TECHNOLOGY FOCUS - ENVIRONMENT - Preferred Process: COD in the enriching culture fluid is realized by adding dextrose or methanol. Specific process of improving the ammonia nitrogen content of culture fluid is done when the ammonia nitrogen content is reduced below 10 mg/L, improving the content of ammonia nitrogen in the culture fluid to be pre-added, the improving extent is 50-200 mg/L every time after adding the culture fluid. Process for improving the ammonia nitrogen content of culture fluid is done by improving the content of ammonia nitrogen in the culture fluid to be pre-added when detecting the ammonia nitrogen content in water. Intermittent type activated sludge method is done according to intermittent type water feeding, aeration, sedimentation and water discharging process periodically, each day for 1-2 periods, the aeration time in each period accounts for 75-96%, and is done according to the intermittent type water feeding, aeration, sedimentation and water discharging process periodically, each day for 1-2 weeks, the aeration time in each period accounts for 75-96%; the activated sludge is mixed with the enriching culture fluid by the inoculation value of 20-40% by volume. Preferred Conditions: Enriching culture of the nitro-bacteria is done at 20-30 degrees C; pH is 6.0-9.0 (6.5-8.0); the sludge sedimentation rate is 15-25% (15-20%); and dissolved oxygen is greater than or equal to 2-10 mg/L.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: Enriching culture fluid comprises element calcium (Ca). Calcium ion (Ca2+) is added by adopting the format of calcium chloride (CaCl2). Using amount and adding mode of the minor elements Fe, Mg, Na and K is: Fe is added in the form of iron(II) sulfate heptahydrate (FeSO4.7H2O); Mg is added in the form of magnesium sulfate heptahydrate (MgSO4.7H2O); Na is added in the form of sodium chloride (NaCl2), sodium carbonate (Na2CO3) and/or sodium bicarbonate (NaHCO3); K is added in the form of potassium dihydrogen phosphate (KH2PO4) and/or potassium phosphate (K2HPO4); and buffer solution is KH2PO4, K2HPO4, or NaHCO3. The pH regulator is Na2CO3 and NaHCO3. Preferred Composition: In the enriching culture fluid, the final content of NH4+-N is 600-1000 mg/L. Content of Ca2+ is 0.01-0.05 g/L; ferrous ion (Fe2+) is 2-14 mg/L; magnesium ion (Mg2+) is 10-20 mg/L; sodium ion (Na+) is 200-1000 mg/L; potassium ion (K+) is 20-70 mg/L; and buffer solution is 50-300 mg/L.