| Based on "treatment technology of micro-pressure internal circulation(IC) multibiofacies" and combing with research results on micro-pressure internal circulation multi- bioreactor( "micro-pressure reactor"), the micro-pressure double circulation multi-bioreactor( "double circulation reactor") is developed. This bioreactor has the ability to separate zones of high oxygen- medium oxygen- low oxygen in a same micro-pressure reactor and remove organic substance, nitrogen and phosphorus at the same time. This paper is based on lab test parameter of double circulation reactor to design, process and debug the pilot plant of the double circulation reactor.Based on research experience of domestic and overseas sewage treatment pilot test, lab test key parameters and the scale of the proposed sewage treatment plant and according to the standards including Code for Design of Steel Structures, this paper designs the pilot plant, which adopts “Q235” steel form, with 291m3/d of treatment scale and 0.23 kgCOD/(kgMLSS·d) of sludge loading. Among them, the reactor is 6.00 m long * 3.85 m wide * 5.20 m high with an effective volume of 96m3 and the sedimentation basin is 2.50 m long * 3.85 m wide * 5.20 m high with an effective volume of 41m3.Meanwhile, according to Code for Construction of Steel Structures(GB 50755-2012), Code for Acceptance of Construction Quality of Steel Structures(GB 50205-2012), etc., the pilot plant is processed, checked and accepted. As for welding of pilot test steel structure, the method of shielded metal arc welding(SMAW) is adopted and backing weld, filling welding and cosmetic welding are applied for panel docking. After derusting the panel with mechanical steel brush, paint by hands the panel with epoxy glass-flake coating. In addition, the intermediate assembled structure has a deviation of 5mm, transverse shearing of 3mm, jointing clearance of 0.10 mm and volume deviation of 0.03% and 0.02%, which all comply with the standards. The pilot plant is also equipped with online detection instruments and electrical devices, which reach the design requirements of the process.As for the pilot plant, water from the aerated grit chamber in a sewage treatment plant is taken as primary water of the test, and the active sludge in the oxic part of the chamber is taken as the seed sludge for debugging. In addition, at 8h hydraulic retention time, 42.35m3/h air flow, 100% recirculation ratio and 23 d sludge age, dissolved oxygen exists in a different gradient manner in the pilot plant, achieving the spatial and temporal coexistence of high, medium and low oxygen zones. In addition, the DO value of the high oxygen zone is basically controlled more than 1.00mg/L, medium oxygen zone between 0.20mg/L~0.50mg/L and low oxygen zone less than 0.20mg/L.Sludge concentration in the pilot plant is stabilized at about 4000mg/L, and SV30 is held between 20%- 30%, achieving good settling performance. Active sludge has good reactivity due to a large number of microorganisms. Meanwhile, the pilot plant provides the removal percentage of COD reaching above 84% and the removal percentage of total phosphorus reaching above 93%. At 85 ~145mg/L of COD and 0.86~2.71mg/L of total phosphorus at the water inflow, the water outflow reaches level 1 class A discharge standard specified in Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant(GB18918-2002). |
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