Modified polysaccharide polymers for use as anti-scalant and dispersant. The polymers are useful in compositions used in aqueous systems. The modified polysaccharides are also useful in detergent formulations, water treatment, dispersants and oilfield applications and as fiberglass binders. Such applications include a modified polysaccharide having up to about 70 mole % carboxyl groups per mole of polysaccharide ASU and up to about 20 mole % aldehyde groups per mole of polysaccharide ASU. The applications can also include a blend of modified polysaccharides and other synthetic polymers.