Abstract: A method and arrangement for sewage pre-treatment in a sewer pipeline infrastructure upstream of a sewage treatment facility of a sewage treatment system includes selecting a site in the sewer pipeline infrastructure between a source of untreated sewage and the sewage treatment facility of the system, providing a source of a biological activity enhancing agent at the preselected site, and introducing the agent from the source thereof into a flow of untreated sewage at the selected site so as to convert the sewage from an untreated state to a pre-treated state in the pipeline infrastructure upstream of the sewage treatment facility.