Domestic and commercial waste sent to landfill
Landfill sites containing domestic and commercial waste produce a variety of volatile organic compounds (VOCs), depending on both the materials they contain and the decomposition processes they undergo.
Many of these compounds can be toxic and/or odorous, and so need to be monitored regularly for negative impacts on local communities and the wider environment.
Reflecting this concern, the European Landfill Directive (1999/31/EC) says that all landfill sites (except those for ‘inert waste’) must be monitored at least annually for various priority pollutants, many of which are VOCs amenable to analysis by thermal desorption (TD)–gas chromatography (GC).
What Markes can offer
The UK Environment Agency has issued a standard sampling and analytical protocol for compliance with the monitoring requirements of the Landfill Directive. Other European countries are also in the process of drafting compliance protocols.
|Siloxanes || |
Siloxanes are ubiquitous in personal hygiene, health care and industrial products, and as a consequence end up in landfill, where the volatile components are released into landfill gas. When this gas is used for power generation, the siloxanes are oxidised to solid silicon dioxide, which can cause failure of microturbines and catalysts. Fortunately, volatile siloxanes are easily monitored using thermal desorption – contact our specialists for more information.
The UK protocol specifies pumped sampling onto two-bed inert-coated stainless steel sorbent tubes (Tenax® TA–SulfiCarb) followed by analysis with thermal desorption (TD)–GC–MS. This is particularly well-suited to landfill gas monitoring because:
- The choice of sorbents allows collection of analytes over a wide volatility range, while also avoiding decomposition of the more ‘labile’ analytes that are a feature of landfill gas streams.
- The high humidity of landfill gas often results in water being collected on the strong sorbents that are needed to monitor landfill gas. However, modern TD systems, such as Markes’ UNITY-xr and TD100-xr, allow the sample to be dry-purged before it enters the gas chromatograph, minimising the amount of water injected into the GC.
As well as ‘spot-monitoring’ by pumped-tube monitoring using a single TD tube (e.g. with Markes’ ACTI-VOC low-flow pump), multiple-tube samplers such as Markes’ MTS-32 can be employed to assess emission profiles over a longer period.
- For more information on the application of thermal desorption to odorous sulfur compounds, see Application Note 032.
- For an example of the use of TD to analyse landfill gas compounds, see Application Note 047.
- For an example of the use of diffusive samplers with Markes’ UNITY thermal desorber to detect various representative odour compounds, see: P. Bruno, M. Caselli, G. de Gennaro, M. Solito and M. Tutino, Monitoring of odor compounds produced by solid waste treatment plants with diffusive samplers, Waste Management, 2007, 27: 539–544.