Wastewater lagoons

Waste lagoon, São Paulo, Brazil

A lagoon carrying a heavy oil and grease load on top of an organic load, with the surface closed over.

99%

reduction in oil and grease

Field result

Duty: Wastewater lagoons
Sector: Industrial
Treatment window: 2 months
What was counted: Fats, oils and grease, BOD and COD

Oil and grease 2,007 mg/L to 21 mg/L
BOD down 87 per cent, COD down 83 per cent

Aerial view of a multi-cell aerated wastewater lagoon, its surface broken by aeration, with grass berms dividing the cells and a small control building alongside. — Illustration — an operating aerated lagoon, not the works described on this page.

01The plant

What was being treated

An industrial waste lagoon in São Paulo, Brazil.

02Before

How the material got there

High-strength organic and oily influent had pushed the lagoon into biological overload. BOD stood at 4,800 mg/L, COD at 6,000, oil and grease at 2,007. The surface had crusted over with solids and grease and the water had gone acid at pH 5.8, which is roughly where a lagoon stops being able to treat itself — neither the oxygen nor the biology is there any more.

03Treatment

What was applied, and how

A facultatively anaerobic blend applied over two months, with aeration running so the organisms had the oxygen and the mixing to work through the crust and down into the accumulated load. No dredging and no chemical dosing.

Every result in this library was measured at an operating plant treating with one of the formulations SediLogic supplies, over the window stated above. It is a field result published as reported, not a controlled trial we ran.

04Method

How the result was established

BOD, COD, oil and grease and pH sampled before treatment and again at two months.

05Outcome

What followed

The lagoon came back without dredging and without chemical addition, which is the comparison the operator was making when the programme was chosen.

At the start

BOD 4,800 mg/L, COD 6,000 mg/L, oil and grease 2,007 mg/L, pH 5.8, surface crusted over.

At the close

BOD 642 mg/L, COD 1,000 mg/L, oil and grease 21 mg/L, pH 7.1, open water restored.

06Limits

What this record does not establish.

Aeration is named as part of what was done and the record does not say whether it was already running or was brought in for the programme. That matters more than anything else on this page: aeration alone moves every figure on it. There is no untreated comparison, no volatile fraction at the start, and no dosing detail of any kind. The pH correction from 5.8 to 7.1 is consistent with organic acids being consumed, but it is reported rather than explained.

Only the volatile organic fraction of a sludge responds to any of this. Grit, sand, silt, mineral precipitates and plastics remain at any dose, here and everywhere else.

—What we would supply

For this duty, in our range.

This is the duty SediLogic supplies and sizes. Which article depends on where the material sits: Sedivore Spike is the denser solid and carries down through depth to an established blanket, Sedivore Puck is a smaller unit that spreads a calculated dose across the bed, and SediLogic Maintain is a soluble pouch for load carried in the water column — with Sedivore Polar for that same duty where the water runs cold enough to stall a standard blend.

A quantity for your own lagoon comes from the dosing planner, sized against your dimensions and loading from the manufacturer's written dose method. It does not come from the figure on this page, which was set for a lagoon that is not yours.

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—Read next

The same duty, measured somewhere else.

Wastewater lagoons
Food processing lagoon, Midwestern United States
IndustrialJune to September
100 to 60%
surface coverage by the grease cap, in three weeks
Field resultConfounded
A fat, oil and grease cap covering the whole lagoon surface, cutting oxygen transfer into the water beneath it and standing between the plant and its irrigation discharge.
- Cap thickness 6 in to 2 in
- 75 per cent less material reported as requiring dredging
- Surface aerators were taken out of service during the same period
Fats, oils and greaseSludge depth and solids
Wastewater lagoons
Barbourville, Kentucky
Municipal24 weeks
43.3%
of accumulated solids digested
Field result
Just over five feet of accumulated solids in the primary aerated lagoon, assessed at 2,365 dry tons. The plant wanted a route that did not involve dredging.
- 1,025 dry tons removed
- Average depth 5.08 ft to 2.65 ft
Sludge depth and solids
Wastewater lagoons
Inkom, Idaho
MunicipalFive months, May to October
48%
reduction in solids volume overall
Field result
Accumulated solids across two lagoon cells, against a specification calling for a 50 per cent reduction. The treatment window was bounded by water temperature, which has to stay above roughly 55°F for the organisms to work at all.
- Cell 1: 75.2 per cent
- Cell 2: 37.5 per cent
Sludge depth and solids

All field results

Your lagoon next

This was measured somewhere else.

A different plant, a different loading and a different sludge. What decides your result is how much of your own accumulation is organic and treatable, and whether the dose is sized against the lagoon in front of us rather than read off this page. Tell us the dimensions and we will size it.

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