JPH07986A - Method and device for treating water - Google Patents

Abstract

PURPOSE:To efficiently treat raw water by propagating microorganisms having a different time of alternation of generation for an appropriate time and activating the microorganisms. CONSTITUTION:This device is provided with a first biological activated carbon bed 3 in which the microorganisms having a relatively short generation alternation time is propagated and a second biological activated-carbon bed 4 in which the microorganisms having a relatively long generation alternation time is propagated. The first bed 3 is furnished with the air feed pipe 6 and backwashing pipe 8 for backwashing the bed at short time intervals, and the second bed 4 is provided with the air feed pipe 7 and backwashing pipe 9 for backwashing the bed at long time intervals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water treatment device used for water supply facilities and the like for purifying contaminated raw water to produce drinking water, and particularly stable to raw water in which ammonia nitrogen changes. The present invention relates to a water treatment device and a water treatment method capable of obtaining the above-mentioned treatment effect.

[0002]

2. Description of the Related Art Generally, water sources for water supply are obtained from surface water or underground water of lakes and rivers, groundwater, etc.
These are called raw water. Usually, various substances are dissolved in this raw water, and individual fine particles, microorganisms, etc. float in the raw water, and turbidity, color, odor, etc. are mixed in. Not for use. Therefore, in recent years, a method of performing ozone oxidation as advanced water purification treatment after coagulating sedimentation of raw water, filtration, etc. to oxidize, deodorize, decolorize organic substances contained in the raw water, and then remove the ozone oxidation product using activated carbon has been proposed. It is being advanced. In particular, in the treatment of activated carbon after the ozone treatment of raw water, microorganisms using ozone oxidation products as nutrient sources grow, the activated carbon becomes so-called biological activated carbon, and many organic substances in the raw water are removed. It is said that when activated carbon is transferred to biological activated carbon, the life of activated carbon will be 10 times or more.

[0003]

However, there are various problems in using bioactivated carbon. In particular, when the concentration of ammonia in the raw water fluctuates, the biological treatment cannot sufficiently cope with the operation of the biological activated carbon, which causes a problem in the practical application of the biological activated carbon.

The present invention has been made in view of the above points, and it is possible to use biologically activated carbon that has recently begun to be used and to reliably remove ammonia even if the concentration of ammonia in the raw water changes. An object is to provide a treatment device and a water treatment method.

[0005]

The present invention provides a first bioactive carbon layer in which a microorganism having a relatively short generation alternation time grows,
A second bioactive carbon layer in which a microorganism having a relatively long generation alternation time grows, and a first reverse layer provided in the first bioactive carbon layer, which backwashes the first bioactive carbon layer at predetermined first intervals. A washing device and a first bioactive carbon layer,
A second backwashing device for backwashing the second biological activated carbon layer at a second interval longer than the interval of, and water using the water treatment device described above. In the treatment method, the water flow is stopped at a predetermined first interval, the first biowashing device is backwashed by the first backwash device, and the water is passed at a second interval longer than the first interval. The water treatment method is characterized in that the water is stopped and the second bioactive carbon layer is backwashed by the second backwashing device.

[0006]

[Function] The inflow of raw water is stopped at predetermined first intervals, and the first
Backwashing the first bioactive carbon layer with the backwashing device described above, stopping the inflow of raw water at every second interval longer than the first interval, and removing the second bioactive carbon layer with the second backwashing device. By backwashing, it is possible to maintain and activate the microorganisms that grow inside each bioactive carbon layer for an appropriate period.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 are views showing a first embodiment of a water treatment apparatus and a water treatment method according to the present invention.

First, the basic principle of the present invention will be described with reference to FIGS.

In the present invention, as will be described later, the biological activated carbon layer of the water treatment device is divided into two parts so that the removal of polluted organic substances and the removal of ammoniacal nitrogen in the raw water are carried out completely. P. of “New Activated Sludge Method” (Industrial Water Research Committee), edited by Hashimoto and Sudo. 34, the metabolism of microorganisms, that is, the growth rate of generation alternation (generation alternation time) is B to remove organic matter.
OD assimilating bacteria (Phodopseudomonas sp
for 34 hours at 34 ° C,
Nitrifying bacteria (Nitrosomonas sp.) At 25 ° C
It has been 12.7 hours.

As described above, the growth rate of generational change of nitrifying bacteria is essentially slow. Therefore, when a single layer of biological activated carbon is used as in the conventional case, it is necessary to prevent the activated carbon from clogging and the growth of metazoans. If backwashing is frequently performed, nitrifying bacteria with a slower generation change will be washed out even if BOD-assimilating bacteria grow.
Therefore, when the ammonia nitrogen exists in the raw water, or when the ammonia nitrogen concentration in the raw water suddenly rises, the raw water may not be treated reliably. An example of this is Kaiga et al., "Advanced water purification plant experiment using ozone and biological activated carbon," Water Supply Association, Vol. 60, No. 6, 2 (Heisei 3).
1) based on June, 1). As shown in FIG. 1, it can be seen that the ammonia nitrogen concentration in the treated water is fluctuating. Such fluctuations in the concentration of ammoniacal nitrogen affect not only the management of the treatment process but also the retention of residual chlorine after treatment.

On the other hand, the present invention is a water treatment device using two bioactive carbon beds in accordance with microorganisms having different generation alternation times. The results of investigating the removal of dissolved organic matter by a bioactive carbon layer in activated carbon are described in Kaiga et al., "Advanced water purification plant experiment by ozone and bioactive carbon", Volume 60, No. 6, No. 2 of the Waterworks Association (June 1991). Based on FIG.

In FIG. 2, coagulation, sand filtration, and ozone treatment were performed before the biological activated carbon layer. As shown in FIG.
The removal characteristics of organic substances obtained by ultraviolet absorption are remarkable in the upper 50 cm of the bioactive carbon layer. Since the dissolved organic matter is metabolized by the microorganisms in the bioactive carbon layer, the microbial cells increase in the upper part of the bioactive carbon layer, and the pressure loss for filtration increases, so backwashing is usually performed once every 1 to 5 days, and It is necessary to remove the extra bacterial cells with increased adhesion and remove them from the layer. If left for a longer period of time, metazoans that grow with microbial cells as food will propagate in the activated carbon layer. Since these metazoans move by themselves and may leak out into the treated water, in consideration of the alternation of metazoans, the backwashing is carried out early for the reproduction of metazoans. That is, in using the bioactive carbon layer, it is important to consider three types of BOD-assimilating bacteria that remove organic substances, nitrifying bacteria that nitrify ammonia, and metazoans that eat and grow microorganisms. Of these, if the metabolites are to be discharged early at the same time as the BOD-assimilating bacteria, a bioactive carbon layer that matches two microorganisms with different generation alternation times (BOD-assimilating bacteria and nitrifying bacteria) will be used. There is a need.

Next, a specific structure of the present invention will be described with reference to FIG. As shown in FIG. 3, the water treatment device has a single water tank 1.
And a first bioactive carbon layer 3 arranged in the aquarium 1 where organisms having a relatively short generation alternation time grow, and a second bioactive carbon layer 4 arranged in the aquarium 1 for organisms having a relatively long generation alternation time. It has and. Also, the first biological activated carbon layer 3
The inlet chamber 13 on the inlet side is connected to the inflow pipe 2 of the water to be treated that has been oxidized by ozone, and the outlet chamber 15 on the outlet side of the second biological activated carbon layer 4 is connected to the outflow pipe 5 of the treated water. Are connected.

Further, an intermediate chamber 14 between the first bioactive carbon layer 3 and the second bioactive carbon layer 4 is provided so that air for air washing can be individually supplied to the respective bioactive carbon layers 3 and 4. A first air supply pipe 6 and a second air supply pipe 7 are provided in the outlet chamber 15, respectively. Similarly, the intermediate chamber 14 and the outlet chamber 15 are provided with a first backwash pipe 8 and a second backwash pipe 9, respectively, for supplying backwash water. In addition, the first and second air supply pipes 6, 7 and the first
The second backwash pipes 8 and 9 are provided with air wash valves 6A and 7A and backwash valves 8A and 9A, respectively.

Further, the inlet chamber 13 and the intermediate chamber 1 are used for drainage when the respective biological activated carbon layers 3 and 4 are backwashed.
4 is provided with a first drain pipe 10 and a second drain pipe 11, respectively, and these drain pipes 10 and 11 have drain valves 10A,
11A are attached respectively.

In the water treatment apparatus shown in FIG. 3, in the first biological activated carbon layer 3, BOD is mainly short in generation alternation time.
The assimilating bacterium grows, and the nitrifying bacterium mainly grows in the second biological activated carbon layer 4 mainly for a relatively long generation alternation time. In this case, not only the adsorption and removal of the pollutants by the bioactive carbon, but also the polluted organic substances in the raw water or the dissolved organic substances which have been changed to biodegradable by ozone oxidation are purified by the BOD assimilating bacteria in the first bioactive carbon layer 3. Ammonia nitrogen, which is one of the pollutants, is nitrified in the second bioactive carbon layer 4.

Next, the operation of this embodiment having such a configuration will be described.

The BOD-assimilating bacterium having a short generation alternation time metabolizes biodegradable organic substances in the upper layer of the first bioactive carbon layer 3 and proliferates as microbial cells. In this case, the BOD-assimilating bacterium grows using the activated carbon particles as a carrier, but the cells of the BOD-assimilating bacterium fill the spaces between the particles and increase the pressure loss of the water flow. Therefore, once every 1 to 5 days, stop the flow of water from the inflow pipe 2,
The air wash valve 6A and the backwash valve 8A are opened to send air and backwash water into the intermediate chamber 14 to backwash the first bioactive carbon layer 3. At this time, the BOD-assimilating bacterium of the microorganism that grows and adheres to the surface of the activated carbon particles of the biological activated carbon layer 3 is separated from the particles and becomes backwash drainage and is discharged from the drain pipe 10. Next, the flush valve 6A
By closing the backwash valve 8A and closing the drainage valve 10A of the drainage pipe 10 and performing normal water flow from the inflow pipe 2, bacterial cells adhering to the surface of particles again grow and purify water. Become.

Eggs, larvae, etc. of metazoans entering from the raw water enter the first bioactive carbon layer 3 and eat and multiply the BOD-assimilating bacteria growing on the interparticle surface. These metazoans include nematodes, earthworms, daphnia and the like. If these flow out into the treated water, they are visible to the naked eye and cause various problems. In particular, the growth of microorganisms changes seasonally, but in order to suppress these phenomena, backwashing is performed at intervals shorter than the generation replacement time of metazoans so that eggs and larvae of metazoans cannot survive in the third bioactive carbon layer. To

In the present embodiment, the generation alternation time of BOD-assimilating bacteria and metazoans growing in the first bioactive carbon layer 3 is regarded as a relatively short time, and the backwashing of the first bioactive carbon layer 3 is performed. Frequently performed at intervals of about 1 to 5 days, the BOD-assimilating bacteria and metazoans can be regularly discharged from the first biological activated carbon layer 3.

By the way, the backwashing with a short interval in the first biological activated carbon layer 3 is good for BOD-assimilating bacteria and metazoans, but is not convenient for nitrifying bacteria with a late generation change, and is washed away by backwashing. Where river water is used as raw water, sewage secondary treated water, human waste treated water, and the like cause large changes in ammonia nitrogen, and nitrifying bacteria generally do not grow easily. In particular, nitrifying bacteria are bacteria that can grow with ammonia nitrogen, carbonate, etc. as nutrients, and grow in places where there are fewer nutrient sources than BOD-assimilating bacteria.

In this embodiment, as shown in FIG. 3, the inside of the second bioactive carbon layer 4 is made into a thin condition of the concentration of dissolved organic matter,
The nitrifying bacteria are grown in the second bioactive carbon layer 4. Second
Since the nitrifying bacteria grow slowly in the biological activated carbon layer 4, the number of backwashing is far smaller than that in the first biological activated carbon layer 3, and may be once every several months or once every several weeks. The operation of backwashing is substantially the same as in the case of the first bioactive carbon layer 3, the water flow from the inflow pipe 2 is stopped, and the air wash valve 7A and the backwash valve 9A are opened. At the same time, open the drain valve 11A,
The nitrifying bacteria in the second biological activated carbon layer 4 are separated from the surface of the activated carbon particles and discharged from the drain valve 11A.

According to this embodiment, the first bioactive carbon layer 3
The organic matter in the raw water can be surely treated by the BOD assimilating bacteria growing in the inside, and the ammonia in the raw water can be surely treated by the nitrifying bacteria growing in the second biological activated carbon layer 4. In addition, BOD-assimilating bacteria, nitrifying bacteria, and the first bioactive carbon layer 3
By performing backwashing on the metazoans that grow in the plant, the BOD-assimilating bacteria, nitrifying bacteria, and metazoans can be appropriately discharged to the outside at an appropriate timing.

Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment shown in FIG. 4, while arranging the first biological activated carbon layer 3 in the first water tank 1A,
A second water tank 1B, which is a separate and independent second water tank 1A
The biological activated carbon layer 4 of FIG. 3 is arranged, and the other points are substantially the same as those of the first embodiment shown in FIG.

In FIG. 4, the same parts as those in the first embodiment are designated by the same reference numerals and detailed description thereof will be omitted. As shown in FIG. 4, in the first water tank 1A, the inlet chamber 13, the first biological activated carbon layer 3, and the first intermediate chamber 14 are arranged in this order from above.
A is provided, and in the second water tank 1B, a second intermediate chamber 14B, a second biological activated carbon layer 4, and an outlet chamber 14 are provided in order from above. Further, the first intermediate chamber 14A and the second intermediate chamber 14B are connected by a connecting pipe 17 having a pump 17a.

Next, a third embodiment of the present invention will be described with reference to FIG. The third embodiment shown in FIG.
A nutrient source supply pipe 12 for supplying a nutrient source to the nitrifying bacteria in the second biological activated carbon layer is arranged therein, and the others are substantially the same as those in the first embodiment shown in FIG.

This embodiment is particularly effective when the ammonia concentration in the raw water fluctuates or the phosphorus concentration, which is an essential condition for microbial metabolism, fluctuates. In addition, when the operation of the biological activated carbon is started up or restarted after backwashing, it is possible to activate the slow-growing nitrifying bacteria. That is, when necessary, a salt solution such as ammonium chloride, ammonium nitrate, or ammonium sulfate is supplied from the nutrient source supply pipe 12 as an ammonium nitrogen source,
When ammonia water or ammonia gas is not added to the raw water for a long time by adding ammonia water or ammonia gas, nitrifying bacteria are minimally grown and trained in the second biological activated carbon layer 4 by the added nutrient source. Can be made.

From the nutrient source supply pipe 12, phosphorus such as phosphoric acid or sodium phosphate can be added as another nutrient source. In river water, which contains a lot of lake water, the phosphorus concentration in the lake water greatly fluctuates due to plankton multiplication, death, and precipitation in the lake in spring and autumn. Therefore, when the phosphorus concentration decreases, a nutrient source can be added from the pipe 12 to maintain the growth of nitrifying bacteria in the activated carbon layer 4.

Next, a fourth embodiment of the present invention will be described with reference to FIG. The fourth embodiment shown in FIG. 6 is one in which a nutrient source supply pipe 12 for supplying ammoniacal nitrogen or phosphorus is arranged in the second intermediate chamber 14B, and the other is the second embodiment shown in FIG. It is almost the same as the embodiment.

In FIG. 6, the inflow pipe 2 into the inlet chamber 13,
A densitometer 2 for measuring the ammonia concentration and the phosphorus concentration in each of the connecting pipe 17 and the outflow pipe 5 from the outlet chamber 15.
3A, 23B and 23C are attached respectively. These densitometers 23A, 23B and 23C are connected to the control device 24. Then, the controller 24 controls the densitometer 23.
The injector 25 can be controlled based on the signals from A, 23B and 23C to supply a predetermined amount of ammonia nitrogen or phosphorus from the nutrient source supply pipe 12 into the second intermediate chamber 14B. In this case, the concentration change is continuously measured by the signals from the densitometers 23A and 23B, the change in concentration is investigated, the shortage is calculated by the controller 24, and ammonia nitrogen or phosphorus is added from the nutrient source supply pipe 12, and nitrification is performed. By measuring the growth and activity of the bacterium with the densitometer 23C and performing feedback control with the control device 23, ammonia nitrogen and phosphorus can be appropriately supplied to the raw water quality that greatly varies depending on the weather, water operation, and the like.

[0031]

As described above, according to the present invention,
By backwashing the first bioactive carbon layer in which microorganisms having a relatively short generation alternation time grow at short intervals, and backwashing the second bioactive carbon layer in which microorganisms having a relatively long generation alternation time grow at long intervals, It is possible to maintain and activate the microorganisms that grow inside each of the biological activated carbon beds for an appropriate period of time and to discharge the microorganisms to the outside at an appropriate timing. Therefore, it is possible to perform stable and efficient water treatment for raw water that greatly changes depending on the season or the weather.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between removal of ammonia nitrogen and water temperature.

FIG. 2 is a diagram showing a change in absorbance in a biological activated carbon layer.

FIG. 3 is a schematic diagram showing a first embodiment of the present invention.

FIG. 4 is a schematic diagram showing a second embodiment of the present invention.

FIG. 5 is a schematic diagram showing a third embodiment of the present invention.

FIG. 6 is a schematic diagram showing a fourth embodiment of the present invention.

[Explanation of symbols]

 3 First biological activated carbon layer 4 Second biological activated carbon layer 6 Air supply pipe 7 Air supply pipe 8 Backwash pipe 9 Backwash pipe

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C02F 3/34 101 D

Claims (4)

[Claims] 1. A first bioactive carbon layer in which microorganisms having a relatively short generation alternation time grow, a second bioactive carbon layer in which microorganisms having a relatively long generation alternation time grow, and provided in the first bioactive carbon layer. A first backwashing device for backwashing the first biological activated carbon layer at a predetermined first interval; and a second backwashing device provided on the second biological activated carbon layer and having a second interval longer than the first interval. A second backwashing device for backwashing the second bioactive carbon layer, the water treatment device. 2. The water according to claim 1, further comprising a nutrient source supply unit for supplying a nutrient source to the microorganisms of the second biological activated carbon layer, upstream of the second biological activated carbon layer. Processing equipment. 3. A concentration meter of a nutrient source for supplying microorganisms of the second biological activated carbon layer is provided on the upstream side and the downstream side of the second biological activated carbon layer, and the nutrient source is supplied based on a signal from each concentration meter. The water treatment device according to claim 2, further comprising a control device for controlling a supply amount from the section. 4. A water treatment method using the water treatment apparatus according to claim 1, wherein water flow is stopped at predetermined first intervals and the first bioactive carbon layer is reversed by a first backwashing apparatus. While cleaning, the water flow is stopped every second interval longer than the first interval to stop the second interval.
The method for water treatment characterized in that the second biological activated carbon layer is back-washed by the back-washing device.