Biomass ashes - useful or harmful for plants?

Activity: Talk or presentationOral presentation


During combustion of biomass (e.g. wood) the organic material is decomposed and the in-organic components remain as ashes. In a biomass incinerator usually two ash fractions are generated: the coarse ash which remains at the bottom of the furnace (bottom ash) whereas the fine ash is collected from the flue gas (fly ash) in a dedusting device. Both ash fractions contain valuable plant nutrients like N, P, K, Ca, Mg, S, and other trace elements. There-fore the aim is that these ashes can be returned to the soil as soil enhancers. On the other hand biomass ashes also contain heavy metals harmful to plants, causing for example minor growth or harm animals or men consuming these plants. As the plant availability of components depends on their solubility at the environmental conditions in the soil (the components are absorbed from the plants in form of ions) it is important to know under which conditions these components are bioavailable. For this reason, plants (e.g. green salad) have been grown in laboratory experiments with ash application. In order to evaluate the leachability and mobility of nutritive components and heavy metals from biomass ashes, distilled water has been used as water source and fly ashes have been added to the plants (either spread on top of the plants or mixed in the earth). In every test line the amounts of ashes was varied and at the same time plants culti-vated without using any ashes were analysed as control group. After growing for a certain time, the plants were collected, dried and milled. A microwave assisted acidic digestion was then performed for bringing the elements into a measurable form. All solutions were then analysed with inductively coupled plasma optical emission spectroscopy (ICP-OES). For the investigated elements the additional uptake of the plants form the biomass ash was calculated. Furthermore the influence of the application mode (on the plants or on the soil) of the ashes on the final concentrations was studied.
Period6 Oct 2010
Event titleThe 36th Symposium on Environmental Analytical Chemistry
Event typeWorkshop
LocationRom, ItalyShow on map