International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Heavy metal pollution from various industries has received much attention worldwide due to their toxicity and persistence in the environment. Traditional water quality monitoring relies on sampling, preservation, transportation and subsequent laboratory analysis. All these procedures require considerable time and make it impossible to timely detect heavy metal contamination. To overcome the drawback, SMFC-based biosensors can be used for monitoring water pollution with heavy metals. The electrochemical characteristics of SMFCs are sensitive to heavy metal ions, therefore, when heavy metals enter them, the cell voltage immediately rises in proportion to their concentration. The change in voltage can be used to find the presence of heavy metals in the water and their concentration. In the present study, the possibilities for monitoring water contaminated with copper, zinc, nickel and chromium by means of SMFC-based biosensors were investigated. The constructed biosensors showed high sensitivity to the ions of the four investigated metals.

Sediment microbial fuel cells (SMFCs) are special microbial fuel cells in which the anode is placed in the anaerobic sediment and the cathode is immersed in the surface layer of water. Natural electroactive bacteria decompose organic compounds in sediment, producing electrons and protons. The electrons reach the cathode through an external electrical circuit, while the protons pa ss through the soil layer, which acts as a kind of membrane. Oxygen is in many cases the preferred electron acceptor due to i ts presence in the cathode region and its high potential. Heavy metal ions and other compounds can also be reduced on the cathode, which will increase the energy generated. Based on the above characteristics, SMFCs would be suitable for application as biosensors and would be suitable for monitoring recurrent water pollution with heavy metals. In the present study, the possibility of application of SMFCs as biosensors for recurrent water pollution with copper has been studied. A high correlation was found between the concentration of copper ions and the voltage generated by SMFC, as the coefficient of determination reached 0.9921.

Heavy metal accumulation potential in the biomass and different plant parts of the selected species of energy crops cultivated on contaminated soil was evaluated. Phytoextraction potential, biomass yield and qualitative parameters of bioenergy plants grown on heavy metal contaminated soil has been measured. Finally heavy metal influence on biomass utilization possibilities, energy recovery and further safe use of the rest products has been evaluated. Demonstrated possibilities to grow bioenergy plants on moderately contaminated soil could increase the use of marginal lands, decrease land use competition between food and liquid biofuels and provide options for a gentle and cost-effective remediation.

Comparable heavy metal extraction efficiency using different chelating aminopolycarboxylic acids was studied with sewage sludge as well as sludge-soil mixtures. EDDS and MGDA showed only slightly lower extraction efficiency in comparison with EDTA, at solution pH 6 and 25°C. Chemical fractions of HM in the sludge were determined using sequential extraction. According to their stability in the environment (in sulphide and residual fractions) the investigated heavy metals can be ranked as follows: Cr> Pb> Ni> Cd> Zn ≈ Cu. It was found out that methylglycinediacetic and S,S’-ethylenediaminedisuccinic acids had much better biological degradation properties than widely for metal complexation used ethylenediaminetetraacetic acid – EDTA. Possibility to utilize metal-contaminated extraction solution by chelant recovery with calcium hydrosilicate was also investigated.

The aim of this experiment is to determine to what levels of toxic load with heavy metals reached different soil types under varied levels of sludge application. Determine the effects of different toxic loading soil on biomass yield and heavy metals content in crop production. The pot experiments are with two cropsperco(Brassica ssp. spantaula) and rye grass(Loliummultiflorum), in two swaths as an after-effect on the yield on four soil types: Carbonate Fluvisols,Leached Vertisols, Leached Cinnamon Forest and gray Forest.The different percentage of sludge level relative to the weight of soil was tested.

It was found, that loading of various soils types with sludge up to 10% supported increasing effect of fertilization with sludge in perco and rye grass and to the same extent accumulation of heavy metals in them. Their concentrations, however, do not have phytotoxicity.