilizer escort pump(140) which escorts liquid fertilizer in the retention tank(110) to the pressure evaporation part(2), and a detector(150) for detecting the acidity of the liquid fertilizer in the retention tank(110). The pressure evaporation part(2) has plural pressure evaporators(210a,210b,210c), plural heat exchangers(220a,220b,220c) for each pressure evaporator, recovery line(230) for recycling some water generated from the pressure evaporator(210a,210b) for heat exchange, a condenser(240) for supplying condensed water from water generated in the pressure evaporators(210a,210b,210c), and a cooling tower(250). The absorptive material mixing part(310) comprises a hopper(311) and a feeder(312), and the hopper(311) supplies the feeder(312) with absorptive material. The feeder(312) transports the absorptive material to a pelletizer(320). The solidifying treatment part(3) comprises a pelletizer(320), a drying part(330) and a packaging part(340).