Immobilisation of PAH in waste materials

E. Mulder, J.P. Brouwer, J. Blaakmeer, J.W. Frénay

This paper gives an overview of the results of a research project into the possibilities of immobilising polycyclic aromatic hydrocarbons (PAH), that are present in waste materials. The results show that with hydraulic binders the waste materials can be solidified. The PAH do still leach to a relatively high extent. However, this PAH leaching can be decreased by more than a factor 10 by means of the addition of a specific additive. The immobilisation product fulfils technological requirements for the use as a road base construction material, such as compressive strength.

The Building Materials Decree: an example of a Dutch regulation based on the potential impact of materials on the environment

R T Eikelboom, E Ruwiel and J J J M Goumans

Some 20 years ago Dutch society became very aware of the problem of the increasing production of waste materials and of the need to find solutions. Technical solutions had to be developed and introduced into society. Due to the discovery of many soil pollution problems and other environmental calamities, people asked for clear criteria on which proper and safe solutions could be based. Therefore a large number of environmental aspects had to be taken into account in the developing field of environmental policy.

The Dutch building materials decree (BMD) is one of the steps on the road towards a sustainable society. The decree is based on the soil protection act and the surface water protection act. The decree gives quality criteria for the application and re-use of stony materials and earth used as building materials. No difference is made between primary materials, secondary materials and waste materials. The decree is applicable in case these materials are used in constructions where they are in contact with rain, surface water and ground water (e.g. in embankments, road building, outside walls of buildings, foundations and roofs.) For implementation of the decree in the construction industry it was necessary to develop standards, methods for testing and certification schemes. In order to guarantee independent testing and judgement, laboratories had to meet quality standards put forward in an accreditation scheme.

Although this legislation does not cover all environmental aspects, it has proved to be an important element in judging the environmental quality of construction materials in a direct or indirect way, and a contribution to the management of waste materials. The question of clear and fair criteria was easily put forward. Answering this question, however, turned out to be a complex task in which a great number of aspects had to be considered and a great many tools had to be developed, checked and thoroughly discussed. In some cases practical choices had to be made in order to prevent an unclear situation continuing too long. After an introduction period of three years, the decree came into full operation on 1 July 1999.

The following papers are poster presentation:

Chemical-mineralogical valuation of the leachate potential of municipal solid waste incineration (MSWI) bottom ashes

G. Pfrang-Stotz, J. Reichelt, R. Roos
 
Within the framework of a research project mineralogical, chemical and structural engineering methods were applied to raw bottom ashes as well as to processed bottom ashes stored for three months, all originating in 15 German municipal solid waste incineration plants operated on different process technologies.

The chemical analysis printed out that bottom ashes contain silicon, aluminum, iron and calcium as the principal elements. Titanium, manganese, sodium, potassium and phosphate occur in addition. Traces of barium, strontium, rubidium and the heavy metals copper, zinc, lead, chromium, nickel and cadmium are present. Accordingly, MSWI bottom ash is a calcium-aluminum silicate mixed with an iron fraction. The anions detected are in the first line chloride and sulfate with lesser concentrations of fluoride.

The concentration of harmful specimen in the bottom ashes is no measure of the environmental risk (polution potential). The environmental impact depends upon the present minerals, the stage of alteration and the mobility or leaching properties of the component in question and thus is mainly controlled by:

In order to characterize the solution behaviour the following 3 leaching tests were applied: Fine cementless concrete from industrial by-products for various uses

S.I. Pavlenko, N.V. Vegerova, A.V. Aksenov, V.I. Malyshkin

The paper presents technologies of fine concretes for various uses consisting of industrial by-products and containing neither cement nor natural aggregates. The development of the technologies contributes much to the environment preservation, saves natural resources and considerably reduces the cost of buildings. The materials used were by-products from thermal power plants, steel making, abrasive industry, extraction and processing of quartzites and other industries. The work got the prize of the governor of the Demerovo region, Kuzbass.

Use of crushed waste aggregates for DBM road bases

A. Montepara, G. Tebaldi

The increasing difficulties encountered in retrieving aggregates have stressed the need to find resources which might be alternative to the natural ones. At the same time, the significant increase of debris volume produced by the demolition of civil works has caused great problems in waste storage. A possible recycling use of demolition waste material is its transformation into aggregates to be employed in casting of mixtures. Some recycling experiences have explored the possible use, in concrete casting, of aggregates obtained through the crushing of demolitions. The present work studies the problem of the use of recycled aggregates in casting of bituminous mixtures.

The research has undertaken the characterisation of recycled aggregates in order to verify the limitations of the technical codes in terms of physical and mechanical requirements. Successively, a study to evaluate the affinity of the bitumen and the workability of the mixture, used as a base layer and prepared with recycled aggregates, has been undertaken. The study has been performed by means of the gyroscopic press in order to determine the volumetric characteristics in accordance to SHRP (Strategic Higway Research Program) guidelines.For the best mixture obtained, a performance characterisation has been executed by determining the value of complex modulus as a function of temperature and frequency. The experimental tests have allowed a comparison of the performances between bituminous mixtures prepared with recycled aggregates and those prepared with natural aggregates.

The Recycled Materials Resource Center: a new partnership promoting the wise use of recycled materials in the highway environment

B J Magee, K H Gardner, D L Gress, T T Eighmy, M Simon

The Recycled Materials Resource Center (RMRC) was formed in late 1998 as a partnership with the Federal Highway Administration (FHWA) to help reduce barriers to the use of recycled materials in the highway environment. The Center has large research and outreach components to its mission. Ongoing research activities are introduced and outreach activities of interest to a European audience are summarized. The Center will be working diligently over the next five years to develop specifications and evaluation methods, transfer appropriate technology, and make information available to the highway community.

Characterization of lagoon sediments and their pollutant charge. Proposals for reusing

E. Peris Mora, J. Monzó, J. Payá, M.V. Borrachero

The production of dredged mud constitutes a problem of first magnitude for two reasons: the huge amount of generated wastes, and the environmental risk as a consequence of the accumulated and persistent pollutants. Dredging is a routine maintenance activity in many industrial harbors. However, the management of dredging wastes also appears in other circumstances. The Albufera lagoon in Valencia (Spain) is located in a Ramsar wetland. This lagoon has received, over many decades, the pollutants of domestic and industrial activities from the surrounding metropolitan area. In the last century, an increase in the sedimentary process produced an acceleration of filling, decreasing the capacity of the basin. The area is being protected because of its high ecological value.. The aim or the study is to characterize and to quantify the accumulated pollution and compare several alternatives for the use of those sedimentary materials. Heavy metals, organochlorine pesticides, PCB's and Polycyclic Aromatic Hydrocarbons have been identified. The availability of such prime materials for cement production, as material for agricultural soil restoration, and as material for civil engineering construction will be evaluated. Chemical analysis data, that evaluate the degree of persistent pollution, permits one to be optimistic in the reuse of those wastes.

A proposed methodology for in-situ treatment of MSW leachate

E. Safari, C. Baronian
 
Municipal solid waste (MSW) leachate consists of different constituents (contaminants) having the potential for undergoing chemical, physical and / or biological processes. The normal leachate handling procedure includes collection and off-site treatment, although the concept of landfill bioreactor was recently introduced in which leachate recycling is the main component. The barrier systems which separate the waste from the underlying soil and groundwater, and which minimize the migration of contaminants from the landfill, frequently consist of natural clayey deposits or recompacted clay. There seems to be a tendency towards using active barriers which are capable of removing certain contaminants within MSW leachate, although they are usually designed on a contaminant specific basis. The main objective of this paper is to propose a methodology for the removal of contaminants within MSW leachate, while it passes through different stages each having a certain effect on a single (or a group of) contaminant(s). The mentioned stages can be categorized into three main groups; adsorbant filters (natural and/or natural modified materials and also some type of waste materials), electrokinetic processes and a media for biological growth. However using the proposed systems, may not necessarily result in elimination of leachate collection facilities, but it can have a beneficial effect compared to the treatment methods, also reducing the risk of groundwater contamination.

Re-use of arisings and waste materials for reinstatements

M.H. Burtwell

The use of secondary aggregates and industrial by-products to modify arisings or excavated materials from reinstatements is discussed in this paper. Laboratory testing and field trials are required to develop mix compositions with the best engineering properties and long-term performance.

Cold in-situ recycling of structural pavement layers

M. Earland

In-situ recycling of pavement materials has become an increasingly important feature in the UK for the maintenance of highways. The concept of using the existing highway as a "linear quarry" from which roadstone aggregates can be reclaimed has gained favour for both environmental and economic reasons and has been the subject of a three year research programme at the Transport Research Laboratory (TRL). The project, which was sponsored by the Highways Agency, CSS (formerly the County Surveyors Society) and Colas Limited, addressed the use of the technique for the structural maintenance of roads carrying between 2.5 and 20 million standard axles (msa).

A preliminary investigation of the removal of heavy metal species from aqueous media using crushed concrete fines

D.C. Johnson, N.J. Coleman, J. Lane, C.D. Hills, A.B. Poole

The crushing of reclaimed concrete in the production of recycled aggregate produces a large volume of fine material which is rich in hydrated cement paste phases, the coarser fraction being predominantly composed of the primary aggregate. It is the coarse fraction which is of use in construction and the fine fraction which is destined for landfill. The application of ordinary Portland cement (OPC) based materials in the solidification and stabilisation of heavy metal-bearing wastes is well established. Accordingly, it is proposed that this fine, cement-rich fraction of OPC-based waste may be used to immobilise heavy metal species from aqueous media. The removal of heavy metal nitrates (Pb2+, Ba2+, Zn2+, Ni2+, Cr3+ and Cu2+) from aqueous solution by the addition of crushed OPC concrete waste (in the particle size range 1 2 mm) is reported herein. The extent of exclusion of the metal ions indicates that mechanisms other than pH-dependent precipitation are in operation. The fate of the heavy metal species has been determined by scanning electron microscopy.