TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Component: The pH of spraying liquid in biological trickling filter tower circularly used for several times is over 6.5-7.5. Saturated Ca(OH)2 and diluted nitric acid are respectively used for adjusting step. The adjusting pond in waste liquid backward spraying system can adjust water quality, after collecting biological trickling filter tower spraying liquid and percolate produced during the aerobic composting process, to obtain a 2:1-4:1 mol ratio of NO3- and calcium ion in backward spraying liquid. The mixed liquid adjusted in water quality adjusting pond can be backward sprayed into primary fermentation reaction channel using a metering pump, pipeline system, valve and water spraying device; where a spraying use amount is 1-10 L/m3 of piled material.day, and a little amount of mixed liquid in water quality adjusting pond is sprayed to control water content in piled material in secondary static fermentation vessel at 25-35%. Preferred Process: The pile overturning step by mechanical pile overturning machine and backward spraying step by waste liquid backward spraying system are optionally simultaneously done. A time for extracting air by high-pressure centrifugal exhauster and ventilating to primary fermentation reaction channel is coherent with a time for supplying air at air inlet by biological trickling filter tower.    TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Component: The high-pressure centrifugal exhauster is controlled by a time relay, and has work cycle of 2-5 minutes starting and 10-25 minutes closing. A centrifugal water pump is used to lift the spraying liquid to upper part of biological trickling filter tower for spraying. A control for backward spraying amount of waste liquid backward spraying system is realized by the time relay controlling work cycle or metering pump, and changing flow rate of metering pump and state of valve in pipeline. Preferred Condition: A spraying amount and spraying time can be realized by the time relay controlling the centrifugal water pump to be started and closed. When temperature of inlet air is higher than 50 degrees C, a spraying rate is 1.00-2.21 m3 of spraying liquid/m3 of filling material.hour. When temperature of inlet air is lower than 50 degrees C, the spraying rate is 0.25-1.00 m3 of spraying liquid/m3 of filling material.hour. ACTIVITY - Fertilizer.