JPH0235999A - Treatment of waste water - Google Patents

Abstract

PURPOSE:To remove an org. substance and nitrogen component by mounting a denitrification treatment process, a nitrification treatment process and a solid-liquid separation process. CONSTITUTION:Org. substance removal/denitrification treatment is applied to raw water 11 in an anaerobic state and, subsequently, org. removal/ nitrification treatment is applied thereto in an aerobic state while the treated raw water is subjected to solid-liquid treatment to obtain treated water 14. The anaerobic and aerobic treatments are performed using a bioreactor having a high reaction speed. By this method, the treated water 14 of a high purifying degree is obtained. An installation area can be reduced because of a small-sized apparatus.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for treating wastewater.

[Prior Art and its Problems] Conventionally, for example, a fluidized bed biological treatment method has been used to remove soluble and insoluble organic substances from wastewater. In this method, first, as shown in Fig. 3, the raw water of the object to be treated is
is supplied to aerobic reactor 2. Aerobic reactor 2
The inside is filled with a microbial immobilization carrier such as plastic, sand, polymer gel, etc., and organic matter decomposing bacteria, nitrite-oxidizing bacteria, nitric acid-killed bacteria, etc. are immobilized therein. By the action of these immobilized microorganisms, organic matter in the raw water 1 is decomposed and ammonia nitrogen is oxidized to nitrite nitrogen or nitrate nitrogen.

Next, this reactor-treated water 3 is led to a solid-liquid separation process 4, where suspended components (SS) in the raw water 1 and microorganisms detached from the immobilized carrier by the flow in the aerobic reactor are separated and clarified. A processing liquid 5 is obtained.

This method has the advantage that the treatment equipment can be made smaller and the installation area can be smaller than the conventional activated sludge method. However, in an aerobic fluidized bed reactor, organic matter removal and nitrification reactions proceed, but denitrification reactions do not occur. Further, as the nitrification reaction progresses, the alkalinity in the treated solution is consumed, resulting in a decrease in pH and a decrease in biological activity.

Eventually, there was a problem that the quality of the treated water deteriorated.

On the other hand, as shown in FIG. 2, the raw water 1 is also purified by a nitrifying solution circulation method. This method consists of an anaerobic tank 6, an aerobic tank 7, and a final settling tank 8. A part of the effluent from the aerobic tank 7 is circulated to the anaerobic tank 6, and the rest is sent to the final settling tank. After the activated sludge is sedimented and concentrated, a portion is returned to the anaerobic tank 6, where the filtration temperature is maintained at 59 degrees.

In the aerobic tank, removal of organic matter by decomposition of organic matter in raw water and nitrification reaction by nitrifying bacteria proceed, so organic and ammonia nitrogen in raw water is oxidized to nitrate nitrogen. Therefore, nitrate nitrogen is present in the circulating fluid from the aerobic tank.

In the aerobic tank, the nitrate nitrogen in the circulating fluid is reduced to nitrogen gas by the action of denitrifying bacteria using organic matter in the raw water, and is dissipated into the atmosphere, removing nitrogen from the fluid. .

In this manner, in the nitrification solution circulation method, the consumption of alkalinity by the nitrification reaction is replaced by alkalinity recovery by the denitrification reaction, so that the pH of the treated water is less reduced and biological activity can be maintained. In addition, the organic carbon source necessary for the denitrification reaction is supplied by organic matter in the raw water. Therefore, there are advantages such as not requiring organic carbon mud such as methanol. However, there were problems in that the equipment was large and the site area was large.

The present invention has been made in view of these points, and provides a wastewater treatment method that can remove organic matter and nitrogen using a compact device without using any carbon source for denitrification other than raw water. This is what we provide.

[Means for Solving the Problems] The present invention includes a step of removing organic matter and denitrifying the raw water of the object to be treated in an anaerobic state, and removing organic matter in the liquid after the denitrification treatment in an aerobic state. A wastewater treatment method comprising: a step of performing a nitrification treatment at the same time; and a step of circulating a part of the liquid after the nitrification treatment to a denitrification step and subjecting the remaining liquid to a solid-liquid separation treatment. be.

Here, the denitrification treatment applied to the raw water is carried out using, for example, a fixed bed using a non-woven fabric, a fixed bed using a polypropylene filter material (<PP filter material), or an anaerobic bioreactor using a sessile biological method. be able to.

In addition, nitrification can be carried out using, for example, a fluidized bed using a pp carrier, a fluidized bed using a pp hollow carrier, a fluidized bed using other carriers, etc.
Alternatively, it can be carried out using an aerobic bioreactor that employs a fixed biological treatment device.

Further, as the solid-liquid separation device, for example, a filtration device using a nonwoven fabric, a sand filtration device, a two-layer filtration device, a sedimentation basin, a coagulation sedimentation device, a coagulation filtration device, etc. can be used.

[Function] According to the wastewater treatment method of the present invention, organic matter removal and denitrification treatment are performed on raw water in an anaerobic state, and then organic matter treatment and nitrification treatment are performed on the raw water in an aerobic state, followed by solid-liquid separation. Apply processing. Therefore, it is possible to perform both nitrification and denitrification as well as the removal of organic matter from raw water using a small-sized device, and it is possible to easily obtain highly clean treated water.

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

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

In the figure, 10 is an anaerobic bioreactor that performs organic matter removal and denitrification treatment on raw water 11 to be treated in an anaerobic state.

The anaerobic bioreactor 10 is configured with a fixed bed made of, for example, nonwoven fabric.

The denitrified liquid in the anaerobic bioreactor 10 is supplied to the next aerobic bioreactor 12.

The aerobic bioreactor 12 is composed of, for example, a fluidized bed using a pp carrier. In the aerobic bioreactor 12, the denitrified liquid is subjected to nitrification treatment. A part of the liquid after the nitrification treatment is guided to the next solid-liquid separation treatment device 13, and the remainder is returned to the anaerobic bioreactor 11 again. The solid-liquid separation processing device 13 is configured with a filtration device using, for example, a nonwoven fabric. Through solid-liquid separation processing by this solid-liquid separation processing device 13, treated water 14 with extremely high purity is obtained, which has been subjected to both organic matter removal, nitrification, and denitrification treatments.

As described above, according to the method of the present invention, the raw water 11 is subjected to organic matter removal and denitrification treatment in an anaerobic state, then organic matter removal and nitrification treatment are performed to the raw water 11 in an aerobic state, and then the treated liquid 14 is subjected to solid-liquid separation treatment. get. Furthermore, both anaerobic and aerobic treatments are performed using a bioreactor with a high reaction rate. Therefore, treated water 14 with a high degree of cleanliness can be easily obtained with a smaller apparatus than that using the conventional nitrified liquid circulation method. In addition, since both digestion and denitrification are performed, treated water with far higher purity than conventional fluidized bed biological treatment can be easily obtained.

[Effects of the Invention] As explained above, according to the wastewater treatment method according to the present invention, it is possible to reduce the facility area with a small device without adding a denitrification carbon source, and to remove organic matter and nitrification. It has remarkable effects such as being able to easily obtain highly clean treated water by performing both denitrification and denitrification treatments.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram showing a waste liquid treatment method using a conventional digestive fluid circulation method,
FIG. 3 is an explanatory diagram showing a conventional fluidized bed biological treatment method for treating waste liquid. 10... Anaerobic bioreactor 11... Raw water,
12...Aerobic bioreactor 13...Solid-liquid separation treatment device, 14... Treated water.

Claims (1)

[Claims] A step of subjecting raw water to be treated to denitrification treatment while removing organic matter in an anaerobic state; a step of performing nitrification treatment to the liquid after the denitrification treatment while removing organic matter in an aerobic state; A wastewater treatment method comprising the steps of circulating a part of the liquid to a denitrification process and subjecting the remaining liquid to a solid-liquid separation process.