A cost-effective solution for the disposal of solvent deasphalting process bottoms that include spent solid adsorbent material containing ash-producing constituents, asphalt and process reject materials is provided by introducing them in the form of a flowable slurry into a membrane wall gasification reactor to produce a synthesis gas and, optionally, subjecting the synthesis gas to a water-gas shift reaction to produce a more hydrogen-rich product stream; process steam and electricity are produced by recovering the sensible heat values from the hot synthesis gas.