You can have a look at the ...
Published by Sarah den Haring, Founder/Director at GreenWater Environmental Water & Sanitation Solutions
You can have a look at the greywater box we designed for low cost housing in Lilongwe, Malawi. This has been incorporated into their physical planning manual. It is designed for a household load. I have for long used one at my own home with great success, see photos here. You are welcome to ask me more on this if you need.
Good luck, Sarah