The article presents the latest results of research on the biological treatment of mining and metallurgical industrial wastewater using higher aquatic plants: Eichhornia (Eichhornia crassipes Solm) and Pistia (Pistia stratiotes L). The features of these plants detected during contaminated wastewater treatment have been identified.
The primary results of experiments are based on single-stage treatment processes that ensure efficient wastewater treatment upon completion of plant adaptation to these waters. However, the duration of the process is long, i.e., 15–30 days; therefore, the process intensification experiments have been conducted. Experiments conducted within a week have achieved significant reductions in calcium, magnesium, sulfate, and chlorine ions.
During the first days of the experiments, the plants continued to grow and develop, but due to high salt concentrations, some of the plants (approximately 50–60 %) died due to insufficient time for adaptation. The remaining plants were slowly recovering and continued vegetation. These plants have demonstrated high cumulative and treatment effects as they are considered most adapted to the chemical composition of wastewater. The use of such plants, however, will require longer periods for wastewater treatment, namely around a month, which does not comply with the production requirements. Therefore, a decision to experiment during 24 hours has been made.
The results of the analysis have shown that the plants completely absorb calcium, magnesium, chlorine, nitrates, zinc, and cobalt already on the first day of planting; bicarbonates and sodium are absorbed on the second day; and iron on the third day. Potassium, manganese, arsenic, and thiocyanates are neutralized during 7–10 days. The average efficiency of wastewater treatment per day is 51% on the condition of frequent renewal of the plant biomass.
Based on the results obtained, a biotechnology built on a multi-stage biological wastewater treatment system of industrial scale has been developed.
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