Constructed wetland (CW), an ecological water treatment system, can purify and repair the damaged saline water body in an open watershed, but its repairing function is limited at low temperature under salt stress. In this study, two different plant species with slag-sponge layer were operated to enhance the purification effect of CW on the damaged saline water body. The results showed that the combination of Scirpus mariqueter and slag-sponges in CW had a better purification effect especially under the condition of salinity of 10‰ (S = 10) with a respective removal efficiency of 91.04% of total nitrogen, 80.07% of total phosphorus, and 93.02% of COD in high temperature (25 ~ 35 °C). Furthermore, ecological traits (enzyme activity and amino acids) of plants, the abundance and distribution of functional microorganisms on the surface of slag-sponges, and the microbial state on the substrate surface of the denitrifying zone of CW were analyzed to explain how exactly the combinations worked. It was found that the enrichment of functional microorganisms in slag-sponge and the anaerobic zone of plants have improved the nitrogen and phosphorus removal. Plants maintained high enzyme activities and the ability to synthesize key amino acids under salt stress to ensure the growth and reproduction of plants and achieve the assimilation function. Scirpus mariqueter combined with slag-sponges in CW effectively improved the purification effect of damaged saline water, indicating that it is an ecological and green saline water treatment way.
Keywords: Biological mechanism; Constructed wetland; Functional microorganism; Salt stress; Slag-sponge.
© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.