Leaching characteristics of the fine fraction from an excavated landfill: physico-chemical characterization

Leaching of fine fraction (<10 mm) obtained from landfill mining activities in an Estonian landfill was done. On-site excavation was carried out in four test pits (TP1, TP2, TP3, TP4) that were further divided in four layers (L1, L2, L3, L4). Total chemical oxygen demand (CODt), dissolved chemical oxygen demand (CODd), total organic carbon (TOC), dissolved organic carbon (DOC) and metals (Zn, Cu, Pb and Cd) were analyzed. The results showed that approximately 70 % of CODt were in particulate/colloidal state. The TOC released ranged between 2326 and 3530-mg/kg dry matter for test pits suggesting spatial differences in the studied landfill. DOC ranged between 365–874 and 317–940 mg/kg for different test pits and sampling layers, respectively. Low average leaching rates of metals were observed (0.2–1.5 %). Pb had a significantly higher average leaching rate (1.0 %) compared to Zn (0.70 %) and Cu (0.35 %). The potential use of CODt as a surrogate indicator of TOC, DOC and Zn on the basis of high correlation coefficients was observed. To conclude, the implementation of adequate strategies to manage fine-grained fractions obtained from excavated waste relies on physico-chemical characterization of both the fine fractions itself and the leachate generated during storage and use. © 2015 Springer Japa

Biochemical methane potential of different organic wastes and energy crops from Estonia

The biochemical methane potential (BMP) of different Estonian substrates as alternative sources for biogas production was studied. For this purpose, the BMP test was carried out in batch mode at mesophilic temperature (36°C). Substrates were divided into 2 groups: agricultural substrates (silage, hay, cattle and pig slurry) and food industry residues (milk, brewery and cereal industry residues). Methane yields obtained were between 286–319 L kgVS-1 for silage and hay, 238–317 L kgVS-1 for animal slurry and 272–714 L kgVS-1 for agro-industrial wastes. The highest methane yield was obtained from sour cream (714 L kgVS-1), the lowest (238 L kgVS-1) from cattle slurry. In overall, our results suggest that all tested substrates can be treated anaerobically and are potential sources for the production of methane

Legal situation and current practice of waste incineration bottom ash utilisation in Europe

Almost 500 municipal solid waste incineration plants in the EU, Norway, and Switzerland generate about 17.6 Mt/a of incinerator bottom ash (IBA). IBA contains minerals and metals. Metals are mostly separated and sold to the scrap market and minerals are either disposed of in landfills or utilised in the construction sector. Since there is no uniform regulation for IBA utilisation at EU level, countries developed own rules with varying requirements for utilisation. As a result from a cooperation network between European experts an up-to-date overview of documents regulating IBA utilisation is presented. Furthermore, this work highlights the different requirements that have to be considered. Overall, 51 different parameters for the total content and 36 different parameters for the emission by leaching are defined. An analysis of the defined parameter reveals that leaching parameters are significantly more to be considered compared to total content parameters. In order to assess the leaching behaviour nine different leaching tests, including batch tests, up-flow percolation tests and one diffusion test (monolithic materials) are in place. A further discussion of leaching parameters showed that certain countries took over limit values initially defined for landfills for inert waste and adopted them for IBA utilisation. The overall utilisation rate of IBA in construction works is approximately 54 wt.%. It is revealed that the rate of utilisation does not necessarily depend on how well regulated IBA utilisation is, but rather seems to be a result of political commitment for IBA recycling and economically interesting circumstances

Biochemical methane potential of different organic wastes and energy crops from Estonia

The biochemical methane potential (BMP) of different Estonian substrates as alternative sources for biogas production was studied. For this purpose, the BMP test was carried out in batch mode at mesophilic temperature (36°C). Substrates were divided into 2 groups: agricultural substrates (silage, hay, cattle and pig slurry) and food industry residues (milk, brewery and cereal industry residues). Methane yields obtained were between 286–319 L kgVS-1 for silage and hay, 238–317 L kgVS-1 for animal slurry and 272–714 L kgVS-1 for agro-industrial wastes. The highest methane yield was obtained from sour cream (714 L kgVS-1), the lowest (238 L kgVS-1) from cattle slurry. In overall, our results suggest that all tested substrates can be treated anaerobically and are potential sources for the production of methane

First international comparative study of volatile fatty acids in aqueous samples by chromatographic techniques: Evaluating sources of error

This first international proficiency-testing scheme evaluated the analytical performance and the state of practice in measurement of volatile fatty acids in aqueous samples. Gas chromatography and high-performance liquid chromatography were used by 25 laboratories from 15 different countries. Two reference materials were selected for analysis. The performance of each laboratory was assessed by the internationally-accepted z-score. The overall performance was rather poor. Among the causes of poor analytical performance, human errors and inadequate calibration were probably the major problems encountered. © 2013 Elsevier Ltd