afvalzorg Deponie methaanreductie door actieve beluchting en ...

Summary
In order to demonstrate a reduction of methane emissions, a Smell-Well system was installed
and operated on a part of the slope of the Braambergen landfill near Almere, the Netherlands in
the period of October 2000 until August 2002. In the Smell-Well system alternately air is
injected or extracted through a relative large number of lances, located about 5 meters away
from each other.
Air injection might have a number of effects:
(i) the existing capacity for methane oxidation in the top-layer can be enhanced;
(ii) further methane formation in the aerobic part of the landfill is prevented, since traces of
oxygen are toxic for the methanogens responsible for methane generation;
(iii) in presence of sufficient oxygen, organic material will decompose aerobically and the
potential for methane formation is removed;
(iv) the dense system of lances will act as an efficient system for surface extraction of
landfill gas, migrating through the top-layer.
The demonstration is intensively monitored; methane emissions are measured, the quality of
pore water is analyzed and waste samples are taken and analyzed prior to and after aeration.
Besides the process of aerobic conversion is enhanced on a lab-scale in order to be able to
study the possibility of an aerobic landfill, in which the waste is composted in-situ.
Main conclusion is that Smell-Well reduces methane emissions with 60-85%. In the
demonstration from January 2001 until May 2001 the emission of 580.000 Nm 3 of methane was
reduced; when the system is continued and operates without any major problems, an average
annual emission reduction can be expected of about 500.000 Nm 3 of methane (0.36 ktonne
CH4 y -1 ; 7.6 ktonne CO2-equivalents y -1 ). The most important mechanism is mechanism (iv): an
efficient surface extraction of the gas. Besides it is demonstrated that mechanism (i), a
stimulation of methane oxidation is also of importance. The extra methane oxidation due to
Smell-Well is 13-23% of total methane flux through the top layer.
Investments were € 1.14 million, and annual operating costs are € 70.000. The costs for
greenhouse gas mitigation were € 27 per tonne CO2-equivalents, which is quite expensive. On
the basis of insights gathered in this study, a simplified system can be designed, costing about
€ 6 per tonne CO2-equivalents.
With regards to the feasibility of aerobic landfills, the full-scale and lab-scale experiments led to
contradictions:
on a full-scale, aerobic conversion of organic material could not be proven to have
occurred;
on a lab-scale aerobic stabilization proceeded rather fast and the organic material was
completely stabilized within about half a year.
On the basis of these results, no conclusions can be drawn about the technical feasibility of
aerobic landfills. One conclusion that can be drawn is that the presence of an dense system for
aeration is no guarantee for swift aerobic stabilization. Additional monitoring of methane
emissions and waste conversion are required in order to demonstrate the feasibility of an
aerobic landfill.
On the full-scale an improvement of pore-leachate is observed. A comparison of fully aerobic
stabilized waste, anaerobically stabilized organic waste and largely inorganic waste showed
3