Advanced treatment method for biochemical tail water of coking wastewater

摘要

The present invention discloses a method for advanced treatment of bio-treated coking wastewater. It employs polymeric ferric sulfate (PFS) and polyacrylamide (PAM) as the flocculant for the pre-treatment of bio-treated effluent. After the process of precipitation and filtration, the effluent is guided through an adsorption column filled with environmentally-friendly nano-composites whereby the advanced treatment of the bio-treated coking wastewater is achieved. When the absorption process reaches the breakthrough point, the adsorption operation will be stopped and sodium hydroxide solution is used as the desorption reagent for regenerating the nano-composites. The high-concentrated component of the desorption liquid is sent out for incineration or production of coal water slurry, meanwhile the low-concentrated component of the desorption liquid is used to prepare sodium hydroxide solution for the adsorption process of the next batch.

主权项

1. A method for removing a pollutant from a bio-treated coking wastewater, comprising:
(A) feeding an effluent from a coking wastewater treatment plant to a flocculation mixer, adding a flocculant comprising polymeric ferric sulfate and polyacrylamide into the flocculation mixer, and mixing the flocculant with the effluent thoroughly to obtain a first solution; (B) feeding the first solution obtained from step (A) into a flocculation reactor for flocculation reaction and obtaining a second solution; (C) feeding the second solution from the flocculation reaction in step (B) into a settling tank so that the second solution separates into a solid precipitate and a supernate; (D) filtering the supernate obtained in step (C) to obtain a first filtrate, feeding the first filtrate to an adsorption column packed with a nano-composite material to obtain a second filtrate; (E) when a concentration of the pollutant in the second filtrate reaches a pre-determined breakthrough point, starting a desorption process, wherein the desorption process comprises stopping feeding the first filtrate into the adsorption column, feeding a first sodium hydroxide solution having a first sodium hydroxide concentration through the adsorption column to obtain a first desorption liquid, and then feeding a second sodium hydroxide solution having a second sodium hydroxide concentration to obtain a second desorption liquid, wherein the first sodium hydroxide concentration is higher than the second sodium hydroxide concentration, wherein the first desorption liquid has a higher concentration of the pollutant and the second desorption liquid has a lower concentration of the pollutant; (F) incinerating the first desorption liquid or mixing the first desorption liquid in a coal slurry.