JPH03296487A - Treatment of high concentration organic waste water - Google Patents

Abstract

PURPOSE:To stably treat waste water in a low cost by oxidizing high concn. org. waste water in a wet catalytic oxidizing tower and filtering the liquid subjected to oxidative treatment in a filter tower using the exhaust gas from the wet catalytic oxidation tower as washing gas. CONSTITUTION:A biological filtered raw solution is introduced into a biological filter tower from an inflow pipe 19 to be passed through a granular medium bed kept aerobic along with the air from an air diffusion pipe as an ascending current. At this time, the biological filtered raw solution is subjected to not only aerobic microbiological treatment by the bacteria membranes bonded to the surfaces of granular media but also filtering action and the obtained treated water of high quality is taken out of a discharge pipe 20. Further, a biological denitrification tower 8 or the biological filter tower 9 are periodically washed but, as the washing gas thereof, the exhaust gas discharged from a wet catalyst oxidation tower 4 and separated in a gas-liquid separation tank 6 is utilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for treating high-concentration organic wastewater, and in particular, wet catalytic oxidation treatment of high-concentration organic wastewater such as human waste, and further biological treatment as post-treatment. In a combination method of performing filtration such as filtration, the spent gas (exhaust gas) obtained in the wet catalytic oxidation treatment is used as a gas source for cleaning the filter tower, thereby eliminating the need for a blower for cleaning the filter tower. Concerning wastewater treatment methods.

[Prior Art and Prior Art] The Zimmerman method has been known as a method for treating wastewater containing high concentration organic matter. The Zimmermann method maintains wastewater under high temperature and pressure, and blows air (oxygen) into the wastewater to solubilize solid organic matter and convert it into ammonia and organic acids.

In addition, a wet catalytic oxidation treatment method in which wet oxidation is performed in the presence of an oxidation catalyst has been proposed as an improvement on the Zimmermann method to increase treatment efficiency.

When wet oxidation is performed in the presence of an oxidation catalyst according to this wet catalytic oxidation treatment method, the reaction efficiency is high and even NH3-N (ammonium nitrogen) can be efficiently decomposed.

Then, the nitrogen component is decomposed into N2 gas and NO3- ions, and the organic carbon is decomposed into CO2 gas.

In this method, furthermore, in order to maintain a predetermined treatment efficiency, the wet oxidation treatment system, particularly the heat exchanger, piping, and oxidation catalyst layer, are periodically cleaned with nitric acid.

However, the above-mentioned wet catalytic oxidation process has the drawback that the reaction time depends on the organic substance concentration of the raw solution entering the heat treatment step, and when the treatment is actually carried out, it is not necessarily advantageous in terms of cost.

That is, when a raw solution containing a high concentration of organic matter is subjected to IA treatment using a wet catalytic oxidation process, the reaction time must be made sufficiently long to obtain high quality IA treated water. For example, it is possible to reduce the concentration of organic matter in the treated water to an extremely low concentration, but prolonging the reaction time directly leads to an increase in the tank capacity and the amount of catalyst.
This leads to a rise in hidden cost.

The present applicants have solved the above problems, and have developed a treatment method for obtaining high-quality treated water at low cost by performing stable and efficient treatment in a wet catalytic oxidation process of highly concentrated organic wastewater. After wet catalytic oxidation, residual CO
We proposed a method for removing component D by biological filtration using oxygen injection (Japanese Patent Application No. 1-161367).

[ff that the invention tries to solve! ! ] The filter media in the filtration tower according to the method of the prior application has living organisms attached to it, and as the water continues to flow through the filter, the amount of organisms that adhere to the filter material gradually increases, and eventually the treatment performance deteriorates and water cannot flow through the filter. For this reason,
Regular cleaning is required. The frequency of cleaning is determined by detecting the water flow rate and the degree of increase in differential pressure, but it is usually 0.5 to 7.
About once a day. Cleaning is performed repeatedly or in combination with air and water, and a dedicated cleaning blower is installed to supply air. Although the operating rate of this dedicated blower is usually extremely low at 10 to 30 minutes/10.5 to 7 days, it is indispensable for cleaning biofouling filter media. The cost of associated equipment such as blower noise prevention equipment is high, which is a factor that increases the cost of the above-mentioned filtration treatment method.

An object of the present invention is to provide a method capable of solving the above problems and treating highly concentrated organic wastewater stably and at low cost.

[Means for Solving the Problems] The method for treating highly concentrated organic wastewater of the present invention includes wet catalytic oxidation of highly concentrated organic wastewater in a wet catalytic oxidation tower, and filtration of the oxidized liquid in a filtration tower. It is characterized in that the exhaust gas from the wet catalytic oxidation tower is used as the cleaning gas for the tower.

[Operation] Due to the wet catalytic oxidation in the wet catalytic oxidation tower, most of the organic nitrogen, NH3-N in the raw solution becomes N2 gas, and a portion remains in the liquid as NOs-N.

Organic substances are also converted into CO2, but some remain as low molecular weight organic acids depending on the operating conditions.

Therefore, the separated gas obtained by gas-liquid separation of the catalytic oxidation treated liquid is an almost odorless exhaust gas that does not contain NOx, SOx, CH compounds, etc. and contains CO2%02 and N2, and does not require deodorizing treatment.

Therefore, this separated gas can be effectively used as it is as a cleaning gas for the filter tower.

Note that this gas is introduced into the lower part of the filter, etc., and bubbles the liquid in the tower. This causes the deposits to be peeled off from the filter medium.

[Examples] Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a system diagram showing an embodiment of the method for treating highly concentrated organic waste liquid of the present invention.

In the present invention, wastewater containing a high concentration of organic matter obtained by finely crushing human waste and/or septic tank sludge is used as a stock solution, and is first subjected to a wet catalytic oxidation treatment.

That is, human waste and/or septic tank sludge is sent to the crushing step 1 through a pipe 11, and after being subjected to fine crushing treatment, the obtained highly concentrated organic wastewater (undiluted solution) is sent to the heat exchanger 2 through a pipe 12. The water is then heated by exchanging heat with water treated by a wet catalyst oxidation tower, which will be described later. Next, the stock solution is transferred to pipe 13, solubilizing group 3, pipe 1
4 to the wet catalytic oxidation tower 4.

The wet catalytic oxidation tower 4 is a high-pressure container filled with a catalyst to be described later to form a catalyst layer, and the stock solution is passed through the catalyst layer in an upward or downward direction, and is heated under high temperature and high pressure. It is then oxidized. That is, the pipe 12 for introducing the stock solution into the heat exchanger 2 is connected to the pipe 12a for supplying oxygen-containing gas such as atmospheric air, which is equipped with a compressor 5, and oxygen-containing gas such as air is blown into the stock solution. After that, it is introduced into a wet catalytic oxidation tower 4 via a heat exchanger 2 and a wet soluble upper tower 3, and in the presence of a catalyst,
Oxidized.

The treated water and treated gas from the wet catalytic oxidation tower 4 are taken out through a pipe 15, cooled to near room temperature in a heat exchanger 2, and then sent to a gas-liquid separation tank 6 through a pipe 16.

In the present invention, preferable catalysts to be filled in the wet catalytic oxidation tower 4 include iron, manganese, cobalt,
Nickel, ruthenium, rhodium, palladium, iridium, platinum, copper, gold, and tungsten, as well as their oxides, chlorides such as ruthenium dichloride and platinum dichloride, and sulfides such as ruthenium sulfide and rhodium sulfide, etc., are resistant to water. Examples include insoluble or poorly soluble compounds, and these can be used alone or in combination of two or more.

Catalysts made of these metals or compounds can be prepared using conventional methods such as titania (titanium oxide) or zirconia (zirconia oxide).
, alumina, silica, silica-alumina, activated carbon, or nickel, nickel-chromium, nickel-chromium-
It is preferable to use it by supporting it on a carrier such as a metal porous body such as aluminum or nickel-chromium-iron, and the amount supported is usually 0.05 to 25%, preferably 0.5% based on the weight of the carrier. It is appropriate to set it to 3%.

The catalyst can be used in various forms such as granules, pellets, cylinders, crushed pieces, honeycombs, or powders.

The reaction temperature in the wet catalytic oxidation tower 4 is 200 to 370
℃, especially preferably 200 to 300℃, and
The reaction pressure is preferably such that the stock solution maintains a liquid phase even at such high temperatures, for example, 30 to 95 kg/c, particularly 70 to 95 kg/c.

Further, the flow rate of the raw solution in the wet catalytic oxidation tower 4 is preferably set so that the reaction time (residence time in the tower) is 40 to 90 minutes.

As the oxygen-containing gas, in addition to air, it is preferable to use a gas with an oxygen concentration of 21% or more. In the case of a gas containing oxygen with a concentration higher than 21%, the amount of blown gas can be reduced. In addition, the amount of heat loss decreases and the reaction rate increases,
Processing efficiency can be increased. Gases with an oxygen concentration of 21% or more include selective oxygen permeation farming, a method of mixing pure oxygen with air, and pressure swing adsorption (PS).
Oxygen-enriched air obtained by method A), pure oxygen obtained by vaporizing liquid oxygen, etc. can be used.

The oxygen-containing gas is blown into the stock solution by supplying it to the pipe for supplying the stock solution to the heat exchanger 2, as well as to the pipe for supplying the stock solution to the wet soluble upper column 3, the wet soluble upper column 3, or the wet catalytic oxidation tower. It can also be carried out by directly supplying it to 4.

The amount of oxygen supplied by this oxygen-containing gas is
The amount of oxygen may be set to be greater than the amount of oxygen required for the amount of organic matter and the amount of N in the stock solution supplied to 4.
Generally, the gas:liquid flow rate ratio (volume ratio at normal pressure) of the oxygen-containing gas and the stock solution is preferably 50 to 500:t.

The liquid separated in the gas-liquid separation tank 6 is sent to the solid-liquid separation tank 7 through a pipe 17, where it is separated into solid and liquid. In the solid-liquid separation tank 7, in order to remove inorganic solids and organic phosphate ions from the liquid, a Linnaeus solubilizing agent is added, and pHI! Perform solid-liquid separation.

Linnaeus solubilizing agents include calcium compounds, aluminum compounds, iron compounds, etc., but it is advantageous to insolubilize phosphate ions in the form of calcium salts such as hydroxyapatite because the cake has good dehydration properties.

The separated liquid in the solid-liquid separation tank 7 is fed through a pipe 18 to a fixed-bed biological denitrification tower 8 filled with a filter medium, where it is subjected to denitrification treatment. Here, residual organic matter in the wet catalytic oxidation tower 4 is used as the organic matter necessary for denitrification of N O2-N, but when organic matter is insufficient due to sudden fluctuations, organic matter such as methanol, ethanol, acetic acid, etc. is supplied. You may do so. The filter material of the biological denitrification tower 8 is sand,
Various filter media such as gravel, anthracite, plastic, activated carbon, natural stone, and artificial materials can be used.

The treated liquid from the biological denitrification tower 8 is sent through a pipe 19 to the biological filtration tower 9, where it is subjected to biological filtration to decompose and remove residual low molecular weight organic acids and the like. The same filter medium as that of the biological denitrification tower 8 can be used as the filter medium of this biological filter tower 9.

Biological filtration of the treated liquid in the biological denitrification tower 8 (hereinafter referred to as "biological filtration stock solution") is preferably carried out, for example, as follows:
0 and a diffuser pipe (not shown), and filled with a granular media layer and a support material layer for supporting the granular media layer.
Using this, the biological filtration stock solution is introduced into the biological filtration tower 9 through the inlet pipe 19, and passed in an upward flow through a layer of granular media maintained aerobically together with gas (air) from the aeration pipe.

At this time, the biological filtration stock solution is subjected to aerobic microbial treatment and filtration action by the microbial membrane attached to the surface of the granular medium, and the resulting high-quality treated water is taken out from the discharge pipe 20.

In the present invention, such biological filtration treatment is preferably carried out at a CODC11 load of the biological filtration tower of 10 kg/m''-day or less, preferably about 2 kg/m''-day.

The treated water from the biological filtration tower 9 is discharged from the pipe 2o, and after being further filtered if necessary, is discharged outside the system.

In addition, in this kind of biological filtration, the surplus biological sludge in the biological filtration tower and the biological sludge separated in the subsequent filter are
It can be returned to the fine crushing process and processed together with raw solutions such as human waste.

In this embodiment, the biological denitrification tower 8 and the biological filtration tower 9 are periodically cleaned for such treatment, but at that time,
The exhaust gas discharged from the wet catalytic oxidation tower 4 and separated in the gas-liquid separation tank 6 is used as the cleaning gas. That is, in this embodiment, a part of the separated gas (exhaust gas) whose pressure has been reduced to about 5 to 20 kg/cm' in diameter is sent to the biological denitrification tower 8 and the biological filtration tower 9 at the necessary frequency through the valve VI. -V 3
Cleaning is carried out by supplying water through pipes 21.22 and 21.23 by opening and closing.

Excess exhaust gas is discharged from the pipe 24.

In the example shown in FIG. 1, a fixed bed biological denitrification tower and a biological filtration tower were used as the filtration tower, but in the present invention,
The term filtration tower refers to all filtration towers that have a built-in filter material, and can also be applied to other filtration towers such as sand filtration towers.

That is, for example, even when a simple filtration tower such as a sand filtration tower is installed downstream of biological filtration, the exhaust gas from the wet catalytic oxidation tower can be used as the cleaning gas source.

Further, the exhaust gas can also be used as a neutralizing agent for the treatment liquid.

In the present invention, since the gas used for cleaning the filter tower has very little contamination, it can be discharged from the system as it is, but if necessary, it may be introduced into exhaust gas treatment equipment related to stock solution storage. Separately, it may be discharged after being subjected to treatments such as water cleaning, chemical cleaning, activated carbon cleaning, etc.

The present invention will be explained in more detail with reference to specific examples below.

Example 1 According to the method shown in FIG.
/11) Human waste was buried. Each treatment condition was as follows.

Raw solution (human waste) water flow rate - 31/hr Wet soluble upper column: Vacant column capacity = 3 u Pressure = 90 kg/c Temperature = 270°C Oxygen source air wet catalytic oxidation column: Catalyst loading amount 31 Pressure = 90 kg/crn'' temperature = 285°C Solid-liquid separation tank slaked lime addition amount: 1000 mg/f (as Ca) Biological denitrification tower filter material filling amount = 4J2 (50 mmφ x 2000 mmH) Upward flow water biological filtration tower filter material filling amount = 101 (80mmφxzooommH) Liquid, air upward flow air supply amount 2 times Amount of dissolved oxygen detected in water In such a process, when cleaning the biological denitrification tower and biological filtration tower according to the specifications shown in Table 1. (The exhaust gas from the wet catalytic oxidation tower, which is separated in a gas-liquid separation tank, is used as the cleaning gas.)

Table 1 As a result, efficient cleaning could be performed without using a cleaning blower.

[Effects of the Invention] As detailed above, according to the method for treating high-concentration organic wastewater of the present invention, in the treatment method in which high-concentration organic wastewater is subjected to wet catalytic oxidation treatment and then filtered in a filtration tower, ■ No need for a blower.

■ Reduces the need to connect accessories such as blower noise prevention.

■ Cleaning can be easily performed by simply switching the valve.

Effects such as these are achieved, and processing efficiency is improved and processing costs are reduced.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an embodiment of the method for treating highly concentrated organic wastewater of the present invention. 1... Crushing process, 2... Heat exchanger, 3...
・・Wet type soluble type tower, 4・・Wet type catalytic oxidation tower, 6・
... Gas-liquid separation tank, 8... Biological denitrification tower, 9...
Biological filtration tower.

Claims (1)

[Claims] (1) In a method in which high-concentration organic waste wood is subjected to wet catalytic oxidation in a wet catalytic oxidation tower and the oxidized liquid is filtered in a filtration tower, exhaust gas from the wet catalytic oxidation tower is used as a cleaning gas for the filtration tower. A method for treating highly concentrated organic wastewater.