Waelz slag-based construction ceramics: effect of the trial scale on technological and environmental properties

The construction industry has already begun the transition to circular economy and intensive research has been conducted over the last decades at laboratory scale to assess the potential use of waste in ceramic applications. However, industrial trials to prove its scale up have been performed to a lesser extent. This work studies the effect of trial scale on the technological and environmental properties of high quality ceramic products incorporating Waelz slag (WS), an industrial by-product from the recovery of electric arc furnace dust. To this aim, three groups of ceramics have been produced varying the WS content and the process parameters, moulding water and pressure, at laboratory and industrial scale. Preliminary laboratory scale tests were used to optimize WS content and process conditions using the software GAMS (General Algebraic Modeling System). Optimum ceramic products were processed at both laboratory and industrial scale and tested for their technological and environmental properties. Results from the laboratory and industrial trials were compared to evaluate the scale effect on the ceramic properties. The introduction of WS in clay bricks seems to be easily scaled-up for additions of WS ≤ 10wt%, but higher percentages of WS promotes relevant differences in the properties of the laboratory and industrial bricks.This work has been funded by the Spanish Ministry for Education and Science (Project CTM 2009-11303). The authors gratefully acknowledge fnancial support for this research from BEFESA STEEL R&D, S.L.U.C. Company at Asua, Vizcaya, Spain

Toxicity bioassays in core sediments from the Bay of Santander, Northern Spain

Δημοσίευση σε επιστημονικό περιοδικόSummarization: The use of Vibrio fischeri as luminescence bacteria is particularly effective in evaluating contaminated sediment. In this study, the ecotoxicity of five core sediments from the Bay of Santander, northern Spain, utilising V. fischeri as marine bacterium, was carried out. Different toxicity assay procedures were applied in order to study the influence of the mobility and bioavailability of the pollutants. Basic Solid Phase Test (BSPT) in whole sediment and acute toxicity test, using pore water and three leaching test procedures as liquid extracts, were applied. In addition, the study of the influence of the pH value on the toxicity results of the leaching tests was conducted. The obtained results show toxicity units (TU50) values in BSPT test ranging from 0.42 to 39.06 with a decrease with depth as general trend and TU50 values from 0.010 to 0.389 in the liquid extracts, where TU50 is calculated as the inverse of EC50 (%). The obtained data show the historical toxicity trends of the Bay of Santander and provides a technical database for the management of contaminated sediments. Moreover, these results showed evidence that each sediment test procedure provided independent and complementary ecotoxicological responses useful for a sediment classification. In order to analyse the correlations between chemical parameters (both organic and inorganic) and the toxicity results, the self-organising map (SOM) neural network and regression equations were applied. Satisfactory correlations (R=0.93) between chemical concentrations of sum of five heavy metals and 16 PAHs and BSPT toxicity were obtained.Presented on: Environmental Researc