| This thesis is based on "tannery cleaner production and key technology research and demonstration for wastewater treatment subproject", which belongs to "National water special project-treatment technology research and integrated demonstration project for water pollution in Huai River". Research on the key technique of tannery comprehensive wastewater was carried out in demonstration enterprise "Xinwan tannery limited company" in Anhui Province and also a pilot-scale treatment system called "Upflow Anoxic Humified media Fillter (UHF)+SBR" was established.Through the "Upflow Anoxic Humified media Filter+SBR" process, peat was applied as filter media which played an important role in adsorbing cation such as NH3-N and refractory organic matter in wastewater, because of common problems of the low removal rate of NH3-N and total nitrogen. Fresh peat dosing is needed to compensate for the loss of filler, which is flowed to SBR with the effluent of UHF. Peat then is interacted, flocculated and discharged with activated sludge.The researchers analyzed the impact of different operating conditions of UHF on the effect of denitrification, and the effect of nitrification in the SBR. By the evaluation of the operating results of UHF and SBR, the optimized process operating conditions were concluded.It has been proved that the process is effective for nitrification and denitrification in this pilot-scale system, water quality of system discharge is good enough to meet the B-level standard in the "Integrated Wastewater Discharge Standard"(GB8978-1996). The results of pilot project indicate that the optimized operating parameters of Upflow Anoxic Humified media Filter is adjusted to7.0～7.5in pH,57h in hydraulic retention time,100%in return ratio and10min per cycle in aeration; At the same time, the operation cycle of SBR is12h (fill6h, aeration8h, settle1.5h, decant2h, idle0.5h) while MLSS remains3g/L. The project achieves the most satisfactory results in terms of average removal rate of COD, NH3-N and Total Nitrogen, which can reach70～80%,80～90%and30～50%respectively. With influent concentration of COD ranging from800mg/L to1200mg/L, NH3-N ranging from150-250mg/L and TN changing from300-450mg/L, effluent concentration of COD, NH3-N and TN is lower than200～300mg/L,20～40mg/L and150～250mg/L respectively. Problems of short cut leaded to a decline in the removal rate of total nitrogen and refractory organic matter, dredging as a temporary treatment method cannot effectively eliminate the blockage.Experimental study on anti-clogging of UHF is carried out to address the potential risk of blocking in application. It is analyzed that the main reason of blockage is the growth of surface biofilm. The variation of percolation property satisfies the two-stage filtration model, feature point of which is exactly right the demarcation point against clogging. The hydraulic permeability coefficient of feature point of UHF with filter smaller then10mm is8m/d with1m/d hydraulic load and the critical hydraulic permeability coefficient needs to maintain10m/d as safeguard mechanism. Recovery test shows that the safe recovery period is3days. In the UHF with filter smaller than20mm and2m/d hydraulic load, pressure of50cm gravel layer has little effect on percolation of bottom padding whose hydraulic permeability coefficient remains around15m/d. |
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