| Tannery wastewater, high-concentration organic wastewater, is usually disposed by bio-chemical techniques in domestic for its good biochemical characteristics. Traditional crafts' scarcities are gradually exposing for the strict sewage exhaustion standard and the sparse land resource, for example, ammonia nitrogen over-standard, big cover area, higher handle cost and so on. Developing new crafts, which are low energy consumption and high efficiency, is an important way to alleviate pollution causing by tannery wastewater. To deal with tannery wastewater effectively, these new techniques should have such advantages like low project investment and running cost, easy management and maintenance, high efficiency for pollutants removal especially for nitrogen and phosphorous, and no second pollution. Considering the problems mentioned above, I did the research on Circulating Humus Filter (CHF) to alleviate the pollution from tannery wastewater.Studies on CHF were carried out in the selection of filling material and lab experiment. Filler of CHF, Impact factors and the optimization of CHF are the mainly contents of this research.Pilot research in lab shows that peat can be used as the filler of CHF. The physics and chemistry characteristics of peat show that it is suit to be used in the field of tannery wastewater. For example, huge capability in adsorbing NH4+-N (about 0.6g/g-peat) short time for adsorption equilibrium(about 30 minutes). It is beneficial for peat to absorb ammonia nitrogen in alkaline condition. Having huge CEC (Cation Exchange Capacity), peat is suit to be taken as biological carrier for it's stability. Humus, a mainly composition of peat, is good in absorbing metal ions.Pilot research in lab studied the performance of CHF in removing pollutants and influence factors, such as water intake mode, temperature, pH, influent loads, etc. The start-up process of CHF technique is simple timesaving, commonly costing three weeks to accomplish bio-film formation in using domestic wastewater. Results show that CHF realized the efficient removal of organic compounds and NH4+-N, and that the anti-blocking performance of CHF is perfect. CHF should adopt intermittent water intake and the W/D (wet to dry time ratio) is aboutl:4. The removal rate of COD keeps stable (about 80%) when temperature increases, while the removal rate of NH4+-N increases. Research shows that the period of hanging membrane keeps stable while the temperature rise from 15℃to 30℃. The removal efficiencies for NH4+-N improved about 15% (from 76.6%-82.4% to 91.3%-94.5%). pH has great influence on the stability of filler. The removal efficiencies of NH4+-N gradually decreased with the increasing hydraulic loading. When the influent ammonium concentration is 300mg/L, ambient Temperature is 20℃, and hydraulic loading was 0.5 m3/(m2·d), the removal rate of NH4+-N close to 100%. Meanwhile, the effluent COD is less than 30mg/L. The removal rate of NH4+-N reduced to 74.6%-81.5% from 75.1%-87.9% with the influent loads increased to 1.5 m3/(m2·d) from 1 m3/(m2·d). Although CHF achieved high-efficiency remove of NH4+-N, the remove rate of TN was non-ideal. The removal efficiencies for TN was 10.4%-30.4% at the condition of the surface load was 365.45-421.1 g-TN/(m2·d). The experimental results show that the stability can be improved by regulating influent quality and operation conditions, and that the removal rate of TN can also be improved by reducing DO and adjusting return flow. In case of adjusting return flow rate to 20%, influent load is 1 m3/(m2·d), and DO<0.4mg/L, the removal rate of TN is up to 54.8%. The most important approach to enhance the stability of CHF is increasing the stability of filler in the microbial environment. The effects of adding different diameter coal into peat are obviously different. Smaller than lmm coal produced negative influence to the original permeability coefficient of CHF, while 1-2mm and 2-3mm coal played a contrary effect. However, adding coal make the permeability stability of CHF and the remove rates of pollutants decreased.In the future, the thorough research to the stability of peat under different water quality conditions should be carried out. The removal efficiencies for TN and filler modification need deep research. Moreover, new sort of fillers should also be developed to perfect CHF system.
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