Water purification apparatus and method

A method of treating a contaminated aqueous solution containing impurities including a perfluoroalkyl substance and/or a polyfluoroalkyl substance, comprising:

• passing the contaminated aqueous solution through a first membrane filter from which a filtered liquid stream is removed, producing a concentrated liquid contaminant stream,
• feeding the concentrated liquid contaminant stream to a photocatalytic reactor,
• introducing a catalyst feed stream which contains a mixture of fresh catalyst particles and recycled catalyst particles into the photocatalytic reactor separately from the concentrated liquid contaminant stream or in combination with the concentrated liquid contaminant stream, the catalyst particles comprising a catalyst configured to reduce chain length of the perfluoroalkyl substance and/or polyfluoroalkyl substance in the presence of UV light, forming a treated aqueous stream, while agitating the catalyst-containing solution during a reaction occurring in the presence of UV light,
• filtering catalyst particles from the treated aqueous stream by passing the treated aqueous stream through a second membrane filter inside the reactor or downstream from the reactor,
• combining the filtered treated aqueous stream with the filtered liquid stream to form a purified aqueous stream, and
• recycling the filtered catalyst particles to the reactor.