Review on pollution control technologies of hydrogen sulfide odor in landfill

Abstract: Landfill is a popular disposal method for municipal solid wastes (MSW) in developing countries such as China. With the rapid increase of urbanization and waste output, some landfills are gradually being surrounded by residential areas. Accordingly, odor pollution arisen from landfill site has become one of the most common public complaints. Hydrogen sulfide (H2S) is one of the major contributors to offensive odors in landfill, which is not only endangers the health of field workers, but also affect the normal life of the surrounding residents. This paper reviewed the recent research progress of H2S odor pollution control technologies in landfill. It shows that the H2S odor pollution in landfill has a very high concentration and intensity with great seasonal and meteorological changing. H2S in landfill gas ranges from hundreds of micrograms per cubic meter up to thousands of milligrams per cubic meter in different MSW landfill sites. Correspondingly, the sulfate, which could be utilized by sulfate-reducing bacteria (SRB) as the electron acceptor to produce H2S, ranges from 70 to 1750 mg/L in leachate. Overall, technologies for H2S odor pollution control in landfill are mainly focusing on the end-up treatment including removing of H2S from landfill gas and using the alterative landfill cover layer to reduce H2S emission into the surrounding atmosphere. Besides, semi-aerobic landfill technology, which can accelerate the stabilization of the refuse, reduce the production of leachate and landfill gas, is another good option for H2S odor pollution control. Moreover, technologies of using easy available and efficient materials to control H2S odor emission has also being developed, especially for resource utilization of wastes with special physical, chemical and biological properties. However, technologies about controlling the source of H2S odor in landfill are still very limited. In order to deeply solve the problem of H2S odor pollution from landfill, it may need to change mind to find source control technologies during the decomposition of MSW in landfill. Thus, some new microbial technologies such as taking advantage of the abandon iron "hidden" in the landfilled refuse and nitrate-reducing, sulfide-oxidizing bacteria (NR-SOB) to control H2S production in landfill were developed. In the method of using the microbial oxidation and reducing of iron, Fe(II) can remove H2S via the formation of ferrous sulfide precipitation, and Fe(III) can also oxidize H2S to elemental sulfur while itself being reduced to Fe(II) and then experience the same process of ferrous sulfide precipitation. Meanwhile, the electronic using priorities of iron-reducing bacteria promote the above process and avoid the further production of H2S by SRB. In the method of using the metabolism of NR-SOB, the abandon nitrate in landfill is used as electronic acceptor to oxidize sulfide and attenuate the H2S production. Although those mentioned technologies are still being studied, they have good application and development potential. Finally, some other novel technologies and research trends related with H2S odor pollution control in landfill were also summarized and discussed. It has important theoretical and practical significance to deeply control H2S odor pollution in landfill and improve the surrounding environmental quality and ecological health.