The presence of which element in water treatment plant effluent serves as a measure of filtration efficiency?

Aluminum is commonly used as a coagulant in water treatment processes, particularly in the removal of particulate matter and other impurities from water. When assessing the filtration efficiency of a water treatment plant, the presence of aluminum in the effluent can indicate how effectively the filtration system is functioning.

If the levels of aluminum are low in the treated water, it indicates that the treatment process is successfully removing coagulants and particulates, demonstrating effective filtration and treatment. Conversely, elevated levels of aluminum might suggest that not all of the coagulant is being removed, which can indicate issues with the filtration process and potential contamination in the water supply.

Other metals like copper, zinc, and lead may have significance in different contexts regarding water quality but do not serve as specific indicators of filtration efficiency in the same way as aluminum does. Copper and zinc may be present in water due to various sources, such as plumbing materials or industrial runoff, and lead is primarily a concern related to drinking water safety rather than filtration efficiency specifically. Thus, aluminum stands out as the best choice for measuring filtration efficiency in this context.