Interception
A bloom is a moving body of organic material inside a moving body of water. Every design decision here follows from that one awkward fact.
The patch you needed on Tuesday is four kilometres downwind by Thursday, sitting eight metres lower than it was, over ground the survey launch cannot reach. Nothing bolted to a jetty solves that. So the treatment plant travels.
Intake, reactor, gas handling, the oxidation stage and the outfall all ride the same hull. The vessel side of that belongs to the SeaBreather platform, which sets it out properly. HABslayer is what the platform does when the thing in the water is alive, multiplying and possibly toxic.
A bloom is the opposite problem to a dead zone
Hypoxia is an absence. Something took the oxygen and nothing gave it back. A bloom is a surplus: there is too much of something, that something has a chemistry, and in many species it carries a toxin into shellfish tissue and, for Karenia, into the air above the surf.
Which makes interception two duties running at once, both of them inside the hull. The oxidation duty destroys the organic load in the water that has been taken aboard. The oxygen duty puts the effluent back carrying more oxygen than it arrived with, because dead bloom material decomposes and decomposition is exactly how a bloom becomes a fish kill three days after everyone declared it over.
Take the first duty without the second and you have swapped a bloom for a crash. That is why this is a mode of an oxygenation platform rather than a boat with an algaecide tank on the back.
It is also why the answer to the question every ministry asks first is short. We put nothing in your water. We take water out, treat it aboard, and give it back against a standard we meet at the outlet.
The chain, in order
- Locate Ocean-colour and hyperspectral products narrow the search box; a boat confirms what is in it. Imagery is good at telling you where to look and bad at telling you what to do when you get there.
- Read the patch Species, cell count, vertical distribution, temperature, salinity, pH, dissolved oxygen, and the background organic material that will absorb oxidant to no purpose. Two patches with the same satellite signature can need entirely different handling, which is why a boat goes out before anything is settled.
- Fix the discharge standard first The standard the effluent will be held to is written for that site before the vessel moves, and the reactor is then operated to meet it. This is the step an inspector reconstructs from the log, which is the reason it is settled in advance rather than argued afterwards.
- Draw from the depth the cells are at Some patches float. Some sit in a subsurface maximum ten metres down, invisible from the quay and untouched by anything working the surface. Intake depth is selectable, and the areas inside a zone where no water is drawn at all are mapped before the season.
- Treat aboard, then hand it back Cells are broken and their toxin destroyed inside the reactor. The effluent leaves oxygen-enriched, so that what has been knocked down does not spend the receiving water's oxygen on its way out.
- Clear the batch, then adjust On a toxin mission the treated batch is held, laboratory-confirmed and only then released — which makes those missions batch-limited rather than continuous, and it is better that you hear that from us than discover it in week two. Counts and assays either side feed the next tasking rather than a document written in November.
Deep Strike, in plain terms
Deep Strike runs the same chain on water that is not yours yet. A patch forming in the next bay gets worked before wind and tide deliver it.
Three things make that worth paying for. A forming patch is smaller, shallower and less concentrated than the same bloom four days on, so the gas budget goes further. A tasking is cheaper to run than an incident, because an incident carries lawyers, press officers and overtime. And a ministry that announces nothing has had a better week than one announcing a closure.
Adjacent Deep Strikes sit inside the base subscription for exactly that reason.
The seawater constraint the whole architecture answers to
Bromide is abundant in seawater and ozone goes after it about eighty-three times more readily than it goes after chloride. The hypobromite that comes out of that reaction can carry on to bromate, and bromate is a regulated substance rather than a footnote.
Two properties decide what you can do about it. It is stable, so there is nothing to quench. And the sea will of course thin whatever is released into it — we simply refuse to bank that, which is a choice about how we account for a discharge rather than a statement about how water behaves. That leaves exactly one honest strategy: stop it forming, inside a volume you control, and hold what you release to a number you meet at the pipe. Containment is what makes that sentence sayable. It is the reason the reactor is aboard the hull rather than around it.
So the effluent leaves at or below 10 micrograms per litre of bromate — a value derived from drinking-water practice, applied to what comes out of the pipe, measured there and nowhere more convenient. Real-time instruments cannot see a stable end-product like bromate, which is why they are paired with independent laboratory analysis rather than trusted to stand in for it. Water that will not meet the number stays in the tank and comes ashore with the vessel. It goes neither over the side nor through a mixing calculation.
What actually does the knockdown
Whether nanobubbles generate hydroxyl radicals on their own is argued in the literature: Moleaer and Arizona State University reported reactive oxygen species from injected nanobubbles in 2020, and a controlled 2023 study by Chae, Kim, Kim and Fortner in ACS ES&T Engineering found that generation minimal at ambient conditions, if it occurred at all. We plan on the oxidant, because a plan that quietly banks a mechanism which may not be there is a plan that under-delivers on the one day it is being watched.
Controls and data
Every batch is a decision, and every decision leaves a record.
Bloom work generates evidence whether you plan for it or not. Better to design the evidence than to assemble it afterwards from memory.
Inline instruments govern the treatment in real time and can cut the oxidant on their own. Behind them sits a defined set of stop conditions, any one of which halts intake or discharge — a discharge assay that does not comply, a sensitive-area exclusion at the intake, a large animal at the bar-rack. The values inside those rules stay ours. That they exist, and what they act on, belongs to whoever is signing.
Where to look
Ocean colour and hyperspectral imagery bound the search area days ahead of a shore sample. Detection and forecasting get proper treatment on HABscan.
What is down there
Vertical profiles either side of each pass, plus counts and toxin assay. The number that matters is rarely the one you can take from the quay.
Where to be tomorrow
Forecast risk across the zone, so a Deep Strike reaches water that is still forming instead of chasing a patch that has already done its damage.
What the ministry gets
Position, time, method, discharge assay and result, batch by batch, in a format a technical reviewer can check rather than a newsletter can quote.
The pillar under the log
Who else is reading the assay.
Bloom work is a public health operation dressed as a boat job. Counts move, a batch is cleared or held, an advisory is kept or lifted, and each of those decisions lands on people who were nowhere near the room. Which is the argument for putting qualified outside scientists inside the programme rather than downstream of its reports.
Alarivean insists on it. Local scientific institutions — a university marine laboratory, the fisheries institute, the health authority's own analysts — are engaged for the duration and sit on every water-quality feed the duty crew reads, from before the first pass until after the last. Bringing their own instruments is encouraged. More sensors beats more assurances every time.
What does it change? What happens on a bad day. The pass that misses, the patch that rebounds overnight, the assay nobody expected — those are the moments when a single-source record stops being evidence and becomes a question of trust. Nothing about bloom season should rest on trusting the contractor.
The three parts most programmes skip
Continuous. Not an induction in May and a slide deck in November. Present through the weeks when the decisions are actually being taken.
Raw, not digested. The telemetry as it arrives, not a summary we wrote afterwards. Those are different artefacts and only one of them is checkable.
Held somewhere else too. A season's record that exists solely on our servers is a record nobody can audit without our permission. Health and safety first means the data has more than one home.
Questions we get asked
Straight answers
Why treat the bloom at all, if the real problem is nutrient loading on land?
Because the two run on different clocks. Cutting nutrient loads is the durable answer and it arrives over decades. A bloom shuts an intake, a beach or a farm inside a fortnight.
Treating the water protects the years in between. It excuses nobody from the catchment work.
Does killing the cells release the toxin they were carrying?
In open water it would. So the cells are not broken in open water — they are broken inside the reactor, and their toxin is destroyed in the same pass.
On a toxin mission the treated batch is then held, laboratory-confirmed, and released only if it clears. One that does not clear stays aboard and is taken away. Verification runs against a functional endpoint rather than a count of the parent compound, because what the assay has to establish is that the toxicity has gone. A tally of surviving molecules would not establish it, and complete mineralisation is not claimed on a single pass.
What actually does the knockdown — the oxidant, or the bubbles?
We plan on the oxidant, deliberately.
Whether nanobubbles generate hydroxyl radicals on their own is contested: Moleaer and Arizona State University reported reactive oxygen species in 2020, and a controlled 2023 study by Chae and colleagues found that generation minimal at ambient conditions, if it happened at all. A treatment plan that quietly banks the optimistic reading is a plan that fails on a hard site.
Reference: Chae, Kim, Kim & Fortner (2023) in ACS ES&T Engineering
Will ozone in our seawater make bromate?
Ozonating seawater can form bromate, and in Gulf and Red Sea water it is the binding constraint rather than a caveat. Ozone attacks bromide far faster than chloride, and the hypobromite that results can carry on to bromate.
What follows from that is the whole design. There is no quench for bromate, and we take no credit for the water on the other side of the outlet. It is therefore stopped before it forms, inside the reactor. Effluent leaves at or below 10 micrograms per litre, measured at the pipe. Anything off-spec is landed ashore for licensed disposal instead of going over the side.
Reaction-rate source: Ozone: Science & Engineering — bromate in seawater ozonation. The discharge standard and the backhaul rule are Alarivean's own commitment.
Has NOAA tested this?
NOAA's coastal science centres put an ozone nanobubble aeration system through an eight-acre pond trial near Fort Myers Beach in 2018. Algae were eliminated inside two days, reoxygenation held, and no harm to aquatic life was apparent.
Different equipment, different partners, a pond rather than a bay. It tells you the approach is sound at that scale. It tells you nothing about our hull at ours.
Source: NOAA NCCOS, September 2018
How big an area can one vessel cover?
It depends on the patch, its depth, the organic background, the vessel tier and how much of the season is contracted.
That answer gets built against your bathymetry and your own bloom record during the site read, then tested on your water in a calibration phase. A single confident sentence on a website would be a guess dressed as a specification.
Next step
Bring us a species and a season.
Historic counts, depth profiles, the months it comes back in, whatever you have already tried. Alarivean reads that against the water and says whether this is the right instrument — including when it plainly is not.