Device for the post-treatment of water from small wastewater treatment plants

Abstract

Device for the post-treatment of water from small wastewater treatment plants, with a reactor vessel having at least one water inlet for the water to be post-treated and at least one water outlet for the post-treated water, characterized in that that the reactor vessel (3) has at least one carbon storage reservoir (6) arranged between the water inlet (4) and the water outlet (5), and that the carbon storage (6) has storage segments (7) aligned on a structured three-dimensional lattice.

Description

[0001] The invention relates to a device for the post-treatment of water from small wastewater treatment plants, with a reactor container that has at least one water inlet for the water to be post-treated and at least one water outlet for the post-treated water.

[0002] Small wastewater treatment plants of the type under discussion here are used when wastewater disposal via central, municipal treatment plants is problematic for technical, legal, or financial reasons. In particular, small wastewater treatment plants regularly exceed the nitrate limits typically prescribed by authorities, even with adequate plant size and careful maintenance. Significant exceedances of these nitrate limits necessitate costly transport of water from small wastewater treatment plants to municipal treatment plants. In reality, compliance with the nitrate limits would only require nutrient removal through comprehensive denitrification. However, such denitrification is not feasible in the small wastewater treatment plants currently in operation, as their primary function is to enable aerobic degradation processes within technical facilities.For this purpose, the chambers of known small wastewater treatment plants are aerated at timed intervals. However, repeatedly interrupted periods of inactivity due to aeration are unsuitable for denitrification, as this process can only occur in an anaerobic environment. Therefore, in known small wastewater treatment plants, denitrification processes are merely incidental phenomena that do not enable the comprehensive reduction of nitrogen compounds.

[0003] The invention is therefore based on the objective of demonstrating a device which enables post-treatment with a significantly improved denitrification of the water leaving small wastewater treatment plants.

[0004] This problem is solved according to the invention by a device having the features of claim 1. Advantageous embodiments of the invention are specified in the dependent claims.

[0005] The device according to the invention for the post-treatment of water from small wastewater treatment plants is characterized in that the reactor vessel has at least one carbon storage unit arranged between the water inlet and the water outlet, and that the carbon storage unit has storage segments aligned with a structured three-dimensional grid. The structured three-dimensional grid allows the storage segments to be kept at a distance from one another, so that the carbon storage unit can be reliably and unimpeded by water flowing through it. The reactor vessel forms flow paths through its carbon storage units as well as bypasses around them, with the individual flow paths being particularly easy to form flow cross-sections that are many times smaller than those of the individual bypasses.In this way, the device according to the invention, unlike the upstream small wastewater treatment plant, is not suitable for sedimentation and mechanical separation, but is advantageously suited for bacterial nitrogen degradation in an anaerobic environment. The carbon storage unit serves as the basic supply for sessile bacteria, which metabolize the problematic nitrogen compounds. By connecting several reactor vessels in series, the device according to the invention is advantageously suited to retrofitting all known small wastewater treatment plants, regardless of their size and capacity.

[0006] In a first further development of the device according to the invention, the storage segments are mesh grids filled with wood chips. The wood chips store the carbon required by the sessile bacteria. Tests on a pilot plant have shown that a mixture of wood chips from different tree species can advantageously be used to produce durable storage segments that can remain in the reactor vessel of the device according to the invention for several years.

[0007] An alternative to constructing the storage segments with grids involves using wire baskets filled with wood chips. Compared to grids, wire baskets have rigid grid structures and can be used particularly if it turns out that a constant geometric shape of the storage segments has a significant influence on the performance of the device according to the invention.

[0008] In a further embodiment of the invention, the storage segments are suspended from lifting elements in the order forming the structured three-dimensional grid. Such lifting elements are, for example, ropes, cords, chains, hooks, eyelets, shackles, swivels, or rods suspended in a horizontal grid plane, each supporting several storage segments arranged in a vertical row. The structured three-dimensional grid is thus defined by a horizontal grid plane and several vertical rows arranged in this grid plane. The structure of the three-dimensional grid particularly enables a uniform spatial distribution of the storage segments within their carbon storage capacity. The vertical rows can each have a single lifting element and several storage segments suspended from it, or they can each have several lifting elements connecting the storage segments to each other in chains.Particularly preferred are the lifting devices designed as hooks or as hook-eye connections, which make it maximally easy to unhook, hook in or change individual storage segments as needed.

[0009] According to a further embodiment of the invention, the lifting devices are suspended from a support structure whose suspension points are evenly distributed across the flow cross-section of the reactor vessel. For this purpose, the support structure is preferably designed in the form of a spoked wheel or a grid, which allows for easy attachment and detachment of the lifting devices with the storage segments suspended from them.

[0010] According to another embodiment of the invention, several planting baskets embedded in a container lid are arranged at the water outlet of the reactor vessel to hold repositioning plants. In such an arrangement, the water, which has already been largely denitrified in the storage segments, reaches the roots of the repositioning plants, where they can extract further nitrogen compounds from the water. Furthermore, the repositioning plants advantageously also extract a whole range of other nutrients from the denitrified water, so that it can be released into the natural water cycle as clear water that is harmless to animals and plants.

[0011] For cultivating the replanting plants in the planting baskets, a planting substrate has proven effective in the pilot plant, consisting of at least a mixture of wood chips and a mineral granulate. According to a further development of the invention, this planting substrate contains sponge particles impregnated with carbon dust to ensure optimal nutrient supply. Species of the iris family (Iridaceae) are particularly suitable for use as replanting plants. However, the invention also allows for the use of other marsh and aquatic plants as replanting plants, thereby supporting the development of ecologically valuable niche habitats.

[0012] To keep the operating costs of the device according to the invention as low as possible, a particularly advantageous embodiment of the invention proposes that the reactor vessel have at least one inspection opening formed as a manhole in a vessel lid. This allows for advantageously simple execution of inspection, cleaning, and maintenance work, for which no expensive camera technology, expensive maintenance equipment, or expensive special tools are required. The inspection opening provides a person tasked with maintaining the device with particularly uncomplicated access to the interior of the reactor vessel.

[0013] An embodiment of the invention, from which further inventive features emerge, is shown in the drawing.

[0014] The single figure shows a perspective schematic of the device according to the invention in field use at a small wastewater treatment plant 1, which is assigned to a farmstead 2. The device has a reactor vessel 3, which has a water inlet 4 fed by the wastewater outlet of the small wastewater treatment plant 1 for the water to be treated and a water outlet 5 for the treated water. The reactor vessel 3 has a carbon storage unit 6 arranged between the water inlet 4 and the water outlet 5, which has storage segments 7 aligned with a structured three-dimensional grid. The storage segments 7 are grids filled with wood chips and are suspended in the spatial arrangement forming the structured three-dimensional grid by lifting elements 8 in the form of hook-and-eye connections.The lifting devices 8 are suspended from a support structure 9, the suspension points 10 of which are evenly distributed within the flow cross-section of the reactor vessel 3. Several planting baskets 12 for receiving repositioned plants 13 are arranged in a lid 11 of the reactor vessel 3. The planting baskets 12 are filled with a planting substrate 14, which is a mixture of wood chips, a mineral granulate, and sponge particles mixed with carbon dust. The reactor vessel 3 has an inspection opening 15 in its lid 11, designed as a manhole, which is closed with a cover 16. Water treated in the reactor vessel 3 is finally discharged as clear water via the drain 5 into a ditch 17, which follows the course of an access road 18 to the farmyard 2.The water inlet 4 has a dip tube 19 centrally inserted into the reactor vessel 3, which carries an outflow nozzle 21 formed on the bottom 20 of the vessel, through which the water to be clarified is supplied to the carbon storage tank 6 from below.

Claims

[1] Device for the post-treatment of water from small wastewater treatment plants, comprising a reactor vessel which has at least one water inlet for the water to be post-treated and at least one water outlet for the post-treated water, characterized by , that the reactor vessel (3) has at least one carbon storage reservoir (6) arranged between the water inlet (4) and the water outlet (5), and that the carbon storage (6) has storage segments (7) aligned on a structured three-dimensional lattice. [2] Device according to claim 1, characterized by , that the storage segments (7) are grids filled with wood chips. [3] Device according to claim 1, characterized by , that the storage segments (7) are wire baskets filled with wood chips. [4] Device according to any one of claims 1 to 3, characterized by, that the storage segments (7) are suspended on lifting means (8) in the order forming the structured three-dimensional grid. [5] Device according to claim 4, characterized by , that the lifting devices (8) are suspended from a support structure (9) whose suspension points (10) are arranged in the flow cross-section of the reactor vessel (3). [6] Device according to any one of claims 1 to 5, characterized by , that several planting baskets (12) embedded in a container lid (11) for receiving repositioning plants (13) are arranged at the water outlet of the reactor container (3). [7] Device according to claim 6, characterized by , that the planting baskets (12) are filled with a planting substrate (14) which is at least a mixture of wood chips and a mineral granulate. [8] Device according to claim 7, characterized by , that the plant substrate (14) contains sponge particles mixed with carbon dust. [9] Device according to any one of claims 1 to 8, characterized by , that the reactor vessel (3) has at least one inspection opening (15) designed as a manhole in a vessel lid (11).

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