加拿大渥太华的不列颠水净化计划处理低碱度有色水，目前在全范围内实施预氯化和低pH值混凝（pH 5.8）。然而，为了整体流程优化，公用事业公司正在研究许多处理方案。本文报告了一项中试规模的对比试验，对比了强化明矾混凝（目前的做法）和酸强化明矾混凝（有和没有预沉降臭氧）。由于污泥处理方面的考虑，在涉及预处理的实验中，对减少明矾用量进行了研究- 沉淀-臭氧氧化。工艺性能根据不可蒸煮有机碳（NPOC）、紫外线吸收率、浊度和颜色降低进行评估。在这项研究中，观察到在絮体形成之前，必须至少施用30至35 mg/L的明矾剂量（无论凝固pH值如何）。这是由于原水中的腐殖酸含量升高。

The Britannia Water Purification Plan in Ottawa, Canada, which treats a low alkalinity, colored water, currently practices prechlorination and low pH coagulation (pH 5.8) at full scale. However, with a view to overall process optimization the utility is examining a number of treatment alternatives. This paper reports on a pilot scale comparison of enhanced alum coagulation, as currently practiced, to acid enhanced alum coagulation with and without pre-sedimentation ozone. Because of sludge handling considerations, reduced alum dosages were investigated in the experiments involving pre-sedimentation ozonation. Process performance was assessed on the basis of nonpurgeable organic carbon (NPOC), UV absorbance, turbidity and color reduction. During this study it was observed that a minimum alum dose of 30 to 35 mg/L had to be applied (regardless of coagulation pH) before floc formation occurred. This was attributed to the elevated humic fraction of the raw water.