In grey water I could find around 8 lacs of bacteria. If I do chlorination of this water, there comes very high chlorine demand. Hence, I need an alternate technique to kill the bacteria.
I don't know of any papers specifically discussing the extend of UV use in greywater treatment or design considerations. I worked on in several papers on a commercial system. In my paper there is a reference to the design of this type of greywater systems (Nolde) that might help you.
Article Estrogenic personal care products in a greywater reuse system
this paper "Enhanced Photocatalytic Disinfection of Escherichia coli Bacteria by Silver and Nickel Comodification of a Nitrogen-Doped Titanium Oxide Nanoparticle Photocatalyst Under Visible-Light Illumination"