Rotten egg smell

intro imageWhat is H2S gas or sewer gas?

If you detect a rotten eggs smell in your neighbourhood or around your home, it is likely that you are in the presence of hydrogen sulphide (H2S). H2S comes from sewage treatment plants, sewerage systems and wastewater treatment plants. Also known as sewer gas, it is extremely toxic to humans.

If your operations are the subject of complaints about odour, contact our experts!

The presence of hydrogen sulphide in a sewer is often discovered as a result of complaints from local residents who suffer from an odour problem. YaraNutriox™ offers a range of products and services that will help you deal with this problem of rotten egg smell in the best way possible, and thus reduce odour problems caused to the local community. 

Yara’s team of experts offer technical support, including site surveys and hydrogen sulphide monitoring, which means they can recommend a treatment programme tailored to your situation. You will only dose what you need, in the right place and at the right time. We also offer on-line telemetry, so you can control the dosing site remotely from your desk, and site-specific storage equipment for the product.

H2S: Where does it come from?

Hydrogen sulphide is produced by a biological reaction in the sewerage or in sewage treatment plants themselves. H2S comes from the anaerobic (without oxygen) fermentation of organic matters found in wastewater. Inside a pipe, if there is a lack of oxygen, microorganisms feed and produce hydrogen sulphide, which smells like rotten eggs. This is called septicity, and is the cause of the H2S and the bad odours that come with it.

Yara has developed YaraNutriox™, an effective preventive solution based on nitrate salts. We work with many sewage treatment plants and industrial sites, in Europe and across the globe, which have eliminated the source of odour complaints. Learn more about the YaraNutriox™ process

Aerobic and ANOxic Processes

Aerobic Anoxic Flowchart

H2S gas is insidious

Hydrogen sulphide is a colourless and insidious gas that forms itself under certain conditions - called anaerobic conditions or septicity– in sewage pipes and sewerage networks where there is no oxygen.

H2S has adverse effects on health. It is very irritating to the eyes and the mucous membrane lining the respiratory tract. Above a certain concentration, hydrogen sulphide anaesthetises the olfactory nerve which means that the smell “disappears “ and the H2S can’t be detected at all. Thus, H2S can hit where we least expect it. For a healthy adult, the effects are lethal above 300 ppm (parts per million). Under certain conditions, in a confined space, hydrogen sulphide can kill instantly.

A Gas with Multiple Hazards:

A toxic gas An explosive gas Unpredictable
Hydrogen sulphide is a poison that has a broad-spectrum. It attacks and paralyzes the nervous system and blocks cellular respiration. At high concentrations, a single breath is deadly H2S is extremely flammable. It forms explosive mixtures with air. Contact with oxidizing products can be a source of fire and explosion Hydrogen sulphide gas is insidious. Heavier than air, it can accumulate at low points in buildings at pumping stations and treatment plants. It forms pockets in stagnant wastewater and releases lethal amounts of gas when the wastewater is moved due to the flow in the pipes. It paralyzes the olfactory nerve and thus thwarts the body’s natural protection against it

The dangers of H2S

Besides its bad smell, in large quantities H2S is irritating, and at very high levels in a confined space, it is particularly toxic. Water company staff who work in a closed environment are particularly vulnerable to this serious danger. It is the manager's responsibility to protect sewer workers against the dangers of H2S.

The different levels of H2S danger

The different levels of H2S danger

Corroded concrete: is H2S the cause?

One of the characteristics of hydrogen sulphide is that it causes corrosion of sewerage and WWTP structures. In the hot and humid atmosphere of a sewage network, H2S is oxidized into sulphuric acid. This sulphuric acid is corrosive and attacks wastewater and sewage treatment facilities. It attacks the concrete, copper, iron and silver that can be found in treatment tanks, buildings and electrical equipment. If no preventative action is taken, pipes exposed to this corrosion may eventually collapse. Corrosion particularly affects the submerged parts of structures in sewers or WWTPs.

The speed of corrosion will depend on the extent of the H2S formed and the level of preventative treatment. However, preventing H2S odour problems with YaraNutriox™ also combats corrosion and avoids the collapse of pipes.

H2S en cause

Fight effectively against H2S

It is possible to prevent the occurrence of bad rotten egg smells in a wastewater treatment plant (WWTP) or sewer system. Yara has developed YaraNutriox™, a process that prevents septicity caused by the lack of oxygen in the pipes of a sewer and in a WWTP. YaraNutriox™ is a mixture of nitrates specially developed by Yara, with proven effectiveness on hundreds of sites around the world in the fight against hydrogen sulphide. Communities throughout the world, from Norway to Brazil and Canada to Australia and South Africa are benefitting from YaraNutriox™ treatment against H2S.