Patent ID: 7416644

Claim:
A system comprising a stripper device for stripping volatile compounds from a liquid medium, said stripper device comprising: a) a shunt to which aqueous liquid medium comprising volatile compounds can be diverted in the form of a side stream to at least one fermentor and/or at least one biogas reactor, b) means for diverting aqueous liquid medium comprising volatile compounds to the shunt from said at least one fermentor and/or at least one biogas reactor, c) an evaporator device comprising a sample of aqueous liquid to which heat obtained from an external heat source can be added, wherein a reduction of the pressure in said evaporator to a first pressure below a predetermined reference pressure generates cold steam, d) means for directing the cold steam generated by the evaporator of c) through said aqueous liquid medium comprising volatile compounds in the shunt of the stripper device at said pressure below a predetermined reference pressure, thereby stripping off volatile compounds and obtaining a cold, volatile compound-comprising steam, e) a first condensing device, f) means for diverting said cold volatile compound-comprising steam at said pressure below the predetermined reference pressure to the first condensing device, and condensing in a first condensing step in said first condensing device said cold volatile compound-comprising steam at said pressure below a predetermined reference pressure, thereby obtaining a first condensed aqueous liquid medium comprising said volatile compounds and vapor not condensed by the first condensing device, g) a stripper unit for stripping volatile compounds at said predetermined reference pressure or at a second pressure higher than said predetermined reference pressure, h) means for diverting said first condensed aqueous liquid medium comprising volatile compounds obtained in f) to the stripper unit, and stripping off at least part of the volatile compounds from said first condensed aqueous liquid medium comprising volatile compounds by injecting hot aqueous steam at said reference pressure or at the higher second pressure, thereby obtaining a hot volatile compound-comprising steam and aqueous liquid stripped off at least part of said volatile compounds, i) a second condensing device, and j) means for diverting said hot volatile compound-comprising steam to a second condensing device, and condensing said hot volatile compound-comprising steam, thereby obtaining a condensate comprising volatile compounds.