Kurita Water Industries Ltd.

Takaaki Tokutomi

Nobuhiro Orita

Hideyo Yamauchi

Hideaki Shinto

Hiroyuki Asada

Isao Joko

Motoyuki Yoda

In an anaerobic treatment method in which contaminated water is introduced into an acidification tank to decompose polymer components in the contaminated water into organic acids, and the effluent from the acidification tank is introduced into a methane production tank containing non-biological fluidized carriers so as to convert the acids into methane, the treatment is carried out stably and continuously by preventing the occurrence of floating of carriers in the methane production tank. The CODconcentration of polymer components other than organic acids in the acidification tank effluent to be introduced into the methane production tank is controlled to be not more than 300 mg/L. This control prevents the occurrence of acid production reactions in the methane production tank and the consequent proliferation of microorganisms, and thereby suppresses sticking of carriers as well as the occurrence of floating and blockage by the carriers.

Anaerobic treatment method

Anaerobic treatment of water is performed under anaerobic conditions with a biofilm formed on a surface of a fluid non-biological carrier in a reaction vessel. Stable high-load treatment is performed by preventing the blockage of the reaction vessel caused by the flotation and adhesion of the non-biological carrier in the reaction vessel and effectively recovering the settleability of the carrier floating owing to adhering air bubbles by simple means. A reaction vessel is charged with a fluid non-biological carrier having a size in the range of 1.0 to 5.0 mm and a settling velocity in the range of 200 to 500 m/h. Part of the carrier that has floated and flowed out of the reaction vessel is fed downward through a pipe having a vertical height of 50 cm or more so as to remove air bubbles adhering to the carrier and is returned to the reaction vessel.

Anaerobic treatment method and apparatus

A method and apparatus of anaerobic treatment which makes it possible to prevent disintegration of granular sludge and perform high-load high-velocity anaerobic treatment stably even in the case where treatment is performed under conditions where the granular sludge is easily disintegrated. In a reaction tankwhich retains the granular sludge, nitric acid or nitrous acid is adjusted so that they have a certain concentration range. For example, nitric acid is added to the liquid to be treated by connecting the nitric acid addition pathto a midway point of the path of the liquid to be treatedwhich introduces the liquid to be treated to the reaction tank, and nitric acid is mixed with the liquid to be treated. By introducing nitric acids within the reaction tank, denitrifying bacteria etc. can multiply, and disintegration of the granules is prevented.

Anaerobic treatment method and anaerobic treatment apparatus

A process and apparatus for treating an aqueous nitrogeneous liquor by performing ammonia oxidation and denitrification using a biosludge containing anammox bacteria and ammonia-oxidizing bacteria. The process and apparatus can obtain treated liquor of a high water quality at a high treating efficiency and a high yield of ammonium nitrogen removal with easy control of supply rate of oxygen-containing gas.

Process and apparatus for treating nitrogeneous liquor

Raw water containing ammonium-nitrogen is introduced into a nitrification tank and nitrification of nitrite-nitrogen by nitrite oxidizing bacteria is inhibited according to inhibition of the ammonium-nitrogen, thereby conducting stable nitrification of nitrous acid type at a high load by the action of ammonium oxidizing bacteria. Carbonate and/or bicarbonate are added into the nitrification tank. The inorganic carbon concentration in the nitrification tankis maintained at 35 mg-C/L or more. The nitrified liquid thus obtained is introduced into a denitrification tank and denitrification reaction is conducted by the action of denitrifying bacteria with the remaining ammonium-nitrogen as an electron donor and the nitrite-nitrogen as an electron acceptor.

Method for treating water containing ammonium-nitrogen

In treating water containing ammonium-nitrogen by a combination of a nitrification process and autotrophic denitrification bacteria, high efficiency denitrification treatment is achieved by providing adequate ratio between nitrite and ammonia in effluent of the nitrification process. Ammonium-nitrogen concentration of the raw water introduced to a nitrification reactor and the ammonium-nitrogen concentration of the nitrified liquid from the nitrification reactor is measured, and on the basis of the measurement, the flow volume for aeration by a blower would be controlled. From the difference in NH&#x2014;N concentration between the influent and the effluent of the nitrification reactor, nitrite concentration A in the nitrified liquid is calculated, and ratio A/B of the nitrite concentration A with the ammonia concentration B in the nitrified liquid is calculated. The flow volume for aeration by the blower to the nitrification reactor is controlled such that the A/B becomes 1.1 or more, preferably from 1.1 to 2.0.

Nitrifying method of treating water containing ammonium-nitrogen

Raw water containing ammonium-nitrogen is introduced into a nitrification tank and nitrification of nitrite-nitrogen by nitrite oxidizing bacteria is inhibited according to inhibition of the ammonium-nitrogen, thereby conducting stable nitrification of nitrous acid type at a high load by the action of ammonium oxidizing bacteria. Carbonate and/or bicarbonate are added into the nitrification tankThe inorganic carbon concentration in the nitrification tankis maintained at 35 mg-C/L or more. The nitrified liquid thus obtained is introduced into a denitrification tank and denitrification reaction is conducted by the action of denitrifying bacteria with the remaining ammonium-nitrogen as an electron donor and the nitrite-nitrogen as an electron acceptor.

Waste water containing nitrogen compounds is processed by adding an oxidant to the waste water. The oxidant may be one or more of a chlorine oxidant or hydrogen peroxide. The oxidant breaks down the nitrogen compounds through a breakpoint reaction. The partially processed water then is contacted with a metal peroxide catalyst. The metal peroxide breaks down and removes excess oxidant. The reaction may be carried out at normal temperature and pressure.

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Tokyo, Japan

Takaaki Tokutomi