I really like DVader1000's second suggestion, though I'd like to know a little more about your basin. Are you plug flow? Full-contact? Oxidation ditch? What do you have available to play with?

I will say this -- if your basin is anything like mine, do NOT place those pumps on the bottom of the basin. You'll be pulling those pumps several times a day to clear rags from the intake. Suspend them at least three feet (or more!) off the bottom if you have the room

Dave McCombs
Double Branch WWTP

Thank you guest. We are using an activated- sludge process where waste water is continuously fed into the aerated tank. Yes, that's right the submersible pump should be slightly suspended but anyway the sludge is free of non biodegradale solids that will block the pump. We use comminutor and bar screen as pre treatment.

Thank you very much. Your answers most likely resolve my problem.This only confirms to what I am thinking. My company is a government agency and procuremet of materials is very difficult. So we need to be resourceful. Thanks for your help anyway. God bless you.

Figures. Between buying much needed spares vital to keeping a plant running and cutting back on his own personal salary or perks to raise the funds to buy the spares, which do you think a typical government bureaucrat will choose?

I rest my case.

400ppm BOD sounds very high (aver. monthly, aver. daily, peak hours, etc.??), check your sources and increase the bills for anything over 250.

Get a lot of air compressors, provide a lot of very small holes in weighted pipes/hoses across the bottom of aerator basin, and use air lift pumps to recirculate/fountain...replace your management OR discharge the "treated" effluent next to their house or across their backyards as managed wetlands.

O2 is not vital to sludge but to aerobic bacteria, and O2 is only 20% of air volume.

Other chemical means - try H2O2, Potas.Permanganate, bleach, etc....if you don't have the money for parts forget these.

Tom

I think we both need to learn more more. Air is composed of 21% oxygen and 79% nitrogen. Sludge is a conglomerate of aerobic bacteria ( useful for waste digestion).The settled sludge ( microbial floc )from clarifier is partially recycled to be reused for for the incoming organic and inorganic waste so it is vital.

Air compressor is not for heavy duty or not for continuous operation and therfore not applicable.

Hiring a portable air compressor and sparging air into the bottom of the chamber until the blowers are repaired - could this be done?

Do you know any alternative source for oxygen in aeration--?

I do:

ElectroCoagulation= most effective kind of Oxygenation+simultaneous DissolvedSolids separation

Problem is, most of these solutions cost money, which our questioner doesn't have. I know how it goes...I'm in the same boat. Sewerage is out of sight, therefore out of mind -- until a pipe breaks in the mayor's backyard!

Oh -- and don't count on your screen and grinder. I don't care how fine they are, they're still going to pass solids, which will clump up in your basins and pumps. I still have to dig clogs out of my RAS pumps and, after ten years of operation, I probably have a good couple of feet of stringy ^%#@ in the bottoms of my basins in spots. (We tried a DO2E mixer to see what it would do. Worked very well for about a week, then all the solids it vacuumed up off the bottom stopped it up.)

Dave McCombs
Double Branch WWTP

<...out of sight, therefore out of mind -- until a pipe breaks in the mayor's backyard...>

Escalating a problem to encourage investment is a little like playing a 'back game' in Backgammon. It requires a little daring to make it work, though it is so satisfying when it does!

I think DVader has the best solution for the resources available. I would go for his vertical / downward option because it may just force air in deeper.

You may also consider egg beater or dough mixer type of stirrers. (fabricated with motor as driver).

Also consider asking public to temporary reduce the settings on the cistern or to put 1/2 a brick into the tank. Almost clean water (bath, washing etc) can also be diverted to the garden. In that manner you may buy some time.