Department of Environmental Science, University of Eastern Finland, Finland.
Environ Technol. 2010 May;31(6):617-23. doi: 10.1080/09593331003592246.
We studied the optimization of nitrogen reduction from municipal wastewater in a laboratory-scale modified Ludzack-Ettinger activated sludge wastewater treatment plant (WWTP). The unit consisted of primary denitrification, secondary nitrification, a sludge clarifier and a post-denitrification unit. The process simulates the Kuopio WWTP, which provided the influent utilized. We describe the effect of varying anox-circulation schemes on the nitrogen removal efficiency. We further compare the denitrification efficiencies of ethanol and methanol applied in the post-denitrification unit, and compare the properties and costs of these chemicals as carbon sources. Maximum efficiency of total nitrogen removal (70.8%) was obtained with 256% anox-circulation. The process was, however, not very sensitive, as a wide range of 150-400% of anox-circulations gave good results for nitrogen reduction. The unit achieved high BOD, and COD reductions of wastewater also when nitrogen reduction was moderate. The addition of 40 mg/L/day of ethanol to the post-denitrification tank meant that the nitrate-levels of effluent could be controlled to below 10 mg/L of nitrate nitrogen. Methanol and ethanol were equally effective for denitrification. The use of ethanol instead of methanol could reduce treatment costs by 30% to 0.02 E/m3 of treated wastewater according to 2008 market prices.
我们研究了在实验室规模的改良 Ludzack-Ettinger 活性污泥污水处理厂（WWTP）中从城市废水中优化脱氮的问题。该装置由初级反硝化、二级硝化、污泥澄清池和后反硝化单元组成。该工艺模拟了提供进水的 Kuopio WWTP。我们描述了改变缺氧循环方案对脱氮效率的影响。我们进一步比较了在后反硝化单元中使用乙醇和甲醇的反硝化效率，并比较了这些化学物质作为碳源的性质和成本。在 256%的缺氧循环下，总氮去除效率（70.8%）达到最大值。然而，该工艺的灵敏度不高，因为 150-400%的缺氧循环范围都可以实现良好的脱氮效果。当氮还原适中时，该装置还实现了高 BOD 和 COD 的废水去除。每天向反硝化池添加 40mg/L 的乙醇，意味着可以将出水的硝酸盐水平控制在 10mg/L 硝酸盐氮以下。甲醇和乙醇对反硝化的效果相同。根据 2008 年的市场价格，使用乙醇代替甲醇可将处理成本降低 30%至 0.02 欧元/立方米处理后的废水。
