Action A1 - Preliminary evaluations

The aim of this group of actions is to make the preliminary evaluations necessary for applying the two proposed methods to the specific case of landfill gas/biogas up-grading. In both the cases the crucial point is to find the correct solid residues able to realise the accelerated carbonation of carbon dioxide contained in the landfill gas/biogas. With this aim the bottom ashes that every day arrive at the landfill – where the pilot plants will be installed – from a Waste-to-Energy plant in the proximity, will be analysed in order to identify their main physico-chemical and mineralogical characteristics.
Concerning the alkali absorption with regeneration method, a preliminary theoretical analysis of the first part of the process – the absorption step – will be performed – also with the support of devoted technical software – in order to identify the alkaline compounds most suitable for carbon dioxide chemical absorption from landfill gas/biogas. This sub-action will be carried out by DEF.
After obtaining these theoretical results, some tests will be carried out at the existing absorption pilot plant, in order to produce load solution samples. This sub-action will be carried out by DEF, at the existing absorption pilot plant at Casa Rota Landfill. At the same time a laboratory characterisation of different solid residues will be performed with the aim of identifying their potential of regenerating the carbon dioxide load solution. In particular, the elemental composition, loss on ignition at 1000°C, leaching behaviour (test EN 12457), acid neutralization capacity, calcite content and mineralogy of different grain size fractions of selected types of residues will be carried out. This sub-action will be carried out by UNIROMA at its experimental facility laboratory. During the solid resides characterisation, a very small laboratory reactor will be set up to reproduce the liquid/solid contact process. This reactor will be filled with samples of specific solid residues and fed with the load solution samples coming from the absorption pilot plant. These preliminary experiments are necessary in order to establish the required contact time for the specific solid residues available and hence for the definitive accurate sizing of the regeneration reactor (carried out in action 2), as well as to identify the influence of the operating parameters and select the operating conditions (temperature in particular). Chemical analysis, as described in the previous paragraph, will also be carried out on the treated material, to assess the effects of the regeneration process on the residues, and in particular on their environmental behaviour. This sub-action will be carried out by UNIROMA at its experimental facility laboratory.
Concerning the BABIU process, in this first part, data about carbon dioxide - and hydrogen sulphide - binding capacities of the bottom ashes available at the CSAI landfill site (coming from a Waste-To- Energy plant in the Province of Arezzo) will be obtained by means of a laboratory-scale pilot plant already available at the laboratory facilities of ABF-BOKU. It will be necessary to collect about 200 kg of bottom ashes delivered at CSAI landfill and transport them to Vienna. The necessary authorisation will be collected.
The existing laboratory equipment at ABF-BOKU consists of static reactors, i.e. the ash is not moved during reaction. Each carbonation reactor consists of a prismatic polyethylene vessel, surrounded by thick styrofoam plates for thermal isolation.

DEF proposed the following sub-actions for action A1:
- Sub-action A1.1_DEF Selection of alkaline compounds through a literature review (February 2010); information about the selected compounds will be supplied to UNIROMA;
-    Sub-action A1.2_DEF: Simulation of absorption with alkaline compounds;
-    Sub-action A1.3_DEF: Modification to the existing absorption pilot plant (addiction of two digital flow meters on entering/exiting gas streams);
-    Sub-action A1.4_DEF: Preliminary test runs of absorption pilot plant; Production of load solution samples to be sent to UNIROMA.

UNIROMA proposed the following sub-actions for action A1:
- Sub-action A1.1_UNIROMA (Selection & Characterization): Selection of different residues suitable for the regeneration step: first candidate is bottom ashes that are accepted in the CSAI landfill, but also other scrap materials will be considered (APC residues, Stainless steel manufacturing residues as EAF slag and AOD slag); Characterization of the selected materials (Elemental analysis, LOI, Environmental behaviour, ANC, XRD, Calcimetry,SEM);
- Sub-action A1.2_UNIROMA (Regeneration)
o A1.2a Regeneration using “model” materials (for example calcium hydroxide)
o A1.2b Regeneration using free CaO-rich residues (for example Air Pollution Control (APC) residues or Cement Kiln Dust (CKD) residues)
o    A1.2c Regeneration using Silicate-rich residues (Argon Oxygen Decarburization (AOD) residues or MSWI bottom ash)

ABF-BOKU proposed the following sub-actions for action A1:
- Sub-action A1.1_ABF-BOKU: optimization of a part of the laboratory equipment (flow control)
- Sub-action A1.2_ABF-BOKU: Laboratory test runs with bottom ashes sent by CSAI
A1.2a CH4 + CO2
A1.2b CO2 + N2 + H2S
Sub-action A1.3_ABF-BOKU: Generate basic technical data for preliminary dimensioning of the pilot reactor

CSAI agreed to carry out the following sub-actions for action A1:
- Sub-action A1.1_CSAI: Supply bottom ash samples to UNIROMA (about 3 kg- 3 bottles), with the indication of the date of arrival into the landfill form the WtE plant, and an indication of the average storage time at the WtE plant

- Sub-action A1.2_CSAI: Supply 250 kg of bottom ash ABF-BOKU, with the indication of the date of arrival into the landfill form the WtE plant, and an indication of the average storage time at the WtE plant