In what units is ALK expressed?

ALK, which stands for alkalinity, is typically expressed in terms of milligrams of equivalent calcium carbonate (CaCO3) per liter. This unit of measurement reflects the capacity of water to neutralize acids, which is an important parameter in water treatment and environmental studies. Alkalinity is essential for maintaining the stability of pH levels in aquatic systems and wastewater treatment processes.

Using the equivalent of calcium carbonate allows for a standardized way to quantify how much acid the water can neutralize, as CaCO3 is commonly found in various water sources and its buffering capacity is well understood. This makes it a suitable choice for expressing alkalinity, providing clear insight into water chemistry related to treatment processes and environmental health.

In contrast, the other units mentioned do not accurately convey the concept of alkalinity or its relevance in water chemistry. Other forms of measurement refer to different attributes of water quality, such as organic pollutant concentration or solid waste, which are not related to alkalinity.