A process for producing and providing a fuel comprising the steps of: (i) pretreating a cellulosic feedstock in one or more processing steps that release extractives comprising at least acetic acid, acetate, or a combination thereof from the feedstock; (ii) conducting a solids-liquid separation on a process stream comprising the extractives and solids, thereby producing an aqueous stream comprising at least a portion of the extractives and a solids stream comprising insoluble components; (iii) feeding at least a portion of the aqueous stream to an anaerobic digester to produce crude biogas that comprises carbon dioxide; (iv) removing at least 80 weight% of the carbon dioxide present in the crude biogas to produce purified biogas; (v) providing an inorganic salt-containing liquid stream originating from the anaerobic digester; (vi) purging said inorganic salt-containing liquid stream by splitting the inorganic salt-containing liquid stream into a purged stream and a main inorganic salt-containing liquid stream, and introducing the main inorganic salt-containing liquid stream to (a) the anaerobic digester; (b) a stage upstream of the anaerobic digester and downstream of step (i); or (c) a combination thereof; (vii) providing solids from at least one stream selected from (a) the solids stream comprising the insoluble components; and (b) a second solids stream derived therefrom arising from the process and comprising insoluble components, and introducing said solids to a thermal process comprising combustion, gasification, pyrolysis or a combination thereof to produce a fuel, fuel intermediate, steam or electricity; (viii) introducing the purified biogas produced in step (iv) to a pipeline, wherein an amount of methane withdrawn from said pipeline corresponds to an amount of the purified biogas introduced to the pipeline; and (ix) providing the fuel or fuel intermediate from step (vii), the purified biogas of step (viii), or a combination thereof, for use as a transportation fuel. (i) pretreating a cellulosic feedstock in one or more processing steps that release extractives comprising at least acetic acid, acetate, or a combination thereof from the feedstock; (ii) conducting a solids-liquid separation on a process stream comprising the extractives and solids, thereby producing an aqueous stream comprising at least a portion of the extractives and a solids stream comprising insoluble components; (iii) feeding at least a portion of the aqueous stream to an anaerobic digester to produce crude biogas that comprises carbon dioxide; (iv) removing at least 80 weight% of the carbon dioxide present in the crude biogas to produce purified biogas; (v) providing an inorganic salt-containing liquid stream originating from the anaerobic digester; (vi) purging said inorganic salt-containing liquid stream by splitting the inorganic salt-containing liquid stream into a purged stream and a main inorganic salt-containing liquid stream, and introducing the main inorganic salt-containing liquid stream to (a) the anaerobic digester; (b) a stage upstream of the anaerobic digester and downstream of step (i); or (c) a combination thereof; (vii) providing solids from at least one stream selected from (a) the solids stream comprising the insoluble components; and (b) a second solids stream derived therefrom arising from the process and comprising insoluble components, and introducing said solids to a thermal process comprising combustion, gasification, pyrolysis or a combination thereof to produce a fuel, fuel intermediate, steam or electricity; (viii) introducing the purified biogas produced in step (iv) to a pipeline, wherein an amount of methane withdrawn from said pipeline corresponds to an amount of the purified biogas introduced to the pipeline; and (ix) providing the fuel or fuel intermediate from step (vii), the purified biogas of step (viii), or a combination thereof, for use as a transportation fuel.