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19 December 2013

Information On Hydrogen Sulfide Reduction In Sewer Systems

By Harriett Crosby


Hydrogen gas is produced in sewer systems, swamps, in volcanic and natural gas. Its production is after organic materials are broken down in absence of oxygen. The most common characteristic of this gas is its smell. It usually smells like rotten and this can explain why sewage system usually produces a foul smell of rotten eggs. This article thus provides information on hydrogen sulfide reduction and why it is important.

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.

There is thus need to control the production of this gas in waste water collection system to very low levels. One way which specialists have found to reduce production of this gas is through addition of a strong alkali or soluble basic solution. The basic solution for instance sodium hydroxide (NAOH) or magnesium hydroxide when added to sewage increases the pH and this leads to limited formation of the gas.

The other method is chemical treatment where certain chemicals are released into the sewer. More often than not, chloride compounds are the ones usually fed into the system. Examples of these compounds include; calcium and sodium hypochlorite, ferric chloride or bleach. When any of these compounds are added to sewage, they lead to oxidation of sulfides hence the gas will not be formed.

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.

To resolve corrosion issues, the environmental specialists have come with measures to increase ventilation in the sewage infrastructure to prevent anaerobic conditions for bacteria. Apart from this, contractors of the systems are now using sewer pipes and tanks with protective coatings on the inner sides. The coatings used include; vinyl, tar products, polythene linings, cement among other materials to protect the system against corrosion.

Crown and manhole spraying is yet the other measure used in corrosion control. When the hydro sulfuric acid is forms, it collects mostly at the crown part of the pipe. The effect on this area is intense decomposition leading to weakening of the pipe and in worst cases collapse. Therefore a Sulfa Lock Gel is sprayed on these areas so as to prevent the bad effects of hydro sulfuric 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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