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Originally Posted by CCS
What happens to the poos after they're done with it? Do they flush it down the bog or maybe put poo samples in petri dishes and keep them in a poo archive? You should see if you can have the poo back once they've checked it all out.
How does the poo selection process go anyway? Do you just plunge a hand into the sewage and grab a fistful of shit? Or is it more like "Oh that looks like a nice big turd, all in one piece, quite plump actually"? How do you retrieve it? Are they usually floating? Do you have a butterfly net type of thing for fishing out the poo? Or do you have a fishing rod and you just cast a line until you hook a poo?
So many questions.
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Poo once it reaches the WWTP is all in liquid form, stools swell up in water and disintegrate pretty rapidly with turbulence. To take a sample, you select what time you wish to sample, this time it was to sample the peak loading, which is usually between 9-12, everyone's morning shits and showers take about 3 hours to go from toilet bowl to treatment stage. I opted for 15min periods so i'd get a nice result. To retrieve the sample i normally opt to lower a bucket into the headworks prior to screening, i aim to dodge rags etc. as they arn't really appropriate.
After retrieving the bucket of effluent I take the S::CAN out of the headworks and mount it on some mounts (obviously, lol) I then clean it with 5-10% nitric acid to remove all the organics on the lens then zero calibrate the s;;can with de-ionized water. I then run the sample through the s;;can and take a finger print sample and make sure the TSSeq is in the range i'm after, today i wanted samples above 200mg/L TSSeq and above a CODeq of 400 mg/L. If the sample is between those ranges i then put some effluent into a 1L bottle, mark the finger print number and the time and date on it and put it on ice, in another container, 250mL, i also fill with effluent, in the smaller bottles I have some sulphuric acid which acts as an inhibitor.
I then continue sampling until i've got a range i'm happy with, i try to capture some effluent which comes in from the sucker trucks as well, this is usually in the vicinity of 2500-3000 mg/L, potent stuff, its good to have these measurements as they show the shock loading that the plant undergoes at regular stages.
Once the lab has finished doing its tests on it, we can map it and have a very accurate portrait of what the treatment plant has to deal with, this helps with chemical dosing and what not, but in this case, we can then sample the effluent post treatment and compare the results and the performance of the plant, so we can then make a educated choice on where money would be best spent to get the effluent to a better treated quality.
The effluent is destroyed after the tests.
I hope this helps.
