TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Apparatus: The apparatus of tendency to heighten added value of methane-fermentation digestive liquid further comprises a phosphorus processing tank which stores distillate, and which is provided between ammonia nitrogen concentration distillate production system and the formation tank, a phosphorus elution material injection unit which produces deposit of phosphorus elution material, and a solution introduction unit which introduces solution containing ammonia nitrogen and phosphoric-acid-form phosphorus into the formation tank. The ammonia nitrogen concentration distillate production system comprises a concentration apparatus comprising distillation tank in which the digestive liquid is injected, a heating unit which is provided in the distillation tank and which heats internal digestive liquid at predetermined temperature, a cooling unit which cools and condenses the gas which is evaporated by the distillation tank, a pressure reduction pump which is connected to the cooling unit, liquid receiving tanks (I,II) to which the condensate which is cooled by the cooling unit is induced, and a switching valve provided between liquid receiving tanks (I,II) and cooling unit, and which switches communicating path.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Process: MAP is produced by inducing distillate to the phosphorus processing tank, injecting phosphorus elution material to the distillate, producing solution containing the deposit, ammonia nitrogen, and phosphoric-acid-form phosphorus of phosphorus elution material from which the phosphorus component is eluted, carrying out solid liquid separation, inducing separated solution to the formation tank, supplying magnesium compound into the solution of formation tank, producing MAP, precipitating, and carrying out solid liquid separation. Preferred Material: The phosphorus elution material is phosphate, carbide, incinerated ash, carbide material derived from biomass, and/or incinerated ash derived from biomass.