It is possible to optimise the bacterial consortia in an activated sludge process by adjusting the operational conditions. Thereby problems like high numbers of free swimming bacteria or sludge with poor settling properties can be reduced. what are the factors that can influence the microbial composition in the process and why?
2007-10-22 14:28:29 · 4 answers · asked by king_dipu 2 in Science & Mathematics ➔ Engineering
Microbial composition is known as "The Bugs" in the industry. You want to have a good bug population.
To have consistently good characteristic sludge, keep the conditions consistent: temperature, DO (dissolved oxygen), pH, BOD levels in influent, nitrogen feed, phosphorus feed, mixed liquor, etc. Every time you change one of these parameters, you’re going to favor one type of bug over another and your bug population will shift to that bug. Bang, you’re on another learning curve. The bugs you had at 35 degrees C will differ from the ones you have at 41 degrees C. (Plus, you’re losing efficiency as your bug population comes up to the new species)
Some sample test results: you never want to have a DO under 1 ppm (you’re starting to favor anaerobes and could start having pockets of them in poor mix areas) or a nitrogen reading in the effluent over 1 ppm (other than polluting the receiving waters, your bugs are going to start floating; you’re risking losing your bug population while increasing your TSS numbers)
Sludge age is a key parameter; when you start getting higher life forms like nematodes, it's time to increase wasting. Stalked ciliates are the highest life form that I like to see. Too young a sludge is also undesirable. (There are a lot of great posters out there that guide you on sludge age. Almost any vendor that supplies this market would be happy to give you one.)
Poor settling is usually bulking filamentous and is controlled by adding a little hypo. There are other poor settling causes: anaerobes, high nitrogen feed, etc. Your microscope and nose will point you in the right direction.
Keep a close eye on your sludge blanket; too thick a blanket will produce anaerobes. Those bugs will produce H2S that 1) stinks and 2) causes pieces of your sludge blanket to float. Sudden changes in your sludge blanket should not be ignored; something is changing and you might want to know what it is!
Keep an eye on your volatile MLSS - you didn't mention what the influent was, but upsets can flood your system with inorganics that can be a pain.
Those are the items that come to mind. This is a huge subject that many doctorial candidates are still writing about. If you have any detailed questions, feel free to email
Update - I added a couple clarifiers for points that might have been brushed over.
2007-10-23 17:15:38 · answer #1 · answered by Thomas K 4 · 0⤊ 0⤋
Air and plenty of it.
Sludge needs to be aerated regularly (it's why it is stirred in the big mixers). Most microbes are aerobic, needing oxygen to exchange for carbon dioxide as they feed on the carbon and nitrogen found in the sludge.
Constant temperature would be your next maximizing control. Too hot or too cold would kill the microbes and stop the breakdown process. Constant temperature levels would keep the process going.
If you could control both the aeration and the temperature, you could maximize your breakdown process.
2007-10-22 14:35:50 · answer #2 · answered by enn 6 · 0⤊ 0⤋
Maybe water and warm temperature for factors.
2007-10-22 14:32:06 · answer #3 · answered by Anonymous · 0⤊ 0⤋
whoa I wish I knew the answer to this...hehe
2007-10-22 14:31:59 · answer #4 · answered by Jamie G 5 · 0⤊ 0⤋