Method for reducing algae and nutrient medium of a body of water and device for carrying out this method

The invention relates to a method for the reduction of algae and nutrient content a body of water, especially of surface water. Furthermore The invention relates to a device for performing this method.

The eutrophication of water, especially standing water provides, due to various physical, chemical and particularly biological Factors an increasingly growing problem is. In particular, the results Introduction of übertrachtetem nutrient water in lakes to increased Algae growth due to excessive nutrient uptake by the algae. Here specifically nitrogen and especially phosphorus compounds as particularly critical to see the increased algae growth even in very small quantities cause an increased in the summer months algal bloom. After death the algae in the following winter then takes the silting of Waters to. The consequences are oxygen depletion, fish kills and the Development of up to several meters thick sludge layers to Cover bottom of the water and suffocate all life in the bud.

In known methods for remediation of eutrophic waters, the appropriate nutrients mostly by means of precipitation chemicals or other precipitated adjuvants or adsorptively bound, where often a great Excess of such precipitating agents is required and significant amounts landfill needed Direction precipitation sludges incurred. The phosphate concentrations to be achieved remain nevertheless often unfortunately in such a rehabilitated water still above the threshold for a critical development of algae. Last but not least at the return of the treated water undesirable precipitation chemicals in the aquatic environment and the cost of the precipitation process is relatively high.

Object of the present invention is to provide a method and a device for Reduction of algae and nutrient content of a body of water available to provide that by a simple manner and essentially without the addition performed CHEMICALS and cost-effective and highly automated can be.

This object is achieved according to the method of the aforementioned type achieved in that the water removed algae-containing water quantities are the waters nutrient-containing water quantities are taken, an Mixture of water withdrawn amounts is irradiated such that the algae at least a portion of nutrients due to photosynthetic activation record, the algae are at least partially separated from the water, and the nutrients and algae reduced water is returned to the water. Of Furthermore, the object of the invention is achieved by a device of the dissolved mentioned type which algenhaltiger by a means for removal Amounts of water, a device for removing nährstoffhaltiger amounts of water, a device for irradiating a mixture of the extracted water quantities, wherein the algae at least part of the nutrients on the basis of record photosynthetic activation, means for at least partially separating the algae from the water and a means for returning the nutrients and algae reduced water is characterized in that water.

The advantages of the invention are, in particular, that the waters existing algae to reduce the contained also in waters Nutrients are used. To this end, amounts of water with the highest possible Algae and nutrients found in the water and a mixture of these Water volumes irradiated to increased nutrient uptake. irradiation is inventively outside of the water, because there the parameters for a optimized nutrient absorption can be adjusted better. The irradiation time of the mixture is preferably in the range of minutes to great Volumes of water in a short time by means of the inventive method to clean. In continuous operation can thus be made large throughput volumes reach, so that for example, expansive lakes can be rehabilitated. The algae absorb during the short exposure time the nutrients - particularly Phosphate - on without an during the irradiation phase Algae growth is desired or is needed. Instead, save the algae the nutrients in the reservoir and enter this only when decomposition or destruction from.

After the irradiation of the mixture, the separated algal biomass then to further economic recovery, for example, for Schwermetallsorption made from water, are used. Another advantage of the present invention Method is that the water to be purified photosynthetic through the Oxygen production of algae during the nutrient uptake and - conversion is enriched with oxygen. Finally, when using the emerge Procedure no deponiebedürfende precipitates or inventive other waste materials.

The inventive method is particularly suitable for surface water such as natural or artificial lakes or rivers to clean.

The novel process is advantageously throughout the Growth phase of microalgae used which usually the end of the Winter begins and lasts until next winter beginning. In winter, the Nutrient concentrations, particularly phosphate concentrations, very high, because at that time the die algae and recorded in the summer Nutrients - possibly in a modified form - back into the water submit. With increasing exposure to light and increasing temperatures in Spring takes the new generation of algae in this for dissolved nutrients. In the summer months, then finds a correspondingly increased algal blooms instead of. To prevent this, at the beginning of the growth phase should already so start, algae and nutrient-rich water for inventive to treat. Thus, at an early stage, the amount of algae in the water reduced so that only correspondingly small amounts of algae in the following winter can give small amounts of nutrients in the water. The procedure should in are repeatedly applied the following years, until an ecologically has set healthy ratio of algae and nutrients.

The specified method is particularly suitable for the simultaneous implementation with conventional Entschlammungsmaßnahmen, such as the Removal of upper soil layers water by means of suitable excavators. Of the caused by this increase in turbidity in the water content affects the Carrying out the process not to any significant extent.

Particular preference for simplicity, the algae-containing and nutrient-containing quantities of water the water in a common step removed. This can, for example, by deriving the amounts of water by a conventional suction tube occur.

Advantageously, a positionable skimmer for removing the algae containing and if appropriate the nutrient-containing quantities of water, with the For example, algal mats can be sucked a large area. The skimmer is preferably positioned about 10 to 50 cm below the water surface, because at this level the greatest concentration of photosynthetic microalgae is available. This small creatures are not mitabgesaugt, has the Skimmer advantageously correspondingly constructed gauze.

Particularly preferred is the mixture of the removed algae containing and nutrient-containing quantities of water supplied to a photobioreactor in which the Mixture is irradiated with natural and / or artificial light. The artificial Light is used, for example at night, to a continuously running to achieve photosynthesis. but it can also in the daytime in addition to sunlight are switched on. The natural and artificial light provides the energy for rapid nutrient uptake by the algae, especially of phosphates, but also ammonium, nitrates and nitrites. The nutrient uptake can also are supported by an induced in photobioreactor dioxide shortage.

When photosynthetic activation produced oxygen, which in itself Water accumulates. Since the water after irradiation and separation process in the water is recirculated, thereby increasing the natural way of Oxygen content of the water.

More preferably, the photobioreactor an upstanding support frame and at least one is arranged on the support frame encircling, transparent tubular on conduit through which the mixture is passed. Advantageously, there is a line of weather-resistant and flexible plastic. Of the Diameter of the tubular conduit and the vertical spacing of the windings adapted optimize light output. Furthermore, the residence time is the Batch in photobioreactor in an optimized in terms of time light absorption by the algae tunable.

Preferably, the support frame is formed substantially translucent, said the tubular conduit is arranged externally to the supporting frame around. The tubular conduit is in this case preferably lie in a plurality of superimposed wound windings, said windings preferably rotationally symmetrical extending around a central vertical axis.

The support frame of the photobioreactor is particularly preferably in the form of a Truncated cone, so that the line turns frustoconically upwards can be arranged tapering. This form is the course of adapted sun throughout the day, thus allowing, compared to an approximately cylindrical support frame has a larger light entry into the mixture carrying line.

The photo bioreactor preferably comprises means for directing light on the tubular duct. This means preferably comprises a pipe above the Converging lens, which focuses the incident sunlight and the optical axis coincides for this purpose advantageously with the vertical axis about which the tubular duct is wound rotationally symmetrical.

Preferably, the means for directing light comprises a - preferably the Lens oppositely disposed in the bottom area of ​​the reactor - the inner reflector having a reflective surface, which both the natural light and the artificial light which the through the lens and optionally between through inlet pipe coils in the reactor, on the tubular conduit reflected and the light yield and therefore nutrient uptake by the algae elevated.

Advantageously, the artificial irradiation of water batch in a Interior of the photobioreactor positionable artificial light source used, whose spectrum preferably the wavelength region of maximum light absorption by the algae covering. For this reason, for example, a sodium-vapor lamp used.

Advantageously, several photobioreactors are series or parallel connected. In various operations of the reactors can thus the respective needs by a suitable reactor number and capacity Be taken into account. In addition to this modular use, as are The reactors also preferred - for example, by arrangement to be moved Containers - designed for mobile use.

If more nutrients are present in the waters to be rehabilitated, as the taken algae can be recorded, it is advantageous to the irradiated batch to inoculate additionally with aquatic alien algae. Hereby it is avoided that the waters extracted nutrient-containing Quantities of water without substantially reducing the nutrient content in the Waters are returned. Water strangers algae can in particular are the winter months used to Nährstoffelimierung because at this time Although the nutritional value very large in the water, the algae content but very low is. Alternatively or additionally, it is also possible that foreign aquatic algae the supplying water.

After irradiation the mixture a separation device is preferably supplied, in which turbid matter and enriched with nutrients algae are continuously deposited.

Particularly preferably, the separation device comprises a dynamic filter with a continuously moving bed of granular material, on which the Algae for the separation of the water to be retained. A dynamic filter has over conventional filters, which periodically backflushings need to be made, the advantage that a continuous and thus low-complexity operation.

When granular material is preferably sand and / or activated alumina are (Al₂O₃) used. Since activated alumina effective at not too high pH values ​​Phosphate can bind, is an appropriate use of this material in particular - in Compared to the concentration of nutrients - low algae concentrations advantageous. In this case, even after the irradiation of the mixture still sometimes high Phosphate concentrations in the batch available, which prior to the return line Batch to be separated in the water. Especially offers itself Such a procedure in winter, because then the Phosophatkonzentration in Waters and high algae concentration is low.

The use of activated alumina has the further advantage that such a represents a flocculant for the algae.

As to be rehabilitated surface water are often basic (take the algae and enter during the growth phase in the water carbon dioxide Hydroxide from), can the batch advantageously carbon dioxide or similarly acting compound before passing through the at least partially with Activated alumina filled dynamic filter may be added to adjust the pH value of the reduce batch and thus the phosphate retention rate from the activated alumina to increase. To the solubility of carbon dioxide in the mixture by to increase turbulence, the carbon dioxide is the mixture preferably before Introduction supplied into the irradiation device corresponding to the dynamic filter is connected upstream.

A preferred dynamic filter of the type mentioned above is erect as standing elongate, substantially hollow cylindrical body with conical tapered lower end is formed. In its upper region, the filter on an inlet from which a central tube in the lower region of the Filter interior leads. In the filter interior, the filter bed is arranged by which is passed through the mixture in an upward movement, whereby the Algae and other suspended contaminants are trapped in the filter bed. The filtered water leaves the filter after passing through a filter overflow via a first outlet. A Pump, for example, a mammoth pump, promotes the soiled filter material from the lower portion of the filter up to a central location in the filter interior arranged scrubber, in which the filter material in a downward movement from one part of the ascending filtered water in the countercurrent principle is washed and trickles back to the filter bed. The resulting wash water, containing the algae and suspended matter, leaves the filter via a second outlet. Such a dynamic filter is for example taken as an "DynaSand" filter the company Axel Johnson Engineering GmbH.

The filtered water is preferably returned to the water, while the washing water - possibly after further thickening for example by means of a Bag filter and an eventual partial separation - preferably from the waters Water extracted quantities mixed and fed to the irradiation again is to possibly a balance of seaweeds / nutrients in the adjust irradiation device.

Additionally or alternatively, the separation device may further include a self-discharging Continuous flow centrifuge and / or a sand filter, preferably with a Chamber filter press or a corresponding drainage device, improved include, with respect to the water quality. odor and appearance and simultaneously by swirling oxygenation of the waters in zurückzuleitenden water is achieved. The sand filter can be used as backwash filter be formed. Also additionally or alternatively, a filter bag from a suitable woven material and / or a septic tank are used.

Advantageously, between the photobioreactor and the separation device a hydrocyclone interposed, in which contaminants or impurities be deposited. These impurities include, for example, sand and Sludge, which are deposited at the bottom of the hydrocyclone.

For reasons of procedural economy, all the steps are in a continuous Durchflußprozeß feasible.

Advantageously, the separated in the separation device Algenbiomassezurweiteren Environmental remediation are used by eg heavy metals absorbed from opening into the water rivers or streams with the help of algae will. Also, use of algae to heavy metal elimination from Wastewaters possible in correspondingly sized devices.

In a preferred additional step, the quality of Waters and / or the purified water before recycling into the waters determined by means of suitable measuring devices. Such measurements relate For example, the pH, the turbidity level, the oxygen concentration, the electrical conductivity and the temperature. Due to the measured values, which preferably are evaluated by a computer, are individual process steps regularly with corresponding devices and controllable. For example, likewise measurable volume flow through the or photobioreactors on a optimized nutrient uptake by the algae tuned. Measured values is either cyclically repeated or carried out continuously.

Preferably, the control center of the rehabilitation device is spatially separated. In this way, the data acquisition and visualization of can controlled and monitored a remote control center over long distances will. The remote data, the evaluation of the data in the control center and the transmission of corresponding control commands for individual process steps People minimizes the use at places of rehabilitation device.

Advantageous developments of the invention are characterized by the features of the claims in.

In the following the invention will be described with reference to the drawing. It show:<dl tsize="7" compact="compact"><dt>Fig. 1</dt><dd>a schematic representation of a first embodiment of the Device as a block diagram;</dd><dt>FIG. 2</dt><dd>is a simplified representation of the apparatus components according to of FIG. 1;</dd><dt>Fig. 3</dt><dd>a truncated photobioreactor in longitudinal section; and</dd><dt>Fig. 4</dt><dd>a schematic representation of a second embodiment of the Device.</dd></dl>

As shown in FIGs. 1 and 2, first embodiment illustrated to It is apparent, be out of the surface area of ​​a lake 1 by means of a Skimmers 2 and a hose removed 3 volumes of water, rich in Microalgae and nutrients are, including in particular phosphorus and Nitrogen compounds. A pump 4 pumps the water amounts to three parallel connected photobioreactors 5, which in one of the sides and top open first container module 20 are arranged.

In Fig. 3 is a photobioreactor 5 is shown in longitudinal section, of the upright on a a pedestal 10 fixed frustoconical support frame 8 with an on having the outside of the wound, transparent and flexible pipe 16th Alternatively, a transparent hose be used. The Support frame 8 has closed walls and is made of transparent Plastic. On the free end of the tube 16 in the lower region of the Supporting frame 8 is a tube inlet 17 attached, through which the material to be irradiated fluid material is pumped into the tube sixteenth The other end of the tube 16 in the upper region of the reactor has a tube outlet 18, through the flowing material at the end of the irradiation process leaves the reactor. Alternatively, the fluid 16 through the tube from top to bottom.

In the interior of the reactor 5 is in the range of its vertical axis a in height slidably positioned light source 19 is arranged, for example, of a Sodium vapor lamp with an optimized light spectrum or a plant light fluorescent lamp is formed. The light source 19 is used for continuous biomass production preferably turned on at night when the photosynthetic activity due to lack of natural light is low. Of course, a consistent Use of the light source 19 in support of the sunlight excited photosynthesis also possible.

Above the top pipe coil is centrally an upwardly curved planoconvex Light collecting lens 14 are arranged. The light collecting lens 14 is a hood formed, which closes the reactor upwards. Together with the closed walls of the supporting frame 8 protects the hood on the one hand Reactor interior 4 under unfavorable weather conditions, on the other hand it prevents to large variations in temperature within the reactor.

is in the base 10 of the photobioreactor a with the mirror surface upward directed, concave inner reflector 12 bordered, the substantially over the Surface area of ​​the reactor and extends to increase the light yield sunlight and / or artificial light on the tube 16 throws. The optical axis 15 of the Converging lens 14 and that of the inner reflector coincide.

The irradiation of led to the photobioreactor algae and 5 nutrient-rich water batch with the aid of sunlight and / or the artificial light, the light source 19 are the algae to increased photosynthesis stimulated, which provides the energy required to absorb nutrients. Due to the induced nutrient uptake by the algae nutrient content is reduces the water at the outlet 18 of the photobioreactor 5 and in the same proportion of the oxygen content due to the oxygen production during photosynthesis increased so that from the outlet 18 of the photobioreactor 5 nährstoffverarmtes and thus Oxygenated tertes water together with the nutrient-enriched algae is discharged.

After passing through the photobioreactors 5 the nutrient-reduced water and therein nutrient enriched algae via hoses 23 to a hydrocyclone pumped 27 in which impurities, in particular sand, be deposited. Then the algae-containing water is two parallel connected separation means 29 supplied, which run centrifuges exhibit and sand filter. Here you will find a separation of the water from algae instead of. While algae are transported away for further utilization, the purified, odorless and water enriched with oxygen by means of Pumping aggregates 32 returned via tubing 33 into the lake. 1 Every single one Process step by means of an electronic measuring and control device 25 controllable.

The hydrocyclone 27, the separation means 29 and the measurement and control device 25 are arranged in a second container module 22nd The two Container modules 20, 22 are arranged on movable chassis 24, the brought example of tractors 35 to their respective locations may be, whereby the application possibilities are considerably expanded.

The use of one or more hydrocyclones 27 can optionally be done because the efficiency of deposition of contaminants in the hydrocyclones 27 may vary depending on the water quality.

In Fig. 4 schematically shows a second embodiment of the present invention Device shown in which the separation device 29, a dynamic Filter 40 with an inlet 42 and a first outlet 44 and a second Outlet 44 has. That the waters 1 provided via a pump 2a Skimmer 2 and the valved tube 3 withdrawn mixture is after Running the photobioreactor 5 via a valve-controlled line 23 the Inlet 42 of the dynamic filter 44 is supplied, in which granular filter material, For example, sand and / or activated alumina, is introduced. The mixture passes through the filter bed 48, preferably in an upward motion, whereby algae and Suspended solids are retained in the filter material. A portion of the filtered Water leaves the filter 40 through the first outlet 44 and is fed via line 33 back into the body of water while another part of the filtered water is used for the continuous cleaning of the filter material. For this purpose the filter material supported by means of a pump 43 continuously so that it in a Scrubber section of this part of the filtered water in the countercurrent principle is run. Here go the algae and the turbidity of the filter material in the waters over which the so-called. wash water via the second outlet 46 the filter 40 exits.

The wash water is depending on the turbidity content, which from a measuring station 60 is determined by a corresponding controlled valve 62 either Lines 50a, 50 to 2 skimmers or in the line 3 (the corresponding Connecting cable is not shown) is returned, or - at higher Turbidity - via a line 52 through a bag filter 55 from a suitable, for example, woven, made of filter material. leaves from bag filter 55 at least a part of the washing water via the lines 50b, 50 in the Skimmer 2 or the line traced. 3 In this way algae in blank the washing water for a renewed nutrient uptake in the photobioreactor 5 use. By the lines 50a, 50b, 50 to 1 water to slope are arranged, in the recirculation of the filtered water and / or the Wash water to water 1 or skimmer 2 advantageously their Gravity can be exploited. Additionally or alternatively, for example for Feeding the filtered water or the washing water in the pipe 3, may a water pump (not shown) are used.

Particularly when using active alumina as a filter material in the dynamic Filter 40 for binding by the algae unincorporated Phopsphat it is advantageous for the pH of the basic frequently, to be filtered, to reduce batch by addition of carbon dioxide, since the phosphate binding at low pH is preferred. For this purpose a pH-measuring station 68 provided, which controls a valve 66 in order, if necessary, carbon dioxide from a carbon dioxide storage 64 involved in the management. 3 The carbon dioxide is preferably present Introduction of the mixture added to the photobioreactor 5 to because of the therefore generated turbulence good solubility of the carbon dioxide to form to achieve carbonation.

Examples are set out below some realistic numbers. Of the Photobioreactor 5 described for example has a volume of about 100 l and is operated at a throughput rate of 7000 l / h or higher. The use the inventive method can be used both for smaller or larger - using surface water - artificial or natural. For example, Lakes an area of ​​approximately 10 hectares for redevelopment provided. If one assume that the skimmer this 50 cm below the water surface is placed, will - without the inclusion of the return flow of the purified water - 50,000 m³ taken from the waters. increased due to the cyclic operation the flow rate still to a considerable extent. With such extensive Waters is a use of the method of some Years away assumed, with of course the period of use with As the number of devices used according to the invention shortened.