Here is the guideline for the State of Illinois. You would be safe to use it. Other states may not have developed these guidelines. You may find something in the Metcalf & Eddy text book.
Nursing Homes (per bed space) 125 gallon per day per bed
BOD = 200 mg/l
TSS = 240 mg/l
2) Organic Design
A) New Systems Minimum Design
i) Domestic waste treatment design shall be on the
basis of at least 0.17 pounds of biochemical oxygen
demand (BOD5) per capita per day and 0.20 pounds of
suspended solids per capita per day.
c) Design Loads
1) Hydraulic Design
A) New Systems
Plans for sewage treatment plants to serve new sewer
systems for municipalities or sewer districts shall be
based upon a design average daily flow of at least 100
gallons per capita