Study On Treating High Color High Ammonia Nitrogen Water At Low Temperature By PAC-MF Process

There are about six months of icebound period in Northeast of China. The self-purification capacity of the water is poor, and it is difficult to treat it in microthermal seasons. It has been a very difficult problem to the treatment of high chroma water, which is caused by humic acid. Meanwhile, the efficiency of biological treatment of surface water with high ammonia which is caused by domestic and industrial waste water discharge is very low. Consequently, the research on the technical process used to remove color and ammonia under low temperature has been an important issue needed to solve urgently in water treatment.We have studied the treatment of the water with low temperature and high color and ammonia, using the combined process of powdered activated carbon-microfiltration (PAC-MF). Firstly, we studied 3 starting methods of the system as follows: A) influent and effluent continuously; B) vaccination, then influent and effluent continuously; C) braised aeration, influent and effluent intermittently. The results showed that: from start to treatment effect stable, the time required for the methods of A, B, C is 27d, 24d and 30d respectively. We also described the mechanism of it.After the system runs stably, we investigated its removal efficiency for the ammonia, total nitrogen, color, UV₂₅₄, TOC and CODMn. The results showed that: the removal efficiency of the combined process for ammonia and total nitrogen are 98.4% and 28.29% respectively; the removal efficiency for color is 90%～100%; the removal efficiency for UV₂₅₄,TOC and CODMn are 93.18%～97.47%,85.2%～91.5% and 54.93～63.61% respectively. Based on the treatment effect, we also analyzed the mechanism for the removel of pollutant.In the study, we optimized four main process parameters of the system, they are the concentration of activated carbon,backwashing strength/backwashing time,hydraulic retention time (HRT) and the volume of discharging sludge. We compared the performance and membrane fouling of the system when the concentration of activated carbon is 10g/L, 20g/L, 50g/L, 80g/L, 120g/L. The results showed that: the optimal concentration of activated carbon is 50g /L. We studied the growth rate of transmembrane pressure and net water production when backwashing strength/backwashing time is 7 times/1min,7times/30s,5times/1min,5times/30s and 3times/2min respectively. After analysis and comparison, we determined the optimal backwashing strength/backwashing time is 7times/30s. we investigated the treatment effect of PAC-MF system when hydraulic retention time (HRT) is 0.5h,1h,2h and 3h respectively. When the HRT is 0.5h, the water quality of effluent can not meet the criteria. When the HRT is 1h, various indices of the effluent can reach the requirements of Standards for drinking water quality. When the HRT is 2h or 3h, it will make volume of the reactor large, take a large of area, and then the economic benefits will decrease. So the optimal hydraulic retention time is 1h. We investigated the removal effect for the ammonia nitrogen, nitrite nitrogen and total nitrogen when the volume discharging of sludge is 5g,10g,20g,32g and 45g respectively. The results showed that: when the volume of discharging sludge is 32g and 45g, it will destroy the original microbial systems greatly, and the treatment effect of the combined process is declining sharply; howerer, when the volume of discharging sludge is 5g and 10g, it can not effectively improve the removal effect of the system for organic matters over a long period of time. Consequently, the optimal volume of discharging sludge is 20g.