JPH0675712B2 - Purification method of organic wastewater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a purification treatment method for purifying organic wastewater such as domestic urine sewage, household wastewater, and sewage.

(Prior Art and Problems to be Solved by the Invention) The present inventors have already proposed, as shown in FIG. 2, a first settling tank 1 and a calcium silicate water as a method for purifying various organic wastewater. The organic wastewater D is sequentially passed through the septic tank 2 and the second settling tank 3 which are filled with the porous granular material containing the main component of Japanese union, and the sludge M accumulated in the both settling tanks 1 and 3 is sludge precipitated. A method of introducing sludge into tank 4 and then treating it with sludge was proposed. According to this method, a biofilm is formed on the surface of the porous granular material filled in the septic tank 2, and organic wastewater is produced by the chemical action of calcium ions and the like eluted from the biofilm and the porous granular material. Since the organic substances, nitrogen, phosphorus, etc. in D are captured, it exhibits an excellent effect in purifying the organic wastewater D.

However, if this method is continuously performed for a certain period of time, suspended solids in the organic wastewater D and dead bodies of microorganisms adhere between the porous particles, and these block the pores of the porous particles. As a result, the purification performance of the porous granular material deteriorates, so it is necessary to introduce fresh water from the lower portion of the septic tank 2 in accordance with a conventional method to carry out so-called backwashing of the septic tank 2. As the backwash water used at this time, a part of the treated water W1 treated and discharged by the second settling tank 3 is reused and the treated water W1 is returned to the septic tank 2.

After being returned to the septic tank 2 and backwashed as described above, suspended water W2 discharged from the septic tank 2 contains suspended substances and dead bodies of microorganisms adhering between the porous particles. It is mixed. Therefore, the suspension water W2 is usually used as the sludge settler 4
And is treated together with the sludge M.

By the way, in the above-mentioned conventional method, the suspended solids floating in the organic wastewater D flow into the septic tank 2 without being sufficiently removed by the first settling tank 1, so that the septic tank 2
Clogging occurs between the porous granular materials inside, and the purifying ability decreases. Therefore, in order to maintain the purification capacity, there is a problem that the capacity of the first settling tank 1 must be increased or the number of backwashing must be increased to increase the size of the sludge settling tank 4.

Therefore, the present inventors have conducted extensive studies in order to solve the above problems, since the suspension water W2 after backwash contains fine powder of calcium silicate hydrate, the suspension water W2 The present inventors have found the fact that, when returned to the first settling tank 1, the above-mentioned suspended solids are captured by the fine powder and the settling of the suspended solids in the first settling tank 1 is promoted, and the present invention was reached.

Therefore, the object of the present invention is to utilize calcium silicate hydrate contained in the suspension water after backwashing to accelerate the sedimentation of suspended solids in the first settling tank, which in turn leads to the porosity in the septic tank. An object of the present invention is to provide a method for purifying organic wastewater that can reduce the amount of suspended solids adhering to the granular material and enhance the purification efficiency in the septic tank.

Configuration of the Invention (Means for Solving Problems) Therefore, in order to achieve the above-mentioned object, the present invention provides a first precipitation tank,
The organic waste water is sequentially passed through the septic tank and the second settling tank that contain the porous granular material containing calcium silicate hydrate as a main component, and the sludge accumulated in both the settling tanks is guided to the sludge settling tank. A method for purifying organic wastewater, which comprises sludge treatment, which comprises, after backwashing the septic tank, introducing suspended water discharged from the septic tank into the first settling tank. It is what

(Function) When the septic tank is backwashed, the surface of the calcium silicate hydrate filled in the septic tank is scraped off by the backwash water. Then, the fine powder of calcium silicate hydrate scraped off at this time is introduced into the first settling tank in a state of being contained in the suspended water discharged from the septic tank. The introduced suspended water captures suspended substances in the organic waste water in the first settling tank and causes them to settle.

(Example) Hereinafter, one example which materialized the present invention is described based on a drawing.

The organic wastewater D in this example consists of livestock urine wastewater,
Suspended substances (SS), phosphorus, nitrogen, etc. are contained.
As shown in FIG. 1, this organic wastewater D is screen 5
Through the first settling tank 1. The screen 5
Is a wire mesh having a mesh size of 2 to 4 inches, and removes relatively large solid matter in the organic wastewater D,
These are prevented from entering the first settling tank 1.
Of the organic wastewater D that has flowed into the first settling tank 1, components having a relatively large specific gravity settle down due to their own weight and become sludge M and accumulate. The sludge M is guided to the sludge settling tank 4.
The pH of the organic wastewater D from which the sludge M has been removed is adjusted in the adjusting tank 6.
The water temperature is adjusted and the water flows into the septic tank 2.

In the septic tank 2, the particle size is 5 to 10 mm, the specific gravity is 0.5, and the porosity is 50.
~ 90% filled with porous granules based on calcium silicate hydrate. This porous granular material is silica stone,
Silica and other siliceous raw materials and calcareous raw materials are used as the main raw materials, these are blended, then an appropriate amount of water and a foaming agent, etc. are added for foaming, and autoclave curing is performed with saturated steam at about 180 ° C. . The porous granular material thus formed has large irregularities on its surface, and microorganisms are easily attached to the irregularities. In addition, the porous granular material
It has a pH buffering capacity and can maintain the pH of the drainage in a container at around 8.

A large number of microorganisms are cultured in the septic tank 2, and these microorganisms adhere to the surface of the porous granular material to form a biofilm, and the organic wastewater D flowing into the septic tank 2 Biodegrades organic substances. An air pump is connected to the lower part of the septic tank 2 so that air is forcibly sent into the septic tank 2, that is, aeration is performed to promote biodegradation by the microorganisms.

The organic wastewater D treated with microorganisms in the septic tank 2 is sent to the second settling tank 3, and the biologically active microbial flocs in the organic wastewater D settle and are deposited as sludge M. The sludge M is guided to the sludge settling tank 4 together with the sludge M accumulated in the first settling tank 1. The substantially transparent treated water W1 from which the sludge M has been removed is sent to the disinfecting tank 7, where E. coli and the like in the treated water W1 are disinfected and then discharged into a river or the like.

In addition, a part of the treated water W1 discharged from the second settling tank 3 to the disinfection tank 7 is transferred to the lower part of the septic tank 2,
It is possible to flow into the septic tank 2 as backwash water. Therefore, the porous granular material filled in the septic tank 2 can be appropriately backwashed with the treated water W1. Then, the suspension water W2 generated by backwashing as in War Record is discharged from the upper part of the same septic tank 2 and guided to the first settling tank 1.

The sludge M deposited in each of the first settling tank 1 and the second settling tank 3 is guided to a sludge settling tank 4, concentrated in a sludge thickening tank 8 and then dehydrated and incinerated.

By the way, when the purification treatment method of the present embodiment is performed for a certain period of time in a pond group, suspended substances adhere between the porous granular bodies filled in the purification tank 2 and the purification treatment capacity thereof is reduced.
In this case, similar to the conventional purification treatment method, backwashing is performed using a part of the treated water W1 discharged from the second precipitation tank 3 to wash the porous granular material. At this time, aeration is performed with a larger amount of air than during normal operation of the purification processing device. Then, the organic substance attached to the surface of the porous granular material,
The dead bodies of the microorganisms are separated from the porous granular material, and the surface portion of the calcium silicate hydrate forming the porous granular material is slightly scraped off by the intense aeration during the backwashing. Thus, the separated fine particles of the organic substance and the scraped off calcium silicate hydrate are discharged from the septic tank 2 while being contained in the suspension water W2, and the first precipitation tank 1
Be transferred to.

The fine powder of calcium silicate hydrate in the suspension water W2 transferred into the first settling tank 1 captures fine and hard-to-precipitate suspended substances floating in the first settling tank 1, and Will settle together.

In order to confirm the effect of the present embodiment, when the suspended water W2 discharged from the septic tank 2 is guided to the first settling tank 1, BOD, suspended solids, nitrogen, and phosphorus flowing into the adjusting tank 6 in (A) When each amount and the suspension water W2 discharged from the same septic tank 2 are led to the sludge settling tank 4 instead of the first settling tank 1 (B)
And the amount of each component of was measured. In this experiment, pig house drainage was used as the organic drainage D, and the septic tank 2 was backwashed while being aerated for 5 minutes with 6 times the amount of air that was used during normal purification treatment equipment operation, and then the suspension was washed. Suspended water W2 was led to the first settling tank 1 or the sludge settling tank 4 in a state where all were taken out.
The measurement results are shown in the following table.

From this measurement result, it is possible to introduce the suspended water W2 discharged from the septic tank 2 into the first settling tank 1 as compared with the case where the suspended water W2 is introduced into the sludge settling tank 4, which are BOD, suspended solids, nitrogen and phosphorus. It can be seen that many of these are removed.

As described above, according to the purification treatment method of the present embodiment, unlike the conventional purification treatment method in which the treated water W1 discharged from the septic tank 2 is guided to the sludge settling tank 4, the second treatment is accompanied by the organic wastewater D. The amount of suspended matter reaching the settling tank 3 is reduced.
Further, in this embodiment, a large amount of the suspended solids is precipitated in the first settling tank 1, so that the amount of the suspended solids sent to the septic tank 2 is smaller than that in the conventional purification treatment method, and therefore, the amount of the suspended particles in the porous granular material is reduced. The amount of adhesion is reduced and the purification treatment efficiency is improved.

The present invention is not limited to the configuration of the above-described embodiment, and may be embodied by being arbitrarily modified within the scope not departing from the gist of the invention as follows.

(1) In addition to the livestock urine sewage,
It can be applied to the purification of various organic wastewater such as household wastewater and sewage.

(2) In the above embodiment, a part of the treated water W1 discharged from the second settling tank 3 is returned to the septic tank 2 as backwash water, but the wastewater discharged from the septic tank 2 can also be used as backwash water. .

Effect of the Invention As described in detail above, according to the present invention, calcium silicate hydrate contained in the suspension water after backwashing can be used to promote the sedimentation of suspended substances in the first settling tank. Therefore, it is possible to reduce the amount of suspended solids adhering to the porous granular material in the septic tank and to enhance the purification efficiency in the septic tank.

[Brief description of drawings]

FIG. 1 is a block diagram showing a method for purifying organic wastewater embodying the present invention, and FIG. 2 is a block diagram showing a conventional technique. 1 ... 1st settling tank, 2 ... septic tank, 3 ... 2nd settling tank,
4: Sludge settling tank, D: Organic wastewater, M: Sludge, W2
…… Suspended water.

Claims (1)

[Claims] 1. A first settling tank (1), a septic tank (2) containing a porous granular material containing calcium silicate hydrate as a main component, and a second settling tank (3) are provided with organic wastewater ( In the method for purifying organic wastewater, the sludge (M) accumulated in the both sedimentation tanks (1, 3) is introduced into the sludge sedimentation tank (4) and sludge treated while passing through D). A method for purifying organic wastewater, which comprises backwashing (2) and then introducing the suspended water (W2) discharged from the septic tank (2) into the first settling tank (1).