MICROALGAE BIOFILM REACTOR

Abstract

The present invention relates to a device for the treatment of wastewater in which the wastewater flows through cultivation areas, wherein the treatment takes place in a housing, as well as corresponding methods for wastewater treatment and uses.

Description

[0001] All documents cited in the present application are incorporated by reference in their entirety into the present disclosure.

[0002] The present invention relates to devices for the treatment of wastewater, in particular for the phytoremediation of wastewater (agricultural, industrial, municipal, aquaculture) by means of a harvestable stationary algal biofilm. State of the art:

[0003] The cultivation of eukaryotic and prokaryotic microalgae for research purposes and biotechnological applications has led to the establishment of numerous fields of application and corresponding reactor types. The ability of microalgae to enrich and / or degrade a wide variety of nutrients and pollutants is already being utilized to a limited extent in the remediation of wastewater and exhaust gases. However, a disadvantage is that most applications focus heavily on monocultures and suspended systems. This severely limits the techno-economic feasibility of many applications. An alternative approach is the cultivation of mixed (mesocosmic) algal biofilms, which exhibit greater metabolic flexibility while requiring lower techno-economic expenditure. Known algal turf scrubber (ATS) systems, such as those described in WO 96 / 13970 A1 and US Pat. No. 4,333,263, are open to the environment and can lead to the release of potentially harmful wastewater and biofilm. Commercially available algal biofilm systems, such as those in WO 2014 / 172691 A1, utilize a mobile cultivation surface that is moved via pulleys. This and comparable systems, such as those in WO 2014 / 085869 A1, exhibit disadvantageous high energy consumption, technical failure rates and costs, as well as biofilm detachment. Enclosed systems such as those in DE 20 2019 005 811 U1 are only suitable for very small amounts of wastewater and are unsuitable for use on a large scale.

[0004] Another state-of-the-art document is D. Reinecke et al., “Nutrient recovery from wastewater by algal biofilm fertilizer production part 1: Case study on the techno-economical aspects at pilot-scale,” Separation and Purification technology 305 (2023) 122471. Depending on the ambient temperature, open systems have a high evaporation rate and release of unpleasant odors and potentially harmful gases (NH3, VOC, CH4).

[0005] Therefore, we are still looking for further methods that enable wastewater to be treated in a simple, reliable and efficient manner.

[0006] The object of the present invention was therefore to provide, with regard to the state of the art, new devices for the treatment of waste water which are improved compared to the devices of the state of the art and have new or further advantages.

[0007] Further tasks for the specialist arise from the following description.

[0008] These and other objects are achieved within the scope of the present invention by the subject matter of the independent claims. Preferred embodiments emerge from the dependent claims and the following description.

[0009] Within the scope of the present invention, the term "comprise" also includes "consisting of" as a particularly preferred embodiment; this means that a corresponding list may contain (=comprise) further elements in addition to the explicitly mentioned elements, or it may contain precisely these elements (=consist of) (whereby non-essential elements such as screws, markings, etc. are not taken into account). For relative information such as top, bottom, left, right or similar, the reference system used in the present invention is an observer standing upright on the ground in front of the object in question.

[0010] In the context of the present invention, the expression “and / or” means that both elements mentioned in the context are included individually as well as the combination of the elements mentioned in the context. In the context of the present invention, all quantities are to be understood as weights unless otherwise stated. For the purposes of this invention, the term "ambient temperature" refers to a temperature of 20°C. Unless otherwise stated, temperatures are in degrees Celsius (°C). Unless otherwise stated, the reactions or process steps described are carried out at atmospheric pressure, i.e., at approximately 1013 kPa. When reference is made to "harvesting" in the context of the present invention, this means that the biomass or (algal) biofilm is removed from the cultivation area, for example, by scraping. The resulting product can then be used as biofertilizer, biogas substrate, soil conditioner, soil additive, or similar.

[0011] The present invention relates, in a first aspect, to a device for treating wastewater which comprises all the necessary devices or equipment in a (single) housing which is closed on all sides.

[0012] Within the scope of the present invention, the interior of the housing is preferably made of a corrosion-resistant and washable material or is coated with such a material; one example of a preferred material is stainless steel. This is because, naturally, a certain level of humidity prevails in the interior during operation of the device according to the invention. This can condense on the walls and – with other materials – could lead to corrosion there. Furthermore, it is dangerous for operating personnel entering the interior, for example for maintenance purposes, if moisture collects on the floor and cannot be wiped away. Finally, the present invention is based on biological processes. Therefore, it is useful to be able to remove contaminants from the surfaces (of the housing) (this could also lead to contamination of the purified water).

[0013] In particularly preferred embodiments of the present invention, the housing is a cuboid-shaped housing, preferably a container, possibly converted, particularly preferably a standard container or ISO container, possibly converted, in particular a 10-foot shipping container, 20-foot shipping container or 40-foot shipping container.

[0014] The fully enclosed housing has one or more openable and closable access points. These can, in principle, be any type of access, such as manholes, hatches, doors, etc. Preferably, these are doors that are either incorporated into the respective head ends of the housing or form the entire respective head ends; the latter is often the case with ISO containers, which are a preferred type of housing within the scope of the present invention.

[0015] For this purpose, two or more cultivation surfaces are arranged one above the other inside the housing. These are preferably arranged parallel to one another, i.e., in particular, the planes formed by their base surfaces are parallel to one another. Furthermore, the cultivation surfaces (or the planes formed by their base surfaces) each have an inclination relative to the horizontal of between 0.5° and 7.5°, preferably between 1° and 5°, particularly preferably between 1.5° and 3.5°, and in particular 2°, with the base surface of the housing (bottom of the container) being considered the horizontal.

[0016] The individual cultivation surfaces can, in principle, be inclined in any way with respect to the housing, for example also diagonally within the housing, but it is preferred if they are inclined in such a way that, in a sectional view of the housing, they are inclined from one side of the housing to the opposite side, whereby it is not necessary and is generally not designed in such a way that the ends of the cultivation surfaces abut the side walls.

[0017] In the context of the present invention, "cultivation surface" refers to flat, level workpieces that have longitudinal edges, forming a space open to one side (at the top) with a usable volume. The space and volume are defined by the base area, the side lengths, and the lowest height of the edges. These workpieces are intended to accommodate biofilms, as well as any growth aids for the biofilms or the organisms forming the biofilms, in the resulting volume. In preferred embodiments, the longitudinal edges are between 1 cm and 10 cm high, particularly preferably between 2 cm and 5 cm.In variants of the present invention, it is possible for the head and foot ends, i.e., the side where the water to be purified is added and the side from which the purified water is discharged, to have higher or lower edges, or even no edges at all—depending on the design of the water supply and discharge devices. Accordingly, it is also possible to provide holes in the edges. The workpieces thus formed—cultivation surfaces—usually, preferably, have rectangular bases; however, parallelogram-like, trapezoidal, triangular, n-sided, or ellipsoidal bases are also conceivable.

[0018] In a preferred embodiment, cultivation areas with dimensions of 11500 mm x 1500 mm can be used in a 40-foot container, the sides of which are preferably bent upwards by 90° and then have a height of 30 mm. In the context of the present invention, the cultivation surfaces are made, in particular, of inert materials—that is, corrosion-resistant, washable, chemical-resistant, and reflective. An example of such a material is stainless steel. In principle, the cultivation areas are not limited in their dimensions as long as they, and any additional devices / equipment present, find space inside the housing of the device according to the invention. In a 40-foot container, for example, a stack of ten cultivation areas measuring 11,500 mm x 1,500 mm x 30 mm (the latter being the edge height) can easily be arranged on one half of the container, while still leaving enough space in the other half to allow access; for example, as a maintenance arm. The distance between the individual cultivation areas in this embodiment can be, for example, 250 mm (area to area, not taking edge heights into account).

[0019] The upper surfaces of the cultivation areas are covered by biofilms, preferably microalgal biofilms. The biofilms applied to the different cultivation areas are all the same, partially the same, or all different. "Same" preferably means that the same microorganisms are used. In a scientific context, comparability refers to biofilms with a similar structure and similar function despite differentiated microbial composition. Even with the same inocculum, ultimately different biofilms can develop on the flowways (cultivation areas; where the water flows) (mathematical-dynamic system).This means that, for example, with three cultivation areas, three different biofilms can be present—a different one on each cultivation area, or the same biofilm can be present on all three, or the same biofilm can be present on two cultivation areas and a different one on the third. This applies analogously to any number of cultivation areas. As is well known to those skilled in the art, various organisms are suitable for these purposes, i.e. for the production of a biofilm, which the expert can select based on his general technical knowledge. The exact biofilm composition varies with the culture conditions (wastewater quality, temperature, light, etc.). Over time, under constant culture conditions, an optimized and selected = cultivated biofilm will form, so that in each device according to the invention, an individual / local biofilm is cultivated during ongoing operation. Initially (i.e. during the initial loading / planting), the following can be used, for example (but not exclusively): From the grouping of pro- and eukaryotic strains: Microalgae (e.g.Spirulina, Chlorella); from the prokaryotic kingdom: bacteria; from the eukaryotic kingdom: metazoa (ciliates) and fungi; in addition to the biofilm matrix: extracellular polymeric substances (EPS) secreted by the microorganisms. In the context of the present invention, organisms occurring locally are preferably used for the biofilms (for example, microalgae from the local environment), which increases environmental compatibility because, for example, contamination of the environment by organisms not resident locally is avoided (keywords: neophyte or neomycete avoidance).

[0020] Furthermore, the device according to the invention comprises at least one feed device for applying wastewater to be treated to one or more cultivation areas. According to the invention, it is preferred if one device distributes the wastewater applied to it to all cultivation areas. However, within the scope of the present invention, it is also possible for multiple feed devices to be present, which then supply wastewater either to individual cultivation areas or to several. In some preferred variants of the present invention, the wastewater is distributed evenly across all cultivation areas by one feed device.In particular, the at least one supply device within the scope of the present invention is arranged such that the water to be treated is applied to the respective higher end of the respective inclined cultivation surfaces; in this way, it is ensured that the wastewater flows along the cultivation surfaces driven by gravity and thus passes through the biofilms. In preferred embodiments of the present invention, the supply device for applying wastewater to be treated comprises a controllable (adjustable) pump for the wastewater.

[0021] Furthermore, the device according to the invention also comprises at least one discharge device for the treated water, wherein the at least one discharge device is arranged such that it discharges the treated water from the lower end of the respective cultivation areas. It thus forms a counterpart to the supply device.

[0022] The at least one supply device and the at least one discharge device comprised by the device according to the invention are, in the simplest case, simple pipes with branches to the individual cultivation areas. It is preferred if the supply devices have adapted branches for even distribution to the individual cultivation areas, for example, with different diameters, or corresponding control devices such as valves. In further preferred embodiments of the present invention, the branches to the individual cultivation areas have widened sections, for example, up to the entire width of the respective cultivation area, in order to ensure even application of the water to the respective cultivation area. In some preferred variants, the discharge devices have corresponding widened sections to collect the purified water.In other variants, the cultivation surfaces have one or more drainage holes at their ends, to which the drainage device(s) is / are connected. If the drainage holes are designed to allow water to be collected at the bottom of the housing by means of a gutter or similar device, then the drainage holes and the gutter are considered a drainage device. The at least one supply device and the at least one discharge device are preferably, but not necessarily, arranged inside the housing, so that transport of the device is easier than if they were arranged on the outside. In some preferred variants of the present invention, this includes associated devices, such as pumps, etc. In preferred variants of the present invention, the at least one feed device and the at least one discharge device are designed such that they are provided with standardized connections, so that the wastewater to be treated or the purified water can be connected on site to the existing water networks or the like using conventional connecting elements. These standardized connections can, for example, be correspondingly standardized connections for hoses or pipelines. However, this is not always necessary for the proper operation of the devices according to the invention, since it is also possible to simply add water to be treated to the feed device using, for example, a gutter or funnel and, in the simplest case, to simply allow the purified water to drain into the environment (which would usually be wasteful and is therefore not usually done). Regardless of how exactly the supply and discharge devices are designed, it is preferred if they can be closed at least to the outside (i.e. to the outside of the housing) (which is particularly advantageous for transport).

[0023] A further component of the device according to the invention is at least one ventilation device for the housing, configured to supply air, in particular ambient air, and to discharge used air. In some preferred variants of the present invention, this is a passive ventilation device, in particular in the form of ventilation holes incorporated into the housing. In this case, it is preferred if one or more ventilation holes are configured on the floor, or near the floor, of the housing, and one or more in the ceiling, or near the ceiling, of the housing. In other preferred embodiments of the present invention, active ventilation devices are used, such as fans and / or blowers. It can be advantageous if shields are attached to the upper edges of the openings of the ventilation devices facing the environment, which, for example, prevent the ingress of rain.In the case of active ventilation systems, it is preferred in variants if the air intake takes place via a filter or similar. Regardless of whether active or passive ventilation devices are used, it is preferred if they can be closed at least to the outside (i.e. to the outside of the housing) (which is particularly advantageous for transport).

[0024] Yet another component is at least one device for supplying light to the biofilms, which can be passive or active. These are preferably designed to be controllable, meaning that the amount and intensity of light entering the housing, and in particular onto the cultivation surfaces, can be adjusted. This can be controlled manually or electronically for the selected device(s). The light supply devices are preferably selected from the group consisting of a) translucent, preferably daylight-permeable, side elements in at least one, preferably exactly one, housing wall (long side of the housing), b) translucent, preferably daylight-permeable, elements in the housing ceiling, c) artificial light sources, preferably lamps, particularly preferably LED, particularly preferably arranged within the housing, in particular arranged opposite a), so that the cultivation surfaces are arranged between a) and c), - and combinations thereof.

[0025] Of these, variant b) is less common (among other things because there are hardly any containers that have corresponding ceiling designs and because the uppermost cultivation area shades the ones below), but is still just as possible as variants a) and c).

[0026] Variants a) and b) are passive devices for supplying light, as they depend on whether and, if so, how much light is present or generated outside the housing. Variant c), on the other hand, is an active device, as it can generate light independently of the environment (assuming a power supply). The devices in variants a) and b) can be controlled using simple measures such as, in particular, reflective blinds; however, they can also include electrically adjustable polarization filters or similar. The devices in variant c) can be controlled in various ways. For example, a lamp can be controlled simply using a dimmer. In the event that several individual lamp elements are present, they can each be dimmed independently of one another, or switched on or off independently of one another.Both the active and passive light supply devices can be modified by using filters so that only specific wavelengths or wavelength ranges of light reach the biofilms.

[0027] The lamps can be positioned in any way; for example, they can be mounted on stands, attached to the walls, or hung. In particularly preferred embodiments, the lamps, in particular LEDs, are designed like a curtain, allowing the lamps to be moved. The lamps hang from the housing ceiling and are mounted in such a way that they can be moved individually or in groups, particularly laterally. This is a particularly flexible solution for supplying light, allowing the light to be intensified or dimmed at desired locations simply by moving it. In embodiments where this lamp curtain does not touch the housing floor but hangs above it, this solution is also advantageous from the perspective of easier cleaning and hygiene.

[0028] In preferred variants of the present invention, the housing has at least one light-permeable, preferably daylight-permeable, side element in a housing wall, and lamps, preferably LEDs, arranged within the housing, in particular as a lamp curtain.

[0029] A wide variety of lamps, well-known to experts, can be used for plant lighting. An example of commercially available (vertical) LED lighting technology in plant cultivation are lamps such as those from Blooms Grow Tech. ® are available.

[0030] The device according to the invention can optionally comprise at least one supply device for CO2-containing gas. This gas serves to provide additional nutrients for the algae in the biofilms and is not required in every case, but is used only in accordance with the specific conditions (since there are cases where additional CO2 is not necessary).

[0031] Optionally, the device according to the invention can comprise electronic and, if appropriate, hydraulic operating devices, such as, in particular, control and regulation devices for temperature, water flow, particularly in the biofilms, lighting, CO2 supply, ventilation, and gas supply and discharge. The control devices can comprise, for example, sensors, for example for pH, conductivity, etc., whereby these can be IoT sensors in order to be able to track and monitor the data continuously and online, which then enables immediate intervention (manual or automated) if this appears necessary based on the data. These operating devices are not necessary in the simplest embodiment, when the wastewater is fed into the feed device, for example via gutters, the water simply passes through the biofilms and finally simply flows out, and only a translucent housing wall serves as lighting.Typically, however, the water inflow and outflow, as well as the flow rate through the biofilms, are regulated or at least adjusted and monitored, so that electronic and, if necessary, hydraulic operating devices are present. These can be arranged in one or more housings and can be located inside or outside the housing of the device according to the invention. In preferred variants of the present invention, these are arranged inside so as not to impair the transportability (and stackability, etc.) of the device according to the invention.

[0032] In some preferred variants of the present invention, the housing and / or the operating devices have interfaces for the optional integration of CO2 supply, the power supply from external sources, for example, and preferably photovoltaics and / or wind power. In further preferred variants of the present invention, the device according to the invention, or in particular its operating devices, has a warning system for pump, air conditioning system and / or LED stop.

[0033] In preferred embodiments of the present invention, a growth material for the biofilm, preferably microalgal biofilm, is first applied to the upper surfaces of the cultivation surfaces. And only then is the respective biofilm, preferably microalgal biofilm, applied thereon. In preferred variants of the present invention, this growth material can be made either of a robust and durable material, preferably glass fiber fabric, polypropylene, stainless steel, particularly preferably as a net or fabric, in particular with a mesh size of >2, or compostable material, preferably made of linen, hemp, cotton, sisal, particularly preferably designed as a net or fabric, in particular with a mesh size of >2; for short cultivation cycles focused on biofilm / fertilizer production, this can also be jute, in particular a net or fabric, in particular with a mesh size of >2, made of jute.

[0034] As already indicated above, the present invention is not limited to a precise number of cultivation surfaces arranged one above the other. Thus, in preferred embodiments of the present invention, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10 or more cultivation surfaces are arranged one above the other in the housing. Accordingly, within the scope of the present invention, it is also possible to arrange, for example, 15 cultivation surfaces or 20 cultivation surfaces (as well as any other number between 10 and 20) or even more on top of each other. This is generally only limited by practicality, because, for example, each container has only a limited amount of space / volume, and not an unlimited number of devices can be arranged in it.

[0035] In preferred variants of the present invention, two openable and closable accesses are provided, which are located on two opposite sides of the housing and are designed as accesses for persons.

[0036] In further preferred variants of the present invention, the cultivation surfaces are arranged in one half of the housing and the other half of the housing is configured as a (walk-in) maintenance room or maintenance area, and lamps are arranged in the middle of the housing, which are configured to illuminate the cultivation surfaces and the biofilms located thereon.

[0037] In still further preferred variants of the present invention, the supply device for applying waste water to be treated (4) and the discharge device for the treated water (8) are provided with standardized connections.

[0038] In yet further preferred variants of the present invention, one or more photovoltaic elements are arranged on the top of the device, which are configured to supply power to the internal electronics of the device. In this case, it is preferred if the device according to the invention also comprises secondary batteries that can be charged by the photovoltaic elements when excess power is generated and that are capable of supplying power to the device according to the invention when the photovoltaic elements cannot generate power (for example, at night). In preferred embodiments, the device according to the invention is provided with corresponding interfaces which make it possible to supply the electricity generated by the photovoltaic elements to external consumers or a local power grid when the generated electricity is not currently needed by the device according to the invention. The photovoltaic elements are therefore optional devices in case a more self-sufficient or sustainable operation is desired.

[0039] Further preferred variants of the present invention are characterized in that the water is treated by phytoremediation.

[0040] In preferred embodiments, the device according to the invention comprises at least one integrated transport lock, in particular a main switch for energizing the container, and / or a main shut-off valve for supplying the ATS system with waste water.

[0041] In yet further preferred variants of the present invention, the device has a fresh water inlet at the foot end of the housing, in particular inside, which can be used in particular for the hygienic final cleaning of the equipment and the personnel (hand washing).

[0042] In preferred embodiments of the present invention, the housing of the device according to the invention can accordingly be an ISO container, for example a shipping container, particularly preferably a 40-foot container, 20-foot container or 10-foot container, particularly preferably a 40-foot container.

[0043] In variants of the present invention, the inclinations of the individual cultivation surfaces can be adjusted as needed. In particular, the individual cultivation surfaces can be adjusted independently of one another. The inclination adjustment can be performed either manually or with mechanical / electronic assistance; motors are installed, in particular, for the latter purpose. In a simple case, the various cultivation surfaces are movably mounted at their lower ends and provided with locking lugs at their upper ends that can engage in corresponding recesses of support rods (similar to what is common in shelving systems). A very simple way, but within the scope of the present invention, of implementing the cultivation surfaces arranged one above the other is through shelving systems, in which the individual cultivation surfaces are arranged on the respective shelves, or the shelves themselves form the cultivation surfaces. For this to work, the shelves must be designed accordingly (especially metal shelves), and the shelves must not be inserted straight, but higher on one side than the other. In this variant, care must be taken to ensure that the upper surfaces of the shelves are either modified so that they can hold the cultivation surfaces, for example, using adhesives or mechanical fasteners such as clamps or screws, or modified so that they can themselves serve as cultivation surfaces. In particular, the front and back sides are provided with edges that prevent water from leaking out.

[0044] Within the scope of the present invention, in principle, all conceivable wastewater can be treated, provided it is not toxic to the available biofilms. Within the scope of the present invention, wastewater can also be treated which is toxic to some species but not to others – in this case, other organisms (tolerant or resistant to this wastewater) would be used for the biofilm. Examples of wastewater which can be treated within the scope of the present invention are: municipal wastewater, wastewater from / from animal husbandry, or biogas wastewater, industrial wastewater from food production and processing (non-critical), from healthcare facilities (critical if contaminated with pharmaceuticals or pathogens), from textile processing (critical if still contaminated with dyes orContaminated wastewater (e.g., contaminated with fixers), from contaminated production facilities (critical if contaminated with heavy metals or PFAS), from decontamination measures for leachate from landfills and contaminated sites (e.g., from active pumping) – although this list is, of course, not exhaustive. "Critical" in this context refers to whether the wastewater contains substances with health or environmental risks as defined by international, national, and / or municipal regulations (e.g., European UWWTD, German AbwV).

[0045] Furthermore, the present invention relates to processes for wastewater treatment in which wastewater is applied to a device according to the present invention and the treated water is collected again.

[0046] A preferred embodiment of a process according to the invention for treating wastewater using the device according to the invention comprises the following steps: i) Installation of the device according to the invention, preferably horizontally (relative to the housing base), particularly preferably at ground level and / or weatherproof; ii) optional functional testing and readjustment of individual components after installation; (iii) connection to the waste water source and outlet, where appropriate connections exist; (iv) Establishment of a uniform wastewater distribution across the entire width of the cultivation areas through the wastewater distributors; (v) optional inoculation of the growth material with natural microalgae collected locally, i.e. at the site of installation or in the immediate vicinity (preferably within a radius of a maximum of 2 km); vi) establishment of the microalgal biofilm and continuous operation with adjusted wastewater volume until a compact growth has developed; vii) Establishment of continuous operation with a wastewater volume according to needs and objectives; viii) continuous or discontinuous testing of the system by means of control measurements of the wastewater quality in the inlet and outlet, and, if necessary, readjustment of the wastewater inlet; ix) manual harvesting of the microalgal biofilm as needed by scraping (particularly in the case of persistent substrates) or changing the growth material (particularly in the case of biodegradable or compostable substrates).

[0047] In step i), at ground level and / or weatherproof means installation in accordance with the climate zone at the installation site, in particular a solid foundation and a housing with sufficient stability to withstand possible snow loads and / or winds (wind resistance), devices for rain drainage, devices for shading or installation in (partial) shade (excessively high temperatures inside may promote water evaporation beyond an acceptable level).

[0048] In preferred embodiments of the present invention, "compact growth" in step vi) is understood to mean continuous growth of the substrate of at least 80%, preferably at least 90%, particularly preferably at least 95% (based on the surface) with a biofilm having a layer thickness of 2 mm to 20 mm, preferably 3 mm to 15 mm, in particular 5 mm to 10 mm. The "adjusted wastewater volume" means that a uniform water flow is established that is neither too slow (insufficient transport of the substances) nor too fast (the water drains off without sufficient interaction); this is readily possible for the person skilled in the art based on their general technical knowledge.

[0049] In preferred embodiments of the present invention, "a wastewater volume according to need and objective" in step vii) is understood to mean, depending on the objective, either an adjustment of the wastewater volume for optimal remediation (e.g., a 50 percent reduction in N or P values) or an adjustment of the wastewater volume for optimal biofilm production (e.g., for biogas substrate). Targets can also correspond to legal and / or operational requirements (e.g., European Regulation 2020 / 741, EU CAP Strategic and Zero Pollution Action Plan).

[0050] In preferred embodiments of the present invention, a distinction is made in step ix) between two basic embodiments: In the case of a long-lasting substrate (see above), harvesting is repeated over long periods (continuous process). Especially in (critical) wastewater and biofilms, where direct composting is not possible, the substrate must be as inert to contamination and robust as possible. In the case of biodegradable or compostable substrates (see above), no scraping is required and the material is used until biofilm thickness is reached. Environmentally safe wastewater can be treated with these substrates, and the harvest is completed with composting.

[0051] Last but not least, the subject of the present invention is the use of a device according to the present invention for wastewater treatment, preferably by means of phytoremediation.

[0052] The arrangement of parallel stacks of (static) cultivation areas in the device according to the invention enables a reduction of the installation area (land consumption).

[0053] In particular, the arrangement of the cultivation surfaces at fixed inclination angles of 2°, as provided for in a preferred variant of the present invention, enables a cost-effective and low-maintenance construction, because 2° is a good value at which the water flows off slowly and laminarly in order to generate good nutrient uptake (contact time) and biofilm growth.

[0054] In variants of the present invention, a regulation of the wastewater flow and the resulting contact time between biofilm, in particular microalgae biofilm, and wastewater can be achieved by means of an adjustable wastewater pump for the supply of wastewater to be treated, which enables an adaptation according to the degree of contamination (objective remediation).

[0055] In addition, an adjustable wastewater pump allows for regulation of the wastewater flow according to the wastewater volume. In this respect, the device according to the invention, in preferred variants, comprises such an adjustable wastewater pump. This can, but does not have to, be an integral part of the wastewater supply device.

[0056] In cases where a pump is used for wastewater, such an adjustable dirty water pump (with distributor to all cultivation areas) enables energy consumption to be minimized compared to systems with multiple pumps.

[0057] The integration of the microalgae biofilm reactor (i.e. the multitude of cultivation surfaces) into a fully enclosed housing, preferably a standard container, with a lateral window and artificial LED lighting enables the containment of contaminated and / or potentially harmful wastewater (pharmaceuticals, heavy metals, etc.).

[0058] Particular advantages of the present invention, especially for cases where the housing is an ISO container or standard container, are: - a transportable, integrable and demand-oriented wastewater treatment system will be maintained, - installation at seasonal and / or remote point sources is possible.

[0059] The preferred embodiments of the present invention, in which the housing has at least one translucent, preferably daylight-transparent, side element in a housing wall, and lamps, preferably LEDs, arranged within the housing, enable i) a continuous operational and work flow, (ii) wastewater treatment independent of climate and weather conditions, iii) consistent microalgal biofilm production.

[0060] The supply of CO2 for phytoremediation, which is possible within the scope of the invention and preferred in some embodiments, enables an increase in microalgal biofilm production.

[0061] Within the scope of the present invention, it is also possible to achieve an optional self-sufficient energy supply by installing and / or attaching photovoltaic and wind turbines to the housing (container).

[0062] A particularly preferred device according to the present invention is a device for treating waste water, the device comprising: I) a housing closed on all sides, which has two opening and closing access points, II) inside the housing, arranged one above the other and parallel to each other, two or more, in particular ten, cultivation surfaces, with an inclination from one side of the housing to the opposite side, with respect to the horizontal, of 2°, III) microalgal biofilms covering the upper surfaces of the cultivation areas, whereby the biofilms applied to the different cultivation areas are all the same, IV) a supply device for the particularly uniform application of wastewater to be treated to all cultivation areas, wherein the at least one supply device is arranged such that the water to be treated is applied to the respective higher end of the respective cultivation areas, and wherein the supply device comprises a controllable pump; V) a discharge device for the treated water, wherein the at least one discharge device is arranged so that it discharges the treated water from the respective lower end of the respective cultivation areas, VI) at least one passive ventilation device for the housing, configured to supply fresh air, in particular ambient air, and to remove used air, in particular in the form of ventilation holes, VII) two, preferably adjustable, devices for supplying light, namely a translucent, preferably daylight-permeable, side elements in a housing wall, and c lamps arranged inside the housing, preferably LED; VIII) a supply device for CO2-containing gas; IX) Electronic and, where applicable, hydraulic operating equipment, such as, in particular, control and regulation devices for temperature, water flow, lighting, gas supply and discharge.

[0063] The individual parts of the products according to the invention are in active connection with one another in a conventional and known manner.

[0064] In contrast to the possibilities cited in D. Reinecke et al., Separation and Purification Technology 305 (2023) 122471, the present invention offers significant advantages. In Reinecke et al.'s study, the key factor was cost reduction through reduced installation space. However, the single-layer system compared there is unsuitable for consistent biofilm development, as a nutrient gradient leads to high variability in the biofilm (starvation at the outlet). The vertical systems also compared there lead to biomass loss and are prone to failure. The stacking of flowways (cultivation surfaces) in the sense of the present invention is novel. The closed and stacked ATS system of the present invention reduces evaporation pressure, increases reactor control options, and enhances biosafety.

[0065] The various embodiments of the present invention, for example - but not exclusively - those of the various dependent claims or individual embodiments described in the figures, can be combined with one another in any desired manner, even if these combinations are not explicitly mentioned, provided that such combinations do not contradict one another. Process steps presented in the examples are to be interpreted as variants of preferred embodiments of the present invention. Example:

[0066] The invention will now be further explained with reference to the following non-limiting example. Example 1:

[0067] The remediation performance of a device according to the invention is presented in tabular form. The device according to the invention was a 40-foot container (with dimensions of 12,200 mm x 2,400 mm x 2,600 mm) in which 10 cultivation surfaces were stacked parallel and equally spaced one above the other, each with an inclination of 2° relative to the horizontal. The individual cultivation surfaces each had a surface area of ​​11,500 mm x 1,500 mm; the sides were bent upwards at a 90° angle (which prevents the biofilms from slipping or falling off the surfaces). The water height was approximately 20 mm. The resulting surface area was 17.25 m². 2 and a volume of 0.35 m 3 (per cultivation surface) and the flow rate of the water through the cultivation surfaces was approximately 20 L / min. The total area was 172.5 m 2 and a volume flow of 200 L / min (corresponding to approximately 288 m 3 / d). Stainless steel was used as the material for the cultivation surfaces. Glass fiber mesh with a mesh size of >2 was used as the growth material for the microalgal biofilm, and microalgae from the local environment (i.e., locally occurring organisms) were used for the biofilm.

[0068] The resulting remediation performance was determined over a period of eleven months. The averaged data are presented in Table 1 below. Table 1: Remediation performance per flow and elemental composition of the algal biofilm (annual mean, 03.2022 to 04.2023). Wastewater Biofilm [% liters] Standard deviation [% Biomass] Standard deviation N -15,6 8,7 2,0 0,283 P -16,9 17,2 7,7 0,845 K -3,4 7,3 0,3 0,039 C 18,5 1,560 rest 71,5 Figures:

[0069] The embodiments of the present invention explained in more detail below with reference to the figures represent various preferred embodiments. Many of the features or embodiments shown in individual figures below can be combined with features and embodiments shown in other figures or the rest of the description, particularly where the features are described accordingly. Furthermore, the figures are not to be interpreted in a limiting manner and are not true to scale. Furthermore, the figures do not contain all features that conventional devices / systems have, but are reduced to the features essential to the present invention and its understanding. For example, screws, hoses, brackets, etc. are not shown or not shown in detail. The same reference symbols / numbers mean the same or equivalent device parts.

[0070] Fig.Figure 1 shows a frontal view of a device 1 according to the invention, i.e., a top view of the housing 2, which, in preferred embodiments of the invention, is formed from a shipping container, in particular a 40-foot shipping container (with dimensions of 12,200 mm x 2,400 mm x 2,600 mm). It is shown here that one side (shown on the left in the image) is partially formed from a transparent material that is permeable to daylight. This translucent side element 5a is normally designed as one or more windows; however, it is also possible to use a larger translucent plate, for example, made of Plexiglas. For the sake of simplicity, it is not shown in this figure, but all sides of the housing 2 can have such translucent elements 5a. Likewise, translucent ceiling elements 5b can be present in the housing ceiling. Fig.Figure 1 shows a variant of the present invention in which the cultivation surfaces 3 are arranged in only one half of the housing 2 (here on the left). While the cultivation surfaces 3 in this figure only take up approximately one-third of the width (which is purely illustrative), the cultivation surfaces 3 can, of course, also take up more or less width than shown in the figure, or even the entire width (which is often undesirable, however, since easy access to the housing 2 or to the cultivation surfaces 3 is then no longer guaranteed; in this respect, at least a small part of the width will generally remain free as a passage / access). Furthermore, the present invention is not limited to the five cultivation surfaces 3 shown arranged one above the other; there can, of course, be more or fewer.The left half also shows a supply device for treated water 4, by means of which the treated water (wastewater) AW is distributed among the individual cultivation areas 3. The treated water (wastewater) AW is supplied from the outside, illustrated here by a spotted arrow, for example via a suitable wastewater inlet such as a hose or a gutter (not shown). Also not shown is the possibility of directing the treated water (wastewater) AW into the inlet of the supply device 4 by means of a (dirty) pump, which can be arranged (externally) at the head end of the housing (container). In some preferred variants of the present invention, the housing has aeration devices, which are shown here as aeration holes 6; however, instead of simple holes, mechanically and / or electronically assisted aeration devices can also be provided.Ideally (for better air circulation), these are located on or at the bottom and top of the housing 2. Approximately in the middle of the interior of the housing 2, lamps 5c are shown as further devices for supplying light; these can be LED lamps, for example, which can be suspended laterally, which is not visible in the perspective view of the figure. Furthermore, a door is indicated in the figure by a dashed line, as a preferred embodiment of an openable and closable access 7. Furthermore, a discharge device for treated water 8, which is located at the other end of the housing, is indicated by dashed lines. It should be noted that in the Fig.1, the window and also the cultivation area are shown on the left. This is preferred but not necessarily always the case—it is preferable if the cultivation area is located directly next to the window (or a window) so that the cultivation areas, and thus the biofilms, receive sufficient light. However, this can be deviated from, especially if lamps 5c and / or translucent elements 5b are present.

[0071] Fig. 2 shows a top view of the same housing 2 as Fig. 1. Shown here is the same supply device for treated water 4 with inflow of treated water AW, as in Fig.1 and at the other end of the cultivation areas 3 (of which only the topmost is visible due to the perspective) is the discharge device for treated water 8. The purified water GW is then discharged to the outside in some variants (shown here by a spotted arrow). However, it is also possible to circulate the purified water and feed it back to the cultivation areas 3 to allow further purification; this is not usually the case, however. It is also possible to temporarily store the purified water in a collection container until it is released, for example, until it has been tested and released in accordance with legal or operational requirements. The lamps 5c can be seen in their lateral arrangement in this illustration, as can the translucent side element 5a. In addition to these two, Fig.2 shows an optional translucent ceiling element 5b (of which one, several or none at all may be present). Similar to Fig. 1, openable and closable accesses 7 are indicated by a dashed line. Electronic / hydraulic operating devices 9 are in Fig. 2 are shown arranged externally, but in some preferred variants of the present invention they are arranged within the housing, since this variant simplifies the transportability of the entire device 1.

[0072] Fig. 3 shows a side view of the same device 1. For the sake of clarity, however, only four cultivation surfaces 3 are shown one above the other. Fig.The inclination angles of the cultivation surfaces 3 shown in Figure 3 are shown for clarity and do not necessarily correspond to the actual angles. The four arrows arranged above the respective cultivation surfaces 3 indicate the flow direction of the water to be treated over the cultivation surfaces 3 or the (microalgal) biofilms located thereon. As shown in Fig.2 Also shown here is the supply device for treated water 4 with the inflow of treated water AW, and at the other end of the cultivation surfaces 3, the discharge device for treated water 8, as well as the fact that in the variant shown, the purified water GW is discharged to the outside. The water inlet of the supply device 4 is arranged higher than the uppermost cultivation surface 3, and the water outlet of the discharge device 8 is lower than the lowermost cultivation surface 3; in this way, the water transport or flow occurs according to gravity and does not require any additional energy-intensive assistance from, for example, pumps. In this figure, the supply and discharge devices for the water are designed, on the one hand, as a distributor and, on the other hand, as a collector.However, within the scope of the present invention, it is also possible to provide a plurality of supply and discharge devices, for example for several cultivation areas and / or for individual cultivation areas; as required.

[0073] Fig. Figure 4 shows the data from Table 1 as a diagram, where the percentage of the different elements (K, N, P, C and the rest) in the total mass is plotted. List of reference symbols: 1 device for the treatment of wastewater 2 housings 3 cultivation areas 4 Feed device for water to be treated 5 Device for supplying light 5a translucent side element 5b translucent ceiling element 5c lamps 6 Ventilation system 7 openable and closable access 8 Discharge device for treated water 9 Electronic / hydraulic operating equipment AW water to be treated (wastewater) GW purified water Arrows flow direction (from AW, GW or general) QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 96 / 13970 A1

[0003] US 4,333,263

[0003] WO 2014 / 172691 A1

[0003] WO 2014 / 085869 A1

[0003] DE 20 2019 005 811 U1

[0003] Cited non-patent literature

[0000] D. Reinecke et al., „Nutrient recovery from wastewater by algal biofilm fertilizer production part 1: Case study on the techno-economical aspects at pilot-scale“, Separation and Purification technology 305 (2023) 122471

[0004] D. Reinecke et al., Separation and Purification technology 305 (2023) 122471

[0064]

Claims

[1] Device for treating waste water, the device comprising: I) a housing enclosed on all sides and having one or more opening and closing access points; II) inside the housing, two or more cultivation surfaces arranged one above the other, each with an inclination relative to the horizontal of between 0.5° and 7.5°, III) biofilms covering the upper surfaces of the cultivation areas, whereby the biofilms applied to the different cultivation areas are all the same, partly the same or all different; IV) at least one supply device for applying wastewater to be treated to one or more cultivation areas, wherein the at least one supply device is arranged such that the water to be treated is applied to the respective higher end of the respective cultivation areas; V) at least one discharge device for the treated water, wherein the at least one discharge device is arranged such that it discharges the treated water from the respective lower end of the respective cultivation areas; VI) at least one ventilation device for the housing, configured to supply air and to remove used air; VII) at least one device for supplying light to the biofilms; VIII) optionally at least one supply device for CO2-containing gas; IX) optional electronic and, if applicable, hydraulic operating equipment. [2] Device (1) according to claim 1, characterized bythat on the upper surfaces of the cultivation surfaces, growth material for the biofilm, preferably microalgae biofilm, either made of robust and durable material, preferably glass fiber fabric, polypropylene, stainless steel, particularly preferably as a net or fabric, in particular with a mesh size >2, or compostable material, preferably made of linen, hemp, cotton, sisal or jute, particularly preferably as a net or fabric, in particular with a mesh size >2, is first applied and then the respective biofilm, preferably microalgae biofilm, is applied thereon. [3] Device (1) according to one of the preceding claims, characterized by that the housing is a cuboid-shaped housing, preferably a container, which may be converted, particularly preferably a standard container, which may be converted, in particular a 10-foot shipping container, 20-foot shipping container or 40-foot shipping container, which may be converted. [4] Device (1) according to one of the preceding claims, characterized by that at least 3, 4, 5, 6, 7, 8, 9, 10 or more cultivation surfaces are arranged one above the other in the housing. [5] Device (1) according to one of the preceding claims, characterized by that there are two openable and closable entrances located on two opposite sides of the housing and designed as pedestrian access. [6] Device (1) according to one of the preceding claims, characterized by that the cultivation surfaces (3) are arranged in one half of the housing, the other half of the housing is configured as a maintenance area, and in the middle of the housing, as a means for supplying light, lamps are arranged which are configured to illuminate the cultivation surfaces (3) and the biofilms located thereon. [7] Device (1) according to one of the preceding claims, characterized bythat the supply device for the application of waste water to be treated (4) and the discharge device for the treated water (8) are provided with standard-compliant connections. [8] Device (1) according to one of the preceding claims, characterized by that one or more photovoltaic elements are arranged on top of the device, configured to supply power to the internal electronics of the device. [9] Device (1) according to one of the preceding claims, characterized by that the water is treated using phytoremediation. [10] Device (1) according to one of the preceding claims, in particular according to claim 6, characterized by that as a device for supplying light, at least one lamp with a plurality of lighting means or a plurality of lamps are provided which hang from the ceiling of the housing and are fastened in such a way that they can be moved individually or in groups, in particular laterally. [11] Wastewater treatment processes, characterized by that waste water is applied to a device according to one of claims 1 to 10 and the treated water is collected again. [12] A process for wastewater treatment, in particular according to claim 11, comprising the following steps: i) installing a device according to any one of claims 1 to 10; ii) optional functional testing and readjustment of individual components after installation; (iii) connection to the waste water source and outlet, where appropriate connections exist; (iv) Establishment of a uniform wastewater distribution across the entire width of the cultivation areas through the wastewater distributors; v) optional inoculation of growth material from the cultivation areas with locally collected microalgae; vi) establishment of a microalgal biofilm and continuous operation with adjusted wastewater volume until a compact growth has developed; vii) Establishment of continuous operation with a wastewater volume according to needs and objectives; viii) continuous or discontinuous testing of the system by means of control measurements of the wastewater quality in the inlet and outlet, and, if necessary, readjustment of the wastewater inlet; ix) manual harvesting of the microalgal biofilm as required by scraping or changing the growth material. [13] Use of a device according to one of claims 1 to 10 for wastewater treatment, preferably by means of phytoremediation.

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