The Impact of Algae and Their Metabolites on Water Quality

Urban sewage discharge and agricultural runoff contribute to eutrophication of water bodies, leading to excessive algal blooms. This is particularly problematic in lakes and reservoirs in southern my country, where abundant sunshine and high temperatures exacerbate algal blooms.

Algae severely impact water treatment efficiency in several ways: they are generally negatively charged, highly stable, and difficult to coagulate; their low density results in poor sedimentation; they adhere to filter media, shortening filter cycles and requiring frequent backwashing; their metabolism produces various odors, making the water undrinkable; some small algae can penetrate filters and enter water supply networks, affecting water quality; and they are also precursors to chlorination disinfection byproducts, reacting with chlorine to produce harmful byproducts like chloroform and increasing mutagenic activity.

Furthermore, some algae (such as cyanobacteria) produce algal toxins during metabolism, posing a serious threat to human and animal health. Some algal toxins can cause chronic diseases (such as hepatitis), and in severe cases, even death.

Although prechlorination can effectively enhance the algae removal efficiency of existing water treatment processes, this process is gradually being restricted by various countries because the reaction of chlorine with high concentrations of organic matter in the raw water during prechlorination generates a series of halogenated organic byproducts that are highly harmful to human health.