COMBINED DEVICE UASB REACTOR-ANAEROBIC SOLIDS DIGESTER AND METHOD FOR WASTEWATER TREATMENT).

Abstract

The present invention relates to a single-stage device for the treatment of wastewater, such as non-sedimented wastewater, especially wastewater that has submesophilic temperatures and / or that shows high temperature fluctuations throughout the year, the device essentially being constituted by a combination of a pulsed UASB reactor with an unheated anaerobic solids digester located below the UASB reactor, comprising an inclined baffle separator element that connects both chambers; so that the sludge produced during the process inside the UASB reactor settles into the digester, is recycled and sent to the UASB reactor by means of a gas lift pump that operates with the biogas generated in the anaerobic digester.The UASB reactor comprises a pulse-operated wastewater mixing and injection device that not only feeds and mixes the reactor but also mixes the digester's sludge bed in different operating modes. The invention also discloses the method for treating the wastewater.

Description

COMBINED DEVICE UASB REACTOR-ANAEROBIC SOLIDS DIGESTER AND METHOD FOR WASTEWATER TREATMENT). FIELD OF INVENTION The present invention relates to wastewater treatment, specifically to upflow anaerobic sludge bed (UASB) reactors, more specifically to pulsed UASB reactors as in patent EP 3009408 A1, and more particularly to UASB reactors for the psychrophilic treatment of municipal wastewater, combined with anaerobic digesters. BACKGROUND OF THE INVENTION The application of direct anaerobic treatment of raw (untreated) municipal wastewater in countries with temperatures below 20°C, and more specifically, with submesophilic temperatures (<15°C), is a persistent challenge for researchers in the field of environmental engineering and technology. The successful use of psychrophilic anaerobic reactors would have significant economic implications because, generally (depending on the wastewater temperature), a considerable amount of energy is required to raise the wastewater temperature to the mesophilic range (above 20°C) and, preferably, to the optimum mesophilic range (30–40°C). This places a significant burden on the economics of the wastewater system. Three technologies can be considered the state of the art in this field: 1. Imhoff tank with a separator and a psychrophilic digester (without UASB); 2. Pulsating UASB (as per patent EP 3009408 A1) with separator and UASB (without digester); and 3. Two-stage UASB digester device, consisting of a separator, UASB and mesophilic digester. 1. Imhoff tank (FIG. 1a, state of the art) The Imhoff tank consists of an upper section known as the settling chamber and a lower section known as the sludge digestion compartment (see the simplified process diagram in Fig. 1, prior art). The forward flow enters the settling chamber. Solids settle in the upper settling chamber, and the digestion of the gradually rising solids occurs in the lower chamber, where they accumulate and are slowly digested. The two chambers are separated by an inclined baffle containing narrow slots through which the solids pass into the lower chamber. The design prevents gas and slag from entering the tank. 7QO7 Ln / Zznz / E / YIAI The sedimentation chamber, due to the narrow slots that prevent gas and sludge particles from entering, stirs the solids as learned in the septic tank. Imhoff tanks were an acceptable form of wastewater treatment used in both small and large wastewater treatment plants during the early to mid-20th century. The main advantage of this type of tank over the septic tank is that the sludge is separated from the effluent, allowing for more complete sedimentation and digestion. When functioning properly, these systems are capable of removing between 30% and 60% of suspended solids and between 25% and 40% of the biological oxygen demand (BOD). Imhoff tanks proved to be more suitable for small-scale treatment applications than for large-scale ones.The Imhoff tank's demise resulted from its inability to meet today's more stringent performance requirements. The Imhoff tank's primary problem is its low efficiency in removing organic matter, reducing BOD by only 25 to 40%, because it lacks anaerobic treatment of the wastewater, providing only primary clarification. 2. Pulsating UASB (Fig. 1b, state of the art: patent EP 3009408 A1). One of the major successes in the development of anaerobic wastewater technology was the introduction of high-speed reactors in which biomass and liquid retention are decoupled, such as the well-known upflow anaerobic sludge bed (UASB) reactors. Several types of full-scale reactors are in operation worldwide, such as the one described in U.S. Patent No. 4,253,956. The UASB bioreactor design has long been considered the most appropriate anaerobic system for treating municipal wastewater due to its simplicity, low investment and operating costs, and prior positive experience in treating a wide range of wastewater types. In tropical regions, the UASB bioreactor configuration is the most widely used process for the anaerobic treatment of municipal wastewater.Hundreds of UASB systems have been implemented for wastewater treatment in several tropical countries, including India, Colombia, Brazil, and Mexico. The ambient temperature in these countries is relatively high year-round (20–35°C), allowing anaerobic digestion (AD) of wastewater to occur in the mesophilic temperature range without the need for process heating. However, experience with single-stage UASB systems for raw wastewater at submesophilic temperatures has yielded limited success in large-scale applications, primarily due to low internal mixing intensities. To address these issues, several key improvements to the conventional UASB reactor design were introduced in patent EP 3009408 A1 (developed by the same inventors of the present invention) to enable their use for untreated wastewater at submesophilic temperatures.The system increases contact between the biomass and the substrate using an injection and mixing device comprising a wastewater feed tank, located outside the reactor and above its water level, to generate gravity pulses. The problem with the pulsed UASB reactor is that its performance at low temperatures (<15°C) and / or with strong temperature fluctuations, transitioning from submesophilic to mesophilic conditions (e.g., between summer and winter (fluctuations of 5°C-15°C above an average temperature)), is limited by the hydrolysis of trapped solids (particulate organic matter) that accumulate in the sludge bed when high loading rates are applied, leading to a deterioration in reactor performance and low removal efficiency.Consequently, the amount of excess sludge increases, leading to a shorter sludge retention time (SRT), which could then limit the growth of methanogens, resulting in poor removal of soluble chemical oxygen demand (COD) and thus deterioration of sludge stability and biogas production. 3. Two-stage UASB digestion device (FIG.Ic, prior art) In Mediterranean countries, ambient temperatures fluctuate between winter and summer, causing a change in wastewater temperature from 15°C to 25°C, respectively (20°C ± 5°C). Furthermore, wastewater is often concentrated with a high fraction of suspended solids. As explained previously, the performance of one-stage UASB reactors in low-temperature climates (between 5 and 15°C) is severely limited by the hydrolysis of trapped solids, which accumulate in the sludge bed. Mahmoud et al. (Anaerobic sewage treatment in a one-stage UASB reactor and a combined UASB-Digester system, Water Research, 2004) investigated a UASB-digester system for the treatment of municipal wastewater at low temperatures. This system treats wastewater in a UASB reactor with a short hydraulic retention time (HRT).The UASB sludge is recirculated to a separate, heated external digester, where the suspended solids from the wastewater, captured in the UASB reactor, are converted into methane. The stabilized and digested sludge is then removed from the digester and returned to the UASB reactor, where it continues to capture organic solids from the wastewater and simultaneously supplies methanogenic biomass to the UASB reactor for the conversion of soluble COD from the wastewater. This is a two-stage UASB digester system that provides excellent soluble COD removal with low excess sludge production, even when operating at a low HRT. However, there are several drawbacks to address in this process. 1) High energy consumption: pumping the recirculation of sludge from the UASB to the digester and from the digester to the UASB consumes energy; 2) Limited process efficiency: The electromechanical pumping recirculation of sludge from the UASB to the digester and from the digester to the UASB breaks down the sludge granules, reducing the efficiency of the process; 3) The high maintenance costs associated with electromechanical equipment translate into high maintenance costs; 4) larger footprint of two separate reactors compared to a single UASB reactor; 5) very limited mixing in the UASB when operating at low temperatures; 6) high energy consumption for heating the anaerobic digester to the mesophilic range; and 7) Biomass loss: Biomass washing during peak flows with a short HRT. Taking into account the aforementioned drawbacks, the present invention provides a highly cost-effective, single-stage system for the sustainable treatment of non-sedimented wastewater, especially under sub-mesophilic temperatures (i.e., at low temperatures: <15°C) and / or more specifically for non-sedimented wastewater that exhibits changes from sub-mesophilic to mesophilic conditions over time due to significant temperature fluctuations (e.g., between summer and winter or due to any other change in weather or wastewater conditions). It should be noted that operating under sub-mesophilic temperatures presents only a technical challenge in the field of wastewater treatment, as biological activity is lower under these climatic conditions.However, the biggest challenge for any expert in the field is the temperature fluctuation between summer and winter, not only because of the thermal impact on the process, but also because the diversity of the microbial community that grows at low temperatures has a different composition than that which grows at high temperatures, and there is no known system in the field that shows the flexibility that would be needed to adapt the process from one condition to another. / 007 ίΠ / ΖΖηΖ / Ε / ΥΙΛΙ BRIEF DESCRIPTION OF THE INVENTION The present invention, according to claim 1, relates to a single-stage device for the treatment of wastewater, such as untreated wastewater, essentially consisting of a combination of a UASB reactor and a digester, comprising a separation element that divides and connects them. A single stage is understood to mean a device capable of treating wastewater simultaneously with the sludge generated in the process in a single tank, i.e., in a single combined stage. Wastewater preferentially has a sub-mesophilic temperature (<15°C) and / or exhibits changes over time between sub-mesophilic (<15°C) and mesophilic (>15°C) conditions due to significant temperature fluctuations. Strong or significant fluctuations mean a fluctuation of ±7.5°C relative to a mean temperature; that is, the mean temperature can be any temperature equal to or less than 15°C or greater than 15°C, for example, 20°C, so that the wastewater temperature can vary over time between 12.5°C and 27.5°C. To improve upon prior art systems, the single-stage device combines a pulsed UASB reactor with an unheated anaerobic digester located below the UASB reactor (i.e., in a tower-like configuration). "Unheated" refers to the absence of heating means (for the solids); the digester is configured to operate at ambient temperature, which is the temperature of the wastewater stream being treated, without the need for external / extra heat. In this way, the sludge produced during the process within the UASB reactor is recirculated downwards to the (unheated) digester below, where the suspended solids from the wastewater captured in the UASB reactor are subsequently converted into methane. The present invention relates essentially to a single-stage device for the treatment of non-sedimented wastewater by a combined action of a UASB reactor and an anaerobic digester, comprising: A tank or container divided into two chambers, where either a first chamber is located in the upper section of the tank (also called the upper chamber), and is a UASB reactor chamber having a sludge bed at the bottom of the chamber, a three-phase separator at the top of the chamber, and an external pulsed wastewater injection and mixing device having a feed tank, configured to feed and mix 7QO7 ίΠ / ZZΖηZ / E / YΙΛΙ the UASB reactor chamber by pulses, causing the influent to pass through the sludge bed of the UASB reactor chamber; and a second chamber, which is located in the lower section of the tank and is an unheated anaerobic digestion chamber (i.e., in the absence of heating means for the wastewater), which is located at the bottom of the tank, i.e., below the UASB reactor chamber, and is configured to receive and hydrolyze trapped solids that accumulate in the sludge bed of the upper UASB reactor chamber; where both chambers are divided and connected through at least one inclined partition, configured to separate the upper chamber of the UASB reactor from the lower chamber of the anaerobic digester, and to collect the biogas generated in the anaerobic digester chamber and the sludge generated in the UASB reactor chamber; and means for recycling the sludge from the anaerobic digester chamber to the UASB reactor chamber, comprising: a gas lift pump that lifts the sludge from the anaerobic digester chamber to a gas sludge separator, with energy supplied by the biogas produced in the digester chamber, and a sludge recycling pipe that sends the sludge from the gas sludge separator to the gravity pulse feed tank; and wherein the pulsed wastewater injection and mixing device of the UASB reactor chamber is also configured to agitate / mix the anaerobic digester chamber, and comprising two valves that alternately allow the flow of wastewater and sludge from the feed tank to the UASB reactor chamber or from the feed tank to the anaerobic digester chamber, and further comprising bypass means for (alternatively) injecting the flow of wastewater and sludge from the feed tank of the external pulsed wastewater injection and mixing device directly into the three-phase separator (i.e., without passing the influent through the sludge bed of the UASB reactor), comprising: a UASB bypass pipe and a valve, for operating the UASB reactor as an Imhoff tank, i.e., as a settling chamber for the wastewater and an anaerobic digester for the solids,preventing the washing away of biomass during flow peaks (e.g., rain events). The combined one-stage reactor-digester device having an inclined partition is preferably configured to treat unsettled wastewater at low temperatures (<15°C) also referred to as submesophilic temperatures, and / or unsettled wastewater that exhibits strong temperature fluctuations, independent of ambient temperature (which may be submesophilic or mesophilic temperatures) as defined above, mainly due to weather conditions, e.g., changes between summer and winter. The claimed device provides optimal wastewater treatment rates. The main advantages of the present invention are: to provide an implemented UASB reactor that functions as a single-stage system, optimizing the removal of soluble COD and the hydrolysis of trapped solids accumulated in the sludge bed, and resulting in low excess sludge production; to provide a low-maintenance device such as the Imhoff tank, as well as pulsed UASB reactors, avoiding the use of the electromechanical equipment required to connect the UASB reactor and digester in the prior art (pumps, mixers, etc.); to allow the use of granular biomass, thereby increasing the efficiency of the process, avoiding the use of electromechanical pumps commonly used in prior art UASB digester devices that cause breakage of the granules; to reduce the footprint in a single vessel as Imhoff tanks and the pulsed UASB do, instead of two connected devices as in the prior art UASB digester; to carry out the entire process within a sub-mesophilic temperature range, eliminating the energy consumption of heating the anaerobic digester as in prior art UASB digester devices; and - that functions as an Imhoff tank during peak flow rates to prevent biomass washing away. In total, the device can function as a UASB reactor, or as a digester, or as an Imhoff tank, having the following additional advantages: - Solid-liquid separation and sludge stabilization are combined into a single unit; - resistant to organic and peak flows; - It has no moving parts / electromechanical equipment, i.e., mechanical mixers, pumps, etc.; / 007 ίΠ / ΖΖηΖ / Ε / ΥΙΛΙ - currently offers a good solution for solids handling and digestion; - provides anaerobic digestion without heating, i.e., there is no need for heating media for the sludge, and the process can be carried out at the ambient temperature of the inlet, even if it is a low temperature (<15°C); and - low operating costs. The minimum solids / sludge retention time (SRT) required for hydrolysis is the main design criterion (Figure 2, state of the art - Reference: Environmental Anaerobic Technology, pp. 59-89 (2010) Anaerobic Sewage Treatment using UASB Reactor: Engineering and Operational Aspects Jules B. van Lier et al.), being directly related to the amount, viable, of active biomass and the reactor's capacity to hydrolyze the trapped solids that accumulate in the sludge bed. The SRT of the UASB bioreactor is estimated from the average sludge production per m3 volume of the UASB reactor per day (dXAVG / dt) and the average concentration of the sludge blanket (XAVG) of the module over the total height (UASB): RTuASB = XaVG / (UXaVG / dt) The average sludge production per m3 reactor per day (dXAVG / dt) is calculated by: dXAVG / dt = P wastewater,VSS / HRT (kg / (m3.day)) where: - HRT = hydraulic retention time in the UASB reactor (days) The production of organic sludge per m3 of wastewater (wastewater P,VSS) can be calculated from the conversion of biodegradable COD (DBG) and the accumulation of solids in the sludge bed: P wastewater, TSS ~ Ytot * BCODremoved * (1-(A / N / 100)) * (1-Z / 100)) +TSSremoved * (AiN / 100) (kg / m3) where: YTOT is the coefficient of performance for the conversion of BCOD into bacteria (kg VSS / kg BCOD). TSSremoved is the solids removed per m3 of wastewater (kg / m3). AIN is the percentage of ash in the solids of the wastewater (%) Z is the percentage of VSS in wastewater that is degraded during its / 007 ίΠ / ZZΖηZ / E / YΙΛΙ stay in the UASB reactor. In the case of the present invention, the sludge produced in the UASB reactor chamber has an additional TER in the unheated anaerobic digester chamber, which is added to the partial TER of the UASB reactor chamber to obtain the required total TER: SRTtotal = SRTUASB + SRTdigester It has been found that, to achieve the minimum sludge retention time (SRT) required for the hydrolysis treatment of common municipal wastewater at the temperatures described herein, the anaerobic digester chamber preferably has an effective volume ranging from 40% to 60% of the total volume of the entire tank (i.e., combining the volume of the upper and lower sections of the device). In this way, the invention provides a sludge retention time exceeding 140 days in the overall system when temperatures are equal to or below 15°C (understood as low or sub-mesophilic temperatures within the scope of the invention). This technical result is the key factor in determining the location of the baffles that divide the tank into two parts and separate the UASB reactor chamber from the digester chamber.This long solids retention time, from 140 days to one year, along with the additional unheated digestion process provided by the digester and the recirculation of sludge from the digester chamber to the UASB reactor chamber, promotes a high diversity of stable microbial communities, both submesophilic and mesophilic, and consequently, a rapid and improved adaptation to temperature fluctuations throughout the year. This is a key factor in the operation of the claimed device. The upper section of the tank described in the present invention, which is the UASB reactor chamber, is as defined and known in the prior art by anyone skilled in the field of water treatment, such as municipal wastewater treatment. For example, standard UASB reactors are known to typically comprise a granular or flocculant fluidized / expanded sludge bed, a three-phase separator, a digester with baffles at its top, a gas collector, and effluent weirs for the discharge of wastewater overflows, among other elements. Preferably, the reactor chamber of the present invention comprises a granular or flocculant fluidized sludge bed. As previously described, this UASB reactor chamber comprises a wastewater injection and mixing device configured to feed the UASB reactor chamber in pulses. That is, it is a pulsed-type UASB reactor. In the most preferred embodiment, the UASB reactor chamber is identical to the reactor disclosed in patent EP3009408 A1, which comprises a wastewater injection and mixing device. 7QO7 ίΠ / ZZΖηZ / E / YILI wastewater configured to feed the UASB reactor by pulses (UASB feed mode) as described in said patent. This preferred non-pressurized wastewater injection and mixing device for the treatment of non-sedimented wastewater in UASB reactors comprises: - an external wastewater feed tank, located outside the UASB reactor chamber and above the reactor water level, having an effective wastewater volume for gravity pulse generation ranging from 0.5% to 1.5% of the total reactor chamber volume, said effective volume within the tank being at a height between a minimum wastewater level Hmin equal to or greater than 0.5 m and a maximum wastewater level Hmax equal to or less than 2.5 m above the reactor water level, Hmax always being greater than Hmin to produce the hydraulic impulse energy; and the feed tank having a top inlet as well as a bottom outlet for the wastewater; and is connected to the reactor chamber via - an inlet manifold, which at one end connects downwards the outlet of the feed tank with - one or more wastewater distribution branches at a second end, each distribution branch having a valve automatically controlled by the effective level of wastewater within the feed tank, the branch or branches are buried in the sludge bed within the reactor chamber to distribute the wastewater pulses to the bottom of the reactor chamber through - injection nozzles with a downward discharge point located at a height of between 200 and 300 mm from the bottom of the reactor chamber to avoid dead zones and energy losses, and - a water level sensor to measure the minimum effective level of wastewater Hmin and the maximum effective level of wastewater Hmax within the feed tank (external), capable of sending a signal to the control means that act by closing or opening the valve. The distance between the injection nozzle discharge point and the bottom of the sludge bed within the reactor chamber significantly influences how the injection device promotes a fluidized / expanded sludge bed, thereby improving sludge-wastewater contact. This distance depends on the reactor chamber size and the overall design of the injection device. 7QO7 ίη / ΖΖΠΖ / Ε / ΥΙΛΙ In a preferred case, said discharge point is at a height of between 200 and 300 mm from (above) the bottom of the reactor chamber. Furthermore, the nozzle density, i.e., the number of nozzles in the branch(es), also varies depending on the size of the reactor chamber. In a preferred embodiment, the number is calculated to achieve a density of 1 nozzle per 4–5 m² of reactor chamber surface area (i.e., in a preferred case, the injection device comprises 1 nozzle per 4–5 m² of reactor chamber surface area). This is a significantly lower density compared to conventional UASB reactors due to the higher discharge flow rates. Additionally, the nozzle diameter is calculated to achieve a suitable wastewater outlet velocity. For example, in a preferred embodiment, the nozzle diameter allows for an outlet velocity of 3–5 m / s, which is high enough to prevent clogging at the discharge point. Thanks to this configuration of the wastewater injection and mixing device inside the reactor chamber, the feed tank accumulates hydraulic energy in the form of what is called the effective wastewater volume, which is a partial and specific volume of the total volume of the feed tank that determines the amount of water in a pulse generated when the automatic valve is open.The effective volume within the feed tank, which must range between 0.5% and 15% of the total volume of the reactor chamber, is defined by an upper (maximum) level of effective wastewater Hmax and a lower (minimum) level of effective wastewater Hmin, so that the hydraulic energy (effective volume) is released in the form of pulses of wastewater and these pulses flow downwards through the inlet manifold emptying it with the automatic valves that open when the effective volume within the feed tank reaches a specific maximum height or level (Hmax) up to 2.5m above the water level within the reactor chamber. Conversely, the wastewater pulse ends when the effective volume of wastewater within the feed tank reaches a minimum height or level, Hmin, never lower than 0.5 m above the water level inside the reactor chamber. That is, the hydraulic energy of the wastewater pulse depends on the difference between the maximum and minimum height levels reached by the wastewater within the tank, which define the effective volume. Both Hmax and Hmin are always different and never equal. The maximum height reached by the effective volume of wastewater (which can also be called the equalization effective volume) within the feed tank acts as a high-level alarm that opens the valve to produce the wastewater pulse; at that moment, the effective volume is full. Hmax preferably ranges between 1.5 and 2.5 m above the reactor water level.The minimum height level acts as a cut-off level that closes the valve, since at that moment there is no effective volume left inside the tank, and it is necessary to refill it; Hmin preferably ranges between 0.5 and 1.5m above the water level of the reactor chamber. In a particular and preferred embodiment of the invention, the injection device comprises means for measuring the effective minimum and maximum levels of wastewater within the feed tank, which automatically controls the valve or valves, i.e., their opening or closing. Specifically, in a preferred case, the valve or valves are automatically controlled by a water level sensor that measures the effective water level within the feed tank (the minimum and maximum levels) and sends a signal to the control means (e.g., a PLC or programmable logic controller, which may comprise a transmitter and a controller) that actuates the valve. In particular, the water level sensor measures the wastewater level within the feed tank and sends a signal to the control system to automatically close the valve when the effective water level reaches Hmin, and to automatically open the valve when the water level reaches Hmax.In other words, it is possible to include only one water level sensor in the injection and mixing device to measure both the minimum and maximum effective levels. However, a first and second level sensor can also be used to measure the minimum and maximum levels, respectively. The level sensor can be located inside or outside the feed tank to measure the residual water level. In the present invention, the wastewater injection and mixing device is adapted to mix both the UASB reactor chamber in the upper section of the tank and the digester chamber in the lower section of the tank, but not simultaneously. It is also evident that this device is configured to feed only the reactor chamber and not the digester chamber. To operate in this manner, the non-pressurized wastewater injection and mixing device disclosed in patent EP3009408 A1 also comprises, in the present invention, the following: - an inlet manifold, connected to the outlet of the feed tank at one end already - a digester distribution chain at the other end; said chain 7QO7 ίη / ΖΖΠΖ / Ε / ΥΙΛΙ connects - an automatic valve on the outside of the digester chamber with the inside thereof, and being buried in a sludge bed of the anaerobic digester chamber, located in the lower part of said digester chamber (i.e., above the bottom thereof); and also having - injection nozzles that are part of the digester distribution chain and are located at a height of between 200 and 300 mm from the bottom of the anaerobic digester chamber. All specifications described for the ropes, nozzles, valves, and other elements of the reactor chamber are also equivalent and applicable to those of the ropes, nozzles, valves, and other elements of the digester chamber. The at least one inclined partition comprising the combined UASB reactor-digester device is configured to a) divide the device tank into two chambers: an upper UASB reactor chamber (located in the upper section of the tank) and a lower anaerobic digester chamber (located in the lower section of the tank), while b) allowing the recirculation of solids and sludge between the two chambers, and also c) collecting the biogas produced within the digester chamber. In one particular embodiment, the device comprises a single inclined partition formed by a pair of baffles separating the chambers: a first baffle fixed to a side wall of the main chamber and facing a second baffle, longer than the first (preferably 0.2 to 0.5 m longer), and fixed to the opposite side wall of the chamber, both baffles being inclined downwards with respect to the perpendicular plane of the axial axis.The baffles are inclined at an angle of between 50° and 60° with respect to the perpendicular plane of the axial axis. A gap at the bottom of the baffles (preferably between 0.1 and 0.3 m) creates an opening to allow the sedimentation of solids and sludge. In this way, the solids and sludge generated inside the UASB reactor chamber fall into the anaerobic digester through this opening, resulting in recirculation from the UASB reactor chamber to the anaerobic digester chamber. Simultaneously, because one baffle is longer than the opposite one, the biogas produced in the digester chamber is retained and cannot enter the UASB reactor chamber. This biogas is then collected by the gas lift pipe of the gas lifting system. In another particular embodiment, the device comprises more than one inclined baffle partition, i.e., multiple inclined baffle partitions, each of which is formed by a pair of baffles having the same inclination as described in the preceding embodiment. In each pair of baffles, one baffle is larger than the other, as discussed above, and each pair of baffles is attached to its opposite. The number of baffle pairs depends on the size and dimensions of the device's tank. The greater the number of baffle pairs, the lower the height of the baffles, allowing for a lower reactor chamber and reducing costs. The slope partition of at least one pair of baffles is positioned within the device (i.e., at a specific height in the tank) such that the lower chamber of the anaerobic digester has an effective volume ranging from 40% to 60% of the total volume of the combined UASB-single-stage anaerobic digester device (i.e., the tank). To achieve this effective volume, the slope of the baffle pair ranges from 50° to 60° with respect to the perpendicular plane of the axial axis, resulting in an effective volume of the total volume of the entire device ranging from 40% to 60%. The sludge recycling system comprises a gas lift pump (also called an air lift pump in the context of this invention), a gas-sludge separator, and a sludge pipeline configured to convey the sludge from the digester chamber to the pulse feed tank. The gas pump is powered by the biogas generated in the anaerobic digester chamber, which is collected by at least one pair of baffles, specifically due to the size difference between the first and second baffles as previously explained. The biogas is directed by the baffle's sloped baffle to the bottom of the sludge pipeline. The biogas, being less dense than the sludge, rises rapidly due to buoyancy. The sludge is then drawn into the rising biogas flow by the pressure of the fluid and moves in the same direction as the biogas.In this way, once the anaerobic digestion process has been carried out inside the digester chamber, the sludge from said anaerobic digestion is returned to the UASB reactor chamber through the sludge recycling system. Certain types of wastewater produce granulated sludge, which is beneficial for increasing treatment rates. When granules are present in the sludge bed of the reactor chamber, they fall into the digester through the baffle. Subsequently, the gas lift pipe raises the granules into the anaerobic digester chamber without damaging them, unlike mechanical pumps. Thanks to this sludge recycling system, the stabilized sludge is returned from the anaerobic digester chamber to the UASB reactor chamber, where it continues to capture organic solids from the wastewater. At the same time, the sludge supplies methanogenic biomass to the UASB reactor chamber for the conversion of the wastewater's soluble COD. The bypass system comprises a flow meter sensor located in the inlet pipe to measure the influent flow rate; a UASB bypass pipe; and a UASB bypass valve. The flow meter is configured to detect peak influent wastewater flow rates and send a signal to the control system configured to close the UASB reactor chamber feed valve (which connects to the distribution branch) and open the UASB bypass valve. This bypass valve directly connects the pulse feed tank to the three-phase separator in the AUSB reactor chamber located at the top of the chamber. This bypass allows the system to operate as an Imhoff tank in continuous feed mode, without pulses, thus preventing biomass backwashing during flow peaks, such as those caused by rainfall events (which significantly increase the influent flow rate). The present invention also relates to a method for treating non-sedimented wastewater using the combined reactor-digester UASB device of the present invention, wherein said method comprises: a) feed the UASB reactor chamber and generate a pulse (UASB feed mode, such as the latest generation device of EP3009408 A1) by: a.1) feed the wastewater injection and mixing device tank with a flow of wastewater and sludge generated within the UASB reactor chamber and digested in the anaerobic digester chamber, fed into the UASB reactor chamber through the recycled sludge pipe; a.2) which automatically opens (only) the feed reactor chamber valve, while the UASB bypass valve and the digester mixing valve are closed, by means of the water level sensor to measure the minimum effective wastewater level Hmin and the maximum effective wastewater level Hmax within the feed tank, which sends a signal to the control means of the feed reactor chamber valve when the effective volume inside the feed tank reaches the maximum level Hmax to generate a gravity-flow pulse of wastewater passing through the inlet manifold connecting the feed tank outlet to the distribution branch, thereby injecting said pulse of wastewater into the sludge bed reactor chamber; 7QO7 ίη / ΖΖΠΖ / Ε / ΥΙΛΙ a.3) distribute the wastewater pulse from the distribution chain to the bottom of the sludge bed in the reactor chamber through the injection nozzles, by gravity; and a.4) automatic closure of the feed reactor chamber valve by means of the water level sensor which sends a signal to the control means when the effective volume within the feed tank reaches the minimum level Hmin to cut off the pulse; b) mixing the anaerobic digester chamber (digester mixing mode) by pulses, by: b.1) feed the wastewater injection and mixing device tank with a wastewater flow, and with the sludge generated within the UASB reactor chamber and digested in the anaerobic digester chamber, fed into the UASB reactor chamber through the recycled sludge pipe; b.2) which automatically opens the anaerobic mixing valve, while the UASB reactor bypass valve and the UASB reactor feed valve are closed, by means of the water level sensor to measure the minimum effective wastewater level Hmin and the maximum effective wastewater level Hmax within the feed tank, which sends a signal to the control means of the anaerobic mixing valve when the effective volume inside the tank reaches the maximum level Hmax to generate a gravity-fed wastewater flow pulse that passes through the inlet manifold connecting the feed tank outlet to the digester distribution branch, thereby injecting said pulse of wastewater and sludge into the anaerobic digester chamber; b.3) distribute the pulse of wastewater and sludge from the anaerobic distribution chain to the bottom of the anaerobic digester chamber through the injection nozzles, by gravity; and b.4) automatically close the digester mixing valve by means of the water level sensor which sends a signal to the control means when the effective volume within the feed tank reaches the minimum level Hmin to cut off the pulse. From reading this text, it is clear to any expert in the field that feeding the wastewater injection and mixing device tank with the sludge generated inside the UASB reactor chamber and digested in the anaerobic digester chamber will only be possible once the sludge is produced in the USAB reactor chamber and then falls into the digester chamber to be digested. 7QO7 ίΠ / ΖΖηΖ / Ε / ΥΙΛΙ In a preferred embodiment, step b), which results from closing the feed reactor chamber valve and opening the anaerobic digester chamber mixing valve, is activated from once every two hours to once per hour. Preferably, the water level sensor is controlled by a programmable logic controller (PLC) that switches between pulses, i.e., UASB feed mode, UASB bypass mode, or anaerobic digester mixing mode. In a third optional mode (UASB bypass mode), the system functions as an Imhoff tank, i.e., as a sedimentation chamber for wastewater and an anaerobic digester for solids, since the influent wastewater does not pass through the sludge bed of the reactor chamber, but through the three-phase separator located at the top of the UASB reactor chamber, which comprises the following steps: c.1) feed the wastewater injection and mixing device tank with a wastewater flow and with the sludge generated within the UASB reactor chamber and digested in the anaerobic digester chamber, fed into the UASB reactor chamber through the recycled sludge pipe; c.2) Measurement of influent flow rate by means of a flow meter sensor, configured to send a signal to the control means when an influent flow peak is detected to open the UASB bypass valve while closing the feed reactor chamber valve and the digester chamber mixing valve; c.3) Distribute the flow of wastewater and sludge from the feed tank directly to the three-phase separator at the top of the UASB reactor chamber, using the UASB bypass pipe. Thanks to this alternative embodiment, the three-phase separator located at the top of the UASB reactor chamber functions as a sedimentation chamber that separates, on the one hand, the solids and sludge that fall through the sludge bed and the inclined partition of at least one baffle into the anaerobic digester chamber, and, on the other hand, the clarified effluent with the water overflow dike. The UASB bypass mode operates without pulses in a continuous gravity feed mode. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1a (Prior Art) Imhoff tank as described in the background of the invention. This system would be similar to the second chamber at the bottom of the tank of the device of the present invention. / 007 ίΠ / ZZΖΙΊΖ / Β / ΥΙΛΙ (1) Influent wastewater (2) Separator (sedimentation separator) (3) Baffle opening (4) Inclined baffle partition (5) Anaerobic digester (6) Residual sludge (7) Effluents The influent wastewater (1) enters an upper section known as the settling chamber (2) and a lower section known as the anaerobic digester compartment (5). Solids settle in the upper chamber (2), and solids digest in the lower chamber (5). The two chambers are separated by a sloping partition (4) containing narrow openings (3) through which solids pass into the lower chamber. The solids settle in the upper settling chamber (2) and gradually pass into the lower digestion chamber (5). In the digestion chamber (5), the solids accumulate and are slowly digested. By design, the entry of gas and sludge into the settling chamber is prevented by the narrow openings of the baffles (3), which block the entry of gas and sludge particles that would otherwise agitate the solids.The normal thickness line highlights the device elements; the thick line highlights the wastewater flow; and the dashed line highlights the water level inside the digester. Figure 1b (prior art) illustrates a schematic representation of the upflow anaerobic sludge bed reactor (UASB reactor), as in patent EP 3009408 A1, with the influent wastewater injection and mixing device. This system would be similar to the first chamber at the top of the tank of the device of the present invention. (1) Influent wastewater (7) Effluent (8) Three-phase separator (9) Water overflow dike (10) UASB reactor (11) UASB biogas pipeline (12) Pulse feed tank (13) Inlet (14) Outlet / 007 iP / ZZΖ / E / YILI (15) Inlet manifold (16) Feed reactor valve (17) Reactor distribution chain (18) Reactor injection nozzles (19) Level sensor (20) Level control valve (21) Sludge bed (22) Baffle Figure 1b shows a UASB reactor (10) fed with an influent wastewater flow (1) and equipped with a specific external influent wastewater injection and mixing device. This device is used in a USAB-type anaerobic reactor to fluidize the sludge bed (21) with non-settled wastewater and operates at submesophilic temperatures. The wastewater injection and mixing device comprises a pulsed, non-pressurized feed tank (12). The tank (12) is fed with a wastewater flow (1) through an inlet (13) located at its top, typically by pumping the flow (1). The wastewater accumulates in the tank (12) until it reaches a maximum height Hmax within the tank.Next, a valve (16) is automatically controlled by a non-contact water level sensor (19) connected to the control means (20) (programmable logic controller). This generates a pulse flow of wastewater by gravity, with a volume equal to the effective volume accumulated inside the tank. This flow is delivered through an inlet manifold (15) that connects the outlet (14) of the feed tank (12) at one end to a distribution branch (17) at the other end via valve (16). This valve (16) allows the pulse of wastewater to pass through it and enter the reactor. The distribution branch (17) connects the automatic valve (16) outside the reactor to the inside, and is buried in the sludge bed (21).The wastewater pulse is injected from the distribution branch (17) to the bottom of the reactor through the injection nozzles (18) that are part of the distribution branch (17) and are located above the bottom of the reactor (i.e., the bottom of the sludge bed (21)). The valve (16), automatically controlled by the water level sensor (19), closes when the wastewater level inside the feed tank (2) reaches a height below Hmin above the water level inside the reactor and is always above the outlet of the feed tank inlet (14) to prevent air bubbles from being drawn into the reactor. The pulses generated with this device produce a flow / 007 ίΠ / ZZΖηZ / E / YΙΛΙ in the inlet collector (15) that is 25 to 80 times greater than the influent wastewater flow (1), thus creating enough energy to expand the bed (21) by gravity. The remainder of the configuration shown in Figure 1b is identical to that of conventional UASB reactors. The reactor further comprises the aforementioned granular or fluidized / expanded flocculant sludge bed (21), a conventional baffle (22), such as baffles; a three-phase separator (8), effluent weirs (9) for the effluent outlet (i.e., treated water flow (7)), and a gas collector for the biogas flow (11). In this way, the wastewater injected with the claimed device passes upwards through the sludge bed (21), and then the biomass, treated water (effluent), and biogas are separated at the top of the digester by a conventional baffle, i.e., the effluent weirs (9) and the three-phase separator (8).That is, the gas flow (11) is collected, the biomass settles back into the active volume of the reactor while the treated water flow (7) leaves the reactor through an effluent outlet as the water overflows through the dike (9). The normal thickness line illustrates the device elements; the thick line illustrates the wastewater flow; and the dashed line illustrates the water level inside the reactor. Figure 1c (State of the art) Two-stage UASB digester as described in the background of the invention. (1) Influent wastewater (6) Sewage sludge (7) Effluent (10) UASB reactor (11) UASB biogas pipeline (23) 35°C heated anaerobic digester (24) Inflow pump (25) UASB sludge recycling pump (26) Digester sludge recycling pump (27) Mechanical mixer (28) Blades (29) Digester biogas pipeline This system treats the incoming wastewater flow (1) entering a UASB reactor (10) by means of a pump (24). The UASB sludge is recirculated over a digester heated to 35°C (23) by means of an electromechanical pump (25) in which the solids in / 007 iP / ZZΖηZ / E / YILI (13) Inlet (14) Outlet (15) Inlet manifold (16) Reactor feed valve (17) Reactor distribution chain (18) Reactor injection nozzles (19) Level sensor (20) Level control valve (21) Sludge bed (22) Baffle (29) Biogas pipe from digester chamber (35) Gas booster pump (37) UASB bypass valve (38) Flow control (39) Gas sludge separator (40) Sludge recycling pipe (41) Digester mixing valve (42) Digester distribution chain (43) Digester injection nozzles Figure 4 (present invention) illustrates a schematic representation of a single-step device according to the detailed description of the invention, comprising a UASB reactor chamber with an unheated anaerobic digester chamber located below it, both connected by an inclined partition made of multiple pairs of baffles. The line of normal thickness in the figure illustrates the device elements; the thick line illustrates the wastewater flow; and the dotted line illustrates the control signal between elements. / 007 ίΠ / ΖΖηΖ / Ε / ΥΙΛΙ (3) (4) (4a) (4b) Baffle opening Inclined partition First baffle Second baffle (5) (6) Anaerobic digester chamber Residual sludge (16) (17) Feed reactor valve Reactor distribution chain (18) Reactor injection nozzles (41) Digester mixing valve (42) Digester timing chain (43) Digester injection nozzles DETAILED DESCRIPTION OF THE INVENTION Figure 3 illustrates the present invention of a combined UASB reactor and single-stage anaerobic digester device. Essentially, the device comprises a tank divided into two sections or chambers: a lower unheated anaerobic digester chamber (5) (i.e., a digester without heating means, operating at ambient temperature) located below the upper UASB reactor chamber (10), which is similar to that shown in Fig. 1b (prior art reactor). (Only) an inclined baffle partition (4) is contained within the tank and is configured to separate the lower UASB reactor chamber from the anaerobic digester chamber, while simultaneously permitting the recirculation of solids and sludge from the anaerobic digester chamber (5) to the UASB reactor chamber (10) and back again to the anaerobic digester chamber (5).The inclined partition comprises a pair of baffles (4a, 4b): a first baffle (4a) attached to one of the side walls of the device tank, specifically below the sludge bed of the reactor chamber and at the top of the digester chamber, and facing a second baffle (4b) that is longer than the first baffle (4a) (preferably 0.2 to 0.5 m longer) and that is attached to the opposite side wall of the device tank, both baffles (4a, 4b) being inclined downwards with respect to the perpendicular plane of the axial axis, the inclination of the baffles having an angle ranging from 50° to 60° with respect to the perpendicular plane of the axial axis, and having a separation at the bottom of the baffles (preferably between 0.1 and 0.3 m apart) that forms an opening, called the baffle opening (3) to allow the sedimentation of solids and sludge.The baffle slope partition (4) is positioned such that the anaerobic digester chamber (5) has an effective volume ranging from 40% to 60% of the total volume of the combined UASB-one-stage anaerobic digester device (i.e., the tank). There is a continuous (re)circulation of solids and sludge from the UASB reactor chamber (10) to the anaerobic digester chamber (5) and from the anaerobic digester chamber (5) back to the UASB reactor chamber (10): 7QO7 ίΠ / ΖΖηΖ / Ε / ΥΙΛΙ 1) Sludge circulation from the UASB reactor chamber (10) to the anaerobic digester chamber (5): The solids and sludge generated inside the UASB reactor chamber fall into the anaerobic digester chamber (5) through the inclined baffle partition (4). The inclined baffle partition comprises a first baffle (4a) and a second, longer baffle (4b) (0.2 to 0.5 m longer). The inclination of the baffle pair has an angle ranging from 50° to 60° with respect to the perpendicular plane of the axial axis, to allow the sedimentation of the solids and sludge. There is a separation between the two baffles (0.1 to 0.3 m apart) at the bottom, forming an opening or baffle aperture (3). 2) Sludge recirculation from the anaerobic digester chamber (5) to the sludge bed (21) of the UASB reactor chamber (10): After the anaerobic digestion process, the sludge from the anaerobic digester chamber (5) is sent back to the UASB reactor chamber (10) via sludge recycling means, comprising a gas lift pump (35), a gas-sludge separator (39), and a sludge recycling pipe (40) that sends the sludge to the pulse feed tank (12). The biogas exits the gas-sludge separator (39) via a pipe (29). The gas lifting pump (35) operates using the biogas generated in the anaerobic digester chamber (5), which is collected by the inclined baffle (4). Biogas collection is the baffle's secondary function. The biogas is conveyed through the inclined baffle (4) to the bottom of the sludge pipe (40), which lifts the sludge from the anaerobic digester chamber (5) to the gas-sludge separator (39). Due to buoyancy, the biogas, which has a lower density than the sludge, rises rapidly. The sludge is drawn into the upward flow of the biogas by the fluid pressure and moves in the same direction. In one embodiment of the invention, the gas lift is a conventional air lift such as that used in the UASB reactor disclosed in WO2006132523A1, which is cited by reference; however, it must be said that the purpose of the air lift disclosed in that WO2006132523A1 is recycling within the reactor itself, but not between the digester chamber and the UASB reactor chamber, unlike the present invention. One of the key technical points of the present invention is that the anaerobic digester chamber (5) is agitated and mixed (but not fed) by the same wastewater injection and mixing device as the one that mixes the UASB reactor chamber (10), but only as a mixing device (i.e., without injection) specifically by the 7QO7 iP / ZZΖηZ / E / YILI same pulse feed tank (12), switching from UASB feed mode to anaerobic digester mix mode, i.e., the injection and mix device operates either towards the UASB reactor chamber (10) or alternatively towards the digester chamber (5), depending on the process conditions, and this is a key difference from prior art feed systems. In addition, a third alternative mode is possible: feeding the UASB reactor chamber (10) directly from the top, i.e., from the feed tank (12) and into the three-phase separator (8). First, during the UASB feed mode, similar to the mode disclosed in patent EP3009408 A1, the UASB reactor chamber (10) is fed and stirred by a pulse generated by filling the tank (12) of the wastewater injection and mixing device with a flow of wastewater and sludge through the recycled sludge pipe (40) with the sludge accumulated inside the UASB reactor chamber (10) and digested in the anaerobic digester (5), automatically opening the feed reactor chamber valve (16) by means of the water level sensor (19) while the UASB reactor chamber bypass valve (37) and the digester chamber mixing valve (41) are closed to measure the effective minimum wastewater level Hmin and the effective maximum wastewater level Hmax inside the feed tank (12).The water level sensor (19) sends a signal to the control means of the feed reactor chamber valve (16) when the effective volume inside the feed tank (12) reaches the maximum level Hmax, generating a gravity-fed wastewater flow pulse that passes through the inlet manifold (15) connecting the feed tank outlet (14) to the distribution branch (17). This wastewater pulse is then injected into the sludge bed reactor chamber (21) and distributed by gravity from the distribution branch (17) to the bottom of the sludge bed (21) in the reactor chamber via the injection nozzles (18). When the effective volume inside the feed tank (12) reaches the minimum level Hmin to stop the pulse, the water level sensor (19) sends a signal to the control means (20), which automatically closes the feed reactor chamber valve (16). Secondly, the digester mixing mode is preferably activated from once every two hours to once per hour, feeding the tank (12) of the wastewater injection and mixing device with a flow of wastewater and sludge accumulated inside the UASB reactor chamber (10) and digested in the anaerobic digester (5), through the recycled sludge pipe (40); the mixing valve of the 7QO7 ίη / ZZΖΠZ / E / YΙΛΙ The anaerobic digester chamber (41) is automatically opened by the water level sensor (19) while the UASB reactor chamber bypass valve (37) and the UASB reactor chamber feed valve (18) are closed, to measure the minimum effective wastewater level Hmin and the maximum effective wastewater level Hmax inside the feed tank (12). The water level sensor (19) sends a signal to the control means (20) of the mixing valve of the anaerobic digester chamber (41) when the effective volume inside the feed tank (12) reaches the maximum level Hmax to generate a pulse of wastewater flow by gravity that passes through the inlet manifold (15) that connects the outlet (14) of the feed tank (12) with the distribution branch of the digester (42), thereby injecting said pulse of wastewater and sludge into the anaerobic digester chamber (5),distributing the pulse of wastewater and sludge from the distribution chain of the anaerobic digester (42) to the bottom of the anaerobic digester chamber (5) through the injection nozzles (43), by gravity; when the effective volume within the feed tank (12) reaches the minimum level Hmin to cut off the pulse, the water level sensor (19) sends a signal to the control means (20) and automatically closes the mixing valve of the digester chamber (41). Third, the UASB bypass mode operates the system as an Imhoff tank (i.e., a settling chamber for wastewater and an anaerobic digester for solids, without passing the influent through the sludge bed) (21). The device operates by feeding the wastewater injection and mixing device tank (12) with a flow of wastewater and sludge accumulated within the UASB reactor chamber (10) and digested in the anaerobic digester (5) via the recycled sludge pipe (40). A flow meter sensor (38) measures the influent flow rate and sends a signal to the control means (20) when an influent flow peak is detected to open the UASB reactor chamber bypass valve (37) while simultaneously closing the feed reactor chamber valve (16) and the digester chamber mixing valve (41).The flow of wastewater and sludge is distributed from the feed tank (12) to the three-phase separator (8) via the UASB reactor chamber bypass pipe (37). This separator functions as a settling chamber, separating the solids and sludge, which fall through the sludge bed (21) and the inclined baffle wall (4) into the anaerobic digester chamber (5), and the clarified effluent (7) via the water overflow weir (9). The UASB bypass mode operates in continuous gravity feed mode, without pulses. 7QO7 ίη / ΖΖΠΖ / Ε / ΥΙΛΙ Preferably, the water level sensor (19) is controlled by control means (20) (programmable logic controller) that switches from one pulse to another, i.e., from UASBa feed mode to UASB bypass mode, or anaerobic digester mixing. EXAMPLES Example 1. Experimental test of the one-stage UASB anaerobic solids digester device for the treatment of non-sedimented wastewater during the summer The raw wastewater was fed into a UASB reactor as described in the present invention (Detailed description of the invention), being inoculated with flocculant sludge in Loulé (Portugal), at ambient temperature. The main design parameters of the system, which includes both the UASB and the Anaerobic solids digester, these are REACTOR PARAMETERS UASB Volume Anaerobic digester volume 4.5 4.5 m3 m3 15 Total digester / reactor volume 50% WASTEWATER INJECTION AND MIXING DEVICE Feed tank - Tank diameter i 300 mm - Feed tank volume 0.190 m3 - Number of inlet collectors 1 20 - Number of distribution chains 1 - Inlet nozzle diameter 45 mm - Number of nozzles 4 - Baffle slopes 60° PROCESS PARAMETERS 25 Incoming wastewater flow rate 0.375 m3 / h Hydraulic retention time in UASB 12 h Number of pulses per day 71 pulses TER 150 days WASTEWATER PARAMETERS 30 Water temperature (summer) 25-29 °C Ambient temperature (summer) 22-39 °C COD 307±63mg / l DQOT 1167±63 mg / l SST 425±87mg / l Sulfate 46±42mg / l The main experimental results were then obtained: RESULTS 7QO7 ίΠ / ΖΖηΖ / Ε / ΥΙΛΙ CODOT (%) 81 RE Sulfate (%) m3 CH4 / kg COD removed Biogas production (m3 / day) 86.3 0.24 2.4 Example 2. Experimental test of a single-stage UASB pulsed anaerobic digester for the treatment of unsettled wastewater during winter The parameters defined in example 1 were also applied to this experimental case, but it was operated under winter conditions. WASTEWATER PARAMETERS - Water temperature (winter) 15-18 °C - Ambient temperature (winter) 6-18 °C RESULTS CODOT (%) RE Sulfate (%) m3 CH4 / kg COD removed Biogas production (m3 / day) 80 82 0.14 1.5 The results obtained represent robust performance throughout the year, and a substantial and significant increase (21.7%, 22%, 22%) in COD removal compared to the values ​​reported from the previous art: Imhoff Tank, Pulsed UASB and digester UASB of two stages, respectively.

Claims

1. A single-stage device for treating untreated wastewater by a combined action of a UASB reactor and a single-stage anaerobic digester, comprising: - a tank divided into two chambers, wherein a first chamber is a UASB reactor chamber (10) located in the upper section of the tank, having a sludge bed (21) at the bottom of the chamber (10), a three-phase separator (8) at the top of the chamber, and an external non-pressurized wastewater injection and mixing device having a feed tank (12), configured to feed and mix the UASB reactor chamber (10) in pulses, causing the influent to pass through the sludge bed (21) of the UASB reactor chamber (10);A second chamber is an anaerobic digester (5) located in the lower section of the tank, below the UASB reactor chamber (10), without any means of heating the wastewater and configured to receive and hydrolyze the trapped solids that accumulate in the sludge bed (21) of the upper chamber of the UASB reactor (10); wherein both chambers are connected by at least one inclined partition (4), configured to separate the upper chamber of the UASB reactor (10) from the lower chamber of the anaerobic digester (5), and to collect the biogas generated in the anaerobic digester (5) and the sludge generated in the UASB reactor;and - means for recycling sludge from the anaerobic digester chamber to the UASB reactor chamber, comprising: a gas lift pump that lifts sludge from the anaerobic digester chamber to a gas sludge separator, with energy supplied by the biogas produced in the digester chamber, and a sludge recycling pipe that sends sludge from the gas sludge separator to the gravity pulse feed tank; and characterized in that the pulsed wastewater injection and mixing device of the UASB reactor chamber (10) is also configured to mix the anaerobic digester chamber (5), comprising two valves (16, 41) that alternately allow the flow of wastewater and sludge from the feed tank (12) to the UASB reactor chamber (10) or from the feed tank (12) to the anaerobic digester chamber (5);and which also comprise a UASB bypass pipe and a valve (37) configured to inject the flow of wastewater and sludge from the feed tank (12) of the external pulse wastewater injection and mixing device directly into the three-phase separator (8).; 2. The device for treating non-sedimented wastewater according to claim 1, wherein the non-sedimented wastewater is at submesophilic temperatures equal to or less than 15°C and / or has a temperature that fluctuates over time between ±7.5°C relative to an average temperature.

3. The device for treating non-sedimented wastewater according to any of claim 1 or 2, wherein the external non-pressurized wastewater injection and mixing device comprises: - an external wastewater feed tank (12), located outside the UASB reactor chamber (10) and above the reactor water level, having an effective wastewater volume for gravity pulse generation ranging from 0.5% to 1.5% of the total volume of the reactor chamber (10), said effective volume within the tank being at a height between a minimum wastewater level Hmin equal to or greater than 0.5 m and a maximum wastewater level Hmax equal to or less than 2.5 m above the reactor water level (10), Hmax always being greater than Hmin to produce the hydraulic energy of the pulse;and the feed tank (12) having a top inlet (13) as well as a bottom outlet (14) for wastewater; and being connected to the reactor chamber (10) via an inlet manifold (15), which at one end connects downward the outlet (14) of the feed tank (12) with one or more wastewater distribution branches (17) at a second end, each distribution branch (17) having a valve (16) automatically controlled by the effective level of wastewater within the feed tank (12), the branch or branches being buried in the sludge bed (21) within the reactor chamber (10) to distribute pulses of wastewater to the bottom of the reactor chamber (10) via injection nozzles (18) with a downward discharge point located at a height of between 200 and 300 mm from the bottom of the reactor chamber to avoid dead zones and energy losses;7QO7 iP / ZZΖ / E / YILI - a water level sensor (19) for measuring the minimum effective wastewater level Hmin and the maximum effective wastewater level Hmax within the feed tank (12), capable of sending a signal to the control means (20) that act by closing or opening the valve (16); - an inlet manifold (15), connected to the outlet of the feed tank (12) at one end and to a digester distribution chain (42) at the other end; said digester distribution chain (42) connects - an automatic valve (41) on the outside of the UASB reactor chamber (10) with the inside thereof, and being buried in a sludge bed of the anaerobic digester chamber (5) located above the bottom of the digester chamber (5);and also having injection nozzles (43) similar to those of the reactor chamber (10), which are part of the distribution chain (42) and are located at a height of between 200 and 300 mm from the bottom of the reactor digester chamber (5).; 4. The device according to any one of claims 1 to 3, wherein the reactor (10) comprises a granular or flocculant fluidized sludge bed (21).

5. The device of any one of the preceding claims 1 to 4, wherein the anaerobic digester chamber (5) has an effective volume ranging from 40% to 60% of the total tank volume.

6. The device of any one of the preceding claims 1 to 5, comprising an inclined partition (4) formed by a pair of baffles, separating the chambers: a first baffle (4a) attached to a side wall of the main chamber (10) and facing a second baffle (4b), longer than the first baffle (4a), and attached to the opposite side wall of the chamber (10), both baffles being inclined downwards with respect to the perpendicular plane of the axial axis, and having a separation at the bottom of the baffles that forms an opening (3) to allow the sedimentation of solids and sludge.

7. The device of any one of the preceding claims 1 to 6, comprising two or more inclined partitions (4), each of them formed by a pair of baffles: a first baffle (4a) attached to a side wall of the main chamber (10) and facing a second baffle (4b), longer than the first baffle (4a), and attached to the opposite side wall of the chamber (10), both baffles being inclined downwards with respect to the perpendicular plane of the axial axis, and having a separation at the bottom of the baffles that forms an opening (3) to allow the sedimentation of solids and sludge.

8. The device of any one of claims 1 to 7 above, wherein the bypass means comprise a flowmeter sensor (38) located in the inlet pipe (1) for measuring the influent flow rate; a UASB bypass pipe and a valve (37), wherein the flowmeter (38) is configured to detect the maximum flow rates of the influent wastewater and send a signal to the control means configured to close the feed valve (16) of the UASB reactor chamber (10) and open the UASB bypass valve (37) which directly connects the pulse feed tank (12) with the three-phase separator (8) of the AUSB reactor chamber (10) located at the top thereof.

9. A method for treating non-sedimented wastewater using the combined reactor-digester device UASB according to any one of claims 1 to 8, wherein said method comprises: a) feeding the UASB reactor chamber (10) and generating a pulse by: a.1) feeding the tank (12) of the wastewater injection and mixing device with a flow of wastewater and sludge generated within the UASB reactor chamber (10) and digested in the anaerobic digester chamber (5), fed into the UASB reactor chamber (10) through the recycled sludge pipe (40); a.2) automatically opening (only) the feed reactor chamber valve (16), while the UASB bypass valve (37) and the digester mixing valve (41) are closed, by means of the water level sensor (19) to measure the minimum effective wastewater level Hmin and the maximum effective wastewater level Hmax within the feed tank (12), which sends a signal to the control means (20) of the feed reactor chamber valve when the effective volume inside the feed tank reaches the maximum level Hmax to generate a gravity-driven wastewater flow pulse passing through the inlet manifold (15) connecting the outlet (14) of the feed tank (12) to the distribution branch (17), thereby injecting said wastewater pulse into the sludge bed reactor chamber (10); 7QO7 ίΠ / ZZΖηZ / E / YΙΛΙ a.3) distributing the wastewater pulse from the distribution branch (17) to the bottom of the sludge bed (21) of the reactor chamber (10) through the injection nozzles (18), by gravity; and a.4) automatically closing the feed reactor chamber valve (16) by means of the water level sensor (18) which sends a signal to the control means (20) when the effective volume within the feed tank (12) reaches the minimum level Hmin to cut off the pulse; and characterized in that the method also comprises: b) feeding the anaerobic digester chamber (5) by pulses, by: b.1) feeding the tank (12) of the wastewater injection and mixing device with a wastewater flow, and with the sludge generated within the UASB reactor chamber (10) and digested in the anaerobic digester chamber (5), fed into the UASB reactor chamber (10) through the recycled sludge pipe (40); b.2) which automatically opens the anaerobic mixing valve (41), while the UASB reactor bypass valve (37) and the UASB reactor feed valve (16) are closed, by means of the water level sensor (18) to measure the minimum effective wastewater level Hmin and the maximum effective wastewater level Hmax within the feed tank (12), which sends a signal to the control means (20) of the anaerobic mixing valve (41) when the effective volume inside the tank (12) reaches the maximum level Hmax to generate a gravity-fed pulse of wastewater flow that passes through the inlet manifold (15) which connects the outlet (14) of the feed tank (12) to the digester distribution branch (42), thereby injecting said pulse of wastewater and sludge into the anaerobic digester chamber (5); b.3) distributing the pulse of wastewater and sludge from the anaerobic distribution chain (42) to the bottom of the anaerobic digester chamber (5) through the injection nozzles (43), by gravity; and b.4) automatically closing the digester mixing valve (41) by means of the water level sensor (18) which sends a signal to the control means (20) when the effective volume within the feed tank (12) reaches the minimum level Hmin to cut off the pulse. / 007 iP / ZZΖ / E / YILI.

10. The method according to claim 9, wherein step b), which results from closing the valve of the feed reactor chamber (16) and opening the mixing valve of the anaerobic digester chamber (41), is activated from once every two hours to once every hour.

11. The method according to one of claims 9 or 10, wherein the water level sensor (18) is controlled by control means that switch from one pulse to another.

12. The method according to any one of claims 9 to 11, wherein the method further comprises: c.1) feeding the tank (12) of the wastewater injection and mixing device with a wastewater flow and with the sludge generated within the UASB reactor chamber (10) and digested in the anaerobic digester chamber (5), fed into the UASB reactor chamber (10) through the recycled sludge pipe (40); c.2) measuring the influent flow by means of a flowmeter sensor (38), configured to send a signal to the control means when a maximum influent flow is detected to open the UASB bypass valve (37) while closing the feed reactor chamber valve (16) and the digester chamber mixing valve (41); c.3) Distribute the flow of wastewater and sludge from the feed tank (12) to the three-phase separator (8) at the top of the UASB reactor chamber (10) by means of the UASB bypass pipe (37).

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