Performance and mechanism of the in situ restoration effect on VHCs in the polluted river water based on the orthogonal experiment: photosynthetic fluorescence characteristics and microbial community analysis

Jia Wang,Peijing Wang,Zhaoxin Li,Lei Li,Yonggang Gu,Shuangrong Wu,Qi Yang

doi:10.1007/s11356-022-18845-4

Abstract

Volatile halogenated hydrocarbons (VHCs) attracted many attentions due to its toxicity and persistence in the environment. In this research, a novel in situ ecological restoration reactor was applied to the degradation of VHCs in polluted river water. The optimized working condition adaptation of the in situ restoration technique was evaluated through orthogonal tests. The experiments showed that when the water depth was 0.4 m, the HRT was 5 days, and the current velocity was 1 m/s, the optimal removal efficiency of VHCs in the reactor was achieved. And the removal rates of CHCl3, CCl4, C2HCl3, and C2Cl4 reached 70.27%, 70.59%, 67.74%, and 81.82%, respectively. The results showed that both HRT and water depth were significantly related to the removal efficiency of reactor. The physiological state of the plants was analyzed by fitting rapid light curve (RLC) model, which showed that the accumulation of VHCs inhibited the photosynthetic performance of plants. Moreover, the microbial community structures of fillers were tested by high-throughput sequencing, and the findings supported that the microbial community made a great response to adapt to the changes in environment of the reactor. The relative abundance of Rhodocyclaceae increased slightly, which hinted that it had good adaptability to VHCs in polluted river water. The research results confirmed that in situ ecological restoration reactor was a potential approach for removal VHCs in polluted river water.

Highlights

Urbanization in China has accelerated the transformation of geomorphological features and ecological environment in urban river, which contained the decrease on the hydrological connectivity and the pollutants accumulated at the bottom of the river channels (Wang et al., 2017)
The results showed that the change of polluted river water led to the change of microbial community structure
The findings in this research suggested that when the water depth was 0.4 m, the HRT was 5d and the current velocity was 1 m/s, Volatile halogenated hydrocarbons (VHCs) removal efficiencies could achieve favorable value, the removal efficiency of CHCl3 CCl4, C2HCl3 and C2Cl4.could reach 70.27%, 70.59%67.74% and

Summary

Introduction

Urbanization in China has accelerated the transformation of geomorphological features and ecological environment in urban river, which contained the decrease on the hydrological connectivity and the pollutants accumulated at the bottom of the river channels (Wang et al., 2017). Volatile halogenated hydrocarbons (VHCs) were constituted with a series of diversified organic compounds, most of which with the characteristics of environmental persistence, bioaccumulation and biology toxicity (Zou et al., 2006; Song et al, 2017). Some VHCs instant vaporized into air environment as a consequence of low boiling points, adding air pollutant and the local people risk of illness in urban area (Mun & Townley, 2021). Variety of VHCs produced by plastics petroleum and landfill leachate influx into urban river alteration the characteristics of water environment and initiation potential adverse effects on human (Wang et al, 2020). VHCs would cause continuous hazard in environmental media, which was the sensitive and prominent in river within the city limits

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