Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, Duebendorf CH-8600, Switzerland.
Water Res. 2011 Feb;45(5):2002-10. doi: 10.1016/j.watres.2010.12.002. Epub 2010 Dec 9.
Five oxidants, ozone, chlorine dioxide, chlorine, permanganate, and ferrate were studied with regard to the formation of assimilable organic carbon (AOC) and oxalate in absence and presence of cyanobacteria in lake water matrices. Ozone and ferrate formed significant amounts of AOC, i.e. more than 100 μg/L AOC were formed with 4.6 mg/L ozone and ferrate in water with 3.8 mg/L dissolved organic carbon. In the same water samples chlorine dioxide, chlorine, and permanganate produced no or only limited AOC. When cyanobacterial cells (Aphanizomenon gracile) were added to the water, an AOC increase was detected with ozone, permanganate, and ferrate, probably due to cell lysis. This was confirmed by the increase of extracellular geosmin, a substance found in the selected cyanobacterial cells. AOC formation by chlorine and chlorine dioxide was not affected by the presence of the cells. The formation of oxalate upon oxidation was found to be a linear function of the oxidant consumption for all five oxidants. The following molar yields were measured in three different water matrices based on oxidant consumed: 2.4-4.4% for ozone, 1.0-2.8% for chlorine dioxide and chlorine, 1.1-1.2% for ferrate, and 11-16% for permanganate. Furthermore, oxalate was formed in similar concentrations as trihalomethanes during chlorination (yield ∼ 1% based on chlorine consumed). Oxalate formation kinetics and stoichiometry did not correspond to the AOC formation. Therefore, oxalate cannot be used as a surrogate for AOC formation during oxidative water treatment.
五种氧化剂（臭氧、二氧化氯、氯气、高锰酸盐和高铁酸盐）在有和没有蓝藻存在的情况下，于湖水基质中被研究其生成可同化有机碳（AOC）和草酸盐的情况。臭氧和高铁酸盐形成了大量的 AOC，即在含有 3.8mg/L 溶解有机碳的水中，用 4.6mg/L 的臭氧和高铁酸盐可形成超过 100μg/L 的 AOC。在相同的水样中，二氧化氯、氯气和高锰酸盐没有产生或仅产生有限的 AOC。当向水中添加蓝藻细胞（鱼腥藻）时，检测到臭氧、高锰酸盐和高铁酸盐的 AOC 增加，可能是由于细胞裂解所致。这一点通过所选蓝藻细胞中发现的胞外土臭素（geosmin）的增加得到了证实。氯和二氧化氯的 AOC 形成不受细胞存在的影响。发现五种氧化剂在氧化过程中生成草酸盐，其形成量与氧化剂的消耗呈线性关系。根据所消耗的氧化剂，在三种不同的水基质中测量到以下摩尔产率：臭氧为 2.4-4.4%，二氧化氯和氯气为 1.0-2.8%，高铁酸盐为 1.1-1.2%，高锰酸盐为 11-16%。此外，在氯化过程中（基于消耗的氯，产率约为 1%）形成了与三卤甲烷相似浓度的草酸盐。草酸盐的形成动力学和化学计量学与 AOC 形成不一致。因此，草酸盐不能用作氧化水处理过程中 AOC 形成的替代物。
