We have wells in sandstone area and recently we increased the depth of these bore wells from 600 ft to 700 ft. Since then, we have started getting smelly water and the pipe infrastructure is also corroding.
When we did the chemical analysis we found out that the drinking water has hydrogen sulfide at the level of 4 mg/l. Some naturally found anaerobic bacteria are forming this in soil and we can not stop it. So the best way is to remove the H2S from the water.
Our technical guide has asked us to opt for aeration, but your suggestions about some other options as well are welcomed.
We have only these three wells as the water source for a village, and we need to solve the problem asap.
Also the recommended method should be very economical... :)
As others have noted/suggested, Aeration & Chlorination are the standard/basic Rx methods of removal: But for Chlorination to work properly, treated water needs to be held - in a pipe or enclosed area - long enough for the chem process to fully interact. Aeration of Bore Hole water could prove both technically & cost difficult; with results depending on extent/source of the H2S tainting. To reinforce other recommendations, you REALLY need to try to determine the natural causal source of this chemical: E.g., in deepening the bore holes, you may have hit some volcanic rock formations. Grasses/weeds can also be a source; but whatever, there's a bacterial factor in the mix. Cautionary Note: "Chlorine" use is the "default" antidote; but this chem has been used for pathogenic "purification" purposes for over half a century now. However, what those "hooked" on this so-called panacea are totally ignoring are these now well known facts: 1) Chlorine is now a well known/recognized CARCINOGEN, with extended/heavy use!; 2) It's ingestion can also cause a number of potentially very negative health side-effects, with even short-term use; some people being HIGHLY sensitive! (NB: I've personally witnessed people go into convulsions, after ingesting heavily chlorine treated "raw" water.); 3) Chlorine has a very short "shelf/use life", & thereby easily loses whatever bacteria conversion/elimination powers it has at full strength. Bottom Line: You first need to determine the causative source creating the H2S condition/problem. Just keep in mind, as you review/consider all those "chemistry" change suggestions/formulae posted above: When one starts mixing chemicals, it's easy to arrive at "unanticipated/unwanted" results: INCLUDING THE CREATION OF POISONOUS/EXPLOSIVE GASES & WATER!!
Regarding your question, please see this published article: Hydrogen Sulfide in Drinking Water:Causes and Treatment Alternatives, Posted as: http://soiltesting.tamu.edu/publications/L-5312.pdf
Do a full analysis incl TOC and Fe and Mn so that you know what other problems are present before you choose a process. A high TOC/Fe/Mn is a game-changer. P
1. Sulfides, such as other inorganic compounds are easily oxidable. Thereby sulfate will be produced. You need 4 Mol O3 for 1 Mol Sulfide. The reaction is as follows: S2- + 4O3 = SO42- + 4O2
2. You could use granulate (catalyticly acitve) filter medium, with high manganese oxide content. This filter medium is normally used for iron and manganese removal as well as hydrosulphides.
This kind of treatment would be a lot cheaper and also easier to maintain.
If you send us a sample of your water, we can try it out, having some of these filter media at hand in our laboratory.
3. You apply a lot of chemicals. Iron chemical produces a disgusting, stinking, black sludge, which has to be disposed of properly. Chlorine has already been discussed in other answers. I wouldn't go for this option if I was to produce drinking water...
Best regards
Christoph WABAG Water Technology Ltd., Switzerland
Hello ANITA. Thank you for sharing with me this concern. In my knowledge, I do not know much about how to eliminate this substance. But I'll talk to my colleagues to see if they know something about it. Thank you for your understanding
You need to do the following tests the water COD & BOD You must know the type of bacteria present in the water to be treated water knowledge Must be examined within the water pipelines and wells to make sure of the safety of the pumps in terms of the absence of any leak because the leak is working on the introduction of the air here, where it is to be a good environment for bacteria After testing the water to make sure the well can be treated substance (hydrogen peroxide) is a hypertext killer bacteria
Dear Madam, In my knowledge, Aeration is normally not used for about more than 2.0 mg/l H2S concentration. As the water from well is going to be used for drinking purpose and the nearby soil contains anaerobic bacteria, the best way to remove H2S may be chlorine dosing with activated carbon filter before its consumption. ONLY IF WATER HAS NO SIGNIFICANT AMOUNT OF IRON. Considering 4.0 mg/l of H2S concentration, you will need 8.0 mg/l of chlorine dosing with approximately 20 minutes of retention time. In the given retention time chlorine will oxidize H2S where as the activated carbon filter will removes the insoluble sulphide particles as well as residual chlorine left after the oxidization of the H2S. Best Regards, Sameer Dohare
When chlorine enters water, it immediately begins to react with compounds found in the water. The chlorine will react with organic compounds and form trihalomethanes. It will also react with reducing agents such as hydrogen sulfide, ferrous ions, manganous ions, and nitrite ions. Let's consider one example, in which chlorine reacts with hydrogen sulfide in water. Two different reactions can occur: Hydrogen Sulfide + Chlorine + Oxygen Ion → Elemental Sulfur + Water + Chloride Ions H2S + Cl2 + O2- → S + H2O + 2Cl- Hydrogen Sulfide + Chlorine + Water → Sulfuric Acid + Hydrochloric Acid H2S + 4Cl2 + 4 H2O → H2SO4 + 8 HCl I have written each reaction using both the chemical formula and the English name of each compound. In the first reaction, hydrogen sulfide reacts with chlorine and oxygen to create elemental sulfur, water, and chloride ions. The elemental sulfur precipitates out of the water and can cause odor problems. In the second reaction, hydrogen sulfide reactions with chlorine and water to create sulfuric acid and hydrochloric acid. Each of these reactions uses up the chlorine in the water, producing chloride ions or hydrochloric acid which have no disinfecting properties. The total amount of chlorine which is used up in reactions with compounds in the water is known as the chlorine demand. A sufficient quantity of chlorine must be added to the water so that, after the chlorine demand is met, there is still some chlorine left to kill microorganisms in the water.