Friday, 3 January 2014

Important Information On Hydrogen Sulfide Reduction In Sewage System

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.

When thinking of this gas in waste water, the concern is mostly its odor and corrosion effects. More often than not, people living near sewer systems usually complain of the odors coming from the system. The corrosion problem results when the gas produced in the sewer atmosphere combines with water to form hydro sulfuric acid. This acid is the one responsible for corroding the sewer infrastructure.

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.

For the rust problems, several measures exist to control this. The first one involves increased ventilation in sewer system to allow aerobic digestion to occur rather than anaerobic. The other measure is use of protective coatings when manufacturing sewer pipes and tanks. These coatings can be polythene linings, cement, vinyl, tar products and the do prevent corrosion of the infrastructure.

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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