Formation of PCDD/PCDF

One option of recycling used contaminated packaging is to recover its high energy content. This can be performed in a normal multi-fuel power plant by co-combustion of packaging-derived fuel (PDF) or refuse-derived fuel (RDF) with fossil fuels, such as coal or peat. This work includes the results of 17 co-combustion tests and an evaluation of the results by the Principal Component Analysis (PCA) and the Partial Least Squares Projections to Latent Structures (PLS). PCA and PLS calculations showed that especially Pb, but also Cr, and Cu correlated with lower chlorinated furans (PCDFs) in the fly ash. Correlation between Sn and lower chlorinated dioxins (PCDDs) in the fly ash was also noticed. CO and PAH emission in the flue gas correlated with total PCDD/Fs in the flue gas. In a real full-scale combustion process, a single parameter in fuel, flue gas or a combustion parameter did not provide a guide to PCDD/F formation or to a level of the total PCDD/F emission, but correlations between different parameters and PCDD/Fs could be found. Although PDFs and RDF had catalytic heavy metals and chlorine, the co-combustion results showed that they can be co-combusted with peat and coal in a fluidized-bed boiler at least up to 26 % with very low total PCDD and PCDF emissions.     

Crown ratio influences allometric scaling in trees

Allometric theories suggest that the size and shape of organisms follow universal rules, with a tendency toward quarter-power scaling. In woody plants, however, structure is influenced by branch death and shedding, which leads to decreasing crown ratios, accumulation of heartwood, and stem and branch tapering. This paper examines the impacts on allometric scaling of these aspects, which so far have been largely ignored in the scaling theory. Tree structure is described in terms of active and disused pipes arranged as an infinite branching network in the crown, and as a tapering bundle of pipes below the crown. Importantly, crown ratio is allowed to vary independently of crown size, the size of the trunk relative to the crown deriving from empirical results that relate crown base diameter to breast height diameter through crown ratio. The model implies a scaling relationship in the crown which reduces to quarter-power scaling under restrictive assumptions but would generally yield a scaling exponent somewhat less than three-quarters. For the whole tree, the model predicts that scaling between woody mass and foliage depends on crown ratio. Measurements on three boreal tree species are consistent with the model predictions.     

Trace metal emissions from co-combustion of refuse derived and packaging derived fuels in a circulating fluidized bed boiler

Energy recovery from refuse derived fuels (RDF) and packaging derived fuels (PDF) is one option in integrated waste management. Nine RDF and PDF co-combustion tests with peat and coal in a circulating fluidized bed boiler were carried out in this work. Heavy metal emissions in flue gas and fly ash were measured. Multivariate data analyses were used to find out the most important parameters affecting metal emissions in the flue gas.

The results showed that total heavy metal emissions were low. Although RDF and PDF had more heavy metals than peat and coal, the multivariate data analysis showed that an increase of the RDF or PDF share in the fuel mixture up to 20% did not correlate directly with the metal emissions in the flue gas. Distribution of Cd, Cu, Zn and Sn between flue gas and fly ash correlated with each other. Injection of limestone to bind sulphur and chlorine did not have a significant effect on heavy metal emissions in the flue gas. Heavy metals concentrated on the fly ash, but all fly ashes passed the EPA-TCLP tests.     

In situ bioremediation through mulching of soil polluted by a copper-nickel smelter

Bioremediation of a heavy metal-polluted soil was investigated in a 3-yr field experiment by adding mulch to a polluted forest floor. The mulch consisted of a mixture of compost and woodchips. The remediation treatment decreased the toxicity of the soil solution to bacteria as determined by the [3H]-thymidine incorporation technique, that is, by measuring the growth rate of soil bacteria extracted from unpolluted humus after exposing them to soil solution containing heavy metals from the experimental plots. Canonical correlation analysis was performed in order to identify the chemical and microbiological changes in the soil. The pH of the mulched organic layer increased by one unit. The concentration of complexed Cu increased and that of free Cu2+ decreased in the soil solution from the mulch treatment. According to basal respiration and litter decomposition, microbial activity increased during the 3 yr following the remediation treatment. The [3H]-thymidine incorporation technique was also used to study the growth rate and tolerance of bacteria to Cu. The bacterial growth rate increased and the Cu tolerance decreased on the treated plots. The structure of the microbial community, as determined by phospholipid fatty acid (PLFA) analysis, remained unchanged. The results indicate that remediation of the polluted soil had occurred, and that adding a mulch to the forest floor is a suitable method for remediating heavy metal-polluted soil.     

Influence of Exercise-Focused Group Activities on the Physical Activity,Functional Capacity,and Work Ability of Female Farmers—A Three-Year Follow-Up

Abstract

The objective of this randomised study was to evaluate the influence of exercise-focused group activities on female farmers’ physical activity, functional capacity, and work ability over a period of 3 years. Physical activity increased more in the intervention group (n = 62) than in the control group (n = 64) during the first year. By the third year physical activity had almost returned to the pre-intervention level. In the 3-year follow-up examination muscular endurance and cardio-respiratory fitness had improved in the intervention group, and musculoskeletal symptoms had decreased more often in the intervention group than in the control group. The index used to measure perceived work ability showed no changes over the 3-year period. It can be concluded that group activities focused on leisure-time physical activity and work habits can be recommended as health promotion measures for farmers’ occupational health services.