Elementry School Wastewater Strength?

[sjohns4]

I'm evaluating an existing package wastewater treatment plant's capacity to handle a school expansion. The original design of the plant is for 1500 gpd at 210mg/l BOD. For an elementry school 210mg/l sounds a bit weak to me. I was thinking we probably need to be using at least 300 mg/l, but that's just my gut. Records of the existing influent are non-existant. Does anyone have any wisdom / expirence they'd care to share? The school has food service and basic sanitary facilities - the upgrade will include water efficient fixtures as well.

Thanks,

Mike

 

[bimr]

I have no basis to think that the waste strength from a school will be any stronger than any other application.

However, the cost of the package treatment plant is more related to the flow capacity than the waste strength.

Increasing the waste load will provide you with a more conservative design basis without increasing the cost of the project.

 

[sjohns4]

Since the school has no collection system, there would be very minimial I/I. 210 seems like a good number for a larger plant serving folks taking showers and washing clothes. Since the school's waste is only food service, hand washing, and tolit's I'd think it'd be stronger than your typical plant influent?

 

[PEDARRIN2]

Also consider that with water efficient fixtures - less water will be flowing with the same waste.

So the organic content will be a higher in proportion to the water content.