Study of removing hydrogen sulfide from ventilation
and sewage gas-air emissions by absorption cleaning

Summary

The results of studying the removal of hydrogen sulfide from ventilation and sewage gas-air emissions by absorption cleaning on a packing irrigated with sodium hypochlorite are presented. The studies were carried out in a laboratory setup. The subject of research was artificially prepared gas mixture of air and hydrogen sulfide obtained by dosing hydrogen sulfide solution into acidic solution (gas generator). Variation of the hydrogen sulfide concentration in the air was achieved by changing the feed from a hydrogen sulfide-containing solution dispenser. The laboratory setup included an absorber with a volumetric packing made on the model of Raschig rings. Chlorine-containing 0.3% sodium chloride solution was used as the absorption solution. The regeneration of active chlorine (reduced by hydrogen sulfide to chlorides) in the absorbent was carried out by direct electrolysis in a flow-through electrolyzer installed in the line supplying the absorbent to the absorber. The actual dose of active chlorine for the oxidation of hydrogen sulfide absorbed by the absorbent was determined. The main dependences describing the chemisorption of hydrogen sulfide and the electrochemical regeneration of sodium hypochlorite in the absorbent are presented. A method for calculating the absorber of the laboratory setup is presented. Specific electricity consumption for removing hydrogen sulfide from air was determined. In the follow-up studies the obtained results will provide for calculating the costs of air purification, estimating the operating costs and conducting an engineering and economical comparison of the proposed and competing methods of removing malodorous substances from ventilation emissions from sewer facilities. The presented method can be recommended in the schemes for cleaning ventilation emissions at the wastewater treatment facilities.

Key words

sodium hypochlorite , reeking substances , hydrogen sulfide , absorption , cleaning of ventilation emissions

Removing malodorous substances from gas-air mixtures in wastewater disposal systems

Summary

A scientific justification is given for the use of the method of hydrogen sulfide absorption by aqueous media containing an oxidizer – hypochlorite ion, obtained electrochemically in a stream of reusable absorption solution, in a countercurrent absorber for gas-air mixture purification in wastewater disposal systems. The results of theoretical and experimental studies of the influence of operational factors on the efficiency of removing hydrogen sulfide from gas-air mixtures using the proposed method are presented. Recommendations for using the method are given. A process flow scheme for gas-air mixture purification in wastewater disposal systems using the method of hydrogen sulfide absorption by aqueous media containing an oxidizer – hypochlorite-ion, as well as the process parameters for its application, are presented. The results of estimating the economic efficiency of the developed technology are provided.

Key words

sodium hypochlorite , hydrogen sulfide , absorption , gas cleaning , absorbent , absorber

The use of chemical scrubbers to eliminate odors
at the wastewater treatment facilities

Summary

The potential and features of using chemical scrubbers to remove from the air hydrogen sulfide and other malodorous substances generated during the transportation and treatment of wastewater are considered. A comparative analysis of the characteristics of various types of scrubbers: alkaline, hypochlorite, peroxide, and based on iron compounds is presented. It has been shown that the use of chemical scrubbers to eliminate malodorous substances at the wastewater treatment facilities has a number of significant limitations. The use of chemical scrubbers is advisable at the primary stage of air cleaning. Relatively low concentrations of hydrogen sulfide in the ventilation emissions of the wastewater treatment facilities at the relatively high concentrations of carbon dioxide result in an increase in the consumption of chemicals for second-order chemical reactions. In this case, significant operating and capital costs in the climatic conditions of Russia, except the southern regions, the operation complexity of the equipment, and the need for additional air cleaning using other methods should take into account.

Key words

wastewater , absorption , industrial methods of removing malodorous substances , hydrogen sulfide removal , chemical scrubbers , odor control