TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Method: A sludge raw material is prepared using a magnetic sorting machine, a horizontal centrifugal dewatering separator, a sealed sludge raw material storage kettle, a slurry pump, a pipeline, and a valve. A straw raw material is prepared using a high-speed attrition pulverizer, a straw raw material storage cabin, and a belt conveyer. In the pipeline for conveying sludge to horizontal centrifugal dewatering separator by slurry pump, potassium nitrate or calcium chloride highly alkaline solution with a concentration of 3% as heavy-metal extract solution with respect to 1% of sludge in volume is added and dissolved, and heavy metals existing in hydrosolvent state are extracted. The newly produced extract solution containing heavy metal is separated using a horizontal centrifugal dewatering separator and discharged along with the separated sewage. In the pipeline for conveying sludge to the horizontal centrifugal dewatering separator by the slurry pump, potassium permanganate ((300-500)x 10-6) or hydrogen peroxide ((100-125)x 10-6) as deodoriferant is added with respect to 1% of sludge in volume, and effluvial substances in the sludge are reduced or neutralized. Simple substance magnetic metals contained in the sludge are separated and removed under strong magnetic action of the magnetic sorting machine, residual water and inorganic impurities such as brick stones with greater particle size, and ceramics and glass contained in the sludge are separated and removed by centrifugal force generated at 800 rpm and screening action of different meshes of a double-layer screen mesh. Some heavy metal particles are separated from the sludge by centrifugal force generated by the weight and rotation, and discharged along with sewage. The processed sludge raw material is sent to the sealed sludge raw material storage kettle by a slurry pump. The entire plant straw with rigid skin is ground into strips of length 40 mm or less and cross-section of 30 mm2 or less by feeding and rolling at 5.8 m/minute, rotatably rubbed, and ground at 360 rpm by the pulverizer. The straw raw materials are then sent to the straw raw material storage cabin by a belt conveyer. Each ingredient in the compound fertilizer is weighed, metered and mixed using a weighing meter, a mixing stirrer, and slurry pump, conveying pipeline, and belt conveyer. The compound fertilizer is filled by a transmission lifting charger. High-temperature aerobic fermentation is carried out by multilayer fluidized-bed fermentation tower. All the operating processes and operating technical parameters are controlled and operated by an electronic automatic controller. The mixing ratio of sludge is 70% and the mixing ratio of plant straw is 30%. Each raw material is mixed by a mixing stirrer and sent to the fermentation tower. When the fertilizer producing process enters the high-temperature control stage, powder coal or zeolite powder is added as harmful heavy metal adsorbent in an amount of 2% of the weight of fertilizer raw materials, and chemically reacted with substances such as humic acid and humin in humus to form a hydroxyl group. The harmful metals are reduced and complexed, and the effluvial substances produced in aerobic fermentation are deodorized. The remaining gas is sucked in the exhaust pipe with equal height by an exhaust fan and directly discharged into atmosphere. The produced substances similar to humus are discharged on the belt conveyer at the discharge port of the fermentation tower, and supplied for curing. The curing treatment involves deep curing treatment of substances similar to humus in a sealed slot turning curing chamber. The fertilizer is collected and stored in a storage chamber. The fertilizer base material is ground and screened using a roller grinding screener. A metering charger is provided for weighing and metering all the raw materials, a horizontal mixing stirrer is provided for mixing all the raw materials, a turning drum comminutor is provided for shaping and comminuting all the raw materials, a roller drying sieve is provided for cooling, drying and sieving the shaped and comminuted granular semi-finished product, and an automatic metering packager is provided for metering and packaging the biological organic compound fertilizer finished product. The organic components are ground and sieved at 360 rpm with a sieve hole diameter of 3 mm. The ratio of all the ingredients in the formulation is determined, and the weights of all the inorganic raw materials such as nitrogen, phosphorus, potassium and micro nutrient elements thrown in the batch are determined. The ingredients are weighed, mixed and stirred at 48 rpm for 25 minutes or more. The raw materials are comminuted to a particle size of 10-12 mm and shaped to 90% or more. The sieved and shaped material is dried and cooled, and the non-shaped material is returned for mixing and shaping. The final product is packaged into bags and sent to the storehouse for inventory. ACTIVITY - Fertilizer.