Getting bacteria to the sludge blanket

Getting organisms to the bottom sludge

A lagoon may be six to fifteen feet deep, with settled sludge at the bottom. Organisms applied at the surface need to reach that material and remain there long enough to work.

That delivery problem is why the dry range is divided by where a product ends up rather than by how strong it is. Sedivore Spike is made dense enough to carry down through the column and release at or within the interface; a soluble pouch dissolves near the surface and works on what the water is carrying, which is a different duty rather than a weaker version of the same one.

Standard limnology sets the terms. An unmixed water body stratifies into layers of different temperature and density, and those density gradients limit the exchange of anything — heat, dissolved oxygen, suspended cells — between the surface and the bottom. A cell released at the top of a stratified lagoon may never reach the floor at all, so the column itself works against delivery rather than for it. Depth is not a detail here; it is the whole difficulty.

Three ways an introduced cell is lost

The peer-reviewed bioaugmentation literature is consistent about what becomes of cells that are freely suspended rather than protected, and three fates dominate. The first is washout: a lagoon is a flow-through system, and a cell that stays in suspension leaves with the effluent before it can settle and work. The second is predation by protozoa, which graze on introduced cells as readily as on any others. The third is competitive exclusion by the resident community — the established population already adapted to the lagoon, which holds every advantage over a newcomer. None of these is a formulation defect. They are the default outcome for a cell that is simply poured onto the water and left to find its own way down.

What the industry's hardware quietly admits

There is circumstantial evidence that the industry itself regards surface dosing as inadequate for bottom sludge. At least a dozen independent manufacturers have separately engineered dense sinking granules or carrier-based formats whose entire purpose is to place organisms down in the sludge layer rather than leave them drifting in the water column. When that many competitors, working independently over two decades, converge on the same answer, the convergence is worth something. But it is worth being precise about what: convergence is circumstantial evidence, not a controlled trial, and a whole industry can agree on an approach without any of its members having published the measurement that would actually settle the question.

Carrier immobilisation, and what it costs

Immobilisation attaches cells to a carrier. A dense porous carrier can help transport cells into sludge and retain them, with some protection from washout and predation. Carriers add cost, and immobilisation can reduce metabolic activity. Better retention does not necessarily mean faster treatment.

Even a sinking solid only reaches the interface

A sinking solid delivers organisms to the sludge interface. It does not distribute them uniformly through the whole blanket. Penetration into dense anaerobic sludge remains a challenge.

Delivery and dose both matter. Choose a format for the material's location, then use the written dose method for that product. The dosing planner records which method it applies.