Which of the following is not typically used as a coagulant for phosphorus removal?

Potassium phosphate is not typically used as a coagulant for phosphorus removal because it can actually add phosphorus to the water system rather than remove it. In wastewater treatment, coagulants are substances that help in the aggregation of small particles into larger flocs, which can then be removed through sedimentation or filtration processes.

Common coagulants for phosphorus removal include aluminum sulfate and ferric chloride, both of which effectively reduce phosphorus levels by forming insoluble compounds with phosphorus that can be removed from the wastewater. Lime is also used, primarily to adjust pH and can help in precipitating phosphorus as calcium phosphate under alkaline conditions.

In contrast, potassium phosphate serves as a source of phosphorus, not a means of removing it, making it unsuitable for this purpose.