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Professor Liu Cheng's team from the school of environment, Hehai University monitored the changes of organic matter and lead content in sewage and soil (or filler) treated by control and Pb, and analyzed the microbial characteristics through two laboratory scale biological retention columns. The results were published in Chemosphere (if = 5.108).
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Highlights?The Pb accumulation reduced the microbial biomass.
?The Pb accumulation produced small-quantity Pb-tolerance microorganisms.
?The COD removal in the soil and filler layer was promoted and inhibited by Pb respectively.
?The Pb affected the ability of microorganisms to bind to organisms by altering their structure.
AbstractBioretention systems have been proved to be a natural approach for effectively reducing stormwater runoff pollution loads. However, the effects of heavy metals in stormwater runoff on microbial characteristics and organics removal in bioretention systems are unclear. In this study, two lab scale bioretention columns including the control and lead (Pb) treatment with the soil and filler layer were established. The changes of organic matter and lead in the effluent water and the soil (or fillers) were monitored during 121 operation days. The soil (or fillers) microbial characteristics were also analyzed. The results showed that most of Pb was intercepted by soil, while a small amount accumulated in fillers after 121 days. The long-term Pb accumulation in the biorentention system negatively affected the microbial biomass and microbial activity, while positively affected the community diversity. Pb accumulation killed some microorganisms, but simultaneously stimulated the growth of some Pb-tolerance microorganisms. The abundance of bacteria with COD degradation function in soil layer decreased, while that in fillers increased, indicating the effect of Pb on the community structure of these two layers was different. The COD removal in the soil and filler layer was promoted and inhibited by Pb contamination respectively. Moreover, Pb affected the removal of organic matter by chelating organic matters and changing their composition. The results suggested that the long-term accumulation of heavy metals in bioretention system would affect microbial degradation function and pollutants removal, causing our concern for the long-term maintenance of the bioretention system.
Biological retention system has been proved to be a natural method to reduce the pollution load of stormwater runoff. However, in the biological retention system, the impact of heavy metals in storm runoff on microbial characteristics and organic matter removal is not clear. In this study, two laboratory scale bioretention columns were established, including soil and filler layers treated with control and Pb. The test run period was 121 days, and the changes of organic matter and Pb content in sewage and soil (or filler) were monitored. The microbial characteristics of soil (or filler) were analyzed. The results showed that most of Pb was retained in the soil and only a small amount of Pb was accumulated in the filler after 121d. The long-term accumulation of Pb in biological retention system has a negative effect on microbial biomass and microbial activity, and a positive effect on community diversity. The accumulation of Pb killed some microorganisms, but also stimulated the growth of some Pb tolerant microorganisms. The abundance of bacteria with COD degradation function decreased in the soil layer, but increased in the filler, indicating that Pb had different effects on the community structure of the two layers. Pb pollution promoted and inhibited the removal of COD in soil and filler layer respectively. In addition, Pb affects the removal of organics by chelating organics and changing their composition. The results show that the long-term accumulation of heavy metals in biological retention system will affect the degradation function of microorganisms and the removal of pollutants. It is necessary to pay attention to the long-term maintenance of biological retention system.
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