A process for the treatment of industrial waste water. The process
includes the steps of admixing partially-treated waste water containing
precipitated impurities with a flocculating agent in a flocculation
basin, directing the admixed waste water to an elongated sedimentation
basin, allowing flocculated solids in the waste water to settle to the
bottom of the sedimentation basin, removing the settled solids from the
bottom of the sedimentation basin and directing the treated water from
the sedimentation basin. The process can further include the step of
adjusting the pH of the waste water to precipitate impurities in the
waste water prior to the addition of the flocculation agent. The
elongated sedimentation basin can include a pair of sloped sides to
consolidate the settled solids at the bottom of the basin. The settled
solids can then be removed by suction. The basins can be formed from the
excavation or impoundment of earth in an area adjacent to a waste
water-generating facility. Furthermore, the flow of the streams between
basins can be controlled by overflow, with flow rates further controlled
by recycle of solids and treated water. The treatment of industrial water
according to the present processes allows removal of impurities such that
the water is suitable for internal re-use in an operating phosphoric acid
facility or release. Additionally, the process is able to treat acidic
industrial waste water by the removal of impurities as a preliminary
treatment stage leading to discharge of the final treated water to
natural water bodies in compliance with the Federal Clean Water Act.
Moreover, treated water may be processed by reverse osmosis to remove
residual impurities. By employing the processes taught herein reverse
osmosis becomes possible and practicable in the context of industrial
waste water treatment. Treatment of waste water in accordance with the
present invention will require less expensive capital equipment for the
separation stages and provide a more concentrated solids stream.