AEROBIC DIGESTION PART TROIS

Now for some process control.  Wake up everybody, and turn off your cell phones.

You can improve your digestion and save a llot of energy by following a few simple rules

Most digesters nitrify.  Nitrification makes acid and reduces the pH.  pH depression can get as low as 3.5, which then pickles all the organisms and you have a pretty dead digester except for some yeasts, and your girlfriend will tell you about those nasty yeast infections.

pH can be restored by turning off the air and allowing it to denitrify.  Denitrification is slower than nitrification, so, for best results, you should turn the air off for twice the time you aerate it, and I'll show you as soon as I can get this pesky blogger to allow me to paste a drawing.  In real world terms, this means you can turn the blowers off when you leave for the day at the end of the day shift, and turn them back in the morning.  You will then track your pH to see if that is effective.  When it's hot out you will have to run the blowers longer.  Thats why you have timers on your blowers.  Pay attention to whats happening and make changes as needed, instead of doing nothng and then blaming the engineer.  You will end up with a sludge tha dewaters/decants better and save energy.

Other indicators

pH is slow to change.  It may be that you need to look at ather values to control your operation.  You all are out of the dark ages and will have these tests available to you, so quit howling at the darkness and get to work.

Ammonia

Nitrification destroys ammonia, meaning you have aerobic conditions.  Septic conditions create ammonia, as it evolves out of protein destruction.  Since you are most likely testing your effluent, you can test your digester too. You;ll have to figure out for yourself what ammonia values are too high, but 125 mg/L is a place to start.

Alkalnity

Alkalinity is a measure of the sludge buffering capacity.  Depending upon conditions, alkalinity will range from 0 (too low)  to 700 or more (too high).  Adjust your air accordingly.

Total Solids

If you are thickening your sludge, especially with a mechanical thickener, you need to watch your solids and make sure it does not get too thick, unless you are going to unerated  storage.


It can be that easy if you are not so stubborn as to do it different just because.