AbstractsBiology & Animal Science

The present PhD thesis focuses on an experimental investigation into applying phytoremediation for the reclamation of sites affected by sewage sludge. Two study sites, one within the area of the Thessaloniki Wastewater Treatment Plant, Greece, which receives sludge for temporary deposition, and the other within the area of the “Bezludivka” Wastewater Treatment Plant in Kharkiv, Ukraine, which is an area with dewatering sludge lagoons, were selected for the experimental investigation. Both sites are characterised by a similar sludge problem in that both have an accumulation of sludge, which is not further utilised. In the city of Kharkiv the problem is particularly acute, as sludge has been accumulating over the 80 years of operation of the BWWTP over a territory of 120 ha. Public and local authorities’ opposition to the use of sludge in agriculture, which would be the best option for both countries, could be due to its contamination by heavy metals, organic pollutants, pathogens, poor structure and texture, as well as its strong and unpleasant odour. Economic considerations and traditions may also be of relevance. The research was based on treatability studies, which tested the suitability of several plant species for sludge phytoreclamation under laboratory and field conditions. The assessment of the results of these studies was based on the plants’ biometric characteristics, their rates of survival, their elements’ uptake, their bioconcentration factor, and the rate of reduction of macronutrients and trace elements in the sludge by the end of the experiments. The results and conclusions of the thesis, in general, can be described as follows:•Phytoremediation can be applied practically in full-scale projects at both study sites as an alternative reclamation method.•There is no need to add any amendments to the sludge in lagoons at the BWWTP. However, fresh sludge produced in decanters at the BWWTP and sludge produced on filter presses at the ThWWTP need to be amended prior to any phytoremediation system being installed.•Taking into account both the high levels of concentration of the majority of metals in the tissue of Brassica napus and Medicago sativa, and the rate of reduction of the corresponding metals in the sludge by the end of experiments, it is concluded that these plants are capable of phytoextraction in the area with sludge lagoons at the BWWTP, Ukraine. Taking into account the same parameters for plants used in the experiments in Greece, Populus alba and Quercus pubescens among woody species, and Helianthus annuus and Zea mays among herbaceous species are suggested being the best suited for the reclamation of the Greek sludge. •The study of native plants grown on the experimental plots during the field experiment in Greece showed that some of them are just as good as other phytoremediative plants, which opens a new and interesting direction for further research. The results of the most of experiments have been published or submitted to peer-reviewed journals. Στην παρούσα διδακτορική διατριβή…