Wan Junfeng, Sperandio Mathieu
Université de Toulouse, INSA, UPS, INP, LISBP, France.
Chemosphere. 2009 Apr;75(2):220-7. doi: 10.1016/j.chemosphere.2008.11.069. Epub 2009 Jan 4.
The aim of this work was to evaluate and quantify the influence of denitrification of nitrate on the aerobic granular sludge development. Two parallel sequencing batch reactors (SBRs) were fed with synthetic wastewater, the first reactor (R1) receiving nitrate at a fixed concentration whereas the second reactor (R2) did not receive any external source of nitrate. Both systems were working at the same operational conditions with a low specific air velocity (0.07cms(-1)), a relatively low and acceptable oxygen concentration (1.8+/-0.8mgL(-1)) and without significant biomass selection pressure (minimal velocity 0.4mh(-1)). The results showed that the sludge settling properties of R1 were comparable to granular sludge (settling velocity approximately 10.6mh(-1), SVI(5) approximately 13-30mLg(-1), SVI(30) approximately 11-28mLg(-1) and SVI(5)/SVI(30) ratio approximately 1.05-1.1). In the opposition, biomass of the reactor R2 reveals more traditional properties. Nitrogen measurements revealed that a significant denitrification (up to 80% of fed nitrate) occurred in R1 in the core of aggregates, as aerobic condition was maintained in the bulk. After the mean particle size was reduced from 250 to 125microm by an increase of mechanical stirring rate, it was shown that denitrification decreased from 80% to 20%. These parallel experiments definitively proved that the presence of nitrate in SBRs can assist the densification of the biological aggregates in aerobic condition. The presence of nitrate (commonly provided by nitrification) should be considered as a possible factor which helps to maintain the granulation process.
这项工作的目的是评估和量化硝酸盐反硝化对好氧颗粒污泥形成的影响。两个平行的序批式反应器（SBR）被投喂合成废水，第一个反应器（R1）接收固定浓度的硝酸盐，而第二个反应器（R2）不接收任何外部硝酸盐源。两个系统在相同的运行条件下运行，气速较低（0.07cm s⁻¹），氧浓度相对较低且可接受（1.8±0.8mg L⁻¹），并且没有明显的生物量选择压力（最小流速0.4m h⁻¹）。结果表明，R1的污泥沉降性能与颗粒污泥相当（沉降速度约为10.6m h⁻¹，SVI₅约为13 - 30mL g⁻¹，SVI₃₀约为11 - 28mL g⁻¹，SVI₅/SVI₃₀比值约为1.05 - 1.1）。相反，反应器R2的生物量表现出更传统的特性。氮含量测定表明，在R1中，由于在混合液中维持了好氧条件，在聚集体核心发生了显著的反硝化作用（高达所投喂硝酸盐的80%）。在通过提高机械搅拌速率使平均粒径从250μm减小到125μm后，结果表明反硝化作用从80%降至20%。这些平行实验明确证明，SBR中硝酸盐的存在可以在好氧条件下促进生物聚集体的致密化。硝酸盐的存在（通常由硝化作用提供）应被视为有助于维持颗粒化过程的一个可能因素。
