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SEQUENTIAL LEACHING OF TRACE ELEMENTS IN BOTTOM ASH FROM A FLUIDIZED BED CO-COMBUSTION BOILER AT A PULP AND PAPER MILL COMPLEX
Hannu Nurmesniemi
Risto Pöykiö
Toivo Kuokkanen & Paavo Perämäki
Ilkka Välimäki
A five-stage, sequential leaching procedure was used to fractionate trace elements (Cd, Cu, Pb, Cr, Zn, Ni, Co, As, V, Ba and Ti ) in bottom ash into the following fractions: (1) the water-soluble fraction (H2O), (2) exchangeable fraction (CH3COOH), (3) easily reduced fraction (HONH3Cl), (4) oxidizable fraction (H2O2 + CH3COONH4), and (5) the residual fraction (HF + HNO3 + HCl). The bottom ash was derived from the electrostatic precipitator of a fluidized bed boiler in the co-combustion (55 % bark and wood residues, 45 % peat) process at a pulp and paper mill in Northern Finland. Because of the strongly alkaline nature (pH ~ 12.6) and elevated Ca (53 g kg1), Mg (3.6 g kg-1), P (1.3 g kg-1) and K (2.4 g kg-1) concentrations, the bottom ash could serve as a soil amendment agent for liming purposes, and is also a potential fertilizer. According to the leaching studies, the elevated concentrations of Pb (6.3 mg kg-1), Cr (3.8 mg kg-1) and Ba (271 mg kg-1) extracted under oxidizable conditions (leaching stage 4), indicate that these metals may be mobilized and become bioavailable
as a result of a change in pH.
Keywords: Bottom ash;
pulp and paper mills; fluidized bed boiler; heavy metals; sequential leaching;
bioavailability
DEVELOPMENT STEPS IN WASTE POTATO-BASED BIOETHANOL PRODUCTION
Henrikki Liimatainen
Toivo Kuokkanen
Juha Tanskanen
Jouni Kääriäinen
According to the directive 2003/30/EC of the
European Parliament and the European Council ‘bioethanol fuel’ means the ethanol
produced from biomass and/or the biodegradable fraction of waste to be used as
biofuels. The target in the EU is to significantly increase the contributions of
these ecologically sustainable biofuels. Therefore a strong need to develop
bioethanol production exists. In this paper bioethanol production from waste
potatoes is discussed. 5-20 % of the potato crop in Finland is waste potatoes
which makes them a potential feedstock for bioethanol production. In this trial
the effect of ten Swedish potato cultivars on lab-scale bioethanol process was
investigated. Additionally, a waste solution produced as a by-product from the
distillation in a Finnish bioethanol plant was analyzed in order to improve the
utilization of these by-products. Preliminary studies to develop the bioethanol
distillation by simulation were performed as well. The lab-scale results
indicate differences between the potato cultivars especially regarding the
properties of mash and ethanol yields. The results also suggest that the
utilization of waste solutions from the potato spirit plant as a fuel or a
solvent could be possible. The preliminary distillation simulation studies show
that azeotropic water-ethanol can be obtained by cutting the lower and higher
boiling ends by conventional distillation. THE UTILIZATION
AND STATUS OF STEEL INDUSTRY SLAGS: A PERSPECTIVE FROM FINLAND
R. Kallio and M. Mäkikyrö
The world’s production of steel, about 900 million
tonnes in recent years, means the generation of around 400 million tonnes of
co-products, solid waste and sludge. More than 80 % of the co-products arising
from steel production are slags, the further processing of which into marketable
products has been an object of research and product development throughout the
steel producing world. The quantities and characteristics of these materials
indicate that environmental loading from the steel industry is above all a
matter of volume.
LANDFILLS IN THE LOWER HUDSON RIVER
VALLEY, NEW YORK STATE: 1963-1988
Andrew D. Lent
Bassim Eid Abbassi
Ex-situ bioremediation for clean up of
diesel-contaminated soil was tested through aerobic and anaerobic co-degradation
process with domestic sewage sludge. Co-digestion experiments of soil sludge
slurry have been carried out using laboratory scale batch reactors. Ex-situ
bioremediation of contaminated soil was achieved in both aerobic and anaerobic
processes. In the aerobic reactors, degradation rate of diesel hydrocarbons was
improved as sludge concentration was increased. Maximum degradation efficiency
(75 %) was achieved at sludge concentration of 10 g TSS/L after 55 hour. The
anaerobic co-digestion of soil-sludge slurry showed a great potential for soil
bioremediation, where 94% of hydrocarbon removal has been achieved at digestion
period of 30 days.
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