JPH0217239B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for rationally treating human waste wastewater using a new process and always stably obtaining highly treated water. [Prior art and problems to be solved by the invention] The most typical process for treating human waste is

[Table] However, this process had the major drawbacks of unstable solid-liquid separation and the generation of large amounts of coagulated and settled sludge that was difficult to dewater. On the other hand, more recently,

[Means for solving problems]

The present invention involves adding magnesium ions and a polymer flocculant to human waste wastewater, then performing solid-liquid separation, and treating the obtained solid-liquid separated liquid in a biological nitrification and denitrification process. This is a human waste wastewater treatment method characterized by membrane separation of activated sludge slurry flowing out from a nitrogen process. [Function] Hereinafter, the function of the present invention will be described in detail with respect to human waste, with reference to the drawings showing one embodiment of the present invention. The human waste 1 carried in is removed with a fine-mesh screen 2, and the removed human waste 3 is treated with magnesium ions (Mg ²⁺ ) 4, such as Mg(OH) ₂ , MgO,
After adding a compound that dissociates Mg ²⁺ selected from MgCl ₂ or the like, a cationic polymer 5, for example, as a polymer flocculant is further injected, and flocs are formed in a flocculation tank 6. The flocculated slurry formed into flocs in the flocculation tank 6 is supplied to a centrifugal dehydrator 8 to dehydrate the SS component, and is separated into a dehydrated cake 9 and a dehydrated separated liquid 10. On the other hand, the residue 11 removed by the screen 2 is dehydrated in a screw press 12 to obtain a residue 13, and the screw press dehydrated separated liquid 14 is mixed with the removed human urine 3 for treatment. By the way, high concentration (usually 500
The amount of PO ₄ ^3- contained in
A precipitation reaction occurs with Mg ²⁺ 4, resulting in MgNH ₄ PO ₄
↓, Mg ₃ (PO ₄ ) ₂ ↓, MgHPO ₄ ↓ and other precipitates are generated and converted into solid phase. Thereafter, by injecting the cationic polymer 5 into the filtered human waste 3 containing these precipitates, crystals such as MgNH ₄ PO ₄ , SS in the human waste, colloids, etc. are co-agglomerated, as will be described later. It is preferable that surplus activated sludge 15 (excess of concentrated slurry 23 separated in membrane separation process 21) generated in the biological nitrification and denitrification process is removed and mixed with urine 3. At this time, microcrystals such as MgNH ₄ PO ₄ , colloids in human waste, etc. are added to excess sludge.
It is adsorbed on the surface of the membrane and removed by coagulation very effectively. Therefore, the dehydrated cake 9 dehydrated in the centrifugal dehydrator 8 is mixed with the dehydrated residue 13 dehydrated in the screw press 12, and is rich in inorganic substances rich in fertilizing ingredients such as MgNH ₄ PO ₄ . It can be used as an organic fertilizer. In addition, agglomerated slurry 7 containing MgNH ₄ PO ₄ crystals
Centrifugal dehydrator 8, which does not require cloth, is suitable as a model for dehydrating. However, Screw Press,
Dehydrators that use cloth, such as belt presses and filter presses, can also be used, although MgNH ₄ PO ₄ tends to adhere to the cloth and clog the cloth. Furthermore, instead of the dehydration treatment using the centrifugal dehydrator 8 or the dehydrator using the cloth, ordinary solid-liquid separation means such as sedimentation separation, flotation concentration, and screen separation may be used. The solid-liquid separated liquid corresponds to the dehydrated separated liquid 10. Thus, the dehydrated separated liquid 10 from which SS and PO ₄ ^3- have been highly removed (more than 90%) is supplied to a biological nitrification and denitrification process to remove BOD, COD, and TN.
As the biological nitrification and denitrification process, the illustrated example shows a nitrification liquid circulation type, which consists of a first denitrification tank 16, a nitrification tank 17, and a second denitrification tank 18.
The nitrification liquid 19 is circulated from the denitrification tank 16 to the first denitrification tank 16. In addition, a small amount remains in the dehydrated separation liquid 10 (several 10 mg/
(below) PO ₄ ^3- is taken up and removed within the activated sludge cells, which are maintained at high concentrations during the biological nitrification and denitrification process. Next, the activated sludge slurry 20 flowing out from the biological nitrification and denitrification process is separated into a membrane separation process 21 equipped with a UF membrane, a microfiltration (MF) membrane, etc. (tubular type or plate-and-frame type is preferred).
The membrane permeate water 22 is separated into extremely clear membrane permeated water 22 with zero SS and several mg/or less of BOD, TN, and PO ₄ ^3- and concentrated slurry 23 . The membrane-permeated water 22 has a quality that can be discharged as it is, but in cases where further removal of COD and chromaticity is required, ozone treatment or activated carbon adsorption treatment may be performed. In addition, if an extremely high level of PO ₄ ^3- removal is required, after adding the required amount of Al-based or Fe-based flocculant to the activated sludge slurry 20 flowing out from the biological nitrification and denitrification process, It may also be supplied to the membrane separation step 21. In addition, most of the concentrated slurry 23 separated in the membrane separation step 21 is removed from the first stage of the biological nitrification and denitrification step.
Although the surplus sludge 15 is recycled to the denitrification tank 16 and is small, it is preferable to mix the surplus sludge 15 with the removed human waste 3 as described above. [Example] Human waste brought to the human waste treatment plant in Z City, Kanagawa Prefecture,
Remove the residue with a 0.7mm fine rotary screen,
Removal of human urine with water quality shown in Table 1 was obtained.

[Table] 1000mg/Mg(OH) ₂ and 1~1.5Kg Dry Solid per 1Kl of the sedimented urine were added to the residual sludge generated from the subsequent biological nitrification and denitrification process, and the mixture was mixed for 30 minutes. After adding 250 mg of Evagrowth C-104G (trade name of Ebara Infilco Co., Ltd.) as a cationic polymer and stirring with a pipe (very good flocs with a diameter of 5 to 8 mm were formed), centrifugal dehydration using a screw decanter was performed. The water was supplied to a machine and dehydrated. As a result, moisture 82-83
% dehydrated cake and a dehydrated separated liquid having the water quality shown in Table 2 were obtained, and SS and PO ₄ ^3- were removed to a high degree.

[Table] Next, this dehydrated separated liquid is processed into a biological nitrification and denitrification process using nitrification liquid circulation (activated sludge MLSS 15000mg/
, residence time: 9 days), and the dehydrated separated liquid was
After biologically removing BOD, COD, TN, PO ₄ ^3- , etc., the activated sludge slurry flowing out was pumped into a tubular type UF membrane module made of polyolefin with a molecular weight cutoff of 40,000 and subjected to membrane separation. ,
Clear membrane permeated water and concentrated slurry having the water pipes shown in Table 3 are obtained. The concentrated slurry is returned to the first denitrification tank of the biological nitrification and denitrification process, and the surplus is added to the filtered urine as described above. did.

〔Effect of the invention〕

According to the present invention described in detail above, the following important effects can be obtained, and the problems of conventional processes can be solved very rationally. Sludge treatment is improved, with almost no coagulated sludge, which is difficult to thicken and dewater and is difficult to treat. A sufficient phosphorus removal rate can be obtained, and there is no need to install a PO ₄ ³ -adsorption removal process that requires complicated operation management. Since there is no need to dispose of the recycled waste liquid of the PO ₄ ^3- adsorbent, a crystallizer, a centrifugal separator for crystal separation, etc. are naturally unnecessary, and construction costs can also be reduced. Process configuration is simplified. Organic fertilizer rich in fertilizing ingredients can be produced.

[Brief explanation of drawings]

The drawing is a flow sheet showing one embodiment of the invention. 1... Human waste, 2... Screen, 3... Removal human waste, 4... Magnesium ion, 5... Cationic polymer, 6... Coagulation tank, 7... Coagulation slurry, 8...
...Centrifugal dehydrator, 9...Dehydrated cake, 10...Dehydrated separated liquid, 11...Residue, 12...Screw press, 13...Dehydrated residue, 14...Screw press dehydrated separated liquid, 15... ...excess sludge, 16...1st
Denitrification tank, 17...Nitrification tank, 18...Second denitrification tank,
19... Nitrification liquid, 20... Activated sludge slurry, 21
... Membrane separation step, 22 ... Membrane permeated water, 23 ... Concentrated slurry.

Claims (1)

[Claims] 1. After adding magnesium ions and a polymer flocculant to night soil wastewater, solid-liquid separation is performed, and the obtained solid-liquid separated liquid is treated in a biological nitrification and denitrification process,
A method for treating night soil wastewater, which comprises membrane-separating activated sludge slurry flowing out from the biological nitrification and denitrification process. 2. The method for treating human waste wastewater according to claim 1, wherein surplus sludge from the biological nitrification and denitrification process is added to the human waste wastewater.