I'm writing an operating manual for our refinery wastewater plants.  During the plant turnaround, there won't be any wastewater for an extended time period.  Do any of you have experiences in managing the activated sludge system during food shortage?

Any tips for how best to keep the biomass active; what percentage of normal food load to feed them, what the best substrates are to feed them, storing normal feed for turnarounds, and how best to startup after an extended outage?

Thanks!

You need to know what your average BOD loading is.

What we use is a dry dog food with 21% protien which equals .4 lbs BOD per pound of dog food.

With this, we also use a sugar water mix which equals .9 lbs of BOD/lb of sugar. We fill a 50 gallon drum with a 50 gallons/50 lbs.sugar ratio and use a Pulsatron chemical pump for 7 gallons a day.This equals 7 pounds of additional BOD.

We use this combination to reduce our Nitrate to less than 10 mg/L.

Since using this combination we havn't had a Nitrate Exceedence.

Stan J

CPO