A Story From the Field: Somphong's First Morning Back on the Farm

Somphong has raised whiteleg shrimp and Nile tilapia for almost twenty years in a quiet sub-district of Ratchasan, a low-lying district of Chachoengsao province east of Bangkok. His farm is typical of the area: a row of earthen ponds, a small hatchery building for post-larvae, a feed and equipment store with plywood walls, and a pair of tin-roofed rooms where two workers live. When the 2026 floods arrived, water from the surrounding fields and waterways rose until several pond dykes disappeared under a brown sheet of water. Somphong harvested what shrimp he could sell, moved the remaining post-larvae to a friend's farm on higher ground, and waited.

When the water finally dropped low enough to walk through, he drove back with his son. The first thing they noticed was not something they saw but something they smelled. Before they even opened the feed store, a heavy odor drifted out through the gaps in the walls: river mud mixed with the sour, rotten smell of high-protein shrimp feed that had soaked for days. Inside, the bottom row of feed sacks had swollen and split. Some had grey-green mold blooming across the surface in round patches. A tide line ran across the plywood walls at waist height, and flies circled in every corner.

In the hatchery, the fiberglass tanks and aeration lines were coated with silt. The concrete floor had turned slick with a film of slime. In the workers' rooms, mattresses and blankets that nobody had time to lift onto shelves were giving off a musty, sour smell that filled the whole space. After half a day of carrying ruined sacks outside, Somphong's son started coughing and sneezing and could not stop. One of the workers, who had waded through the mud in sandals, had a small scrape on his foot. Two days later it was red and swollen.

"During the flood, all we worried about was shrimp escaping and the money we were losing," Somphong said. "Once the water went down, we realized the real work was only starting. If we want to stock a new crop, every building has to be clean. Otherwise whatever the flood brought in will follow us straight into the ponds." That is exactly the challenge many aquaculture operations in Ratchasan, Bang Khla and the other lowlands of Chachoengsao are facing right now.

Why Aquaculture Farms Are More at Risk After a Flood Than Most People Think

Floodwater does not simply rise and fall. On its way to your farm it flows across rice fields, roads, livestock pens, septic tanks and drainage ditches, and it picks up whatever it touches. That includes bacteria associated with sewage, such as E. coli, organisms that cause diarrhea, and Leptospira, the bacterium responsible for leptospirosis, which thrives wherever rats are common. Feed stores, with their sacks of protein-rich pellets, are among the places rats love most. When the water recedes, these germs do not leave with it. They settle into mud, into the tide line on the walls, into porous concrete floors and into every material that soaked up water.

1. Health risks for the people who work on the farm

Farm workers are the people most exposed after a flood. They shovel mud, lift wet sacks, scrub tanks and then sleep in rooms that have only just dried. The common risks include leptospirosis from contact with contaminated water or mud through cuts and scrapes, skin infections that start from small wounds on hands and feet, diarrhea from eating with hands that were not properly washed, and allergy or asthma flare-ups from mold spores in damp, closed rooms. Anyone who develops a high fever, aching calf muscles, or a wound that becomes red and swollen after wading through floodwater should see a doctor promptly and mention the flood exposure. Prevention is far easier than treatment, and it starts with clean buildings and proper protective gear.

2. Risks to the next crop

Every experienced shrimp farmer knows that biosecurity is the heart of the business. Equipment that sat in floodwater, such as holding tanks, air lines, air stones, hand nets, baskets and feed carts, can carry contamination from outside straight into the culture system if it is reused without proper cleaning. Feed that has become damp can grow mold and may carry mold toxins, which is why wet or moldy feed should never be fed to animals. The hatchery, where young post-larvae are at their most vulnerable, needs to be cleaner than any other building on the farm.

3. Lost money and lost time

Every day a farm cannot stock is a day without income, so the temptation to rush is very real. But stocking new post-larvae while the support buildings are still dirty is a gamble. If animal health problems follow, the loss will be far greater than the cost of a few extra days spent preparing properly. There is also the long-term cost to the buildings themselves. Plywood, timber and untreated concrete that are left damp with mold growing inside will rot and deteriorate faster, which means more frequent repairs and earlier replacement.

4. Reputation with buyers and neighbors

Shrimp buyers and post-larvae suppliers pay attention to how a farm is managed. A farm that clearly takes cleanliness seriously after a disaster earns more confidence than one that looks like it is cutting corners. Meanwhile, the stench of rotting feed can drift a long way on a humid evening, and neighbors who are already stressed by the flood are not likely to be patient about it. Restoring your buildings properly protects both your business relationships and your relationship with the community around you.

The Usual Fixes That Do Not Quite Finish the Job

• Pouring bleach over everything. Chlorine can disinfect smooth, clean surfaces, but its effectiveness drops sharply when it meets mud and organic matter, which is exactly what a flooded farm is covered in. It also cannot reach the roof frame, the gaps between wall boards, or the underside of pallets and shelves. Used too strongly in a closed building, its fumes irritate the eyes and lungs of the very workers trying to clean.
• Turning on fans and calling it done. Fans help surfaces dry, and drying is important. But airflow does not kill germs, and in a moldy room it can actually blow spores around and spread them further through the building.
• Air fresheners, incense or scented sprays. A pleasant smell can cover a rotten one for an hour or two. The organic residue and mold that cause the smell remain exactly where they were, and the odor returns as soon as the fragrance fades.
• Painting over the water stains. Fresh paint hides the tide line for a few weeks. Mold living inside the timber or concrete pushes through as new black spots, and paint applied over damp, contaminated surfaces tends to peel early.
• Stocking first and cleaning later. Skipping the support buildings, especially the hatchery and the feed store, because the ponds look ready is like locking the front door and leaving the back door wide open.

The Solution: Chemgene HLD4H Disinfection Fogging Plus Ozone Treatment in Animal-Free Buildings

World Health Disinfection (WHD) restores flood-affected buildings with two techniques that work together. The first is our disinfection service, which uses CHEMGENE HLD4H applied through ULV (ultra-low volume) foggers. The fogger turns the disinfectant into a very fine mist that floats into corners, under shelves, along roof beams and into gaps that a cloth or brush could never reach. The second is our ozone treatment service, which fills a sealed space with ozone gas at a controlled concentration to deal with airborne mold spores and break down the odor molecules that have soaked deep into walls, roofs and fabrics.

The golden rule for aquaculture farms: our work focuses on buildings and dry areas only. That means the feed store, equipment rooms, hatchery and nursery buildings once the post-larvae have been moved out, the farm office and the workers' housing. We do not fog disinfectant or release ozone into ponds that contain animals, and we do not treat any building while animals are inside. Every animal on the property, including guard dogs and backyard chickens, must stay outside the treatment area for the whole process. Decisions about pond water and pond preparation should follow the guidance of fisheries officers or your farm's own aquaculture adviser.

Our step-by-step service process

1. Site survey. Our team walks every building with you, measures floor areas, checks the height of the water line, notes moisture levels and identifies the places where mold is heaviest. Together we agree on an order of work so that the buildings you need first are ready first.
2. Mud and clean-up advice. Disinfection works best on surfaces that are not buried under thick dirt. Before treatment day we explain what to shovel out, which feed and materials to discard, and which surfaces to scrub. Workers should wear rubber boots, rubber gloves and a mask during clean-up, and keep any cuts covered.
3. Moving animals, feed and sensitive items out. Post-larvae, pets, livestock, good feed, aquaculture medicines and plants all leave the building before we start. Sensitive electronics such as aerator control panels and water quality meters are covered or removed.
4. ULV disinfection fogging. We fog Chemgene HLD4H across walls, floors, shelving, fiberglass tanks, roof frames and any equipment you plan to reuse. The fine mist settles on surfaces that manual cleaning misses.
5. Ozone shock treatment. The building is sealed, ozone generators sized to the space are set up, and treatment runs for the planned time. During this period nobody, no animal and no plant may be inside.
6. Ventilation. When treatment ends, doors, windows and exhaust fans are opened so the remaining ozone can break down back into oxygen. Our team tells you when it is safe to go back in.
7. Re-check. We check smell and visible mold again. If certain spots are still damp or holding odor, we recommend extra drying and schedule a targeted repeat treatment.

Priority Areas on a Shrimp or Fish Farm

The aquafeed store. This is almost always the worst-smelling building on the property, because protein-rich pellets spoil and rot quickly once wet. Throw away every sack that got wet or shows mold. Clear and wash the floor and pallets, then disinfect and run ozone treatment to tackle the odor that has soaked into the plywood and roof. Before bringing in a new delivery of feed, raise pallets well off the floor and leave a gap between sacks and the walls so air can circulate and you can inspect for damp and pests.

The hatchery and nursery. Tanks, aeration lines and work surfaces need to be exceptionally clean. After our team has fogged the building, the farm should still clean any equipment that will touch culture water directly according to its own standard procedure, rinse as that procedure requires, and allow it to dry fully before filling. Think of our treatment as the building-wide reset, and your standard hatchery protocol as the final step for the equipment that touches the animals.

The equipment room. Hand nets, baskets, feeders and plastic buckets that sat in floodwater should be scrubbed, dried in the sun and then brought inside to be disinfected along with the room. Engines and pumps should be checked by a mechanic before use, since floodwater can damage them in ways that are not visible from the outside.

Workers' housing and the farm office. Mattresses, pillows and blankets that were soaked in floodwater are usually best discarded. The rooms themselves are an excellent candidate for ozone treatment, which reduces musty odors and airborne mold spores in the place where workers spend many hours every night. For mattresses that survived and are still usable, our dust mite removal service can help as an extra step.

The grounds and standing water. After the flood, the farm will be dotted with puddles and containers holding water, all perfect breeding sites for mosquitoes. Empty and remove what you can, and consider our mosquito spraying service around the living areas, keeping well away from culture ponds.

10 Reasons Farm Owners in Ratchasan Choose WHD

1. We use CHEMGENE HLD4H, a disinfectant designed for high-level surface disinfection.
2. ULV fogging carries the mist into roof frames, under pallets and into the gaps of timber walls.
3. Ozone treatment breaks down the smell of spoiled feed instead of just masking it.
4. We plan the work building by building, so your most important spaces are back in use first.
5. We are strict that every animal stays outside the treatment area, and we never work over ponds holding stock.
6. We give practical advice on mud removal and worker protection before treatment day.
7. Ozone dose is matched to room size, and delicate electronics are covered or removed.
8. Treating workers' housing reduces mold spores where people sleep. Learn more about residential ozone disinfection.
9. We supply products for ongoing care, such as the CHEMGENE 750 ml spray for high-touch points.
10. We are easy to reach by phone and LINE, and we schedule around your farm's routine.

In a Farm Owner's Words

"At first I thought washing everything down and running fans would be enough, but the smell in the feed store just would not go away. After the team fogged and then ran the ozone, the smell eased enough that we could work in there normally again. What I appreciated was how they kept reminding us to move every animal out first, and how clearly they told us when we could go back in. It made planning the next crop much easier."
— A shrimp farm owner in Ratchasan district (field scenario)

Frequently Asked Questions

Can you fog disinfectant or use ozone directly in a shrimp pond?
No. We only treat buildings and dry areas with no animals inside. Pond water management and pond preparation should follow the advice of fisheries officers or your farm's aquaculture adviser.

How far away do animals need to be during ozone treatment?
All animals must be outside the building being treated and should also be kept away from doors and windows during ventilation. Our team will tell you when it is safe to bring animals or post-larvae back.

Our feed got wet but has no visible mold. Can we use it after ozone treatment?
We do not recommend it. Feed that touched floodwater may be contaminated and can develop mold later. Ozone treatment is for restoring the building, not for making flood-soaked feed safe again.

Do we have to finish removing the mud first?
Remove as much thick mud and debris as you can beforehand. Disinfectant works best on surfaces that are not buried under heavy dirt. During the survey we will point out anything extra that should be cleared.

How long does it take? Do we have to stop work across the whole farm?
It depends on the number of buildings and their size. We usually work one building at a time, so the rest of the farm can keep operating. The only rule is that nobody enters a building under treatment until it has been ventilated.

How is the service priced?
Pricing depends on floor area, number of buildings and the level of damage. Please contact us to arrange a survey and request a quotation.

What should we do to keep the buildings in good shape afterwards?
Control humidity in the feed store, keep pallets raised, check for mold weekly during the first month or two, and use a disinfectant spray on high-touch points. If odor or mold comes back, contact us for a targeted repeat treatment.

A Simple Recovery Timeline for Farm Owners

Days 1 to 3 after the water drops: Make the site safe. Check electrical systems before switching anything on, and keep children away from ponds and soft dykes. Remove ruined feed, wet bedding and debris. Photograph damage for your records before you throw things away. Make sure everyone doing clean-up has boots, gloves and masks, and that any wounds are covered and kept clean.

Days 3 to 7: Shovel out mud, scrub the main surfaces and open the buildings to dry. This is the right time to call us for a survey, so the disinfection and ozone schedule can be planned around your drying progress rather than after it.

Days 7 to 14: Disinfection fogging and ozone treatment, building by building, with animals and sensitive items moved out. Repair any structural damage you discover once surfaces are clean and visible.

Before stocking: Complete your standard hatchery and equipment preparation, bring in fresh feed onto raised pallets, and continue weekly checks for mold and odor. Treat this timeline as a guide rather than a rule; every farm and every flood is different, and safety always comes before speed.

Get Your Farm Ready for the Next Crop

Talk to the WHD team to arrange a survey of your feed store, hatchery and workers' housing in Ratchasan and nearby districts of Chachoengsao.

View Our Disinfection Service

Book Ozone Treatment

Call 065-556-6294 · LINE @whd268 · Email worldhealthdisinfection@gmail.com

Further Reading

• Ozone treatment for odors and chemical residue
• Master Ozone Generator
• Residential ozone disinfection
• All articles
• External sources: WHO fact sheet on floods and the Department of Disease Control, Thailand