Britta Bergfeldt

Anti-oxidative and inflammatory responses induced by fly ash particles and carbon black in lung epithelial cells

Combustion-derived nanoparticles as constituents of ambient particulate matter have been shown to induce adverse health effects due to inhalation. However, the components inducing these effects as well as the biological mechanisms are still not fully understood. The fine fraction of fly ash particles collected from the electrostatic precipitator of a municipal solid waste incinerator was taken as an example for real particles with complex composition released into the atmosphere to study the mechanism of early biological responses of BEAS-2B human lung epithelial cells. The studies include the effects of the water-soluble and -insoluble fractions of the fly ash and the well-studied carbon black nanoparticles were used as a reference. Fly ash induced reactive oxygen species (ROS) and increased the total cellular glutathione (tGSH) content. Carbon black also induced ROS generation; however, in contrast to the fly ash, it decreased the intracellular tGSH. The fly ash-induced oxidative stress was correlated with induction of the anti-oxidant enzyme heme oxygenase-1 and increase of the redox-sensitive transcription factor Nrf2. Carbon black was not able to induce HO-1. ROS generation, tGSH increase and HO-1 induction were only induced by the insoluble fraction of the fly ash, not by the water-soluble fraction. ROS generation and HO-1 induction were markedly inhibited by pre-incubation of the cells with the anti-oxidant N-acetyl cysteine which confirmed the involvement of oxidative stress. Both effects were also reduced by the metal chelator deferoxamine indicating a contribution of bioavailable transition metals. In summary, both fly ash and carbon black induce ROS but only fly ash induced an increase of intracellular tGSH and HO-1 production. Bioavailable transition metals in the solid water-insoluble matrix of the fly ash mostly contribute to the effects.

Effect of short-term natural weathering on MSWI and wood waste bottom ash leaching behaviour.

Short term natural weathering was applied on municipal solid waste (MSW) and wood waste incinerator bottom ash (BA). The materials were analysed at different steps of treatment and characterized for chemical and mineralogical composition. Both short and long term leaching behaviour of main elements and heavy metals were investigated as well. Lead, zinc and copper were the main heavy metals to be released. After 12 weeks of treatment the concentration of leached zinc decreased. Lead concentration was not found to be influenced by pH and decreased only for the biomass samples. Weathering did not have beneficial effects on copper leaching, which was well described by complexation processes with DOC. The findings from the experimental campaign indicated that weathering reactions improved the mineral stability of the analysed materials but, in contrast with previous works, the treatment was not sufficient to guarantee pH stability and to comply with leaching law limits.

Formation of deposits on the surfaces of superheaters and economisers of MSW incinerator plants

Mineralogical and chemical investigations of deposits from superheaters and economisers from a MSWI plant in Mannheim, Germany, lead to a classification system which provides information about the most critical parameters leading to fouling and corrosion. With the help of this classification system parameters like the geometry of boilers and the waste input can be changed in order to prolong run times between revisions and enhance energy efficiency of MSWI plants.

Effect of natural ageing on volume stability of MSW and wood waste incineration residues

This paper presents the results of a study on the effect of natural weathering on volume stability of bottom ash (BA) from municipal solid waste (MSW) and wood waste incineration. BA samples were taken at different steps of treatment (fresh, 4 weeks and 12 weeks aged) and then characterised for their chemical and mineralogical composition and for volume stability by means of the mineralogical test method (M HMVA-StB), which is part of the German quality control system for using aggregates in road construction (TL Gestein-StB 04). Changes of mineralogical composition with the proceeding of the weathering treatment were also monitored by leaching tests. At the end of the 12 weeks of treatment, almost all the considered samples resulted to be usable without restrictions in road construction with reference to the test parameter volume stability.

Large Scale Co-combustion Demonstration of Electrical and Electronic Shredder Residue at the Wuerzburg Municipal Solid Waste Incinerator (MHKW)

In a controlled test campaign, a broad consortium of international stakeholders has demonstrated the effects of end-of-life electrical and electronic equipment shredder residue (ESR) on the performance of a large scale municipal solid waste energy recovery combustor MHKW in Wuerzburg, Germany. The ESR was highly concentrated with electrical and electronic plastics. Three test conditions were investigated: 1) base case without additional electrical and electronic shredder residue; 2) addition of 11 weight percent ESR containing E&E plastics; 3) addition of 26 weight percent ESR with E&E plastics. The fact that some electrical and electronic equipment is already in the mixed MSW feed to many waste-to-energy plants made the testing important for the MHKW operator as well as for the local regulatory authorities (EPA). The tests investigated the effect of ESR on plant operations, air emissions (acids, organics, and metals), and ash characteristics, and on the destruction efficiencies for several chlorinated and brominated substances present in the ESR. The large scale test used 103 tons of ESR derived from 650 tons of a typical mix of information technology equipment, consumer electronics, small household appliances, and other products. The ESR was supplied by Electrocycling in Germany. The tests were successfully completed from an operational standpoint without long time delays and did not show any mechanical blockage during the test in spite of the high heating value, 23 GJ/t, of the ESR. The grate was operated at close to 90 percent throughput