JPH06335697A - Method for purifying organic sewage by algae - Google Patents

Abstract

PURPOSE:To provide the treating method capable of easily separating algae from treated water and stably maintaining a high alga concn. by immobilizing one or several kinds of green algae filaments, the cells of which are monocolpate, monostring and non-branched into water courses, passing org. sewage along these water courses under bright conditions and bringing the sewage into contact with the green algae filaments. CONSTITUTION:One or several kinds of the green algae filaments (b) (e.g. Ulotrichales), cells of which are monocolpate, monostring and non-branched are immobilized in the water courses a1, a2 and the org. sewage is passed along the water courses a1, a2, by which the sewage is brought into contact with the green algae filaments (b) and the org. sewage is purified. Consequently, the sepn. of the algae from the treated water is easy and the algae are hardly captured by rapidly propagating microanimals, such as water flee Rotatoria. The purifying method capable of stably maintaining the high alga concn. is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for purifying organic sewage such as sewage and livestock sewage using algae, and particularly BO
The present invention relates to a method for removing nitrogen and phosphorus from secondary treated water from which D and SS have been removed. [Prior Art] Conventionally, there is an oxidation pond method as a method for treating wastewater using algae. This utilizes floating green algae and cyanobacteria, and aerobic bacteria remove the BOD source by utilizing oxygen generated by photosynthesis of algae, and nitrogen and phosphorus are fixed to the algae. Green algae have mitochondria,
It decomposes and removes BOD sources as well as aerobic bacteria. Since algae can use carbon dioxide as a carbon source, nitrogen and phosphorus can be removed even without a BOD source, which is an excellent feature. Algae fix carbon dioxide, which is a cause of global warming as an environmental problem of recent global regulation, along with purification of sewage. The grown algal biomass can also be reused as feed, fertilizer, or energy source.
Therefore, the treatment method using algae is becoming more important. The problems of conventional wastewater treatment methods using planktonic algae are as follows. (1) Since the algal bodies are minute and dispersed, it is difficult to separate them by natural sedimentation and mechanical separation is required, so the cost for separation is high. (2) Daphnia magna because the alga is minute. The concentration of algal bodies is unstable, such as rotifers that are easily eaten by small animals that grow rapidly and the pond may become transparent overnight. (3) Since the growth of planktonic algae is slower than that of bacteria and is planktonic, the increase in the inflow of sewage tends to cause a decrease in the concentration of algal bodies and further washout of algal bodies. [Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned problems, and it is easy to separate algae from treated water. It is an object of the present invention to provide a treatment method that is unlikely to be eaten by a small animal such as a rotifer that proliferates and that can stably maintain a high algal cell concentration. [Means for Solving the Problem] That is, the present invention is to fix one or several kinds of green alga filamentous filaments in which cells are single-row, single-row, and unbranched in a waterway to remove organic wastewater under light conditions. By flowing along the water channel, filthy water is brought into contact with the green algae filamentous material, thereby purifying the organic filthy water, thereby constituting a method for purifying organic filthy water by algae. [Examples and Operations] Next, the present invention will be described in more detail with reference to the drawings. 1 and 2 and 3 show an apparatus for carrying out the method of the invention, FIG. 1 being a plan view,
FIG. 2 is an AA vertical sectional view, and FIG. 3 is a BB vertical sectional view. A water channel-shaped water tank 1 opened to the atmosphere is divided into upper and lower parts by partition walls 2, and the upper and lower parts of the water tank 1 communicate with the communication flow path a1.
And a2 are connected to each other to form one endless flow path. A corrugated plate-shaped attachment surface t is formed on the upper surface of the partition wall 2, and a green alga filamentous body g (hereinafter abbreviated as filamentous body), in which cells are single-row, single-row and unbranched, is fixed by self-adhesion. There is. As a result, the upper part of the partition wall 2 is the algae part b and the lower part is the return part r. The communication flow path a1 is opened at the bottom surface of the algae portion b, extends vertically downward, reaches below the bottom surface of the water tank 1 and then bends, extends vertically upward, and is opened at the bottom surface of the return portion r. The communication flow path a2 is formed by providing the partition wall 2 slightly away from the side wall of the water tank 1. The communication channel a2 is provided with a screen 3 for capturing and collecting the detached filaments. At the inflow part of the algae part b, a foam stopper 4 is provided across the flow path for preventing bubbles from floating on the water surface. A ventilation pipe 5 for activating a circulating flow of water is provided in an opening below one of the communication flow paths a1 which is vertically provided, and an air diffuser pipe 6 is provided in this opening.
Is provided, and a flow control valve 7 is provided in the ventilation pipe 5. When a gas such as air is pressed into the water tank 1 filled with dirty water through the air diffuser 6, an upward flow of the gas-liquid mixing system is generated in the re-communication flow path a1 due to the air lift effect, and as a result, the circulation in the direction of the arrow A stream is formed. Filament g self-adhered to the adhesion surface t
With this circulating flow, while oscillating under the surface of the water, it is irradiated with light, absorbs nitrogen components, phosphorus components, organic substances and the like, and grows and propagates. As a result, the sewage is purified by removing nitrogen components, phosphorus components, organic substances and the like. Filament g elongated to a certain length
Is cut by the frictional force of the circulating flow, is carried downstream by the circulating flow, and is captured by the screen 3. The water depth of the algae part b is 10 to 50 cm, more preferably 20 to 40 cm. The deeper the installation water depth of the air diffuser 6 is, the larger the circulation amount per unit ventilation amount is, but it is usually desirable to be 1 m or more. Algae part b
The flow velocity at 10 to 30 cm / s is suitable. When the filament g is irradiated with light, oxygen is generated by photosynthesis,
The fine bubbles of oxygen adhere to the filamentous body g. Therefore, the tip portion of the filamentous body g tends to float on the water surface. Filament g
Is floated on the surface of the water for a long time, it is yellowed and inactivated by strong light, and the inactivated filaments g hinder the transmission of light downward. As described above, the floating of the filaments g on the water surface adversely affects the growth of the filaments g, and thus the treatment capacity. Under the flowing condition, the filaments g are dispersed and oscillated under the water surface by the buoyancy due to the oxygen fine bubbles and the frictional reaction force of the flow, so that the environment suitable for the proliferation of the filaments g is maintained. The filaments used in the present invention are limited to green alga filaments with single-row single-row cells, that is, filamentous filaments without branching. The inventor tried culturing various filamentous algae using the apparatus shown in FIGS. 1 to 3, but in the case of branched filaments, the branching portion has a large frictional force of water flow. The filamentous material that has worked or detached and floated is entangled and receives a larger force, so that it is easily cut and does not extend for a long time. Therefore, it is possible to cover the entire attachment surface t with the filamentous material. It turned out to be difficult and the light loss was high. Regarding this point, in a filamentous filamentous green algal cell with a single row and a single row, since it extends long (several meters), it overlaps in the vertical direction, and it is possible to easily compensate all of the filamentous material on the attachment surface t, and use light There is an advantage that the property significantly increases. In addition, the contact area with the liquid is larger than that of the frond. Examples of cells having such an advantage include filamentous green algae having a single row and a single row. Genus Ulotrix sp. Hormium sp. Spodoptera Oedonium s
p. Genus Yokowa Sphaeropleas
p. Chrysanthemum Mougeotia sp. Zygnema sp. Spirogyra sp. In order to attach and proliferate these algae on the attachment surface t, these filaments may be pulverized into fine particles and dispersed in the liquid. 1-2
Filaments that adhere and proliferate over the course of the week are visually observed. Also,
As another method of immobilizing the filamentous green algae in the water channel, there is a method of restraining the filamentous material with an article protruding into the water channel, and FIG. 4 is an explanatory view showing this and is a vertical sectional view. The drawing shows a portion corresponding to the algae portion b in FIGS. 1 to 3, and a rod-shaped filamentous member support tool 10 whose tip is bent is erected on the upper surface of the partition wall 2. This thread support 10
Thus, the filamentous body g is wound or hung and fixed in the water channel. It is appropriate to provide the filament supporter 10 slightly above the bottom of the water channel, and the filament g is unlikely to float due to the flow, and good growth is possible. In this embodiment, there is an advantage that the amount of immobilization of the filamentous body g can be easily increased in a short time. Further, even in the method of restraining the filamentous g with a container projecting into the water channel, a filamentous body with a branch does not extend for a long time. However, there is a drawback that it is more difficult to support than those of the undivided skill. In this respect, since the unbranched filamentous material extends longer, it is possible to cover the entire surface of the algae part b with the filamentous material by installing less supporting tools. FIG. 5 is a plan view showing an embodiment in which the water channel is configured as an end channel. Inflowing sewage is caused by natural flow,
The filamentous material g is contacted with the filamentous material g and discharged while being purified. In this aspect, it is necessary to configure the water channel depth and the channel width to be a flow velocity of 10 to 30 cm / sec depending on the inflow amount of sewage.
In this embodiment, there is an advantage that less power is required for water flow.
In the embodiment shown in FIGS. 1 to 3, the water channel is configured as an endless water channel, and there is an advantage that the flow velocity in the water channel can be controlled regardless of the inflow amount of sewage. Further, in the embodiment shown in FIG. 1, the endless water channel circulating in the vertical direction is used, but the endless water channel circulating in the horizontal direction can also be used. [Effects of the Invention] As described above, in the treatment method of the tree invention, one or several species of green algal filaments in which large cells as algae are unbranched in a single-row single row are used by being immobilized in a water channel.
It is easy to separate, dehydrate, and dry algal cells, and the Daphnia magna. Difficult to be eaten by fast-growing micro-animals such as rotifers, and it is easy to cover the entire waterway with algal cells, and it is possible to maintain a stable high algal cell concentration in the water channel and form a one-way water flow. Algae can be harvested easily in one place. According to the present invention having such advantages, it is possible to treat sewage significantly more economically than the conventional treatment using microalgae.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1, 2, and 3 show an example of an apparatus for carrying out the method of the present invention, FIG. 1 is a plan view, and FIG. 2 is AA. FIG. 3 is a vertical sectional view taken along the line BB. Fourth
The figure is a partial longitudinal cross-sectional view showing an example of an apparatus for carrying out the method of restraining algal bodies with a container projecting into a waterway. Fifth
The figure is a plan view. The arrow indicates the direction of flow of the culture medium. 1 is a water tank, 2 is a partition wall, 3 is a screen, 4 is a foam stopper, 5 is a ventilation pipe, 6 is a diffuser pipe, 7 is a flow control valve, 8 is a blower, 9 is exhaust gas, 10 is a support tool, 11 is dirty water. An inflow pipe, 12 is a treated water outflow pipe, a1 is a communication channel, a2 is a communication channel, b is an alga part, r is a return part, g is a filament, and t is an attachment surface.

Claims (1)

[Claims] 1. By immobilizing one or several types of green algal filaments in which cells are single-row, single-branched and unbranched in a channel, and flowing organic sewage along the channel under bright conditions, A method for purifying organic wastewater by algae, which comprises contacting wastewater to purify the organic wastewater. 2. The method for purifying organic wastewater by algae according to claim 1, wherein the waterway is an endless waterway, and sewage is circulated and brought into contact with the filamentous body of the green algae. 3. The method for purifying organic sewage by algae according to claim 1 or 2, wherein the filaments are immobilized in a water channel by self-adhesion by an adsorber formed by the green algae. 4. The algae organic matter according to claim 1 or 2, characterized in that the filamentous body is fixed in the water channel by restraining the filamentary rest with a container projecting into the water channel. How to purify sewage.