Vegetation engineering structure for heavy metals absorption

Abstract

The treatment of contaminated water is a pressing issue. As a solution it is proposed to use a biological engineering construction with the aquatic vegetation - a bioplato. The process of water purification takes place at the expense of the natural capacity of a number of living organisms and plants to transform and absorb contaminants [1]. The phytoremediation method helps to extract heavy metals from water and makes it suitable for consumption and use. However, in order to be most effective, it is necessary to choose the planting method and optimal environmental conditions. Therefore, several types of bioplato were created and tested during the experiment: with different planting methods (bare root, container grown) and in the presence of microorganisms (Pseudomonas fluorescens and Rhodococcus erythropolis).The contaminants were water-soluble salts of lead (II) acetate and cadmium chloride. Iris pseudacorus and Typha gracilis were selected for the experiment, as the plants are capable of significant heavy metals accumulation. The sampling was carried out according to GOST R 56237-2014 «Drinking water. Sampling at water preparation stations and pipeline distribution systems» and GOST 31861-2012 «Water. General requirements for sampling». The samples were analyzed using an atomic emission spectrometer with inductively bound plasma iCAP 6300 Duo.Studies have shown that the purification rate of plants in both planting methods is quite high - more than 92 %. In bare root samples, purification is more efficient (99% in the solutions with the cadmium ions concentration 20 times above the threshold limit value (TLV). The use of microorganisms contributed to the reduction of Pb2+ absorption by 18% in the bioplato with bare root planting method. However, a bioplato with container grown planting method in the presence of micro-organisms is 8,7% better at purifying water from Cd2+ ions