Wood ash improves composting processes and end products
© European Compost Network ECN e.V. (6/2014)
The use of biomass as a renewable energy source results in the production of ashes that are often landfilled. This is a waste of nutrients like P, Ca, Mg, K, and a number of micronutrients. It is known that wood ash can be used as fertilizer or lime replacement, as well as an additive in composting. This is owed to its ability to buffer pH and reduce compost malodours. Nevertheless, the Austrian Compost Ordinance allows a maximum admixture of 2% ash.

Define waste criteria for the production of high quality compost
© European Compost Network ECN e.V. (6/2014)
The Waste Framework Directive 2000/98 (WFD) contains specific provisions to define end-of-waste criteria (EWC). The objective of EWC is to remove the administrative loads of waste legislation for safe and high-quality waste materials, thereby facilitating recycling. The objective is achieved by requiring high material quality of recyclables, promoting product standardisation and quality assurance, and improving harmonisation and legal certainty in the recyclable material markets.

Digestate and Compost qualities focus on nitrogen and organic matter respective brings to crops and to cultivated soils
© European Compost Network ECN e.V. (6/2014)
CIRSEE team contributes for Suez Environnement and in collaboration with different public and private partners to the collaborative R&D program DIVA that is partially financed by ANR and that is dedicated to the characterization and agricultural recovery of different digestates produced in France. CIRSEE participates to the task “agronomic characterization” that is led by INRA and realizes different laboratory and “on land” tests in order to precise and compare the agronomic value of different organic products : raw digestates, composted digestates as Methacompost or simple composts produced from domestic or agricultural waste.

Organic matter transformation drives the fate of organic micropollutants during anaerobic digestion and composting of sludge
© European Compost Network ECN e.V. (6/2014)
In France, sewage sludge is very often recycled on cropped soils as fertilizer substitute. To avoid impacts related to organic micropollutant input in soil, it is necessary to ensure their dissipation from the sludge during the stabilization processes like anaerobic digestion and composting. The behaviour of organic micropollutants (13 polycyclic aromatic hydrocarbons, nonylphenols, 2 antibiotics (sulfamethoxazole and ciprofloxacin), 1 hormone (β-estradiol) and 1 anti-inflammatory drug (ibuprofen)) was experimentally studied during lab-scale anaerobic digestion followed by composting. At the same time, the fate of organic matter was studied during the treatments. To go further on the comprehension of organic micropollutants dissipation mechanisms, the organic matter was chemically fractionated according to its accessibility.

A new organic matter fractionation methodology applied on a large panel of organic wastes: accessibility characterization for bioaccessibility prediction and process modelling improvement
© European Compost Network ECN e.V. (6/2014)
The huge amount of organic wastes can be treated through biological processes such as anaerobic digestion or composting for their energetic and agricultural valorization. In order to predict the fate of the organic matter in these processes, knowledge on biodegradability and bioaccessibility is crucial. However, in the literature there is a lack of protocol to assess organic matter bioaccessibility. Recently, a methodology based on chemical sequential extractions combined with fluorescence spectroscopy has been developed for sewage sludge. A successful correlation with bioaccessibility was shown. However, this technique was based on alkaline extractions which target proteins and humic acids and was not sufficient for the carbohydrates or lignocellulosic substrates characterization.

Quality of liquid digestate as fertilizer – challenges for analytical procedures and regulations
© European Compost Network ECN e.V. (6/2014)
During anaerobic digestion (AD), methane and CO2 are released during decomposition of organic matter. Consequently, the concentration of heavy metals and other possible harmful substances will increase on dry matter basis (DM). The concentrations of plant nutrients in the digestate will also increase. The quality of the feedstock is therefore important.

Digestates origin and post-treatment influence their biological stability, potential nitrogen availability for plants and reactive nitrogen gas emissions
© European Compost Network ECN e.V. (6/2014)
The objective was to evaluate how digested wastes and post-digestion process determine the interest of digestates as organic amendments, source of nitrogen for plants and their potential environmental impacts through NH3 and N2O emissions. Digestates of different origins were sampled at various process steps: raw effluent, solid and liquid phases from phase separation, composted or dried solid phases and concentrates from membrane operation. All experiments were done in laboratory controlled conditions: potential nitrogen availability and organic matter stability during incubation of soil-digestate mixtures, NH3 emission using a modified wind-tunnel method and N2O emission using soil-digestate incubation during three months.

Effect of sewage sludge compost application on the potential toxic elements of soil and plant in 2009-2012
© European Compost Network ECN e.V. (6/2014)
In the spring of 2003 we established a small plot experiment with sewage sludge compost that contains 40% sewage sludge, 25% straw, 30% rhyolite and 5% bentonite. In 2006, 2009 and 2012 the experiment was re-treated. We ploughed into the soil 0, 9, 18 and 27 t ha-1 sewage sludge compost in five repetitions. We used spring crops and autumn cereals as corn, pea and triticale in crop rotation. Now we present some potential toxic elements (Co, Cu, Ni and Pb) content of soil samples collected from the 0-30 cm soil layer after harvesting, in 2009-2012.

Greenhouse gases from composting and anaerobic digestion of biowaste in Germany
© European Compost Network ECN e.V. (6/2014)
Greenhouse gas (GHG) emissions from 12 to 120 kg CO2äq/Mg from composting and anaerobic digestion of biowaste are important for environmental impacts and results in Life Cycle Assessment (LCA). Poor operation can cause even higher emissions up to 400 kg CO2äq/Mg. The amount of CH4 and primary N2O differ in a range of factor 10 between different plants and is a result of variation in substrate (feedstock) and basic process parameters like: porosity, density, temperature, moisture, C:N ratio, O2 and pH-value.

Defects and efforts approach in the use of biofilter for waste gas purification
© European Compost Network ECN e.V. (6/2014)
According to the IED and the so-called Brefs the exhaust of reactors and aerated rotting windrows from composting plants must be sent to an exhaust air treatment. A Biofilter is the most used method for the waste gas purification. Biofilters are reactors which are filled with a support media, for example an organic material like wood bark or chopped wood. The air contents are metabolized by microorganisms. To ensure that on the pure-gas side the required 500 OU/mÂł are abided, a lot defaults for the planning, dimensioning and the operation are needed.

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