JPH01228593A - Purification of sewage - Google Patents

Abstract

PURPOSE:To purify sewage by a simple purifying equipment without bringing about eutrophication and the lowering of water quality by adding soap to sewage to be subjected to biological purifying treatment as an org. nutritive source for bacteria. CONSTITUTION:The nitrogen compound in sewage to be purified is decomposed in a denitrification tank (anaerobic filter bed) 12 by bacteria. At this time, soap 63 is added to the sewage in the denitrification tank 12 as a nutritive source for bacteria. Subsequently, the sewage treated in the denitrification tank 12 is supplied to an aeration tank (aerobic filter bed) 14 to be subjected to aeration treatment and subsequently again refluxed to the denitrification tank 12 by a pump 20 to be subjected to purifying treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for biologically purifying wastewater, and particularly to a method for purifying wastewater suitable for biologically removing nitrogen from wastewater.

(Prior Art) Biological purification methods for wastewater generally involve adding an organic carbon source such as methanol to the wastewater to be treated as a nutrient source for purification microorganisms, especially denitrification, and This improves the purification efficiency and prevents the reduction and death of microorganisms due to the fact that raw water containing nutrients for microorganisms does not flow in for a long period of time.

(Section 2) Inventing or solving a problem When chemicals such as methanol are added in excess, they flow out of the purification equipment without being consumed and can cause eutrophication. This causes a decrease in the quality of the so-called treated water discharged from the equipment.

Therefore, a purification method using a chemical such as methanol as an organic carbon source for a microbial river requires purifying a device that adds just enough of the chemical as a carbon source, a device that sufficiently removes the chemical from the treated water, etc. This results in the purification equipment being complex, large, and expensive.

An object of the present invention is to provide a purification method that does not cause eutrophication or deterioration of the quality of treated water, and can be constructed as a simple and inexpensive purification equipment.

(Means for Solving the Problems) The present invention is characterized in that soap is added to the wastewater as an organic nutrient source for microorganisms to be treated by a purification facility that biologically purifies wastewater.

The purification equipment decomposes nitrogen compounds in the wastewater to be purified by microorganisms in a denitrification tank, supplies the wastewater treated in the denitrification tank to an aeration tank, and decomposes the wastewater treated in the aeration tank into the denitrification tank. Preferably, there is purification equipment for refluxing the nitrogen to the tank, and the soap is added as a nutrient source for microorganisms in the denitrification tank.

Preferably, the soap is dissolved in at least one of the wastewater flowing from the aeration tank to the denitrification tank and the wastewater in the denitrification tank.

Preferably, the soap is a bar soap.

(Operations and effects of the invention) Soap is easily consumed by microorganisms in purification equipment as well as in lakes and rivers, and even if it remains in treated water discharged from purification equipment, it can lead to eutrophication. There is no fear.

Therefore, according to the present invention, it is not necessary to equip the purification equipment with a device for adding just enough of the soap as an organic nutrient source for microorganisms, a device for sufficiently removing the soap remaining in the treated water, etc. Therefore, it is possible to provide purification equipment with a simple structure and low cost.

(Example) Embodiments of the present invention shown in the drawings will be described below.

The purification apparatus 10 shown in FIG. 1 includes a denitrification tank or anaerobic filter bed 12 for removing nitrogen, and an aeration tank or aerobic filter bed 14 to which wastewater treated with the anaerobic filter bed is supplied.
, a sedimentation tank 16 to which the so-called nitrified water nitrified in the aerobic filter bed is supplied, and a pump 20 that returns the nitrified water at the bottom of the sedimentation tank to the anaerobic filter bed 12 via a vibrator 18. .

For example, the anaerobic filter bed 12 can be a sedimentation separation tank in accordance with the construction standards for human waste septic tanks of the Ministry of Construction Notification No. 1292, and the aerobic filter bed 14 can be a contact aeration tank. The anaerobic filter bed 12 and the aerobic filter bed 14 are divided into two chambers 22.degree. 24 and 26.degree. 28, respectively. Lid 12a of anaerobic filter bed 12 and aerobic filter bed 14.

14a, so that the stiffness can be easily removed,
It is divided into multiple parts.

The raw water to be purified is supplied to the anaerobic first chamber 22 through the water conduit 30, where it is subjected to organic matter decomposition and denitrification effects by anaerobic microorganisms. 1st
The chamber 22 contains a contact material 32 to which anaerobic microorganisms are attached.
and an agitator 34 that forcibly causes the wastewater in the first chamber 22 to flow in the direction of the arrow. Therefore, it is possible to accommodate a large amount of microorganisms in the first chamber 22, and to ensure that the raw water and/or reflux water comes into contact with the microorganisms. Denitrification ability improves. The contact material 32 is
It consists of a plurality of brush-shaped members and is placed at a location separated from the bottom of the tank.

The wastewater in the first anaerobic chamber 22 is supplied to the second anaerobic chamber 24 through the water conduit 36, where it is further subjected to organic matter decomposition and denitrification by anaerobic microorganisms. receive and be purified.

Also in the second chamber 24, a contact material 38 made of a plurality of brush-like materials is arranged at a portion separated from the tank bottom.

The water subjected to the organic matter decomposition action and the denitrification action is supplied to the aerobic chamber 26 and the aerobic chamber 28 in that order via the water conduit 40. Each aerobic chamber 26,28 has a contact material 4
2.44 is arranged at a location separated from the tank bottom, and is also arranged below a plurality of aeration pipes 46.48 or contact members 42.44. Each diffuser tube 46.48 is supplied with air via a pipe 54.56 from a pump 50.52.

Therefore, the wastewater supplied to the aerobic filter bed 14 is subjected to nitrification by aerobic microorganisms in the aerobic filter bed 14. Nitrification is achieved by converting organic nitrogen and ammonia nitrogen into nitrite or nitrate nitrogen.

The nitrified wastewater, that is, nitrified water, is supplied to the settling tank 16 after passing through the water pipe for five days. The nitrified water in the settling tank 16 is supplied to the purification device 10 from raw water or the water conduit 30.
When the water level within 0 rises, it is discharged from the discharge pipe 60 as secondary treated water.

A part of the nitrified water in the settling tank 16 is supplied to the anaerobic first chamber 22 via the pipe 18 by the pump 20, and
In the chamber, the denitrifying effect is caused by denitrification. This denitrifying poisonous action is caused by denitrifying bacteria reducing nitrite or nitric acid,
As a result, nitrogen gas is generated.

In order to optimize the denitrification effect in the anaerobic filter bed 12, the purification device 10 includes a sensor 62 that measures the oxidation-reduction potential, or ORP, in the first chamber 22, and a pump based on the output signal of the sensor. i control circuit 64 for controlling 20.

The sensor 62 is a sensor commercially available as an ORP sensor with a brush washer. The output voltage of the sensor 62 is
If the oxidation of the anaerobic filter bed 12 is progressing, the value will be high, and if it is not, the value will be low.

The control circuit 64 controls the return water from the pump 20 so as to maintain the redox potential within the aerobic first chamber 22 within a predetermined range. That is, the control circuit 64 operates the pump 20 when the oxidation power manually inputted from the sensor 62 falls below the lower limit value, and disables the pump 20 when it exceeds the upper limit value.

For this reason, the control circuit 64 includes an amplifier that amplifies the output signal of the sensor 62, a setter for the upper limit value and the lower limit value, and a control circuit 64 that determines whether the output signal of the amplifier is within the range of the upper limit value and the lower limit value. It is provided with a determination circuit that determines whether or not the pump is present, and a drive circuit that controls the pump 20 based on the output signal of the determination circuit.

The upper limit value and the lower limit value are, for example, −120 mV and −140 mV, respectively, in terms of the output signal of the sensor 62.
mV. However, in the case of newly installed purification equipment, nitrification does not progress sufficiently for one to two months after the start of use, and the pH tends to increase, so in order to perform good denitrification, it is necessary to It is preferable to set a lower value as an upper limit value and a lower limit value, and then set the above value.

An auxiliary tank 66 is arranged in the flow path of the nitrified water that is returned from the settling tank 16 to the anaerobic first chamber 22 . Inside this auxiliary tank 66, there is a stone made of animal or vegetable oil.
68 is accommodated.

The soap 68 is dissolved in the nitrified water, acts as an organic nutrient source for the microorganisms in the purifier 10, and is digested by the microorganisms. In order to appropriately put the stones 68 into the auxiliary tank 66, the auxiliary tank 66 includes a box-shaped main body that opens upward and a lid that closes the opening of the main body.

It is preferable to use solid 6-point soap for laundry or cosmetics as the stone@68, since it dissolves more slowly in water than powdered soap.

Instead of dissolving the stone @ 68 with the nitrified water that is returned from the settling basin 16 to the anaerobic first chamber 22, soap is introduced into the first chamber 22 as shown at 70 in FIG. Alternatively, it may be dissolved in the wastewater in the first chamber 22 by storing it in the first chamber 22 with a net suspended from the lid 12a of the purifier 10. However, if one soap is placed in the auxiliary tank 66, the soap 66 will not be dissolved when the nitrified water is not being refluxed, so that the soap will not be dissolved unnecessarily.

The soap 68 may be placed at regular intervals.

However, when raw water containing organic nutrients for microorganisms does not flow into the septic tank 12 for a long period of time, such as when raw water does not flow into the purification device 10 or when raw water with a high nitrogen concentration relative to organic matter flows into the purification device 10, for example, It is preferable to arrange them for a certain period of time, for example, every three days, during school spring, summer, and year-end and New Year winter vacations.

That is, if raw water containing an organic nutrient source for microorganisms does not flow into the purification device 10 for a long period of time, the microorganisms in the septic tank will lack nutrients, and the microorganisms will decrease or die. Decomposition power and denitrification capacity are reduced. However, if the soap 66 is placed at a predetermined time, nitrogen in the wastewater is removed, microorganisms are reduced and killed, and the purification ability is prevented from deteriorating.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of a purification apparatus used for carrying out the present invention. 10: Purification device, 12: Anaerobic filter bed, 14: Aerobic filter bed, 16: Sedimentation chamber, 18: Vibrator for 1 flow, 20; Pump for reflux, 32.38, 42.44・Contact material , 46.48: Diffusion pipe, 68: Soap. Agent Patent Attorney Nobuyuki Matsunaga

Claims (4)

[Claims] (1) A method for purifying sewage comprising adding soap as a nutrient source for microorganisms to the sewage treated by a purification facility that biologically purifies sewage. (2) The purification equipment decomposes nitrogen compounds in the wastewater to be purified by microorganisms in a denitrification tank, supplies the wastewater treated in the denitrification tank to an aeration tank, and supplies the wastewater treated in the aeration tank to the denitrification tank. The method for treating sewage according to claim 1, wherein the wastewater treatment method is a purification equipment that causes the water to flow back to the denitrification tank, and the soap is added as a nutrient source for microorganisms in the denitrification tank. (3) The wastewater treatment method according to claim (2), wherein the soap is dissolved in at least one of the wastewater returned from the aeration tank to the denitrification tank and the wastewater in the denitrification tank. (4) Claims (1) and (2) wherein the soap is a bar soap.
) or the sewage treatment method described in (3).