| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2005: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2004: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Research Abstract |
An upflow anaerobic sludge blanket (UASB) reactor was applied and operated under reduced pressure for the anaerobic treatment of municipal wastewater (the effluent from a primary settling tank). Furthermore, post-treatment was combined to remove the nutrients, nitrogen and phosphorus, and thus the total treatment system was evaluated.
Three of UASB reactors with the volume of 7.9 L were prepared ; the first was the control, the second added with trace nutrients (Fe,Ni,Co and Zn), and the third operated at reduced pressure (0.08 MPa). The experiments were run for several months at the temperature of 9-30℃ and the hydraulic retention time (HRT) of about 2 hrs. Compared to the control, the reactors with the trace nutrient addition and reduced pressure operation gave better effluent quality on the average. Those reactors appeared to prevent sludge from floating due to gas removal or coagulation.
Post treatment was performed with microbial nitrification-denitrification and precipitation with iron for nitrogen and phosphorus removal respectively. The HRT was about 2hr for the denitrification (30% v/v of sponge carriers in the fixed bed), about 4hr for the nitrification (1 kg of a wire net in the tank), applying the recycle flow of 100%, the sludge return of 50% and DO of 2-3 mg/L. During 84 days of the operation, the temperature shifted from 27 to 7℃. However, the effluent showed almost always less than 10 mg/L of BOD, TOC and SS. In addition, although more NH3-N remained as the temperature decreased, <10 mg/L of T-N and <1 mg/L of T-P were achieved for the most of time. Therefore, it was demonstrated that the wastewater treatment system with anaerobic treatment was able to simultaneously remove organics as well as nitrogen and phosphorus.
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