Wastewater treatment method and wastewater treatment apparatus

Patent metadata

Field	Value
Publication number	US-2016251241-A1
Application number	US-201415026448-A
Country	US
Kind code	A1
Filing date	Oct 6, 2014
Priority date	Oct 16, 2013
Publication date	Sep 1, 2016
Grant date	—

Abstract

A wastewater treatment method and a wastewater treatment apparatus securely and readily remove selenium, which is considered harmful, by removing not only 0-valent selenium, 4-valent selenium, and 6-valent selenium, but also -2-valent selenium. In the wastewater treatment method and the wastewater treatment apparatus for treating wastewater including selenium, -2-valent selenium included in the wastewater is oxidated by using an oxidant, or -2-valent selenium included in the water is removed by using a remover.

First claim

1 - 8 . (canceled)

9 . A wastewater treatment method for treating wastewater including selenium,
wherein -2-valent selenium included in the wastewater is oxidated by using an oxidant or -2-valent selenium included in the wastewater is removed by using a remover, and wherein a silver chloride is used as the remover which is generated by reacting hydrochloric acid with a silver nitrate.

10 . The wastewater treatment method according to claim 9 , wherein an aqueous solution of hydrogen peroxide is used as the oxidant.

11 . The wastewater treatment method according to claim 10 , comprising a coprecipitation treatment step of separating 0-valent selenium and/or 4-valent selenium from the wastewater including oxidated selenium by coprecipitation with iron hydroxide by oxidating the -2-valent selenium with the aqueous solution of aqueous solution of hydrogen peroxide.

12 . The wastewater treatment method according to claim 9 , comprising a coprecipitation treatment step of separating 0-valent selenium and/or 4-valent selenium from the wastewater by coprecipitation with iron hydroxide after the silver chloride has adsorbed the -2-valent selenium for separation.

13 . A wastewater treatment apparatus configured to remove selenium included in wastewater drained from a coal gasification compound power generation facility, the apparatus comprising:
a receiving tank into which the wastewater including -2-valent selenium, 0-valent selenium, 4-valent selenium, and 6-valent selenium flows; an oxidation tank configured to oxidate the -2-valent selenium by using an aqueous solution of hydrogen peroxide or a removal tank configured to adsorb the -2-valent selenium and allow the -2-valent selenium to precipitate by using silver chloride generated by a reaction between silver nitrate and hydrochloric acid; a reduction tank configured to reduce the 6-valent selenium into 0-valent selenium and/or 4-valent selenium by using a reductant; and a precipitation tank configured to allow the 0-valent selenium and the 4-valent selenium in the water that has flowed in from the reduction tank to precipitate and separate by iron coprecipitation.

14 . The wastewater treatment apparatus according to claim 13 , wherein the oxidation tank or the removal tank is an aeration tank configured to remove volatile substances in the wastewater that has flowed in from the receiving tank.

Assignees

• Mitsubishi Heavy Ind Ltd

Inventors

• Chiyomaru Masaru

Classifications

• B01J20/0288

  Halides of compounds other than those provided for in B01J20/046 · CPC title

• C02F1/5245

  using basic salts, e.g. of aluminium and iron · CPC title

• C02F2209/42

  Liquid level · CPC title

• C02F9/00 Primary

  Multistage treatment of water, waste water or sewage · CPC title

• B01J20/0233 Primary

  Compounds of Cu, Ag, Au · CPC title