NOVELTY - Integrated process for the conversion of a ligno-cellulosic biomass feedstock comprised of lignin and carbohydrates of glucans and xylans, comprises: (a) pretreating the ligno-cellulosic biomass feedstock with treatment water; (b) converting at least a portion of the glucans and xylans to chemicals other than glucose and xylose and their respective glucose and xylose oligomers and polymers; (c) converting the lignin of the obtained ligno-cellulosic biomass stillage to products other than lignin; (d) recovering a treated water from the obtained liquid phase; and (e) using the treated water.    USE - The integrated process is useful for the conversion of a ligno-cellulosic biomass feedstock comprised of lignin and carbohydrates of glucans and xylans (claimed), where the conversion products are useful to prepare polyester intermediates for use in polyester preforms and bottles.    ADVANTAGE - The integrated process: provides high yields, where 80% of the lignin in the feedstock is recovered as usable products; significantly reduces the amount and cost of water treatment; and utilizes conversion pressure so as to avoid the formation of char.    DETAILED DESCRIPTION - Integrated process for the conversion of a ligno-cellulosic biomass feedstock comprised of lignin and carbohydrates of glucans and xylans, comprises: (a) pretreating the ligno-cellulosic biomass feedstock with treatment water which includes steam explosion to create a pre-treated ligno-cellulosic biomass feedstock; (b) converting at least a portion of the glucans and xylans to chemicals other than glucose and xylose and their respective glucose and xylose oligomers and polymers to create a ligno-cellulosic biomass stillage comprising lignin, a pre-treatment biochemical oxygen demand (BOD) concentration and a pre-treatment chemical oxygen demand (COD) concentration; (c) converting the lignin of the ligno-cellulosic biomass stillage to products other than lignin by exposing the ligno-cellulosic biomass stillage to hydrogen and a first catalyst to produce a liquid phase at 25 degrees C; (d) recovering a treated water from the liquid phase having a post-treatment BOD concentration and a post treatment COD concentration, both of which are 50% less than the pre-treatment BOD and COD concentrations; and (e) using the treated water in at least one of the steps comprising a waste water treatment process and any process step preceding recovering the treated water from the liquid phase.