JPS5962396A - Treatment of organic waste water containing ammonia - Google Patents

Abstract

PURPOSE:To simplify considerably process by treating biologically org. waste water contg. ammonia, evaporating and concentrating the treated water, supplying the condensed water of the evaporated steam to an ammonia stripping stage, and using the outflow water of the stage as the highly treated water of the above-described org. waste water. CONSTITUTION:Org. waste water 1 contg. ammonia is biologically treated in a biological treatment stage 2, and the activated sludge slurry 3 flowed out thereof is subjected to a solid-liquid sepn. in a solid-liquid sepn. stage 4. Separated water 7 is preheated in a heat exchanger 8 and is then fed to an evaporator 9'. Evaporated steam 10 is compressed and heat-up with a steam compressor 11, and is utilized as a heat source for the indirect heating section 12 of the evaporator 9 and is made into condensed water 13. The water 13 is fed to an ammonia stripping stage 14, and is removed of the remaining ammonia, whereby highly treated water 15 is produced. The water is further cooled with the heat exchanger 8 and is utilized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating ammonia-containing organic wastewater such as human waste and various industrial wastewaters.

A process that has been evaluated as the most advanced in conventional human waste treatment, and the number of examples of which has been rapidly increasing, is, for example, adding dilution water (approximately 10 times the amount) to human waste, performing biological nitrification and denitrification treatment, and then using the treated water. This method involves coagulating sedimentation, sand filtering, ozone treatment, activated carbon adsorption, and sterilization.

Although this process is currently regarded as a powerful process, upon technical evaluation from a strict viewpoint, the present inventors have come to realize that it inherently has the following serious drawbacks.

Namely.

(i) Since many unit operations are arranged in series, the process is complicated and maintenance is poor.

■ It is necessary to add a large amount of inorganic flocculant to the coagulation-sedimentation or coagulation-floating process, which consumes a large amount of resources and generates aqueous coagulation-sediment sludge, which requires a large amount of processing and disposal power. Requires expenses. ′However, the presence of flocculated sludge reduces the quality of the compost product.

■ Ozone generation requires a large amount of power, approximately 25 IαVfl/Ky-Q, and activated carbon treatment requires approximately 500 IαVfl/Ky-Q.
It requires a high cost of 600 yen/kl-L urine.

The present inventor had strong doubts about the current state of the art, and conducted studies to develop a method to eliminate the various drawbacks of the conventional process described in J1 and A4, and completed the present invention.

The effects of the present invention can be said to be surprising; the conventional steps of coagulation and sedimentation, sand filtration, ozonation, activated carbon adsorption, and sterilization are completely unnecessary, and the quality of treated water is significantly improved. Furthermore, operational management of the biological treatment process becomes easier and the required volume is reduced.

That is, in the present invention, after biologically treating ammonia-containing organic wastewater, the biologically treated water is subjected to evaporative concentration treatment, the condensed water of the evaporated steam is further supplied to an ammonia strinovating process, and the effluent of the process is treated with the organic wastewater. This is a method for treating ammonia-containing organic wastewater, which is characterized by highly treated wastewater.

An embodiment of the present invention will be described below with reference to the drawings.

A biological treatment process using the biological nitrification denitrification bed method or biological nitrification method, in which human waste (often contaminated with septic tank sludge) is added to it with dilution water. 2 to remove most of the nitrogen components such as BOI) and NH3-N. Adding a large amount of dilution water to the biological treatment step 2 is extremely undesirable because it not only causes a drop in water temperature but also increases the amount of liquid to be evaporated and concentrated.

Therefore, activated sludge nulla I flowing out from biological treatment process 2
J-31r: I, solid-liquid separation is performed in the solid-liquid separation process 4 using a centrifugal compressor, etc., and most of the separated sludge 5 is recycled to the biological treatment process 2 as return sludge 5', and excess activated sludge is 6 is processed in a sludge dewatering process (not shown) using a filter press, screw press, or the like.

In biologically treated water 7, although BOD and nitrogen components have been successfully removed, large amounts of non-biodegradable COD, phosphoric acid, chromaticity, and organic nitrogen remain, and ammonia nitrogen also remains. There is. For this reason, in the conventional process, the biologically treated water 7 is subjected to coagulation sedimentation, sand filtration, ozone treatment, and activated carbon treatment to remove COD, chromaticity, phosphoric acid, and organic nitrogen. Do not use conventional methods that have many problems.

That is, after the biologically treated water 7 is preheated in the heat exchanger 8, it is supplied to the evaporator 9' of the evaporation concentration step 9, and the evaporated water vapor 10 is
After being compressed and heated by the vapor compressor 11, the evaporator 9
', and the latent heat of condensation of the water vapor is reused as a heat source for evaporation.

The condensed water 13 flows into the ammonia strinobing step 14 and then passes through the heat exchanger 8 to become highly treated water 15.

Since the condensed water 13 is distilled water, it is colorless and transparent and COD, B
OD, phosphoric acid, and SS are in trace amounts, and the water quality is of the highest quality that could not be expected in conventional processes as undiluted human waste treated water. However, ammonia nitrogen in biologically treated water 7 easily evaporates and condenses. Since the water is contained in the water, the ammonia is removed by the strinoping step 14. The higher the temperature, the more easily ammonia is dissipated, but in the present invention, the temperature of the condensed water 13 is as high as about 100°C (the pressure inside the evaporator 9' is almost normal pressure), so ammonia is very efficiently dissipated into the Strinopyrite/Group. removed.

On the other hand, the ammonia-containing steam 18 is disposed of through a sulfuric acid or ioammonia absorption step, an ammonia decomposition step by combustion (none of which are shown), and the like.

Next, this embodiment includes the following points as one of the important concepts. In other words, the microbial oxidation heat generated when human waste 1 is biologically treated (according to the inventor's actual measurements, 30,000
The effect is that the temperature of the liquid in the biological treatment tank, and therefore the temperature of the biologically treated water 7, rises by 20 to 30 degrees Celsius over the temperature of the inflowing human waste 1. Focusing on this, evaporation and concentration of materials whose temperature has been raised by microbial oxidation heat has been an important concept. This saves external thermal energy for evaporation.

Therefore, a small amount of the evaporation source m liquid 16 is disposed of in an optional disposal process 17 including combustion, evaporation and drying.

In the above-described embodiments, the vapor compression method is used as the evaporation concentration step 9, but it is also effective to use the multiple effect method or a combination of the vapor compression method and the multiple effect method. Needless to say.

The important effects of the present invention as described above are as follows.

■ Nitrogen components such as ammonia are removed in a very rational manner, and the highest quality treated water that could not be expected with conventional processes is obtained, and at the same time, the process is significantly simplified.

(n) Flocculants, ozone generation electricity, activated carbon, sterilizers, and activated carbon regeneration energy are all unnecessary.

■ Coagulated sludge (Al(OH)
Since 3Fe (OH)3 is the main component) is not generated at all, the sludge that must be treated is only surplus biological sludge, resulting in a significant reduction in sludge treatment and disposal costs.

■ Complete removal of ammonia does not need to be achieved through the biological treatment process alone; it is assisted by the ammonia nutrinoping process, making the operational management of the biological treatment process easy.
The amount of waste required for the biological treatment process can also be significantly reduced.

■ Since the dewatered cake does not contain inorganic flocculated sludge that is difficult to dewater, the calorific value of the dehydrated cake is as high as approximately 4000 ki/7-D, S, and the water content can be easily reduced to 65 ki or less. Because of this, it has excellent fuel properties. Therefore, since it self-combusts, it does not require auxiliary fuel such as heavy oil.13 This effect greatly contributes to energy saving.

■ The water to be evaporated is biologically treated water, and the human waste is not directly evaporated, so there is no odor generation, ammonia, or volatile organic acids scattering, and the high concentration of SS components in the human waste inside the evaporator No problems such as clogging or inability to flow the liquid.

■ The chloride ion concentration of conventional human waste water is 300-30
00 Due to the high level of Ir7/, it is difficult to use the water for irrigation in mountains and fields due to salt damage, but since the chlorine ions in the treated water of the present invention are about 0 to 1 mg/L,
Water can be easily reused for cancer treatment.

■ Furthermore, when human waste is subjected to IM direct heat evaporation treatment, there are compounds present in the human waste (G).There is a high possibility of corrosion of the evaporator due to the acid, but the present invention eliminates sulfurization by biological treatment. Since organic acids and organic acids are removed, the above problem is solved.

Next, examples of the present invention will be described.

Example: Human waste transported to the Kanagawa Moito human waste treatment plant (septic tank sludge 1)
After removing the sludge using a rotary screen, the waste was treated without dilution in a biological nitrification and denitrification process VC with nitrification liquid circulation at a processing volume of 1 u/a+. MLSS of biological nitrification and denitrification process is 18,000 to 20,000
rng/l, the residence time was 3 days. The water temperature in the biological treatment tank was 33 to 42°C due to heat of microbial oxidation.

A chemical-free pouring type centrifugal concentrator (Tomoe Kogyo products) is used for solid-liquid separation of the biological treatment tank effluent slurry, resulting in a concentration of 1! If5~6
Most of the sludge was recycled to the denitrification tank, and a portion was supplied to the dewatering process as surplus sludge.

A fully automatic filter press was used for the dehydrator.

The moisture content of the dehydrated cake was 63 to 64 inches, the cake calorific value was about 4000 kd/Kp-D,S, and it easily self-combusted in a fluidized bed incinerator.

Therefore, centrifugal concentrated separated water (SS100-120ηA)
is supplied to a vapor compression evaporator and concentrated to a concentration ratio of 50 times, and
A concentrated solution of 0 vinegar and 180 g/day of steam condensate were obtained, and then residual ammonia was removed in a steam ammonia stripping step.

The water quality of the filtered human waste, biological nitrification and denitrification treated water, condensed water, and effluent from the Strinobing process is shown in the table below.

(All units are 2 A)

[Brief explanation of the drawing]

The drawings are flow sheets illustrating embodiments of the invention. 1... Human waste, 2... Biological treatment process, 3... Activated sludge slurry, 4... Solid-liquid separation process, 5... Separated sludge, 5'... Returned sludge, 6... Surplus activated sludge, 7...
・Biological treatment water, 8... Heat exchanger, 9... Evaporation concentration process, 9'... Evaporator, 10... Evaporation steam, 11...
・Vapor compressor, 12...Indirect heating section, 13...Condensed water, 14...S) IJ nobbing process, 15...Highly treated water, 16...Evaporation concentrate, 17... Disposal step, 18...Ammonia-containing steam. Patent applicant: Patent attorney representing Ebara Infilco Co., Ltd.
Go Hayama - Patent attorney Sen 1) Minoru

Claims (1)

[Claims]] After biologically treating ammonia-containing organic wastewater, the biologically treated water is subjected to evaporative concentration treatment, the condensed water of the evaporated water vapor is further supplied to an ammonia strinoping process, and the process effluent is A method for treating ammonia-containing organic wastewater, which is characterized in that the organic wastewater is treated as highly treated water. 2. The method according to claim 1, wherein the biological treatment step is a step in which at least a biological nitrification reaction occurs. 3. The method according to claim 1 or 2, wherein the evaporation concentration step is of an indirect heating type.