The process by which pollutants in wastewater are removed before water is released is known as:

The process by which pollutants in wastewater are removed before water is released is appropriately termed pre-treatment. This phase is crucial in wastewater management as it involves preliminary steps to reduce or eliminate various contaminants before the water undergoes more intensive treatment processes.

During pre-treatment, larger solids and debris are screened out, and chemical processes may be employed to neutralize harmful substances, set the stage for effective biological treatment, and safeguard treatment facilities from damage or operational issues. This initial phase is pivotal for enhancing the efficiency and effectiveness of subsequent treatment stages.

In this context, filtration typically refers to a specific technique used to separate particles from water, which could be part of the pre-treatment process but does not encompass the broader actions taken in pre-treatment. Disinfection is a later step focused on eliminating pathogenic microorganisms and is not about removing pollutants per se, while secondary treatment involves biologically degrading dissolved and suspended organic matter, occurring after initial pollutant removal actions have been completed in the pre-treatment stage.