The methane gas created by the anaerobic process in a waste landfill must be vented to prevent explosions.  The gas may be safely flared off to atmosphere. This process can use one or multiple  multistage centrifugal or positive displacement  exhausters. EURUS blowers are great technology solutions for this application and will use packing ring seals, whereas larger exhausters will require carbon ring seals to prevent methane leakage.  Carbon ring seals require purging, so a compressor will need to be nearby. The casing is Heresite coated, and non-sparking coupling guards are used.  Aluminum impellers are acceptable.  A stainless steel shaft is optional.