What factor causes the greatest increase in chlorine demand?

The factor that causes the greatest increase in chlorine demand is the increase in organic matter. Organic matter, which can include materials such as leaves, food waste, and other biodegradable substances, provides a substrate for bacteria and other microorganisms to thrive. When chlorine is applied to water containing high levels of organic matter, a significant portion of the chlorine is consumed by the reactions with these organic compounds. This demand results from the need for chlorine to effectively oxidize and disinfect the organic materials present, thereby preventing their decomposition and possible release of harmful byproducts.

Furthermore, as the amount of organic matter increases, the demand for disinfection rises, making it essential to understand this relationship in wastewater treatment. While factors such as alkalinity, phosphate concentration, and pH can influence overall water chemistry and subsequent chlorine efficacy, organic matter is particularly important for its direct and substantial impact on chlorine consumption. Thus, managing organic load is crucial in wastewater treatment processes to ensure adequate disinfection and efficient chlorine usage.