A method for treating a fluid waste, comprising adding one or more process additives to the fluid waste in an amount sufficient to change the wasteform chemistry is disclosed. The addition step may be chosen from adding a dispersant or a deflocculant an additive to decrease the reactive metal components, to bind fission products and decrease volatilization of toxic or radioactive elements or species during thermal treatment, or to target and react with the fine particle size component of the waste to decrease dusting and immobilize components in a durable phase. After mixing the fluid waste with the described additives the waste is eventually hot-isostatic pressing, to form a durable and stable waste form.