Up to 95%
odour reduction
Up to 99%
surface coverage
25+ years
expected life, 10 year warranty
50+ countries
installed since 2004
Why open wastewater basins smell, and why complaints follow
Odour from a sewage treatment plant comes off the open liquid surface. Equalisation tanks, anaerobic and facultative ponds, sludge holding tanks and effluent lagoons all release odorous gases into the air above them, and wind carries those gases to the fence line. In a hot climate the release is stronger: the warmer the liquid and the calmer the weather, the higher the odour concentration.
For plants close to housing, hotels, factories or public roads, that means complaints, visits from the authorities and pressure to act. The usual answers are costly. A fixed roof or tensioned membrane needs a structure and restricts access. Chemical dosing and biofilters bring a running cost that never ends.
A floating cover works differently. It sits on the liquid itself and reduces the open surface, which is where the odour is released.
Hexa-Cover® on an industrial wastewater basin, installed to control odour and emission.
How Hexa-Cover® controls odour
Thousands of hexagonal tiles are poured onto the liquid. They spread out on their own and settle edge to edge into one closed floating layer.
1. Pour
Tiles arrive in big bags and are emptied onto the surface. No crane, frame, anchoring or special equipment is needed, and the basin can stay full and in operation.
2. Self-arrange
The ribbed hexagonal shape makes the tiles distribute themselves and lock into a grid that covers up to 99% of the surface, whatever the shape of the tank or pond.
3. Stay covered
The layer rises and falls with the liquid level. On sloped banks the tiles rest on the slope when the level drops and float again when it returns.
What the cover does for an STP
- Odour: up to 95% stable, constant reduction of odour from the covered surface.
- Emission: up to 95% reduction of emissions such as ammonia.
- Algae: sunlight is blocked, so algae cannot grow in polishing ponds and effluent lagoons. Algae carried over in the effluent is a common cause of high suspended solids.
- Birds and insects: the small tiles leave no open water to land on.
- Access: sampling, pumps and desludging remain possible. The tiles are pushed aside and close up again.
- Aeration: the cover allows aeration to continue so aerobic conditions are maintained.
Independently tested odour and ammonia reduction
Hexa-Cover® R114 holds the DLG APPROVED test mark for reduction of ammonia and odour emission (DLG test report 7593). DLG is the German Agricultural Society, an independent testing body.
The test compared covered and uncovered tanks of pig slurry, one of the strongest odour sources there is, with odour measured to DIN EN 13725. Reduction was highest when the odour load was highest: at 18°C with no ventilation, the conditions closest to a still, hot day.
Laboratory test on pig slurry. Results on sewage and industrial wastewater depend on the liquid, the basin and the coverage achieved, which is why we ask for your site details before quoting.
View test reports and certificates| Measured | Result |
|---|---|
| Odour reduction, range across all tests | 81 to 96% |
| Odour reduction, average | 88.6% |
| Ammonia reduction, tank diameter over 10 m | Over 90% |
| Ammonia reduction, tank diameter over 20 m | Over 95% |
| Ammonia reduction, tank diameter 30 m | 98% |
| Mechanical coverage during tests | 95 to 98% |
Where it is used
Hexa-Cover® is used on tanks, basins, lagoons and ponds of any shape and size, in concrete, steel or lined earth.
Sewage treatment
- Equalisation and balancing tanks
- Anaerobic, facultative and maturation ponds
- Sludge holding and thickening tanks
- Effluent and polishing lagoons
Industrial wastewater
- Food, beverage, brewery and dairy effluent
- Sugar, starch and agro-processing ponds
- Pulp and paper effluent
- Chemical and petrochemical wastewater
- Emergency and retention basins
Waste and agriculture
- Landfill leachate ponds
- Pig and cattle slurry tanks and lagoons
- Biogas digestate storage
- Composting plant run-off
- Aquaculture and process water
Palm oil mill effluent (POME), rubber or tapioca processing ponds? These are among the strongest odour sources in Southeast Asia. They are not yet in the published reference list, so we check each case with the manufacturer. Give us the effluent temperature and pH in the quote form and we will confirm which Hexa-Cover® version is suitable.
Floating cover compared with other odour control methods
| Hexa-Cover® floating tiles | Fixed roof or tensioned membrane | Chemical dosing or biofilter | |
|---|---|---|---|
| Civil works | None | Structure, anchoring and engineering | Dosing skid or ducting and fans |
| Installation | Hours, with the basin in operation | A construction project | Equipment installation and commissioning |
| Running cost | None | Inspection and repair | Chemicals, media, power |
| Access to the liquid | Unlimited | Through hatches only | Unlimited |
| Changing level and odd shapes | Adapts automatically | Designed for one geometry | Not affected |
| Wind and tearing | No sheet to tear or lift | Exposed to wind load | Not affected |
| Gas-tight | No | Can be | No |
If you need to capture biogas or achieve full gas-tight containment, a floating tile cover is not the right choice and we will tell you so.
Sewage and wastewater references
A selection from Hexa-Cover’s published reference list for water and industry. Hexa-Cover A/S of Denmark manufactures the product; Mguard Pro is the distributor.
Municipal sewage and wastewater treatment
| Location | Application | Purpose |
|---|---|---|
| Ramtha, Jordan | 8,800 m² wastewater treatment plant | Odour, emission |
| South Island, New Zealand | 19,500 m² wastewater facility | Odour, emission |
| Taipei, Taiwan | Municipal wastewater treatment plant | Not published |
| City of Patterson, California, USA | Municipal wastewater treatment plant | Odour, emission |
| Queensland, Australia | Sewage treatment plant | Odour, emission |
| North Burnett, Queensland, Australia | 1,100 m² STP | Algae |
| Biggenden, Queensland, Australia | 1,035 m² STP effluent | Algae |
| South Island, New Zealand | 1,040 m² sewage treatment pond | Algae |
| D-50129, Germany | Sewage treatment plant | Odour, algae |
| PL-22-100, Poland | 1,050 m² wastewater treatment plant | Odour, emission |
Industrial wastewater, Asia and Middle East
| Location | Application | Purpose |
|---|---|---|
| Beijing area, China | 7,500 m² industrial wastewater | Odour, emission |
| Tianjin, China | 3,300 m² petrochemical wastewater tanks | Odour, emission |
| Beijing, China | Dairy wastewater | Odour |
| Tokyo, Japan | Industrial wastewater and digestate tank | Odour, emission |
| Seoul, Korea | Wastewater | Odour, algae |
| Gujarat, India | Industrial wastewater | Not published |
| Singapore | Chemicals | Odour, emission |
| Dammam area, Saudi Arabia | 6,000 m² refinery wastewater | Odour, emission |
| Qatar | 4,200 m² industrial wastewater | Odour, emission |
| Saudi Arabia | 4,800 m² petrochemical wastewater | Odour, emission |
| Turkey | 6,100 m² sugar factory wastewater | Odour, emission |
Before installing the Hexa-Cover® our customer, a brewery, had many complaints from neighbors about the odor. After the installation the problem is solved.
First of all the Hexa-Cover® ensure an effective reduction of odors but also because the solution is simple and straightforward. … The lifetime of 25 years was another factor.
The main reasons for choosing Hexa-Cover® were its ability to reduce odors and that it is a solution that does not require permanent structures, and therefore minimizes the installation and maintenance costs associated with this type of roof.
Case: equalisation basins at a wastewater treatment plant, Napa, California
Raw sewage from homes and a resort is screened and held in two concrete equalisation basins before membrane treatment. These basins have a high odour and algae potential because of the nutrient load. The designers had planned to install aeration, then chose Hexa-Cover® because it cost less. After installation, a visitor to the plant reported no odour from the covered basins and no algae, while the two uncovered basins beside them were covered in algae. The discs were poured in from big bags and installation took less than an hour.
All referencesProduct specifications
Hexa-Cover® is moulded from recycled polypropylene as a solid tile with ribs on both sides. It has no hollow chambers, no fill holes and no water ballast, so there is nothing to crack, leak or clog.
- 10 year warranty, life expectancy over 25 years
- Unaffected by rain
- Can be installed in a full or an empty tank
- Tiles can be added or removed if the basin changes
- Certified for contact with drinking water to AS/NZS 4020:2018
| Hexa-Cover® R90 | Hexa-Cover® R114 | |
|---|---|---|
| Diagonal | 18.0 cm | 22.8 cm |
| Height | 5.0 cm | 6.0 cm |
| Weight per tile | 0.120 kg | 0.243 kg |
| Tiles per m² | 43 | 28 |
| One big bag covers | 50 m² | 40 m² |
| Material | 100% recycled polypropylene | |
Heavy duty and UV versions are available for oil, gas, chemical and high temperature liquids. Tell us the liquid and temperature in the quote form.
Questions plant operators ask
Will it remove the smell from my STP completely?
No cover removes odour completely. Hexa-Cover® gives up to 95% reduction of odour from the surface it covers, and independent testing measured 81 to 96% on pig slurry. The result at your plant depends on how much of the odour comes from open liquid surfaces compared with inlet works, screens and sludge handling. Send us your site details and we will tell you where a floating cover will and will not help.
Is it a gas-tight cover? Can I collect biogas with it?
No. Hexa-Cover® is a floating layer of individual tiles. It reduces the release of odour and emissions but it does not seal the basin and cannot be used to capture biogas. Normal gas safety procedures for hydrogen sulphide and confined spaces still apply at a covered basin.
Does it work in a basin with aerators or mixers?
The cover allows aeration to continue so that aerobic conditions are maintained. Tell us what equipment is in the basin, such as surface aerators, diffused air, mixers or floating decanters, so we can advise on the layout.
Our water level changes a lot. Is that a problem?
No. The tiles float freely and follow the level. In ponds with sloped banks they lie on the slope when the level falls and float again when it rises.
Do we have to empty the tank or stop the plant to install it?
No. The tiles are poured in from big bags and spread out by themselves, in a full or an empty tank, without special equipment. A 2,185 m² pond at Green Bay airport in the USA was covered in less than four hours.
How do we sample, desludge or service pumps?
You have unlimited access to the liquid. Push the tiles aside with a pole, a sampler or a boat and they close up again afterwards. For major works the tiles can be collected and reused.
Can people or animals walk on the cover?
No. The tiles float individually and do not carry weight. A covered basin can look like solid ground, so keep the same fencing, signs and access rules as for open water.
How long does it last and what maintenance does it need?
The warranty is 10 years and the life expectancy is over 25 years. There is no maintenance, inspection or running cost.
What does it cost?
The price depends on the surface area, the model, the liquid and the delivery location. Give us the dimensions and location in the quote form and we will prepare a quotation.
Tell us about your basin and we will quote it
We need the surface area, the type of wastewater and the location. Photos or a drawing help. Mguard Pro Sdn Bhd supplies Hexa-Cover® from Malaysia to projects across Asia.