TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Device: The anaerobic biological treatment reactor uses expanded granular sludge bed (EGSB), where temperature is controlled to 33-35 degrees C, volume load is 18-22 kg chemical oxygen demand s(COD)/(m3-day), water power staying time is 2.5-3.5 days and outlet water COD/TN is 4-5. The anoxic biological treatment, one-stage aerobic biological treatment, two-stage aerobic biological treatment all adopts moving-bed biofilm reactors (MBBR). The anoxic moving-bed biofilm reactor generates denitrification reaction. The one-stage aerobic MBBR is mainly used for degrading organic pollutants. The two-stage aerobic MBBR generates nitrification reaction, where water power staying time is 36-48 hours and water temperature is 18-28 degrees C. The filling rate in reactor is 50-70%. The filler is polyethylene light filler with density of 0.95-0.99 g/cm3 and shape of hollow cylinder having cross support.    TECHNOLOGY FOCUS - ENVIRONMENT - Preferred Method: The coagulating sedimentation includes:(A) reacting high-concentration metal ions (such as iron ion (Fe3+), magnesium ion (Mg2+)) in waste filtrate with added sodium, hydroxide, generating colloidal precipitate such as iron hydroxide (Fe(OH)3) and magnesium hydroxide (Mg(OH)2) at pH 9-10.5 and forming flocculation effect; and(B) when ions of Fe3+, Mg2+ are not enough in the filtrate, properly adding coagulant polyaluminum chloride, and configuring stirring device in reaction region of coagulating sedimentation tank, reacting for 5-10 minutes, staying water power for 3-4 hours in sedimentation region, and processing and obtaining suspended solid removable rate of 40-60%.The carbon dioxide adding deposition method includes:(A) continuously adding sodium hydroxide to calcium removing reaction process to keep pH value of wastewater at 9-10, and controlling addition amount of alkali solution by pH online control system;(B) configuring stirring device in reaction region of chemical deposition calcium removing tank for preventing calcium carbonate deposition from blocking aeration plate, staying water power for 10-15 minutes, controlling ratio of gas (CO2) to water to 3:1-5:1, and staying water power for 4-5 hours in sedimentation region; and(C) making calcium content in filtrate to be less than 300 mg/L.