Oxidation-reduction potential changes in aeration tanks and microprofiles of activated sludge floc in medium- and low-strength wastewaters
Oxidation-reduction potential changes in aeration tanks and microprofiles of activated sludge floc in medium- and low-strength wastewaters
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DOI：
10.2175/106143004x151662
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发表时间：
2004-09-01
影响因子：
3.1
通讯作者：
Bishop, PL
中科院分区：
文献类型：
--
作者：
Li, BK;Bishop, PL
曝气池运行的实时控制是高效除污节能的关键。本研究的目的之一是考察氧化还原电位(氧化还原电位)在曝气池处理中(化学需氧量为70~150 mg/L)和低(化学需氧量为15~30 mg/L)、污染物浓度较高的废水中在线指示废水水质的潜力。现场尺度的数据提供了曝气池长度方向上的ORP值与营养物去除之间的良好关系。随着曝气池中有机物的去除，ORP值急剧增加，表明原液的氧化还原状态有所改善。溶解氧大于1 mg/L是良好的生物降解性和改善液体氧化还原状态的必要条件。硝化作用发生的ORP值(380~420 mV)高于有机基质氧化(250~300 mV)。通过微电极测量得到的微轮廓证实了活性污泥絮体内微生物过程的异质性。由于微生物对氧气的利用，活性污泥絮体中的好氧区域仅限于中等浓度废水中活性污泥集合体的表层(0.1~0.2 mm)，絮体内部主要是缺氧区。当原水溶解氧大于4 mg/L时，絮体内的缺氧区消失。在废水污染物浓度较低的情况下，活性污泥团聚体内的ORP和溶解氧均高于中等浓度废水。讨论了ORP作为曝气池运行的在线控制方法的前景，以及活性污泥絮凝体尺寸随污染物浓度变化的潜在原因。
Real-time control of aeration tank operation is key to high-efficiency pollutant removal and energy savings. One of the aims of this study was to examine the potential for using redox potential (oxidation-reduction potential [ORP]) to indicate wastewater quality online in aeration tanks treating medium (chemical oxygen demand [COD] of 70 to 150 mg/L) and low (COD of 15 to 30 mg/L),pollutant-concentration wastewaters. The field-scale data provide a good relationship between ORP values and nutrient removal along the length of the aeration tanks. The ORP values increased dramatically as organic matter was removed along the aeration tanks, indicating the improvement of the bulk liquor redox status. Dissolved oxygen higher than 1.0 mg/L was necessary for good biodegradation and improvement of the liquid redox status. Nitrification occurred at higher ORP values (380 to 420 mV) than was the case for organic substrate oxidation (250 to 300 mV). The microprofiles obtained from microelectrode measurements substantiate the heterogeneity of the microbial processes inside activated sludge flocs. Because of microbial oxygen utilization, the aerobic region in the activated sludge floc was limited to the top layer (0.1 to 0.2 mm) of the activated sludge aggregate present in medium-strength wastewater, with an anoxic zone dominating inside the flocs. When dissolved oxygen in the bulk water was higher than 4.0 mg/L, the anoxic zone inside the floc disappeared. At low wastewater pollutant concentrations, the ORP and dissolved oxygen inside the activated sludge aggregates were higher than those from medium-strength wastewater. The prospect of using ORP as an online control approach for aeration tank operation and the potential reasons for activated sludge floc size varying with pollutant strengths are also discussed.