PROJECT DESCRIPTION
BACKGROUND
Poland produces more than 1.1 million tonnes of municipal and industrial sewage sludge every year. Most of this is either sent to landfill, or used for composting or as soil fertiliser. A lack of incinerators means that the combustion of sewage sludge is not a feasible method of disposal in Poland. Therefore, it is important to examine other sewage disposal technologies. The Institute of Mechanised Construction and Rock Mining has developed a new disposal method for sewage sludge that incorporates it with a variety of wastes, neutralising the mixture in a single process, to produce lightweight aggregates that have good potential for use in the construction sector.
OBJECTIVES
The main objective of the DIM-WASTE project was to demonstrate the operation of an innovative technology for the management of selected waste streams, including sewage sludge, for the production of various lightweight aggregate products. The project aimed to construct a pilot demonstration installation, to determine the technical requirements needed to start full-scale commercial production of lightweight aggregates from mineral (silica) waste and municipal sewage sludge, and to conduct an information campaign about the developed technology targeting the widest possible audience of both potential project stakeholders, as well as the general public.
RESULTS
The DIM-WASTE project’s sole beneficiary, the Institute of Mechanised Construction and Rock Mining in Poland, designed, built and tested a full-scale prototype to transform sewage sludge and mineral waste (silica and glass dust) into various types of lightweight aggregate to be used in the construction sector. The implemented tests showed that the installation produced aggregates with the foreseen characteristics and that the aggregates can be used by different commercial firms within the construction sector.
The up-scaled mobile demonstrated line involved heat treating a combined mixture of sewage sludge, silica mineral waste and powdered glass cullet, and adding water to produce granules of various sizes (in a granulator). This material is then dried and passed through a rotary furnace, with the exhaust gases being treated in an exhaust installation. The burnt aggregate is sorted and sold as lightweight aggregate.
The prototype was tested and monitored under different operational conditions of known parameters. A total of 10 tests were performed to assess aggregate quality and 16 to assess post-reaction gas emissions. Monitoring of environmental performance showed that the emission levels were in compliance with legal standards and the technology does not produce any solid waste (ash). The main characteristics of the produced aggregates were as follow: bulk density of 663 g/cm3 (+/-13%); impregnability 24.5% (+/-28%); crushing or compressive strength 2.9 MPa (+/-40%); and frost resistance 0.5 (+/-30%). All samples of the aggregates met Polish standards regarding lightweight aggregate products used in the construction sector.
To promote the prototype installation at national and international fairs, the beneficiary organised four meetings in Poland, and also one each in the Czech Republic and Germany. In addition, ten demonstration visits were organised for stakeholders potentially interested in replicating the method. The project’s findings were disseminated via press articles and promotional materials (folder, brochure and leaflet), which were distributed among interested stakeholders, a film, noticeboards, and the project website.
The results of the project help in achieving the objectives of the 7th EU Environmental Programme with respect to reductions of mineral waste and the amount of sewage sludge deposited in landfills. The innovative technology, if it is commercialised and widely used, could support the transition to the circular economy in Poland and other EU countries. The management of sewage sludge is a growing environmental problem in the EU, as it cannot be widely used in the agriculture sector because of contamination by heavy metals or hydrocarbons. Therefore, every technology which supports the re-use of sewage sludge can be considered as an important environmental measure.
The project showed that it is possible to produce lightweight aggregates for the construction sector from sewage sludge and mineral wastes. However, the effectiveness of the technology in the re-use of the sewage sludge and mineral wastes will depend on the way in which the installations (and products made by them) are promoted and developed in the coming years. It will also depend on whether the prototype will be commercially used. In the After-LIFE phase, the prototype will be tested under further different conditions to demonstrate its wider use. The beneficiary plans to find a partner who can help to promote the prototype and to organise demonstration visits to it.
Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).
