Study on the Potential of Nitrogen and Phosphorus Removal in Oxida-tion Ditch Process in Low Carbon Source Urban Sewage Plant
[Purposes]Taking an urban sewage plant as an example,this paper discusses the feasibility of excavating the potential of oxidation ditch process in low carbon source urban sewage plant,which pro-vides a direction for the transformation of oxidation ditch process in other sewage plants in China.[Meth-ods]Firstly,the original oxidation ditch reflux door was closed and its steel concrete was reinforced.Two low-head and large-flow through-wall pumps were installed in the vertical direction of the reinforced re-flux door,which strongly promoted the reflux of nitrification liquid,so that the internal reflux ratio of the oxidation ditch reached 300%～400%.Secondly,an aeration disc was added at the two curved sections of the oxidation ditch to adjust the dissolved oxygen(DO)concentration in the oxidation ditch and the anoxic zone.Finally,the original single sludge was refluxed to the anaerobic tank,and the double sludge was refluxed to the anaerobic tank and the anoxic zone of the oxidation ditch.The sludge reflux ratio was increased to 100%～200%.[Findings]After the transformation,the effluent quality of TN and TP in the oxidation ditch was significantly improved,and the effluent concentration of TN was reduced from 25～30 mg/L before the transformation to 10～19 mg/L,and the nitrogen removal potential was released by 11%～22%.The effluent concentration of TP was reduced from 1～1.5 mg/L before the modification to 0.1～0.5 mg/L,and the phosphorus removal potential was released by 14%to 23%.[Conclusions]Through the adjustment of the oxidation ditch reflux gate,the aeration disk,the sludge reflux point and the reflux ratio,the potential of nitrogen and phosphorus removal of the oxidation ditch system is further explored and released.Since there is a large proportion of the oxidation ditch process in the large sewage treatment plants in operation,excavating its potential of nitrogen and phosphorus removal can be re-garded as a direction of energy saving and consumption reduction of sewage treatment plants.
low carbon source sewageoxidation ditchupgrading and reconstructionnitrogen and phos-phorus removal
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