Source: http://www.patentinformationsearch.com/water_treatment/watertreatment-267.php
Timestamp: 2018-01-23 08:09:49
Document Index: 365638418

Matched Legal Cases: ['art 3', 'art 3', 'art 3', 'art 15', 'art 15', 'art 15', 'art 15', 'art 3', 'art 3', 'art 3', 'art 15', 'art 15', 'art 3']

Water treatment patent 5676836
1. A method for waste water treatment, comprising steps of:
2. The method for waste water treatment according to claim 1, further comprising a step of:
culturing inside the contact circulation part an aquatic plant which has been accelerated in rate of growth of leaves and roots by improvement of breed and which has been mass cultured by biotechnology.
3. The method for waste water treatment according to claim 1, further comprising a step of:
growing on the cultivation bed an aquatic plant picked from a river into which waste water is discharged.
As the method of waste water treatment for use in the factories, available are chemical treatment methods such as neutralization, reaction, and flocculation, biological treatment methods such as biological films, contact oxidation, activated sludge, and special microorganism treatment, and physical treatment methods such as precipitation, filtering, adsorption, floatation, and film treatment (hereinafter, these biological and physical treatment methods will be abbreviated generically as pretreatment process), which would be selected depending on water quality of the waste water. Actually, the aforementioned treatment methods are used singly or in combination of some of them, so that high concentration toxic waste water is treated and discharged (see Japanese Patent Laid-Open Publications HEI 1-95000 and SHO 64-43306). Further, in actual cases, the conventional apparatus for waste water treatment would be provided with an activated charcoal adsorption tower at the treatment terminal, as necessary, under stringent discharge regulations.
As described above, in the case of treatment within factory sites, it has been common practice that waste water is subjected to chemical treatment, biological treatment, and physical treatment by spending long time and finally treated at the activated charcoal adsorption tower, generally within factory sites. Then, high concentration toxic waste water containing surfactants is treated up to a water quality level lower than the legal regulation level and, as such, discharged.
Also, since the activated charcoal to be contained in the activated charcoal adsorption tower is expensive in its unit price itself, short in service life before regeneration, and high in its running cost, the so-called activated charcoal with microorganisms is nowadays increasingly spreading in which microorganisms are propagated in activated charcoal and organic substances adsorbed by the activated charcoal are treated by the microorganisms.
In particular, in areas with good natural environments, the river into which factory waste water is discharged may be so good at water quality as can be classified as a clear stream. Such rivers with good water quality mean water areas of lean saprobic or .beta.-median saprobic water areas in terms of the soil water biology system. The .beta.-median saprobic water areas refer to slightly dirtied water areas where ayu fish or fireflies are living.
In contrast to this, the above-mentioned conventional counterpart is purposed to achieve waste water treatment so that only legal restrictions are observed in respects of TMAH, surfactants, alcohols, and resists. As a result, even after the waste water treatment is executed, slight amounts of hard-to-decompose surfactants and slight amounts of resists may remain in the treated water. The hard-to-decompose surfactants may be a cause for a slight amount of foams in the treated water. Also, the light amounts of resist will color the treated water yellowish. The conventional counterpart has not been cared for economically preventing these slight amounts of foaming and coloring in the treated water.
In the semiconductor factories and liquid crystal factories, even foaming due to surfactants derived from treated water and coloring of resist components of treated water would matter for the neighbor residents from the viewpoint of maintaining the local environment. In particular, when the water of the effluent river is utilized as agricultural water, it would matter for the neighbor residents.
Recently, there have been developed various types of treatment apparatus using activated charcoal with microorganisms (Japanese Patent Laid-Open Publications HEI 2-229595 and HEI 4-260497). Those are however designed for no more than water purification of relatively good water quality and, in particular, not designed for treatment of waste water containing hard-to-decompose surfactants that would take considerable time. Besides, the apparatus are those which use granular activated charcoal with high initial cost. Also, those use various types of methods or systems to fill activated charcoal in the particular tower for use of activated charcoal charge, thereby achieving water purification.
Meanwhile, malodorous gas is generated from the aforementioned factories, although in very small amounts. More specifically, they include malodorous gases derived from chemicals used in production processes and special gases, malodorous gases generated from source tanks and the like for household waste water treatment and production system waste water treatment, and the like. Even these malodorous gases of small amounts may matter in districts with particularly good environments. However, although such malodorous gases of small amounts would be a matter, planning general apparatus for malodorous gas treatment would cause increase in construction cost and maintenance cost, problematically. In other words, there is a desire for means for malodorous gas treatment that requires extremely low initial cost and running cost. Several treatment systems have conventionally been available as the means for treatment of malodorous gases, including the scrubber system with washing by chemicals or water, the adsorption system with the use of activated charcoal and the combustion system. However, as a matter of course, they have encountered great problems of initial cost, running cost, maintenance, large installation spaces, and the like.
In particular, as in the aforementioned semiconductor factories and liquid crystal factories, apparatus for malodorous gas treatment should be planned when, even if legally acceptable, malodorous gases may be generated more or less so as to give rise to neighbor residents' claims. However, actually, it is excessive and uneconomical to provide a full-scale apparatus for malodorous gas treatment in order to solve such small amount of malodor.
The following description is based on experimental results. Even if the high concentration toxic waste water treated without dilution by the conventional method of waste water treatment is considered to be sufficiently safe on the basis of its analytical values from the standard of the current analytical technique, there will arise a phenomenon that foaming is caused by the small amounts of surfactants provided that effluence gap exists in the flow of effluence. This foaming phenomenon, although legally acceptable, may be misunderstood to be imperfect as treatment from the standpoint of neighbor residents. Further, when the high concentration waste water is treated by increasing the concentration of microorganisms without dilution, both the microorganism concentration and the waste water concentration are high in the aeration tank so that slight amounts of organic malodorous gases will be generated. Meanwhile, the treated water having such quality that larger quantities of foams due to hard-to-decompose surfactants are generated could not be said to be safe to small fish living in the rivers of the aforementioned good natural environment districts and to the biological ecosystem of marsh snails, which are a kind of snail that is a feed for fireflies. Those local creatures such as small fish and marsh snails generally have low resistivity to environmental changes so that they could not live in the treated water, especially when the treated water is derived from treatment of the high concentration waste water only by the conventional method without dilution.
(1) Even if the treated water discharged into public water regions with good environments satisfies the above-mentioned legal restriction values and regulation values, a gap between effluent piping and effluent public water region, if any, would cause the foaming phenomenon due to small amounts of hard-to-decompose surfactants, resulting in bad appearance. Also, the colored substances, if not completely treated, would also cause bad appearance. A matter of course as it is, the conventional activated charcoal tower could not treat malodorous gases. In addition, in principle, the activated charcoal tower could not treat nitride, phosphorous, and salts.
In other words, in effluent regions which are free from environmental disruption and have small amount of river water, like the recent planned sites for semiconductor factories and liquid crystal factories, the treated water, even if it meets regulation values such as described above so as to be legally acceptable, may often affect the biological ecosystem. As a result, if such treated water is discharged, there arises a great danger of destroying the biological ecosystem of creatures vulnerable to environmental disruption, to a problem.
In order to achieve the aforementioned object, the apparatus for waste water treatment according to the present invention is characterized by comprising a contact circulation part having a cultivation bed on which an aquatic plant has been grown, and charcoal in which microorganisms have been grown, the contact circulation part being so arranged that treatment-object water pretreated in a pretreatment process is introduced into the contact circulation part so that the contact circulation part will be submerged in the treatment-object water; and
an air-diffusing part disposed above the contact circulation part and having charcoal in which microorganisms have been grown, the air-diffusing part being so arranged that the treatment-object water derived from the contact circulation part is introduced by an air lift pump and sprinkled on the air-diffusing part, and that the treatment-object water that has passed through the contained charcoal is returned to the contact circulation part so that the air-diffusing part will not be submerged in the treatment-object water.
The charcoal is a porous body having a large number of thin pores, a set of various types of pores whose diameter ranges from a few microns to a few hundreds of microns, such that various types of microorganisms will easily propagate in the charcoal. Also, because of the presence of various types of pores, microorganisms matching their sizes will easily get life. Further, since biological film layers are formed inside the charcoal as a result of the propagation of the various types of microorganisms, such chemical substances as hard-to-decompose surfactants and resist components, which are generally difficult to biodecompose, are adsorbed to the charcoal and biodecomposed. Small amounts of minerals contained in the charcoal lend themselves to growth or culture of aquatic plants, and the aquatic plants in turn lend their chemical substance absorbing ability to the biological treatment of waste water.
Thereafter, the treatment-object water, i.e., the waste water circulates to make repeated contact with the activated charcoal on which microorganism films are formed. As a result, such organic substances as hard-to-decompose surfactants and resist components are treated in contact decomposition at high level.
Microorganisms that will well propagate in the charcoal are exemplified by bacteria, fungi, actinomyces, algae, photosynthetic bacteria, and the like. The surface area of the charcoal per gram is publicly reported to be not less than 200 m.sup.2 (according to Japanese National Charcoal Association). Accordingly, the charcoal has substantially large areas of biological film layers in its inside and therefore has substantially high ability of treating organic substances.
Also, since the treatment-object water derived from the contact circulation part is introduced to the sprinkling circulation part by an air lift pump, a sufficient-amount of oxygen is fed to the treatment-object water so that aerobic microorganisms are activated for more action, which facilitates biological treatment of the treatment-object water.
According to an embodiment of the present invention, the contact circulation part has Bincho charcoal in which microorganisms have been grown, while the sprinkling circulation part has black coal in which microorganisms have been grown. The Bincho charcoal (a kind of white charcoal), because of its specific gravity not less than 1, will be immersed in the contact circulation part that is submerged in water and moreover will hardly be fractured even by intense aeration. Further, the black coal of the sprinkling circulation part, because of its specific gravity smaller than 1, is superior in adsorbability to other charcoal, thus suited for treatment in the case of treatment-object water colored thick.
Also, according to an embodiment of the present invention, the air-supply agitating means feeds air to the contact circulation part from below and agitates the treatment-object water in the contact circulation part. The operating ability of the air-supply agitating means is controlled to higher or lower level by a agitation control means. Accordingly, anaerobic and aerobic conditions are forced to appear alternately within the contact circulation part. As a result, anaerobic denitrifying bacteria immobilized at the depth of the charcoal and nitrating bacteria immobilized on the surface of the charcoal are both put into effective operation, so that the treatment-object water can be nitrated and denitrified.
The contact circulation part 3 comprises a circulation-in-tank use air-diffusing tube 4 for agitating tank interior, and Bincho charcoal 9, which is a kind of charcoal and serves as the filler material, the filler-material use air-diffusing tubes 5 for stirring the Bincho charcoal 9, an air lift plate 10 for rectifying the up water streams in the tank, and a cultivation bed 11 attached to the air lift plate 10 and disposed at an upper portion thereof. The cultivation bed 11 has an aquatic plant 20 under growth. The aquatic plant 20 accommodated in aquatic plant baskets 21 installed on the cultivation bed 11 at regular intervals. The aquatic plant baskets 21 is preferably mesh containers of such a structure that the roots of the aquatic plant 20 can freely stretch. As the material of the aquatic plant baskets 21, polyethylene and polyvinyl chloride that will not affect water quality are selected. The aquatic plant 20 is, for example, Hydrilla verticillata, wizard waterweed, water cultrop, Vallisneria asiatica, tortuose waterweed, or the like, which are aquatic plants of submersed type available in the effluent district. The aquatic plant 20 may also be floating type water hyacinth, watercress, Japanese parsley, which can also be foods, packbun, which is well known as an aquatic vegetable, or the like. However, since the purpose is waste water treatment, the aquatic plants 20 is most suitably an aquatic plant which grows throughout the year and which is of the submersed type and normally submerged, which is exemplified by the aforementioned Hydrilla verticillata, water caltrop, and the like. These will seldom die if the water temperature is kept at specified values throughout the year. Also, the aquatic plant 20 was prepared in bulk of a species that has a large treatment capacity by biotechnologies such as tissue culture and cell fusion. As shown in FIG. 2, the aquatic plant 20 has leaves 22 and roots 24. Particularly, the above-mentioned waterweed, if sufficiently grown, will have a white root 24 grown from its stem 23.
The Bincho charcoal 9 is accommodated in a container 2. The container 2 is unspecific in its material and whatever can accommodate the Bincho charcoal 9 therein will do. The container 2 may be a mesh container made of a resin such as polyethylene, or stainless container, for example.
The Bincho charcoal 9 is a Japanese traditional charcoal, meaning a white coal of an ilex, which is a broadleaf tree. The white coal is a charcoal carbonized at around 1000.degree. C. and classified as a high temperature carbonized charcoal. Meanwhile, as the Bincho charcoal 9 used in this embodiment, it is preferable, but not indispensable, to select 4 to 6 cm diameter and 5 cm or more long Bincho charcoal, so that successful contact stirring in the contact circulation part 3 can be obtained. Since the Bincho charcoal 9 having a certain level of size will not be flowed away from the tank at the time of back washing, it is convenient to select rather large Bincho charcoal 9 for the management's sake. Also, since the Bincho charcoal 9 has a specific gravity of not less than 1, it will submerge in the water, and will almost never be crushed even by strong aeration. Thus, the Bincho charcoal 9 is suited for the filler material for high level waste water treatment, as compared with other types of charcoal.
Denoted by numeral 7 is an air lift piping. The air lift piping 7 and air piping 16 make up an air lift pump. This air lift pump functions to flow the treatment-object water present in the contact circulation part 3 into a water-sprinkling tube 14 installed upward of a sprinkling circulation part 15. The treatment-object water is sprinkled above the sprinkling circulation part 15 as plane and uniform as possible by the water-sprinkling tube 14. Black coal 12 is filled between upper and lower mesh sheets 13, 13 provided in the sprinkling circulation part 15. The charcoal to be filled in the sprinkling circulation part 15 is not limited to the black coal 12 but may be other type of charcoal. FIG. 3A is a view of a typical charcoal as seen from the front and FIG. 3B is a view of the same as seen from the side. The charcoal may be, for example, the aforementioned Bincho charcoal, and otherwise retorted charcoal, open-hearth charcoal. However, if the treatment-object water is colored heavily, the black coal 12, which is superior in adsorbability, should be selected. This is because the black coal 12 exhibits the highest adsorbability at an iodine adsorption test, as compared to other charcoal.
Also, since an illumination 8 is installed under the lower mesh sheet 13, light from the illumination 8 is applied to bottom part of the black coal 12 below, where various types of algae will propagate and serve for treatment of the treatment-object water.
The treated water discharged from the pretreatment process 19 has not been treated so securely that the hard-to-decompose surfactants or resist components may be discharged into districts with good environments. Therefore, if the treated water is discharged as it is, the water at the place of discharge may be foamed or colored.
Air is discharged from the air piping 16 and rise within the air lift piping 7, whereby the treated water in the contact circulation part 3 is introduced to the air lift piping 7 and released out from the water-sprinkling tube 14. The treated water discharged from the water-sprinkling tube 14 reaches the black coal 12 in the mesh sheets 13, where the surfactants and resist components are adsorbed by the black coal 12. Further, the black coal 12 can effectively adsorb, in particular, iodine, as compared with other charcoal.
In this way, the malodorous gas is blasted from the air-diffusing tubes 5 to the Bincho charcoal 9 of the contact circulation part 3. As a result, the malodorous gas is decomposed by biological films formed of microorganisms propagated in the Bincho charcoal 9. Then, the malodorous gas, after lifted through the contact circulation part 3 and treated, is introduced to the sprinkling circulation part 15. The malodorous gas contacts and collides also with the biological films formed on the surface of the black coal 12 of the sprinkling circulation part 15, where the malodorous gas is treated also by these biological films on the surface of the black coal 12. Accordingly, the malodorous gas is treated in two steps with reliability.
Up streams are generated by the air discharged from the air-diffusing tube 4 for circulation in the tank and by the air lift plate 10. Further, the inside of the tank is more successfully mixed and agitated by malodorous air discharged from the air-diffusing tubes 5 for filler materials. Surfactants foam at the water surface. However, the water surface of the contact circulation part 3 in the present embodiment is in its most portion agitated by two types of air, thus having no space for foams to stay. As a result, foams themselves are treated with high efficiency.
Whereas no change was observed in the upper and lower charcoal at the beginning of trial operation, a thing like a biological film was formed slightly on the surface of the charcoal. There appeared a unique, thin biological film based on charcoal, although it was not so thick as biological films that would appear on contact materials of the rotating disc system or immersion bed system for general waste water treatment.