Purification of water from hydrogen sulfide
Hydrogen sulfide water treatment
Hydrogen sulfide water treatment is used for effective removal of high concentrations of iron and manganese from water and for significant reduction of hydrogen sulfide content. For drinking, technical water supply and wastewater treatment. The basis of the filtering medium is a mixture of natural materials based on manganese dioxide, which has been used in the process of water treatment for many years for effective reduction of iron, hydrogen sulfide and manganese. The filter media has a large capacity and successfully maintains very low concentrations of contaminants in the treated water, and can be used in conjunction with aeration, chlorination, ozonation and other supplemental treatment methods in cases where the source water contains high concentrations of contaminants. Chlorine and other oxidizing agents accelerate the catalysis reaction, is a close analogue of Pyrolox loading, but has a lower density (20% lighter). Filtering medium is developed and produced at the enterprise in Russia is the leader in the field of production of filtering materials. Action of filters from hydrogen sulfide is based on the following principle: hydrogen sulfide, iron and manganese, at the expense of process of catalytic oxidation, pass in an insoluble form and are detained in loading with the subsequent removal at back washing with initial or purified water, use of additional chemical reagents at regeneration of a material is not required. Strength of grains of initial materials provides wear resistance and long-term operation of the loading and prevents the removal of material particles into the treated water of the consumer.
Water purification from hydrogen sulfide
From the content of this interesting article you will learn:
1. Why hydrogen sulfide appears in the water
2. Methods of hydrogen sulfide removal
3. Comparison of methods
4. Conclusions and recommendations
1. Why hydrogen sulfide appears in water
The presence of hydrogen sulfide in water is a fairly common phenomenon. In itself, it is a gas from the composition of sulfur-containing elements. It has no color at all, but gives the water a unique aroma of rotten eggs. Hydrogen sulfide can be contained in the air. In normal conditions, its concentration does not exceed the established norms, but with an increase in the level of gas can adversely affect human health. It can block the sense of smell and paralyze the nervous system.
In water sources, the gas has a dissolved form. It is converted by active bacteria called sulfur bacteria. They live at the bottom of water bodies or wells, in places where oxygen is not available, and convert sulfur into hydrogen sulfide. In addition to serobacteria, anaerobic bacteria can contribute to the appearance of gas in the water, which provokes the rotting of protein deposits. Human activity, namely industrial enterprises, can also affect the appearance of hydrogen sulfide. In the process of production, many compounds are formed, which are then discharged into the drain with wastewater. After sewerage such water falls into a water body, where there is a further chemical reaction and formation of hydrogen sulfide. Taking into account outdated water treatment equipment of the majority of enterprises and poor-quality filtration of sewage, we can safely say that the constant discharge of dirty water provokes the appearance of new impurities.
Hydrogen sulfide can be saturated with any water. In the well appear due to bacteria and the lack of oxygen. In the water supply comes from groundwater sources and poor-quality water treatment. In addition, old pipes with many different deposits contribute to the formation of bacteria. Mostly unpleasant odor, in the presence of hydrogen sulfide, is characterized by cold water. If it starts to smell hot, it is worth checking all heating elements.
Removal of hydrogen sulfide from the water is mandatory. First, you do not want to use such water because of the unpleasant odor. Secondly, it has a negative effect on the body, up to lethal outcome. The level of intoxication of an organism directly depends on its concentration in water. In addition, hydrogen sulfide disables equipment and plumbing. First of all, pipes suffer, being subjected to corrosion. Sinks, bathtubs and other sanitary ware acquires a dark plaque that is quite difficult to eliminate. If there are signs of hydrogen sulfide, it is required to take water to analyze and install a filtration system.
Fig. 1 Physical properties of hydrogen sulfide
2. Methods of hydrogen sulfide removal
There are several main methods of hydrogen sulfide purification: aeration method, reagent, biochemical and with the help of sorbents. Hydrogen sulfide in water can be in the form of molecules or ions, it depends on the hardness of the water. Let's assume that using aeration method it is possible to remove ions only partially. For complete removal it is necessary to reduce the acid-alkaline balance to 5. When oxidizing water, hydrogen sulfide is able to change form and change into a molecular state. In this form, it is much easier to remove it. Each method will be effective only at a certain concentration of hydrogen sulfide. In addition, the quality of purification is affected by the characteristics of the source water. Before choosing a method, a chemical analysis of water is necessarily carried out.
Physical method. It is used only if the concentration of hydrogen sulfide is low. Aeration is used. The method is based on the oxidation of water with the help of oxygen. Air is supplied to the water stream, which oxidizes the medium. For aeration, a special column is installed, in which the oxidation process will take place. You will also need a pump to pump out clean water. And a compressor for air injection, if the method of pressure aeration is chosen. This method of purification is suitable for cottages and country plots.
Fig. 2 Diagram of pressure aeration with dosing system
Reagent method. Can be applied at high concentration of hydrogen sulfide. Reagents are used to oxidize the medium. The most popular are potassium permanganate, chlorine and ozone, sodium hypochlorite. When chemicals are added to the water, the medium is oxidized. Further, the water must pass through the load, leaving all impurities in it. Filtration after treatment is mandatory to remove decomposition products-sulfates. When purification with chlorine, as in principle with any other reagent, compliance with the proportions is required. In this case, it is 8.4 mg per 1 mg.
When purification with potassium permanganate, aka manganese, hydrogen sulfide breaks down into sulfur and manganese dioxide. In this process, the water is not yet completely pure. Due to the presence of decomposition products, it has an unpleasant brown color and must be filtered.
Another active reagent is hydrogen. It also oxidizes the medium and the remaining sulfur is removed by sorbents. The simplest load is activated carbon. It can not only clean the water from decay products, but also improve the organoleptic properties.
Iron hydroxide solution is a powerful oxidizer. When it is added to water, iron ions and hydrogen sulfide stick together and precipitate. The water is poured into a separate container and sedimented, then blown with air. Iron hydroxide cannot be replaced after the first purification and can be used several times.
Another gas that can defeat hydrogen sulfide-ozone. It too oxidizes water, resulting in the formation of sulfuric acid. In addition to purification, ozone is an excellent disinfectant.
Fig. 3 Sorption carbon filter
Biochemical method. It is used if hydrogen sulfide is contaminated by a terrestrial source. They appear there because of sewage from industrial enterprises or bacteria living in sludge. In this case, a multistage system consisting of two stages will help. First, the water is treated with an aerooxidizer, then filtered.
Sorbents. The simplest, but no less effective method is the use of activated carbon, which is the basis of the filter. It is used at low concentrations of hydrogen sulfide. Can be installed in domestic conditions. Sorbents oxidize the medium and remove residual hydrogen sulfide. At the same time disinfecting. If the level of contamination is too high, a chemical oxidizer can be added
3. Comparison of methods
Each method has one thing in common-elimination of hydrogen sulfide impurities. However, there are both pros and cons. Physical method, based on aeration, allows you to remove viruses and bacteria. Since oxygen is used in the purification process, such water becomes more useful for the body. But at the same time, aeration units are quite voluminous, for oxidation requires the installation of large containers. It is also possible to release hydrogen sulfide into the air, since during aeration, excess gases are released outside. There is no possibility to fine-tune the system and effective purification only at low gas concentrations.
The reagent method has advantages in fast and effective purification, making it indispensable in manufacturing. It helps to purify water from viruses. But it is necessary to automate the system and install additional components-dosing units. Dispensers will produce an accurate supply of reagents, without exceeding the prescribed rate. In the absence of automation, constant monitoring is needed, which is not very convenient. Also, the method uses chemicals, which is not environmentally friendly.
Biological method allows not only to eliminate hydrogen sulfide, but also disinfects water. But, as in the case of the chemical method, reagents are used. Automation of the system is required.
The use of sorbents eliminates viruses, improves the color and smell of water. This method is quite simple, and water treatment systems are small. But, like aeration, it is effective only at low levels of hydrogen sulfide.
4. Conclusions and recommendations
Purification of water from hydrogen sulfide is necessary and important process, Therefore, before choosing a method of purification is recommended to make a chemical analysis of water. The obtained data will allow you to see the concentration of the gas. In addition, it is worth paying attention to the performance of the system. For example, aeration columns, require quite a lot of time and space for cleaning. But the reagent method is able to quickly remove impurities, but additional filtration of wastewater is required. Therefore, this method may be suitable only for industrial production. An important role is played by the cost of equipment and operating costs. This category includes additional elements, electricity consumption, the purchase of reagents, filter washing. If there are difficulties with the choice, it is recommended to contact specialists.
Below is a video on sorption filter assembly
