A reliable sperm cell toxicity test procedure has been developed for the Mediterranean sea urchin Paracentrotus lividus. The sensitivity and discriminatory ability of the test were investigated with regard to surfactants and their biotransformation products. Aromatic and aliphatic surfactants of anionic (linear alkylbenzene sulfonates [LAS]) and nonionic (alcohol polyethoxylates [AE] and nonylphenol polyethoxylates [NPE]) types and their aerobic biodegradation products, i.e., sulfophenylcarboxylates (SPC), polyethylene glycols (PEG), carboxylated polyethylene glycols (PEGC), carboxylated AE (AEC), and nonylphenol (NP), were examined in order to elucidate the influence of their molecular structure on toxicity. Experimental results reveal that the sperm cell test showed good discriminatory ability among all tested compounds, median effective concentration (EC50) values differing by about four orders of magnitude. The toxicity of anionic surfactants depends on the length of the alkyl chain and that of nonionic surfactants is due to their length and branching. Much lower toxicity was shown by aerobic biodegradation products in comparison with that of their parent compounds, with the exception of NP. The obtained EC50s were comparable with available literature data and constitute new toxicity data regarding surfactants for sea urchins.

This study introduces a novel geotechnical composite material comprising two types of fill material sourced from the paper industry—deinking paper sludge ash (DPSA) and deinking paper sludge (DPS). Five composites with different DPSA and DPS contents were investigated. Two composites were selected for further analyses. The technology and procedure for composite installation were implemented in field tests. The composites with 80% and 70% DPSA exhibited the elasticity required to withstand minor landslide slip deformations, in addition to achieving sufficiently high values of uniaxial compressive strength. The composites had a low maximum dry density value, which led to fewer settlements in the entire support structure. The enhanced shear characteristics can enable the construction of a thinner retaining wall. The delay between preparation and installation of the composites was further investigated. The field tests confirmed that the composites with 80% and 70% DPSA can be installed on the construction site 4 h and even 24 h after mixing. In 2018, a retaining wall structure with 70% DPSA and 30% DPS was successfully implemented near a railway line using conventional technology as followed-up research to the herein presented study. Results have been derived from work performed in the scope of the H2020 Paperchain project in which novel circular economy models centered on the valorization of the waste streams generated by the pulp and paper industry as secondary raw material for several resource-intensive sectors, including the construction sector, have been developed. Environmental benefits are savings in natural raw materials, reduction of landfill disposal as well as CO2 emission reduction.

The construction industry uses a large amount of natural virgin material for different geotechnical structures. In Europe alone, 11 million tonnes of solid waste is generated per year as a result of the production of almost 100 million tonnes of paper. The objective of this research is to develop a new geotechnical composite from residues of the deinking paper industry and to present its practical application, e.g., as a backfill material behind a retaining structure. After different mixtures were tested in a laboratory, the technology was validated by building a pilot retaining wall structure in a landslide region near a railway line. It was confirmed that a composite with 30% deinking sludge and 70% deinking sludge ash had a high enough strength but experienced some deformations before failure. Special attention was paid to the impact of transport, which, due to the time lag between the mixing and installation of the composite, significantly reduced its strength. The pilot retaining wall structure promotes the use of recycled materials with a sustainable design, while adhering to government-mandated measures.

By using recycled waste in construction, natural materials are being replaced, thus establishing a circular economy at the local level. An important aspect is also the conservation of natural resources. This is especially important in case of earthworks (embankments, backfills), which are large consumers of materials. Compared to natural aggregates and earth, geotechnical composites based on recycled materials can contain a higher total content of potentially toxic elements (heavy metals, chloride, sulphate, fluoride, organic pollutants etc.). The prerequisite for beneficial use of such composites is that the potentially toxic elements are immobilized in the composites, meaning that they are chemically inert. Potential environmental impacts, especially those associated with transfer of potentially toxic elements from new geotechnical composites into soil (aquifer respectively), are usually evaluated on laboratory scale, while their behaviour in real environment is usually poorly investigated. For this reason, there is a demand for the development of sensitive, reliable, and cost and time efficient monitoring tools for determining mass flows of potentially toxic elements from building materials, for example geotechnical composites, which are under the influence of various environmental factors. This paper presents the construction of field laboratory, based on a system of pan lysimeters. The lysimeters are used to collect leachate from geotechnical composites based on recycled materials. They are constructed in a way to be relatively low cost and at the same time large enough to representatively reflect the processes in geotechnical fills. Obtained data on the amount and quality of leachate can be used as a basis for the study of immobilization processes and for water balance. Moreover, this data will be used as input in the geochemical numerical model for the simulation of transport of potentially toxic elements released from geotechnical fills in different types of aquifers (alluvial aquifer with intergranular porosity, aquifer in consolidated rocks with fissure porosity).

Abstract. Very strong winters with temperatures under 0°C and hot summers with temperatures more than 30°C are observed in the South East part of Slovenia. Those big differences in temperature during the year and especially temperatures below freezing point have strong influence on asphalt layer and sub base of road pavement. The freeze/thaw cycles lead to formation of ice lenses in base course causing cracks in asphalt layers and degrade the pavement usually in a few years. For this reason one section of the national road in the South East part of Slovenia was rebuilt with cold in-situ pavement retreatment. A test field with inbuilt sensors for measuring water content, temperature and deformation in various depths and locations was constructed during the remediation works to study the mechanism of freeze-thaw degradation of pavements. The main goal of the test field is to determine water content in sub base, freezing depth, temperature distribution and deformations, which lead to cracks in asphalt layer after the remediation work in the road construction.