JP2906257B2 - Biological contact filtration device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial application field> The present invention uses mold water in raw water by using river water as raw water, treating the river water and using it together with a coagulating sedimentation device and a filtration device. The present invention relates to a biological contact filtration device for removing odor and ammonia nitrogen.

<Conventional technology> In order to adsorb COD components and chromaticity components from secondary effluent water obtained by treating organic wastewater such as sewage and human waste by the activated sludge method, and to remove these adsorbed components by microorganisms A biological contact filtration apparatus in which a column is filled with granular or crushed bone char or activated carbon having a particle diameter of 3 to 15 mm to form a filter layer is known from JP-A-57-10382.

<Problems to be Solved by the Invention> Since the above-mentioned conventional apparatus removes COD components and pigment components from secondary treatment water such as sewage and human waste, bone carbon and activated carbon as filter media have a particle diameter of 3%. 1515 mm seems to be preferred.

However, when the raw water is river water as in the present invention and mold odor and ammonia nitrogen are removed from the water by the biological contact filtration device, if the trapping rate of the turbid matter by filtration is large, the differential pressure (pressure loss). It is necessary to wash frequently and the mold must be cleaned frequently. In addition, since the removal of mold odor is due to the direct biodegradation of the microorganisms held by the filter layer, it takes about half a month to two months until the microorganisms become accustomed. Has a problem that only insufficient treatment can be performed, and that the concentration of ammoniacal nitrogen in raw water sharply increases, and that the load fluctuates greatly. For this reason,
The filter layer does not have a high turbidity trapping rate, must be able to completely treat mold odor even if the microorganisms are not acclimated, and should be sufficient even if the ammonia nitrogen concentration in the raw water is high. It is required that the microorganisms always hold an amount that can be treated in a suitable manner, and the material and dimensions of the filter medium must be selected so as to satisfy the above conditions.

<Means for Solving the Problems> Accordingly, the present invention provides a biological contact filtration device in which a filtration layer filled with a filter material is provided in a filtration tower, microorganisms are retained in the filtration layer, and raw water is passed through. It is characterized by being filled with cylindrical granular activated carbon having a diameter of 2.0 to 4.0 mm.

<Embodiment> In the illustrated embodiment, reference numeral 1 denotes a filtration tower, and reference numeral 2 denotes a filtration layer having a height of about 0.5 to 4.0 m, which is formed by filling a filter medium in the tower.

The installation place of this filtration tower, even before the coagulation treatment device,
Although it may be in the latter stage, it is preferably installed in the former stage of the coagulation treatment apparatus in order to prevent turbidity in raw water and microorganisms such as bacteria from being mixed into the final treated water.

The direction of water flow in the filter layer 2 may be a downward flow method in which raw water is supplied to the filtration tower from above, or an upward flow method in which raw water is supplied to the filtration tower from below as shown in the drawing. An upward flow method in which the increase in differential pressure due to trapping is small is more preferable. In the case of the upward flow method, the flow rate is determined so that the filter medium does not flow while air or oxygen gas is blown to the extent that dissolved oxygen can be detected in the treated water.

By the way, the filter medium for forming the filter layer 2 adheres a mold odor decomposing bacterium which directly removes a mold odor in raw water by a biodegradation action, and a nitrifying bacterium which oxidizes and removes ammonia nitrogen in the raw water. Activated carbon that absorbs and removes mold odor in raw water with its own adsorptivity until mold odor-decomposing bacteria acclimatize.

If the size is large, the surface area becomes small, and in particular, the amount of nitrifying bacteria that oxidizes ammonia nitrogen in raw water decreases, and if the size is small, instead of increasing the surface area, the trapping function of turbidity is increased. As a result, the differential pressure rises faster, and as a result, the frequency of washing increases, and the amount of washing water increases. In consideration of these problems, the problem of strength such as less damage during washing is taken into consideration, and the filter material 3 made of activated carbon is formed into cylindrical particles having a diameter d of 2.0 to 4.0 mm as shown in FIG. Here, the term “granular” refers to not a rod having low strength but a length L corresponding to a diameter.
It is about 0.5 to 2.0.

The filter layer 2 composed of the filter medium 3 has a low trapping rate of suspended matter,
Also, within about two months from the beginning of operation until the mold odor-decomposing bacteria acclimated, it absorbs mold odor by the property of activated carbon itself of the filter medium,
Furthermore, since the filter medium has a moderately large surface area, even if the concentration of ammoniacal nitrogen in the raw water rapidly increases, the amount of nitrifying bacteria necessary to oxidize and remove the ammoniacal nitrogen adheres to the filter layer. Hold in.

A column with a diameter of 30 mm and a height of 400 mm is filled with 200 ml of various filter media to form a filter layer with a diameter of 30 mm and a height of 283 mm. River water is aerated as raw water and then ammonia and mold odor substances (2-methyl (Isoborneol) was added to adjust the concentration, and the concentration was added to the column at a flow rate of 24 / day (SV = 5.0 ¹ /
At the time), the river water is passed upwards, and the river water is washed upward by a flow amount of the filter medium once every 1 to 2 days.
After acclimatization for ammonia decomposition for 60 days, the raw water was continuously passed in an upward flow without performing a washing operation, and a rise in pressure loss and a treatment state of ammonia and 2-methylisoborneol were examined. However, the results in the following table were obtained. The filter materials packed in the column are as follows.

Also, in the acclimatization process, no mold odor substance was detected in the treated water of the activated carbon filter medium from the start of acclimation, and after 10 to 15 days from the start of acclimation, ammonia was sufficiently treated, and thereafter, stable treated water was obtained. Was.

According to the above table, mold odor (methyl isoborneol) can be removed regardless of the size and shape of activated carbon, and odorless treated water can be obtained. As for the removal of ammonium nitrogen, the smaller the diameter, the better the removal effect.However, there is a difference depending on the shape.
In the crushed type, the particle size is preferably 1 mm or less. Sand has almost the same performance as the crushed activated carbon.

FIG. 3 shows the relationship between the increase in the differential pressure and the average particle shape following the removal of ammoniacal nitrogen. As is clear from this, in the crushed form of activated carbon, removal of ammonia nitrogen and the differential pressure rise show the same tendency, whereas in the case of columnar activated carbon, those with a diameter of 2.0 to 4.0 mm have the same tendency as ammonia nitrogen. The removal effect is good, and there is no increase in the differential pressure.

<Effects of the Invention> According to the present invention, even if the mold odor-decomposing bacteria attached to the activated carbon filter medium are not acclimated, the activated carbon absorbs the mold odor in the inflowing raw water, so that the treatment can be performed during the acclimation period. Even if the concentration of ammonia nitrogen in the inflow raw water changes to a high concentration, stable treated water having an allowable concentration of ammonia nitrogen of 0.5 mg / can be obtained as tap water.

Further, since the amount of washing wastewater is small, the treatment equipment can be downsized, and since the filter medium is not crushed at the time of washing, there is little loss of fragments flowing out together with the washing wastewater.

In addition, surfactants in the influent raw water are also adsorbed by activated carbon,
And it can be removed by biodegradation on activated carbon, and troubles due to foaming can be prevented.

[Brief description of the drawings]

1 is a cross-sectional view of one embodiment of the biological contact filtration device of the present invention, FIG. 2 is a perspective view of the filter medium, and FIG. 3 is a relation between the diameter of the filter medium, the increase in differential pressure and the removal of ammonia nitrogen. FIG. In the figure, 1 indicates a filtration tower, 2 indicates a filter layer, and 4 indicates a filter medium.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tadashi Takadoi 3-4-7 Nishi-Shinjuku, Shinjuku-ku, Tokyo Kurita Kogyo Co., Ltd. (72) Inventor Toshiro Gasumaro Genji-cho, Munakata-gun, Fukuoka Prefecture No. 350, Munakata District Water Supply Corporation (72) Inventor Yoshiteru Abe 350, Mureta District Waterworks Corporation, Genkai-cho, Munakata-gun, Fukuoka Prefecture (56) References JP-A-2-157096 (JP, A) JP-A-1-94999 (JP, A) JP-A-61-249588 (JP, A) JP-A-60-156549 (JP, A) JP-A-3-38289 (JP JP, A) JP-A-62-171797 (JP, A) JP-A-52-138063 (JP, A) JP-A-51-122944 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , (DB name) C02F 1/28 C02F 3/02-3/10

Claims (1)

(57) [Claims] 1. A biological contact filtration apparatus in which microorganisms are retained in a filter layer filled with a filter medium in a filtration tower and raw water is passed through the filter, wherein the filter layer is filled with cylindrical granular activated carbon having a diameter of 2.0 to 4.0 mm. A biological contact filtration device, characterized in that: