Thursday, December 26, 2013

Important Information On Hydrogen Sulfide Reduction In Sewage System

By Harriett Crosby


Hydrogen sulfide is a colorless gas produced when organic matter is being broken down by bacteria in absence of oxygen. This procedure is usually referred to as anaerobic digestion and can occur in swamps and sewers. It can also occur naturally as natural gas or in volcanic gases. This gas has a characteristic smell of rotten eggs no wonder the foul smell usually produced by sewers. It is no wonder specialists are concerned with hydrogen sulfide reduction in the sewer system.

With the production of the gas in sewer lines, environmental specialists usually worry about the odor and corrosion troubles. People who live near sewer lines often complain of the odor issue while the municipal usually worries about infrastructure destruction through corrosion. This usually results when water in the system mixes with the gas forming hydro sulfuric acid that corrodes the surfaces.

For these two reasons, specialists saw the need of controlling this gas in the sewer line. There are many ways that have been devised to control this problem. One method is by adding strong alkali solution to the sewage. Examples of two strong alkalis include magnesium hydroxide and sodium hydroxide and these are the ones used in this process. Each of these hydroxides when added raises the pH of the sewage making it difficult for this gas to be produced.

Chemical treatment is the other way of control used by specialists. The chemical compounds used mostly are chlorine compounds such as bleach, ferric chloride, sodium and calcium hypochlorite. When any of these are added to the sewer system, work by oxidizing sulfides hence the gas will not be formed at all.

There is usually problem however when using this chemical treatment; when there is no pumping section to feed the chemicals into the system, this procedure cannot work well. For this reason, specialists have to create a pumping section first before beginning the procedure. When the feed system is established, it has to be monitored constantly to ensure the treatment is effective. Other than this, safety is always considered during this procedure.

When it comes to corrosion problems there are certain measures that are taken to reduce or prevent this. Increasing ventilation in the sewer infrastructure to prevent break down of organic matter conditions with no oxygen is one way. The other way is through the use of protective coatings on tanks and sewer pipes on their inner part. These coatings are usually composed of tar products, polythene linings, vinyl, cement, plastics and many other materials.

The other method of corrosion control is crown and manhole spraying. Usually, corrosion is worst at the crown of the pipe since the acid collects at this point. This causes the pipe to weaken and eventually collapse if the problem is persistent. Spraying a Sulfa Lock Hi Gel onto the manhole and sewer surfaces protects them from harsh effects of the acid.

Lastly, a monitoring instrument called the liquid phase sulfide meter has been formulated to help in observing sulfides levels in industrial wastes. If the instrument shows the sulfide to be higher than the wanted amount, the waste undergoes pre treatment before its release to the waste water collection system. All in all, these strategies on hydrogen sulfide reduction have helped a lot in control of the negative effects of the gas. But specialists are still coming up with other methods to manage this issue more effectively.




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