H2S in a wastewater treatment plant

wastewater treatment plant

If you experience odour complaints from the community around your site because of H2S release, you must implement a solution to remove H2S, but also to prevent it forming again, whether the problem is in your sewage or in the sewage systems.

In South Africa Yara’s YaraNutriox™ offers a preventive solution against H2S and the odour pollution that comes with it. This solution includes a full set of services:   

  • On-site diagnosis to identify the source of hydrogen sulphide
  • Preventive treatment
  • Dose monitoring

Dynamic YaraNutriox™ dosing allows sites with H2S problems to eliminate odour, and prevent the exposure of WWTP employees to this toxic gas. Specially developed dosing equipment responds to the specific flows and other characteristics of the network to achieve the optimum usage rate.

Unlike some other treatment methods, controlled dosing of YaraNutriox™ has no negative impact on the wastewater treatment process and YaraNutriox™ can also fight against the corrosive effects of hydrogen sulphide.

Yara has developed YaraNutriox™, a process that prevents septicity caused by lack of oxygen in the pipes of the sewer network and of the WWTP. YaraNutriox™ is a mixture of nitrates specially developed by Yara, with proven results in hundreds of sewer systems to fight against the corrosive effects of hydrogen sulphide. Yara markets YaraNutriox™ in South Africa and around the world.

YaraNutriox™ Reference: Over 2000 sites in Europe and the world.

Fight corrosion

One characteristic of hydrogen sulphide is that it corrodes sewerage and WWTP structures. It attacks the concrete, copper, iron and silver. In the hot and humid atmosphere within a sewer, hydrogen sulphide will be oxidised into sulphuric acid by Thiobacillus bacteria (Gram-negative), on the walls of the pipe. This sulphuric acid is corrosive and attacks the wastewater and sewage treatment infrastructure. Corrosion particularly affects the submerged parts of structures in sewers or WWTPs.

The H2S that results from this condition gradually degrades the pipe until it actually collapses. The speed of corrosion will depend on the extent of the septicity  and the effectiveness of any treatment against H2S in the network. Preventing H2S with YaraNutriox™ also combats corrosion and avoids the collapse of pipes.

04 Thiobacillus

Fight efficiently against corrosion and H2S

The corrosive effects of H2S can be limited by taking action in the wastewater treatment plant (WWTP) or the sewer system.

Preventive treatment tailored to your needs

Following an on-site diagnostic, Yara recommends a treatment tailored to your situation. Dose only what you need. Our team of experts offers services such as on-site problem assessment, trials, guidance on dosing strategy, web-based telemetry (to control the dosage on site remotely from your desk) and tailored YaraNutriox™ storage and dosing equipment.

Protect your employees against the dangers of H2

In their daily work, operators and other employees at sewage treatment plants are potentially exposed to the harmful effects of hydrogen sulphide on their health. Since 1995, Hydrogen sulphide is classified as a hazardous chemical substance by the South African Department of Labour. The Hazardous Chemical Substances Regulation (under the Occupational Health and Safety Act) sets Occupational Exposure Limit values (OEL) for Hydrogen Sulphide of 10ppm (TWA-OEL) and 15ppm (Short Term OEL). Under the regulations, it is the manager's responsibility to protect workers.

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 accumulates at the bottom of the cavities. It forms pockets in stagnant wastewater and can release lethal amounts of gas when the wastewater is disturbed or pumped through pipelines. It paralyzes the olfactory nerve and thus undermines 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

Treating H2S problems by prevention

This film presents in detail our YaraNutriox™ solution

YaraNutriox™ is being used in hundreds of communities

YaraNutriox™ is a nutrient solution based on various nitrate salts - it acts as a biological reactor. Ensuring the bacterial balance in the sewer and pipes, YaraNutriox™ prevents the formation of H2S. This process has been specially developed by Yara thanks to our knowledge of nitrates and actions nutrients. This is a natural process that acts at the source of the problem, to prevent hydrogen sulphide and odours that result.

We recommend to inject YaraNutriox™:

  • Automatically
  • Where and when it is needed
  • In the right quantity

YaraNutriox™ allows the site affected by the H2S odour problem to treat only what is necessary. Not only does it eliminate the odor complaints from the community, but also the risk of employee exposure to this highly toxic gas.

Dynamic YaraNutriox™ dosing allows sites with H2S problems to eliminate odour, and prevent the exposure of WWTP employees to this toxic gas. Specially developed dosing equipment responds to the specific flows and other characteristics of the network to achieve the optimum usage rate.

Discover our full range in detail