Cost effective technologies for treating intermittent wet weather overflows

As part of the Central Interceptor Programme Watercare has engaged AECOM to assess treatment technologies for addressing overflows which occur during wet weather events. Internationally these technologies are generally referred to as “wet weather treatment systems”, but can consist of a range of processes which provide various degrees of treatment for overflows. A common element to all of these technologies is the ability to provide intermittent treatment during wet weather events, usually done with a form of physical/chemical treatment that can be turned on and off when needed. This is in contrast to a conventional biological treatment system which must run continuously and generally is not appropriate or capable of treating intermittent high peak flows associated with wet weather overflows and bypasses. It is also important to note that some forms of wet weather treatment technology can also be configured to include a disinfection process, including the use of UV disinfection. This paper explores various technologies and options for treating intermittent wet weather overflows and provides an assessment of the cost effectiveness relative to other more conventional options.