Process for reducing the sulfate concentration in a wastewater stream by employing regenerated gibbsite

摘要

A method for removing sulfate from a wastewater stream includes mixing gibbsite and a calcium source to precipitate Ettringite from the wastewater stream and produce an effluent with a reduced sulfate concentration. The gibbsite in the precipitated Ettringite is regenerated by mixing an acid with the Ettringite and precipitating gibbsite particles, after which the gibbsite particles are subjected to a crystallization process to increase the size of the gibbsite particles which are recycled back to the main stream.

主权项

1. A method for removing sulfate from a wastewater stream, comprising:
(a) mixing gibbsite and a calcium source with the wastewater stream to precipitate ettringite and produce an effluent, wherein the sulfate concentration in the effluent is substantially less than the sulfate concentration in the wastewater stream; (b) regenerating gibbsite by:
i. mixing an acid with ettringite and precipitating gibbsite particles;ii. increasing the average size of the precipitated gibbsite particles to at least 25 μm by subjecting the precipitated gibbsite particles to a crystallization process; and (c) recycling the regenerated gibbsite having an average particle size of at least 25 μm by mixing the regenerated gibbsite with the wastewater stream.