JP3243061B2 - Water treatment device and water treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water treatment apparatus used for water supply facilities to purify contaminated raw water to produce drinking water, and more particularly to a water treatment apparatus which is stable against raw water in which ammonia nitrogen fluctuates. TECHNICAL FIELD The present invention relates to a water treatment apparatus and a water treatment method capable of obtaining a reduced treatment effect.

[0002]

2. Description of the Related Art In general, water sources for water supply are obtained from surface water, underground water or groundwater of lakes and marshes and rivers.
These are called raw water. Usually, various substances are dissolved in the raw water, and fine particles and microorganisms of the individual float in the raw water, and turbidity, color and odor are mixed. Not for use. Therefore, in recent years, a method of performing ozone oxidation as an advanced water purification treatment after coagulating sedimentation and filtration on raw water, performing oxidation, deodorization, and decolorization of organic substances contained in raw water, and then removing ozone oxidation products using activated carbon has been proposed. Is underway. In particular, in the activated carbon treatment of the raw water after the ozone treatment, microorganisms using the ozone oxidation product as a nutrient source grow, the activated carbon becomes so-called biological activated carbon, and many organic substances in the raw water are removed. When activated carbon is transferred to biological activated carbon, the life of activated carbon is said to be 10 times or more.

[0003]

However, there are various problems with the use of biological activated carbon. In particular, when the ammonia concentration in the raw water fluctuates, biological treatment cannot sufficiently cope with the operation of biological activated carbon, and there is a problem in practical use of biological activated carbon.

[0004] The present invention has been made in view of such a point, and uses a biologically activated carbon which has recently begun to be used and is capable of reliably removing the ammonia concentration in the raw water even if it fluctuates. It is an object to provide a treatment apparatus and a water treatment method.

[0005]

SUMMARY OF THE INVENTION The present invention provides a first biologically activated carbon layer in which microorganisms having a relatively short generation alternation time grow,
A second biologically activated carbon layer in which microorganisms having a relatively long generation change time grow, and a first biologically activated carbon layer provided below the first biologically activated carbon layer and backwashing the first biologically activated carbon layer at predetermined first intervals. And a second backwashing device provided below the second bioactive carbon layer and backwashing the second bioactive carbon layer at a second interval longer than the first interval. In the water treatment apparatus and the water treatment method using the water treatment apparatus described above, the flow of water is stopped at predetermined first intervals, and the first organism is removed by the first backwashing apparatus. Water treatment, wherein the activated carbon layer is backwashed, water is stopped at every second interval longer than the first interval, and the second bioactive carbon layer is backwashed by a second backwashing device. Is the way.

[0006]

The flow of raw water is stopped at every predetermined first interval, and
Backwashing the first biological activated carbon layer by the backwashing device, stopping the flow of raw water at every second interval longer than the first interval, and removing the second biological activated carbon layer by the second backwashing device. By performing the reverse washing, the microorganisms that grow inside each biological activated carbon layer can be maintained and activated for an appropriate period.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show 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.

According to the present invention, the biological activated carbon layer of the water treatment apparatus is divided into two, as will be described later, to completely remove contaminant organic substances and ammonia nitrogen in raw water. Hashimoto and Sudo eds., "New Activated Sludge Method" (Industrial Water Research Committee) According to No. 34, the metabolism of microorganisms, ie, the growth rate of generation alternation (generation alternation time),
OD assimilating bacteria (Phodopseudomonas sp.)
heroides) at 34 ° C. for 2.4 hours,
Nitromonas sp. At 25 ° C
It is 12.7 hours.

As described above, since the growth rate of the generation change of nitrifying bacteria is essentially low, when the biological activated carbon layer is made into one layer as in the past, it is necessary to prevent clogging of activated carbon and growth of metazoans. If backwashing is performed frequently, nitrifying bacteria whose generations are changed slowly will be washed away even if BOD-utilizing bacteria grow.
For this reason, when ammonia nitrogen exists in raw water, or when the concentration of ammonia nitrogen in raw water sharply rises, raw water may not be reliably treated. An example of this is Kaiga et al., "Experiment of an advanced water purification plant using ozone and biologically activated carbon," Vol.
FIG. 1 is shown in FIG. As shown in FIG. 1, it can be seen that the ammonia nitrogen concentration in the treated water fluctuates. Such fluctuations in the concentration of ammonia nitrogen affect not only the management of the treatment process but also the retention of residual chlorine after the treatment.

On the other hand, the present invention is a water treatment apparatus using two biologically activated carbon layers in accordance with microorganisms having different generation alternation times. The results of the investigation of the removal of dissolved organic matter by the activated carbon layer in the activated carbon were reported in Kaiga et al., "Experiment of an advanced water purification plant using ozone and activated carbon," Vol. 60, No. 6, paragraph 2 of the Water Works Association (June 1991). FIG.

In FIG. 2, agglomeration, sand filtration, and ozone treatment were performed before the biological activated carbon layer. As shown in FIG.
The removal characteristics of organic substances determined by ultraviolet absorption are remarkably exhibited in the upper 50 cm of the biological activated carbon layer. Dissolved organic matter is metabolized by the microorganisms in the biological activated carbon layer, and the number of microorganisms increases in the upper part of the biological activated carbon layer, and the pressure loss for filtration increases. It is necessary to peel off extra cells that have increased adhesion and remove them from the inside of the layer. If left for a long period of time, metazoans that grow as microbial cells as food will propagate in the activated carbon layer. Since these metazoans move by themselves, they may leak into the treated water. Therefore, considering the alternation of generations of metazoans, backwashing is performed early on the propagation of metazoans. In other words, in utilizing the biological activated carbon layer, it is important to consider three species: BOD-utilizing bacteria that remove organic substances, nitrifying bacteria that nitrify ammonia, and metazoans that eat and grow microorganisms. Among these, metazoans are to be discharged early at the same time as BOD-utilizing bacteria, and a biological activated carbon layer that matches microorganisms (BOD-utilizing bacteria etc. and nitrifying bacteria) having two different generation alternation times is used. There is a need.

Next, a specific configuration of the present invention will be described with reference to FIG. As shown in FIG. 3, the water treatment apparatus has a single water tank 1.
And a first biologically activated carbon layer 3 in the aquarium 1 where living organisms with a relatively short generation alternation proliferate, and a second biologically activated carbon layer 4 in the aquarium 1 where organisms with a relatively long generation alternation proliferate. And In addition, the first biological activated carbon layer 3
The inflow pipe 2 of the water to be treated oxidized by ozone is connected to the inlet chamber 13 on the inlet side, 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. Is connected.

An intermediate chamber 14 between the first biological activated carbon layer 3 and the second biological activated carbon layer 4 so that the air for cleaning can be individually supplied to the respective biological activated 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, a first backwash pipe 8 and a second backwash pipe 9 are provided in the intermediate chamber 14 and the outlet chamber 15 to supply backwash water. Also, the first and second air supply pipes 6, 7 are
The second backwash pipes 8 and 9 are provided with empty wash valves 6A and 7A and backwash valves 8A and 9A, respectively.

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

In the water treatment apparatus shown in FIG. 3, in the first biological activated carbon layer 3, the BOD is mainly a relatively short generation change time.
Utilization bacteria proliferate, and nitrification bacteria proliferate mainly in the second biologically activated carbon layer 4 with a relatively long generation change time. In this case, not only the adsorption and removal of contaminants by the biological activated carbon, but also the contaminated organic substances in the raw water or the dissolved organic substances that have been converted to biodegradable by ozone oxidation are purified by the BOD assimilating bacteria in the first biological activated carbon layer 3. Ammonia nitrogen, one of the contaminants, is nitrified in the second bioactive carbon layer 4.

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

The BOD-utilizing bacteria having a short generation change time metabolize biodegradable organic substances in the upper part of the first biological activated carbon layer 3 and grow as cells. In this case, the BOD-utilizing bacteria grow using the activated carbon particles as a carrier, but the cells of the BOD-utilizing bacteria fill up the particles and increase the pressure loss of water flow. For this reason, once every 1 to 5 days, the water flow from the inflow pipe 2 is stopped,
The air washing valve 6A and the backwash valve 8A are opened, and air and backwash water are sent into the intermediate chamber 14 to perform backwashing of the first biological activated carbon layer 3. At this time, BOD-utilizing bacteria of microorganisms that have grown and adhered to the activated carbon particles on the surface of the biological activated carbon layer 3 are separated from the particles, become backwashed drainage, and are discharged from the drain pipe 10. Next, empty flush valve 6A
Then, the backwash valve 8A is closed, the drain valve 10A of the drain pipe 10 is closed, and normal water flow is performed from the inflow pipe 2, so that the bacteria adhering to the particle surface again grow and purify the water. Become.

Eggs and larvae of metazoans entering raw water enter the first biological activated carbon layer 3 and eat and multiply BOD-utilizing bacteria growing on the surface between the particles. These metazoans include, in particular, nematodes, earthworms, daphnia and the like. When these leak into the treated water, they cause various problems because they are visible to the naked eye. In particular, the growth of microorganisms changes seasonally, but in order to suppress these phenomena, backwashing is performed at intervals shorter than the generational alternation time of metazoans, so that eggs and larvae of metazoans cannot survive in the third activated carbon layer. To

In this embodiment, the generation change time of the BOD-utilizing bacteria and metazoa growing in the first biological activated carbon layer 3 is regarded as a relatively short time, and the back washing of the first biological activated carbon layer 3 is performed. By performing the treatment frequently at intervals of about 1 to 5 days, the BOD-utilizing bacteria and metazoans can be periodically discharged from the first biological activated carbon layer 3.

By the way, backwashing at short intervals in the first biologically activated carbon layer 3 is good for BOD-utilizing bacteria and metazoans, but is inconvenient for nitrifying bacteria of late generation change, and is washed away by backwashing. Where river water is used as raw water, there is a large fluctuation of ammonia nitrogen due to the discharge of sewage secondary treatment water, human waste treatment water, and the like, and nitrifying bacteria are generally difficult to grow. In particular, nitrifying bacteria are cells that can grow using ammoniacal nitrogen, carbonate, and the like as nutrients, and grow in places with less nutrients than BOD-utilizing bacteria.

In the present embodiment, as shown in FIG. 3, the inside of the second biological activated carbon layer 4 is set to a condition in which the concentration of dissolved organic matter is low.
Nitrifying bacteria are proliferated in the second biological activated carbon layer 4. Second
Since the growth of nitrifying bacteria in the biologically activated carbon layer 4 of the present invention occurs slowly, the number of times of backwashing is much smaller than that of the first biologically activated carbon layer 3 and may be once every several months or once every several weeks. The operation of the backwash is substantially the same as the case of the first biological activated carbon layer 3, and stops the flow of water from the inflow pipe 2, and opens the empty washing valve 7A and the backwash valve 9A. At the same time, open the drain valve 11A,
Nitrifying bacteria in the second biological activated carbon layer 4 are separated from the activated carbon particle surface and discharged from the drain valve 11A.

According to this embodiment, the first biological activated carbon layer 3
The organic matter in the raw water can be surely treated by the BOD-utilizing 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. BOD-utilizing bacteria, nitrifying bacteria, and the first biological activated carbon layer 3
The BOD-utilizing bacteria, nitrifying bacteria, and metaphysis can be appropriately discharged to the outside at an appropriate timing by performing backwashing on the metaphytes that grow in the culture according to each generation change time.

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

In FIG. 4, the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description is omitted. As shown in FIG. 4, in the first water tank 1A, an inlet chamber 13, a first biological activated carbon layer 3, and a first intermediate chamber 14 are sequentially arranged from above.
A is provided, and a second intermediate chamber 14B, a second biological activated carbon layer 4, and an outlet chamber 14 are provided in the second water tank 1B in this order from above. 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 disposed therein, and the other components are substantially the same as those of the first embodiment shown in FIG.

This embodiment is particularly effective when the ammonia concentration in raw water fluctuates or the phosphorus concentration which is an essential condition for metabolism of microorganisms fluctuates. In addition, when the operation of the biological activated carbon is started, or when the operation is restarted after the backwashing, nitrifying bacteria having a slow growth can be activated. That is, when necessary, a salt aqueous solution such as ammonium chloride, ammonium nitrate, or ammonium sulfate is supplied from the nutrient source supply pipe 12 as an ammoniacal nitrogen source,
By adding ammonia water or ammonia gas, if the raw water does not contain ammonia nitrogen for a long time, the nitrifying bacteria are grown and trained in the second biological activated carbon layer 4 at least with the added nutrient source. Can be done.

Further, phosphorus such as phosphoric acid or sodium phosphate can be added from the nutrient source supply pipe 12 as another nutrient source. In river water containing a large amount of lake water, the phosphorus concentration in the lake water fluctuates largely due to plankton proliferation, death, sedimentation, etc. of the lake in spring and autumn. Therefore, when the phosphorus concentration decreases, a nutrient can be added from the pipe 12 to keep the nitrifying bacteria growing in the activated carbon layer 4.

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

In FIG. 6, the inflow pipe 2 to the inlet chamber 13
A concentration meter 2 for measuring an ammonia concentration and a phosphorus concentration is provided to each of the connecting pipe 17 and the outflow pipe 5 from the outlet chamber 15.
3A, 23B and 23C are respectively attached. These densitometers 23A, 23B and 23C are connected to a control device 24. The control device 24 controls the densitometer 23
A predetermined amount of ammonia nitrogen or phosphorus can be supplied from the nutrient source supply pipe 12 into the second intermediate chamber 14B by controlling the injector 25 based on signals from A, 23B and 23C. In this case, the concentration change is checked by continuously measuring with the signals from the concentration meters 23A and 23B, the shortage is calculated by the control device 24, 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 by the concentration meter 23C and performing feedback control by the controller 23, it is possible to appropriately supply ammonia nitrogen and phosphorus 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 with relatively short generation alternations grow at short intervals and backwashing the second bioactive carbon layer with microorganisms with relatively long generation alternations at long intervals, The microorganisms that grow inside each biological activated carbon layer can be maintained and activated for an appropriate period, and can be discharged to the outside at an appropriate timing. Therefore, stable and efficient water treatment can be performed on raw water that fluctuates greatly due to seasonal or weather conditions.

[Brief description of the 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 view 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

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ identification code FI C02F 3/34 101 C02F 3/34 101D (58) Field surveyed (Int.Cl. ⁷ , DB name) C02F 3/02-3 /Ten

Claims (4)

(57) [Claims] 1. A first biologically activated carbon layer in which microorganisms having a relatively short generation alternation grow, a second biologically activated carbon layer in which microorganisms having relatively long generation alternations grow, and a layer below the first biologically activated carbon layer. Provided in a predetermined first
A first backwashing device for backwashing the first biological activated carbon layer at intervals of: a second biological activated carbon provided below the second biological activated carbon layer at a second interval longer than the first interval A water treatment apparatus, comprising: a second backwash apparatus for backwashing a layer. 2. The water according to claim 1, further comprising a nutrient source supply section for supplying a nutrient source to the microorganisms in the second biological activated carbon layer, upstream of the second biological activated carbon layer. Processing equipment. 3. A nutrient source concentration meter for supplying microorganisms in the second bioactive carbon layer is provided upstream and downstream of the second bioactive carbon layer, and the nutrient source is supplied based on a signal from each densitometer. The water treatment apparatus according to claim 2, further comprising a control device that controls a supply amount from the section. 4. The water treatment method using the water treatment apparatus according to claim 1, wherein the flow of water is stopped at predetermined first intervals, and the first bioactive carbon layer is reversed by the first backwashing apparatus. Washing, and stopping the flow of water at every second interval longer than the first interval.
Water treatment method, wherein the second biological activated carbon layer is back-washed by the back-washing device.