Margareta Wahlström

By-products and recycled materials in earth construction in Finland—an assessment of applicability

Over 6 million tonnes of industrial by-products and recycled materials are produced annually in Finland. Many of these materials are potentially suitable for earth construction. There is also an evident need for substitute materials for natural aggregates. The environmental aspects and prerequisites of utilisation were studied as a part of the Ecogeo Technology programme, which was funded by the National Technology Agency, Tekes. Guidance for the assessment of the environmental and technical applicability of industrial by-products for use in earth and road construction was developed. The guidance presents recommendations for the investigation of applicability, recommendations for environmental and technical criteria of the utilisation in earthworks and recommendations for production control procedures. As a consequence, national production control standards are prepared for reclaimed concrete and blast-furnace slag. As an example, a two-stage research project on the environmental properties of foundry sands is presented. The general environmental criteria for the utilisation of foundry sands in earth constructions were established. In addition, specific quality control procedures were developed for two selected foundries.

Environmental quality assurance system for use of crushed mineral demolition wastes in road constructions

Annually 1 million tons of mineral demolition wastes, mainly consisting of concrete and bricks, is produced in Finland. In field studies the crushed materials have shown favourable geotechnical properties for use in road constructions. The test samples from two crushing plants were chemically characterised and the leaching behaviour was studied by using column, two-stage batch leaching and pH static tests. Only sulphate and chromium leaching from the crushed material was detected. There was a good agreement between column and batch leaching tests. The contents of harmful organic compounds were very low. Based on experience and the results of the experimental study, a practical sampling and testing strategy for an environmental quality assurance system was developed. A two-stage batch leaching test was chosen for the quality control of demolition waste. Preliminary target values for leaching of sulphate, Cr, Cd, Cu and Pb were set. Both geotechnical and environmental properties of the crushed material indicate that the use of demolition waste in road constructions is acceptable and can be recommended to replace landfilling of this material. However, a detailed demolition plan is most important in order to have an acceptable material for utilisation in road constructions.

Leaching of PCBs and chlorophenols from contaminated soil and waste-influence of leaching test characteristics

Organic contaminants are found in soil at sites where chemicals containing organics have been used or handled. Sites contaminated with chlorophenols are a typical problem in Finland due to their large use as wood preserving agents at saw mills. The major compounds identified in the contaminated soils are tetrachlorophenols and pentachlorophenols. PCBs were used in the 1960s and 1970s in polysulphides containing sealing compounds for wall elements. The PCB-contents in these compounds were at least 20% resulting in PCB contamination in soils near the wall elements. PCB-contaminated soils can also be caused from leackage of PCB-condensers. PCBs and Chlorophenols have been chosen in this study as typical organic contaminants with different chemical properties. The aim of this study was to assess the effect of leaching test characteristics on test results for Chlorophenols and PCBs. Furthermore, the effects of some relevant environmental factors controlling the leaching behaviour were evaluated. The study was especially focused on practical aspects aiming to test conditions ensuring reproducible test results. In particular, the influence of filters and the needed equilibrium time for the leaching process were studied. The work was a part of the EU-project “Development of standard leaching tests for organic pollutants in soils, sediments and granular waste materials” co-ordinated by ECN (contract SMT4-CT97-2160). The results will give background data for development of standardised leaching test methods for some organic contaminants.

Acid neutralization capacity of waste - specification of requirement stated in landfill regulations

The EU regulation of landfill aims to the safe disposal of waste in the long term. The regulation requires the collection of information on waste characteristics before landfilling. Acid neutraliza ...

Hazardous substances in plastics

The aim of the project is to create knowledge on how plastics recycling can increase without increasing the risk of emitting hazardous substances to the environment.The first general conclusion is ...

ENCORT-CDW : Evaluation of the European recovery target for construction and demolition waste

The present EU target for recovery of construction and demolition waste does not promote sustainability. Interpretations of waste and recovery definitions rather than resource efficiency and safe h ...

Evaluation of Long-Term Post Process Inactivation of Bioleaching Microorganisms

The H2020 BioMOre project (www.biomore.info, Grant Agreement #642456) tests the feasibility of in-situ bioleaching of copper in deep subsurface deposits in the Rudna Mine, Poland. Copper is leached using biologically produced ferric iron solution, which is recycled back to the in-situ reactor after re-oxidation by iron-oxidizing bacteria (IOB). From a post operational point of view, it is important that the biological processes applied during the operation can be controlled and terminated. Our goal was to determine the possibility to use natural saline mine water for the inactivation of introduced IOB remaining in the in-situ reactor after completion of the leaching process of the Kupferschiefer ore. Aerobic and anaerobic microcosms containing acid-leached (pH 2) sandstone or black shale from the Kupferschiefer in the Rudna mine were further leached with the effluent from an iron-oxidizing bioreactor, at a temperature of 30°C, for 10 days, to simulate in-situ leaching. After the removal of the iron solution, residing IOB were inactivated by filling the microcosms with saline water (65 g L-1 Cl-) originating from the mine. The saline water completely inactivated the IOB and the naturally occurring saline water of the mine can be used for long-term post process inactivation of bioleaching microorganisms.

Plastic Waste Markets : Overcoming barriers to better resource utilisation

This project examines the market for recycled plastic, with a primary focus on post-consumer plastic waste because this is considered to be the more problematic. The market for plastic waste genera ...

Policy Brief – Plastic Waste Markets : Overcoming barriers to better resource utilisation

This policy brief outlines the main findings from the project Plastic Waste Markets: Overcoming barriers to better resource utilisation. The aim of the project is to provide an overview of the key ...

Water Conscious Mining (WASCIOUS)

The main objective of the NordMin WASCIOUS project was to develop a technology concept for water conscious mining, where innovative water and tailings treatment technologies provide good-quality wa ...