The goal of this work is to find a solution for disposal of Vitroplast FR4, a material found in waste printed circuit boards. In this study, the influence of addition of Vitroplast, generated by mechanical treatment of printed circuit boards waste on concrete properties such as compressive strength was investigated in laboratory conditions. By substitution of filler (i.e. sand) in a mass ratio of 5, 10, 15 and 20% with Vitroplast in concrete mixture, the compressive strength decreased into 57.5, 84.5, 95.0 and 95.9%. The results of leaching tests have shown that by incorporating Vitroplast in concrete mixtures in a 10% mass ratio, the elution of arsenic and cadmium is below the limitations prescribed for inert wastes. The studied approach offers the possibility for environmental friendly recycling of printed circuit boards.
Polystyrene concrete, as a type of lightweight aggregate concrete, has been used in civil construction for years. The use of waste expanded polystyrene (EPS) as a fi ll material in lightweight concrete production is highly recommended from the point of view of the circular economy. Published data shows that an increase in the proportion of lightweight aggregates, i.e. EPS, results in a decrease in strength, bulk density and thermal conductivity of the concrete. Utilizing large quantities of waste EPS in non-structural polystyrene concrete production is particularly important. Unlike structural polystyrene concrete, according to the published papers, non-structural polystyrene concrete has not been investigated suffi ciently. The purpose of this paper is to determine the infl uence of the ratios of the basic components in a concrete mixture on the bulk density and compressive strength of non-structural polystyrene concrete produced by utilizing waste EPS as a fi ll material. The test specimens, i.e. cubes with an edge length of 100 mm each, were prepared in laboratory conditions by varying the proportions of EPS, sand up to 600 g and cement ranging from 300 g to 450 g per specimen. Bulk density and compressive strength were determined for the test specimens. Laboratory research results show a dependence of the component ratio on the bulk density ranging from 360 kg/m 3 to 915 kg/m 3 and compressive strength ranging from 0.385 MPa to 2.538 MPa.
The usage of old equipment (over 10-year-old diesel-fuelled waste collection vehicles, WCVs) for municipal solid waste (MSW) collection in Ludbreg for longer than a decade has had a negative environmental impact, which has been reduced by replacing an old diesel WCV with a new diesel WCV. This study aims to assess the share of air emissions of two old WCVs (FAP 1990 and MAN 2003) and one new (MAN 2015), expressed in CO emissions. In addition, these vehicles have been found easily to reach the limit of 100 dB, which can cause hearing damage in their surroundings. Furthermore, their average fuel consumption is more than 80 l per 100 km, which makes them ineffective in terms of fuel consumption. Generally, higher fuel consumption results in more emissions and for a more eco-friendly operation, the MAN 2003 from Ludbreg WCV fleet should be technically amended and adjusted, and the FAP 1990 should be retired. Although the MAN 2015 is diesel fuelled, the best solution for replacement, according to Maimoun et al. (Waste Management 33: 1079-1089, 2016), would be the use of hydraulic-hybrid vehicles, which provide the best environmental benefits over other alternatives. According to Maimoun et al., hybrid is better environmentally, diesel is the best environmental-economical option and landfill gas-sourced natural gas is the best alternative when accessible because it significantly (up to 80%) reduces emissions of hazardous gases as well as noise levels (50-98%).
A wide range of published scientific articles on metal content in printed circuit boards show that it is necessary to determine the content of individual metals. The aim of this paper is to show how metal content varies according to the type and age of waste electrical and electronic equipment collected in the Republic of Croatia. Samples of cell phones, TV sets, and computers are collected. The metal content is determined for electronic components and printed circuit board base plates separately for different grain sizes (1-4 mm, 0.5-1 mm, 0.1-0.5 mm and < 0.1 mm). The results show that electronic components form a larger part of printed circuit board mass fraction depending on the equipment age and type. Generally, electronic components do have a higher mass fraction for most metals (like: aluminium, copper, nickel, zinc, gold, and silver in most cases) in comparison to printed circuit board base plates, but for certain metals (like: lead, tin) the opposite applies. The electronic components of larger grain sizes (1-4 mm and 0.5-1 mm) contain more aluminium, copper, and zinc, and less lead, while the smaller grain size fractions are richer in gold. The bare boards base plates of larger grain sizes contain more copper, lead and tin, while the smallest grain size class (< 0.1 mm) contains more aluminium and gold. No clear trends are noticed in the case of silver and lead.
The aim of this paper was to investigate the possibility of incorporation non-metal fraction (NMF) in concrete products as a substitute for aggregate on industrial scale, while other studies are mostly based on NMF incorporation in concrete only on laboratory scale. Mineral filler was supplemented with 5, 10, 15 and 20 wt.% NMF from waste printed circuit boards (WPCBs) and its influence on concrete quality was assessed based on compressive and tensile strength conducted on laboratory and industrial scale samples. The efficiency of pollutants encapsulation from NMF incorporated in concrete products was determined by eluted elements, ions and chemical compounds such as As, Cd, Cl-, Cu, Pb, Zn, SO4 2-, DOC and TDS. Based on obtained results, it was determined whether is possible to incorporate NMF in concrete products on industrial scale. Finally, results showed positive outcome. Leaching test results imply that the procedure is acceptable from the environmental point of view, while at the same time, technical aspects showed loss in some mechanical properties.
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