JPH0419920B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides a process system that can rationally treat human waste using a unique process and always obtain stable and good treatment.

[Prior Art] The most typical process for treating human waste at present is the process of undiluted biological denitrification→coagulation sedimentation→activated carbon treatment process. (This is referred to as conventional method 1) However, this process has the drawback of generating coagulated and settled sludge.

On the other hand, very recently, undiluted biological denitrification treatment→
A process has been proposed in which UF membrane separation → activated carbon → phosphorus adsorption using a zirconium-based adsorbent.
(This is called conventional method 2.) However, while this process does not require the coagulation-sedimentation step, it does not require the phosphorus adsorption removal step, which requires complicated steps such as pH adjustment, re-neutralization, and adsorbent regeneration operations.
It has the disadvantage that it must be installed after the UF membrane process.

The reason why such a phosphorus adsorption and removal process has to be incorporated is that the UF membrane does not completely separate phosphorus and passes through it as is. It was.

[Problems to be Solved by the Invention] The present invention aims to solve the problems of conventional methods 1 and 2. Specifically, the present invention aims to solve the problems of conventional methods 1 and 2. Obtaining a removal rate.

To make it unnecessary to provide a phosphorus adsorption step as in conventional method 2 after the UF membrane separation step.

is the problem to be solved.

[Means for solving the problem] After adding organic sludge, a magnesium compound, and a polymer flocculant to human waste, solid-liquid separation is performed, and the separated liquid is subjected to anaerobic or aerobic biological treatment, and then
Treat human waste by separating solid and liquid using a UF membrane.

The present invention will be explained in more detail below with reference to the drawings. FIG. 1 shows a flow sheet of one embodiment of the present invention.

When surplus activated sludge 3 discharged from biological treatment process 2 and magnesium compounds 4 such as Mg(OH) ₂ and MgO are added to human waste 1 and stirred in a mixing tank, NH ₄ ⁺ and PO contained in human waste 1 are added. ₄ ^3- ion and Mg ²⁺
A rapid chemical reaction occurs with the ions (precipitate formation reaction),
A precipitate of NH ₄ MgPO ₄ (fine particles and difficult to separate from solid to liquid) is formed. Next, a polymer flocculant 5 (a cationic polymer is preferred, and a combination of cationic and anionic polymers is particularly optimal) is added and stirred (flow path stirring is sufficient), thereby dissolving the SS in human waste,
It was observed that colloidal components and fine particles of NH ₄ MgPO ₄ co-agglomerated with excess activated sludge 3 very effectively.

This agglomerated floc has a large particle size (5 to 6 mm) and can be easily separated into solid and liquid by rotating or using an inclined screen 6 without precipitation. The important thing here is that without adding organic sludge 3, Mg compound 4
Adding only the polymer flocculant 5 and the polymer flocculant 5 did not produce good results, and the fine particles of NH ₄ MgPO ₄ were added to the screen 6.
It was confirmed that the coexistence of organic sludge 3 plays an extremely important role.

The organic sludge 3 and the Mg compound 4 may be added in whichever order or at the same time.Although the polymer flocculant may be added at the same time as the organic sludge and the Mg compound, it is preferable to add it later.

However, the screen separated sludge 7 is 3 to 4%
(solid matter concentration), and can be highly dehydrated by the screw press dehydrator 8, and the moisture content of the dehydrated cake 9 is extremely low at 50 to 60%. The reason why cake 9 with such low moisture content is obtained is due to the fiber content of toilet paper etc. in human urine.
This is because the dense crystals of NH ₄ MgPO ₄ function as an effective dehydration aid.

On the other hand, screen separated water 10 and dehydrated separated water 11
(About 90% of SS and phosphoric acid in human urine 1, and 50% of BOD
% has been removed) is biological treatment step 2
(aerobic biological treatment or anaerobic digestion);
BOD, COD, and nitrogen components are removed. (Nitrogen components are not removed in the case of anaerobic digestion.) If an aerobic method (including biological nitrification and denitrification method) is adopted in biological treatment step 2, phosphorus can also be removed biologically.

Next, the microbial slurry 15 flowing out from the biological treatment process 2 is directly passed through the UF membrane separation process (Ultra
Solid-liquid separation is performed at step 12 (Filtration) 12. The appropriate molecular weight cutoff for the UF membrane is 20,000 to 40,000.

Phosphorus, BOD, COD, and N components have been highly removed from the UF membrane permeated water 13, and the water quality is such that it can be discharged as is, except when the purpose is to remove very high chromaticity and COD. Therefore, there is no need for the troublesome phosphorus adsorption/removal process as in process 2 of the conventional method described above.

The reason for this is that the present invention can effectively remove phosphorus from human waste through the UF membrane and the precipitate formation reaction of NH ₄ MgPO ₄ in the first stage of the biological treatment process.

Furthermore, if aerobic biological treatment (including biological dephosphorization) is adopted in the biological treatment process, phosphorus can be removed biologically, so the NH ₄ MgPO ₄ precipitate formation reaction and biological dephosphorization can be combined. Phosphorus is removed to a high degree by both, and the phosphoric acid concentration in the water permeated through the UF membrane is 1.
This is because the amount is about 3 mg/.

In addition, as a result of examining the optimal method when adopting an anaerobic digestion method in biological treatment step 2, it was found that the upward flow blanket method (UASB method) and the immobilized growth microorganism method of anaerobic digestion bacteria are optimal in the present invention. One thing was recognized.

In other words, both of these anaerobic digestion methods have the remarkable feature of being capable of extremely high-speed methane fermentation, but on the other hand, methane fermentation of liquids containing SS and colloidal organic matter has problems with scum formation. In addition to this, there is a major drawback in that it is inappropriate in principle. However, in the present invention, the SS
It is possible to almost completely remove colloidal organic matter using a unique flocculation method.
The disadvantages of the USAB method and the immobilized growing microorganism method are resolved and only the advantages are brought out.

Furthermore, in the dehydrated cake 9,
It contains a large amount of NH ₄ MgPO ₄ crystals and organic matter, and has a low moisture content, so it can be used as is as a fertilizer with extremely high fertilizing properties.

[Example] Human waste (BOD 10,000-14,000 mg/, SS 13,000-16,000) is delivered to the human waste treatment plant in Otsu City, Kanagawa Prefecture.
mg/, PO ₄ 900-1200 mg/) to Mg(OH) ₂
1000mg/added, and furthermore, excess activated sludge (solids concentration 1.5%) from the activated sludge treatment process was added to human waste 1
After adding 1 Kgds to Kl and mixing for 30 minutes,
DAM-based cationic polymer per SS of the mixture
As a result of adding 1.5 to 2.5% (wt%) and stirring for 1 minute, large particle size flocs were formed and
Solid-liquid separation was quickly performed using a 60° inclined wedge wire screen.

The solid concentration of screen thickened sludge is 3.5%~
4.0%, SS of screen separated water is 400~600
mg/, and the soluble _PO4 was 80-110 mg/.

The solid concentration of screen thickened sludge is 3.5%~
The moisture content of the dehydrated cake was 4.0%, and it could be dehydrated as it was using a screw press dehydrator (without steam heating), and the moisture content of the dehydrated cake was 52 to 55%.

Mixed liquid of screen separated liquid and screw press dehydrator separated water (soluble BOD 2700-3300 mg/)
After being treated with a biological dephosphorization type activated sludge method (with an anaerobic section before the aerobic section),
MLSS18000mg/activated sludge slurry is directly UF
Membrane (molecular weight cut off 40000, flux 1000/ ^m2・
hr), the quality of the permeated water was BOD5.
-8 mg/, SS zero, PO ₄ 0.1-3 mg/, which was extremely good, and there was no need to provide a phosphorus adsorption step after the UF membrane.

[Effects of the Invention] By treating human waste using the unique process of the present invention, a sufficient phosphorus removal rate can be obtained without requiring the coagulation and sedimentation step of the conventional method, and UF
A rational human waste treatment that does not require a phosphorus adsorption step after the membrane separation step can be performed.

[Brief explanation of drawings]

FIG. 1 is a flow sheet showing the process flow of an embodiment of the present invention. 1... Human waste, 2... Biological treatment process, 3... Excess activated sludge, 4... Magnesium compound, 5... Polymer flocculant, 6... Screen, 7... Screen separated sludge, 8... Screw Press dehydrator, 9
... Dehydrated cake, 10 ... Screen separated water, 1
1... Dehydrated separated water, 12... UF membrane separation process, 1
3... UF membrane permeated water, 15... Microorganism slurry.

Claims (1)

[Claims] 1. After adding organic sludge, a magnesium compound, and a polymer flocculant to human waste, solid-liquid separation is performed, the separated liquid is subjected to anaerobic or aerobic biological treatment, and further solid-liquid separation is performed using a UF membrane. Human waste disposal method.