Study On Biological Activated Carbon For The Resourceful Utilization Of Iron And Steel Industry Drainage

This article studied on Biological Activated Carbon for the resourceful utilization of iron and steel industry drainage, including the treatment effect, influence factors, the optimization of running parameter and backwash parameter. It also made a deep discussion on the mechanism of biological removal iron and manganese.Ater the membrane forming of BAC, BAC filter column had good treatment effect to the drainage in Baosteel Factory Moat. The result of experiments showed that the average concentration of turbidity, COD, NH₃-N, total iron and manganese in effluent respectively were 3.11 NTU, 6.72mg/L, 0.29 mg/L, 0.15 mg/L, 0.18 mg/L and 0.12 mg/L, when the average concentration in influent were 17.6 NTU, 13.6mg/L, 0.93 mg/L, 0.21 mg/L, 0.70 mg/L and 0.54 mg/L.The main influence factors of were vacant bed contact time, temperature and dissolved oxygen (DO). Prolonging vacant bed contact time could improve the removal rate. The average removal rate of turbidity, COD, total iron and manganese respectively were 78.7%,38.3%,70.1%å’Œ75.7% when vacant bed contact time was 30min, which increased to 90.9%,69.8%,86.2% and 86.8% when vacant bed contact time was 60min. The removal rate descended along with reduced of temperature, especially when water temperature was lower than 15℃. The average removal rate of turbidity, COD, NH₃-N, total iron and manganese respectively droppedd 22.7%,13.9%,29.7%,18.9% and 16.9% compared with these in 20℃～25℃. In addition, increasing DO of influent could improve the removal rate of COD and NH3-N, but had no obvious impact on total iron and manganese.The suitable technical parameters were abtained after many experiments. The vacant bed contact time was 45～60min, DO was about 5mg/L, temperature≥10℃, and the depth of filter layer≥100cm. The suitable backwash parameter were expansion rate of filter layer of 25%～30%, backwash time of 6～8min, the backwash period depended on raw water quality, commonly was 3～4d.The effect of dissolve iron and manganese removed by BAC were batter than by AC, which proved that biological removal of iron and manganese was existent. The iron and manganese were removed through adsorption of active carbon, catalysis and oxidation effect of microorganism and filtration mechanism. The removal of iron mainly depended on chemical oxidation and physical function, partly was biological oxidation. The removal of manganese mainly depended on chemical oxidation and the function of biological oxidation was about 62%.The biomass of iron bacteria in the BAC filter column was abundant, the number in the top was 7.60×10³cfu/g. A pure bacterium was obtained through three times separation and purification, and bacterium maybe was Gallionella ferruginea, which was the high efficiency bacterium of removal iron. The oxidation and removal velocity of iron and manganese was direct ratio to consistency of iron and manganese. The consistency of iron and manganese in the BAC filter column in Baosteel had the relationship with the time, which respectively were ln(C_Fe0/C_Fe)=0.01t+0.1401, R²_Fe=0.8746 and ln(C_Mn0/C_Mn)=0.0228t+0.1863, R²_Mn=0.946.