System and method for treating sanitary landfill leachate

Abstract

The present invention relates to a system for treating sanitary landfill leachate, comprising: at least one screen having a filtering mesh (1) that receives the leachate; at least one homogenising tank (2) that receives the filtered leachate; at least one electrolytic reactor (3) in which the leachate is subjected to electrochemical oxidation; at least one coagulation-flocculation reaction tank (4) that receives the leachate from the electrolytic reactor (3); at least one filter carriage (5) to carry out a first separation of the solids generated in the coagulation-flocculation reaction tank (4); at least one clarifying system (6), capable of forming leachate aggregates; at least one advanced ozone oxidation reactor (8); at least one ozone generator device (9); and at least one nanofiltration device (10) that retains particles of 0.001-0.01 μm, for removing hardness, SST, TDS, DQO and DBO. The invention further relates to a method for treating sanitary landfill leachate to substantially reduce the environmental impact caused by the landfill leachate in drainage networks or surface bodies of water. The method uses combined technologies of advanced physicochemical treatments in combination with dissolved air flotation (DAF).

Description

[0001] SYSTEM AND PROCESS FOR TREATING LANDFILL LEACHATE

[0002] SANITARY

[0003] TECHNICAL FIELD OF THE INVENTION

[0004] The present invention relates to the technical field of Mechanics and Construction, since it relates to a system and process for the treatment of leachate from sanitary landfills.

[0005] BACKGROUND OF THE INVENTION

[0006] Leachate from landfills

[0007] Landfill leachate refers to the contaminated liquid water resulting from the interaction between any water in a landfill, for example, as a result of rainwater infiltration, and the waste deposited at the landfill. Leachate constitutes one of the major environmental and health risks associated with landfills. Typically, leachate is almost always a very complex liquid, with a wide variety of contaminants, many of which can be harmful to people and the environment. As the waste and the landfill age—that is, when reactions occur between the deposited waste and water infiltrating through the landfill bed—the composition changes, and therefore, so does the composition of the leachate. This further complicates the control of effluents emanating from landfills.Leachate control, that is, the prevention of unacceptable harm to people and the environment, is a fundamental aspect of landfill design, planning, construction, operation, and closure. It is also a major challenge for landfill operators, owners, users, and inspectors (Akgün & Daemen, 2012).

[0008] Rainfall has a major influence on leachate formation. Precipitation infiltrates and percolates through deposited waste and binds dissolved and undissolved waste components through various physical and chemical reactions. Groundwater inflows, surface runoff, and biological decomposition also contribute to leachate formation. The liquid fractions of waste combined with the moisture content of the soil cover also contribute to leachate formation (Vaverková, 2019).

[0009] Moisture can be removed from the landfill by consuming water to form biogas, through water vapor evaporated into the biogas, or through leachate removed through the drainage system. Thus, leachate discharge is closely related to precipitation, surface runoff, and groundwater infiltration, which absorbs the landfill. The method of soil protection at landfills (impermeable covers, requirements for insulating layers such as clay (cohesive mineral soil), geotextiles, and / or plastic materials) is crucial for controlling the amount of water infiltrating and percolating into the landfill, and thus for mitigating the risk of soil contamination. Leachate production is also greatly affected by climatic conditions, as they influence the entry of precipitation into the landfill and evaporation losses (Vaverková, 2019).

[0010] Furthermore, leachate production depends on the nature of the disposed waste, i.e., the water content and degree of compaction of the upper layers of the landfill. The technology routinely applied at landfills established in Europe in the 20th century was the dilute-and-disperse leachate treatment technology. Landfills were typically not properly sealed, and the leachate produced leaked into the wider surroundings, where it mixed with groundwater and was dispersed. Such dilution and dispersion facilities are no longer built today; however, existing ones have left old environmental burdens throughout Europe in the form of landfills, which can pose a risk of contamination, particularly in areas with shallow water tables (Vaverková, 2019).

[0011] Environmental Impacts of Leachate. The continuously growing industrial production and trade in many countries around the world in the last decade has accompanied a rapid increase in the production of municipal and industrial waste. In the second half of the 1990s, the annual volume of waste production ranged between 300 and 800 kg per capita in developed countries and less than 200 kg per capita in other countries. Global waste is expected to nearly double to 2.2 billion tons annually by 2025, and almost all cities worldwide are struggling to meet their waste reduction targets. Landfills and / or open dumps have been the most common practice for municipal solid waste (MSW) disposal worldwide; for example, in the USA, 52.6% of MSW is disposed of in landfills, in Brazil 59.1%, in the Kingdom of Saudi Arabia (KSA) 85%, and in Malaysia 94%.5%, in China 79%, in Venezuela 32% is destined for sanitary landfills, 43% for controlled disposal and 24% for uncontrolled disposal or open-air dumps, in Mexico 65% is destined for sanitary landfills, 30% for uncontrolled and open-air disposal and in Thailand 27% (Vaverková, 2019).

[0012] A radical change of massive proportions with enormous impact occurred in the 1970s when the extensive environmental impacts of the hitherto excessively casual approach to waste disposal were finally recognized. As a result of regulations introduced since then, landfill design, planning, operations, and closure have become a highly sophisticated effort, aimed at protecting the public and the environment from the potentially harmful effects of uncontrolled landfill operations, and in particular the uncontrolled formation and release of leachate. In parallel with regulatory and operational improvements in practices, significant research efforts have been developed, aimed at improving understanding of what actually happens in landfills, and how leachate control in particular can be improved.This research is ongoing and has resulted in a vast literature addressing virtually every conceivable aspect of leachate control (Akgün & Daemen, 2012). While it is true that rigorous rules and regulations for landfill leachate control have been established in most advanced societies, this is often not the case in many less developed societies, where landfill leachate control is still not perceived as a high priority.Therefore, the environmental and potential health impacts of landfill operations in many parts of the world can be considered more like open dump type operations which were the most common in most parts of the world until about 50-70 years ago, i.e. casual dumping in natural depressions in the ground, or even on the surface, with minimal attention paid to any potential health or environmental hazards associated with the disposal of waste (Akgün & Daemen, 2012).

[0013] Composition of leachates

[0014] Numerous studies have shown that landfill leachate is a significant source of pollutants due to the leaching of hazardous substances. Leachate contains four main components: nutrients (namely nitrogen), volatile organic compounds, heavy metals, and toxic organic compounds. Nitrogen in the ammoniacal form of NH4N was identified as one of the priority substances to be removed to mitigate leachate toxicity (Vaverková, 2019).

[0015] The composition of leachate from transfer stations can vary depending on several factors, including the degree of compaction, the composition of the waste, the climate, and the moisture content of the waste (Raghab et al., 2013). In addition, other factors affect leachate quality, such as the age of the landfill, seasonal climate fluctuations, the total amount of precipitation, and the type of waste and its composition (Vaverková, 2019). The composition of leachate varies significantly, especially depending on the age of the landfill. There are three types of leachate defined by the age of the landfill: young, intermediate, and old (see Table 1 and Table 2). The concentration of organic compounds (COD) in leachate decreases with increasing landfill age, while the concentration of NH4-N increases (Vaverková, 2019; Mojiri et al., 2021).

[0016] Table 1. Classification of landfill leachates (adapted from Vaverková, 2019).

[0017] Concentration of organic compounds (COD), Biochemical oxygen demand (BOD), Total organic carbon (TOC).

[0018] Table 2. Leachate characteristics and treatability depending on the age of the landfill (adapted from Mojiri et al., 2021).

[0019] VFA = volatile fatty acids, HFA = humic and fulvic acids.

[0020] As a rule, leachates are characterized by high COD, pH, ammonia nitrogen, and heavy metals, as well as strong color and unpleasant odor. At the same time, leachate characteristics also vary with respect to its composition and volume, and the biodegradable material present in the leachate over time. All these factors make leachate treatment difficult and complicated (Raghab et al., 2013). Table 3 shows the chemical composition of landfill leachates.

[0021] Table 3. Chemical composition of leachates (adapted from Raghab et al., 2013).

[0022] N / A = Not applicable.

[0023] In addition to what was published by Raghab et al. (2013), the works of Jayawardhana et al. (2016) and Mojiri et al. (2021) also report the physicochemical characteristics of leachate vapors from several landfills located in different parts of the world.

[0024] Color in leachates

[0025] Color is a common contaminant in landfill leachate. The decomposition of certain organic compounds, such as humic acid (HA), can turn water yellow to dark brown; these substances and particles produce the brown color and turbidity characteristic of leachate. Total dissolved solids (TDS) show the integrative influence of certain cations and anions, such as calcium, chlorides, magnesium, sodium, potassium, and bicarbonates, in the leachate. Furthermore, TDS can be produced from small amounts of dissolved organic matter and can inhibit or decrease the biological degradation of dissolved organic carbon. High electrical conductivity and TDS have also been reported to indicate the presence of dissolved organic and inorganic substances in samples (Aziz et al., 2007; Mojiri et al., 2021).

[0026] Leachate treatment technologies

[0027] Due to the importance of the environmental problem posed by leachate, a considerable number of scientific and technological reports have recently been published dealing with the collection, storage, and proper treatment of leachate from landfills (Mojiri et al., 2021). According to these reports, a range of technologies is available for the treatment of landfill leachate, aimed at meeting the standards established by the regulations established in each country. According to Vaverková (2019), various technologies have typically been used in leachate treatment, among which the following can be mentioned:

[0028] (1) Biological processes: activated sludge, aerobic and anaerobic stabilization lagoons and biological filters;

[0029] (2) Physicochemical processes: flotation, coagulation / flocculation, adsorption, chemical precipitation, air extraction, pH adjustment, chemical oxidation, ion exchange, electrochemical treatment;

[0030] (3) Membrane filtration such as microfiltration, ultrafiltration, nanofiltration and reverse osmosis,

[0031] (4) Advanced oxidative treatments (ozonation), and

[0032] (5) Natural systems such as artificial wetlands.

[0033] On the other hand, Raghab et al. (2013) mention that the following technologies are commonly used in the treatment of leachates from landfills: (1) Aerobic biological treatment, such as aerated lagoons and activated sludge.

[0034] (2) Anaerobic biological treatment, such as anaerobic lagoons, reactors.

[0035] (3) Physicochemical treatments such as air extraction, pH adjustment, chemical precipitation, oxidation and reduction.

[0036] (4) Coagulation with lime, alum, ferric chloride and treatment with earth.

[0037] (5) Advanced techniques such as carbon adsorption and ion exchange.

[0038] Robinson (2005) mentions that the most cost-effective form of treatment for high levels of BOD, COD and ammonia is intense biological oxidation, and in the UK, the sequential batch reactor is the most widely used technology. Sequential batch biological reactors (SBRs) are a form of activated sludge treatment that has received attention in technology development and subsequent market transfer (Mace & Mata-Álvarez, 2002). Traditional activated sludge plants use an aerobic / biological tank followed by a settling chamber. Solids / sludge separation is achieved by gravity sedimentation, with solids settling to the bottom of the vessel. The supernatant liquid is removed as clean / treated leachate, and the remaining solids are recycled to the aerobic / biological tank for reuse (Mace & Mata-Álvarez, 2002).

[0039] To cite an example, Wehrle Environmental has installed 85 lateral flow MBR plants to date, 58 of which are dedicated to the treatment of landfill leachate. For low-concentration, high-volume wastewaters, e.g., sewage, low ultrafiltration energy costs per cubic meter are important. This requirement is generally best met with a process based on a submerged membrane biological reactor (MBR) where high fouling factors are not a major issue. However, for high-concentration, low-volume wastewaters, the tubular lateral flow MBR is often the best option. Most industrial wastewaters and leachates belong to the second category (Robinson, 2005; Chen & Liu). Recently, Mojiri et al.(2021) reported the technologies that are being most studied and used commercially for the treatment of leachates from landfills, which can be classified into four large families:

[0040] (1) Co-treatment with wastewater.

[0041] (2) Physicochemical processes. a. Advanced oxidation process b. Adsorption c. Membranes d. Coagulation / Flocculation

[0042] (3) Biological processes. a. Aerobic bioreactors b. Anaerobic bioreactors c. Phytoremediation d. Bioremediation

[0043] (4) Combined methods. a. Physicochemical / Biological b. Physical / Chemical c. Aerobic / Anaerobic Biological (e.g. Anammox)

[0044] A state-of-the-art analysis suggests that landfill leachate often has significant contamination potential with high concentrations of organic and inorganic contaminants (Vaverková, 2019). Primary landfill leachate treatment techniques include physical, chemical, and biological methods, as well as combined methods (Mojiri et al., 2021).

[0045] Due to the high concentrations of pollutants in landfill leachate and its low biodegradability, some experts recommend integrated treatment methods with wastewater treatment (Kalka, 2012). According to the literature reviewed, membrane filtration and integrated biological methods (nitrification / denitrification / anammox) have demonstrated high performance in removing nitrogen and ammonia from landfill leachate. Furthermore, coagulation / flocculation methods have shown high efficiency in removing suspended solids and turbidity, with a removal rate of over 90%. Bioremediation has demonstrated vague removal efficiencies for COD, ranging from 17.5 to 60% depending on the bacterial or algal species, so it does not show high performance in COD reduction. Finally, physical / chemical treatments have shown high performance in removing heavy metals.There is no single method that could be described as the best performer given the wide range of treatment possibilities available on the market (Mojih et al., 2021). On the other hand, dissolved air flotation (DAF)-based methods show that a physicochemical-based treatment plant incorporating a dissolved air flotation (DAF) stage can be used as an effective alternative for the pretreatment of landfill leachate (Durmusoglu & Yilmaz, 2006; Palaniandy et al., 2010; Adlan et al., 2011; Palaniandy et al., 2017).

[0046] Therefore, in order to contribute to the solution of the aforementioned drawbacks in the state of the art, a system and method for the treatment of leachate from sanitary landfills have been developed.

[0047] The characteristic details of the present invention are clearly shown in the following detailed description, figures and accompanying examples, for the purpose of illustrating the conception of the invention and some of its preferred embodiments; therefore, they should not be considered as a limitation on the scope of protection of the present invention.

[0048] BRIEF DESCRIPTION OF THE FIGURES

[0049] Figure 1 is a schematic diagram of a system for treating leachate from sanitary landfills, in accordance with the present invention. Figure 2 is a flow diagram of a process for treating leachate from sanitary landfills, in accordance with the present invention.

[0050] DETAILED DESCRIPTION OF THE INVENTION

[0051] The present invention relates to a system and a method, physical and chemical, for the treatment of leachate from sanitary landfills, with which the quality of the final discharge of the water resulting from the treatment process complies with the official Mexican standard NCM-001-SEMARNAT-2021.

[0052] A. System for the treatment of leachate from sanitary landfills.

[0053] Therefore, an object of the present invention is a system for the treatment of leachate from sanitary landfills, which comprises: i) at least one filter mesh screen (1), which receives the leachate, which only allows the passage of solids with an average particle diameter < 1 mm; this screen can be a hydro-screen made of 304 type stainless steel;

[0054] (i) at least one homogenizing tank (2) to receive the filtered leachates, which may be a lagoon with geomembranes, reinforced plastic, reinforced concrete or a tank made of any type of steel or corrosion resistant coating material; and may comprise a mechanical agitation mechanism, or by means of air, or any other mechanism suitable for maintaining a homogeneous mixture; and at the outlet of the flow of this tank there will be installed sensors (not illustrated) that will monitor the flow, the total suspended solids (TSS) and the total dissolved solids (TDS), etc., in order to make adjustments to the subsequent stages of the process when necessary; (iii) at least one electrolytic reactor (3) to subject the pH-adjusted leachates to an electrochemical oxidation, this electrolytic reactor (3) may be constructed of reinforced plastic, using a stainless steel anode and cathode;iv) at least one coagulation-flocculation reaction tank (4) where the leachates coming from the electrolytic reactor (3) are received, where coagulant and / or flocculant substances are added to said coagulation-flocculation reaction tank (4) to separate and eliminate the solids suspended in the leachates; v) a first tank with agitator (11) containing coagulant and / or flocculant substances, to supply them to the coagulation-flocculation reaction tank (4); vi) at least one filter car (5) to carry out a first separation of solids generated in the coagulation-flocculation reaction tank (4); where said filter car (5) has, for example, a 30 micron mesh, to retain solid particles larger than this average particle diameter;(vii) at least one clarification system (6), which may be a dissolved air flotation (DAF) system, which has an air microbubble generator (7) which are incorporated into the wastewater line and bind to the particles to be removed, forming aggregates capable of floating because they have a lower density than water in order to facilitate the separation of solids, without the need to use ultrafiltration, eliminating backwashing and / or filter media changes; (viii) a second agitator tank (12) that also contains coagulant and / or flocculant substances, to supply them to the clarification system (6);ix) at least one advanced ozone oxidation reactor (8), wherein the potent non-selective hydroxyl radical (OH*) is generated, which has a much higher oxidation potential than ozone or hydrogen peroxide, and usually reacts at least a million times faster, allowing for a shorter contact time and less environmental impact since the oxygen molecule is regenerated upon its decomposition; and said advanced oxidation reactor (8) comprises a flow meter (not illustrated) for monitoring the amount of treated leachate; x) at least one ozone generating equipment (9) for providing ozone to the advanced ozone oxidation reactor (8); x¡) at least one nanofiltration equipment (10) capable of retaining particles in the range of 0.001-0.01 pm, for the removal of hardness, TSS, TDS, COD and BOD, which allows for improving the removal of residual compounds from the leachates, as well as the color and odor of the treated wastewater;and xii) hydraulic pumps (not illustrated) to transfer the aqueous phases from one compartment to another of the system.

[0055] In one embodiment of the system for the treatment of leachates from sanitary landfills, of the present invention, it may comprise a first flow buffer tank (13) between the homogenizing tank (2) and the electrolytic reactor (3), to ensure water flow to the electrolytic reactor (3).

[0056] A further embodiment of the system for the treatment of leachates from sanitary landfills, in question, is that it may comprise a second flow buffer tank (14) between the filter car (5) and the clarification system (6), to ensure constant water flow, and absorb possible variations in the inflow to the clarification system (6).

[0057] In another embodiment of the system for the treatment of leachates from sanitary landfills, according to the present invention, it may comprise a third flow buffer tank (15) between the advanced ozone oxidation reactor (8) and the nanofiltration equipment (10), to ensure the constant flow of leachate and absorb possible variations in the inlet flow to the nanofiltration equipment (10).

[0058] In a further embodiment of the system of the present invention, it may further comprise at least one sludge container (not illustrated) for containing the resulting solids or sludge. B. Process for the treatment of leachate from sanitary landfills.

[0059] Another object of this invention is a process for treating leachate from sanitary landfills, which aims to contribute to a substantial reduction in the environmental impacts generated by the discharge of landfill leachate into the municipal drainage system or surface water bodies. This process uses combined technologies of advanced physicochemical treatments in combination with dissolved air flotation (DAF).

[0060] The diagram shown in Figure 2 shows that the process for the treatment of leachates from sanitary landfills comprises the following stages: i) sifting the leachates in a filter mesh sieve (1), which will only allow the passage of solids with an average particle diameter < 1 mm. This sieve is made of 304 type stainless steel and its design is that of a conventional hydro-sifter, with a capacity to remove solids up to 1 mm in average diameter;

[0061] (i) recovering the aqueous fraction from the previous stage; (iii) homogenizing the aqueous fraction from the previous stage in a homogenizing tank (2) by means of agitation or air bubbling for homogenization; the homogenizing tank (2) may be a lagoon with geomembranes, reinforced plastic, reinforced concrete, or a tank made of any type of steel or corrosion-resistant coating material; said homogenizing tank (2) may comprise an agitation mechanism of the mechanical type, or by means of air, or any other mechanism suitable for maintaining a homogeneous mixture;iv) electrochemically oxidize said aqueous phase in an electrolytic reactor (3), for 4 to 120 min, to cause a first break in the chains of recalcitrant or refractory organic compounds and facilitate their separation by means of coagulation-flocculation, thereby achieving a reduction in the biological oxygen demand (BOD), the chemical oxygen demand (COD), the total organic carbon (TOC), and eliminate ammoniacal nitrogen (N-NH4; +), and degrade the color of the leachate (Moraes & Bertazzoli, 2005; Galváo et al., 2020); the electrolytic reactor (3) comprises stainless steel anode and cathode electrodes that may or may not be sacrificial, which are energized by an alternating current or direct current power source (not illustrated), which is defined according to the physicochemical characteristics of the leachate to be treated, where the current applied in the electrochemical oxidation can range from 6 to 15 volts and 8 to 15 amperes; v) coagulating the oxidized aqueous phase from the previous stage in a coagulation-flocculation reaction tank (4), where 50 ppm of a cationic coagulant substance, for example a solution of Q-7029® aluminum salts and 10 ppm of an anionic flocculant substance, for example a water-soluble anionic polymer Q-4055 COL®, are used to accelerate the sedimentation of the solids;It should be noted that the concentrations of both substances vary depending on the composition of the leachate to be treated; vi) filter the aqueous phase obtained in the previous stage, in a filter cart (5) that has, for example, a 30 micron mesh, to retain solid particles larger than this average particle diameter, to carry out a first separation of solids generated in the coagulation-flocculant reaction tank (4); vii) recover the filtered aqueous fraction from the previous stage; viii) clarify the aqueous fraction recovered in the previous stage, for 3 min in an advanced dissolved air flotation (DAF) system (6), to remove suspended solids without the need to use ultrafiltration, eliminating backwashing and / or filter media changes; achieving the removal of up to 99% of the fats, oils, hydrocarbons, suspended solids and colloidal particles still present in the liquid phase of the leachate;where the suspended solids that remained dissolved in step iv) will be removed in this step; ix) recover the clarified aqueous fraction from the previous step; x) oxidize the clarified aqueous fraction from the previous step with a potent non-selective hydroxyl radical (OH*) to eliminate recalcitrant organic compounds in the wastewater; for this purpose, an ozone generating equipment (9) that generates 420 g of O3 per h can be used, for example, to provide O3 to an advanced oxidation reactor (8) where the oxidation of recalcitrant organic compounds present in the clarified aqueous fraction is carried out, by means of complex oxidation reactions with O3;In said advanced ozone oxidation reactor (8) the potent non-selective hydroxyl radical (OH*) is generated, which has a much higher oxidation potential than ozone or hydrogen peroxide and usually reacts at least a million times faster, allowing for a shorter contact time and less environmental impact since the oxygen molecule is regenerated in its decomposition; In said advanced oxidation reactor (8) there is a flow meter (not illustrated) to monitor the amount of aqueous fraction treated, and fine bubble diffusers (not illustrated) to inject the ozone; and the retention time at this stage will depend on the results obtained from the analysis of the clarified leachate, in this case a retention time of approximately 1 h was used;xi) nano-filter the aqueous fraction obtained from the previous stage, with a filtration system capable of retaining particles in a range of 0.001- 0.01 pm, thereby removing suspended solids, remaining nitrogen, color and odor from the water; and xii) recover the filtered liquid fraction from the previous stage, which is now suitable for discharge into water bodies or for reuse since it complies with the corresponding environmental regulations. It should be noted that the solid waste or sludge resulting from each filtration was removed from the system and placed in a sludge container (not illustrated) for final disposal in accordance with the applicable standard.

[0062] With the process for treating leachate in sanitary landfills, proposed by the present invention, the following advantages are achieved: a) Eliminate solids greater than 1 mm before entering the processing train. b) Reduce total dissolved solids (TDS) to values ​​<500 mg / L. c) Reduce total suspended solids (TSS) to values ​​<10 mg / L. d) Removal of chemical oxygen demand to values ​​<100 mg / L. e) Deliver water with true color in accordance with NOM-001-SEMARNAT-2021. f) Deliver a final water discharge with high percentages of removal of the contaminants regulated in NOM-001-SEMARNAT-2021. g) The process will be able to operate in continuous flow 24 hours a day, 365 days a year without requiring maintenance shutdowns.h) Treated water can be reused in accordance with NOM-003-SEMARNAT-1997, which establishes the maximum permissible limits of contaminants for treated wastewater that is reused in public services.

[0063] Results achieved with the system and process in the treatment of leachate from sanitary landfills

[0064] At the end of the landfill leachate treatment process, the following values ​​were obtained for the main monitored physicochemical and microbiological parameters (see Table 4). Table 4. Characteristics of the landfill leachate generated and physicochemical and microbiological results of the water obtained at the end of treatment. *Daily average discharges to rivers, streams, canals, and drains. **According to NOM-001-SEMARNAT-1996 for the protection of aquatic life. NA = Not Applicable

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Claims

CLAIMS 1. A system for the treatment of leachates from sanitary landfills, characterized in that it comprises: i) at least one filter mesh sieve (1), which receives the leachates, which will only allow the passage of solids with an average particle diameter < 1 mm; (i) at least one homogenizing tank (2) for receiving the filtered leachates, comprising an agitation mechanism suitable for keeping the leachates homogeneously mixed; and sensors at the flow outlet of the homogenizing tank (2) to monitor the flow, the total suspended solids (TSS) and the total dissolved solids (TDS); in order to make adjustments to subsequent stages of the process when necessary; (iii) at least one electrolytic reactor (3) for subjecting the pH-adjusted leachates to electrochemical oxidation, this electrolytic reactor (3) can be constructed of reinforced plastic, using a stainless steel anode and cathode;iv) at least one coagulation-flocculation reaction tank (4) where the leachates coming from the electrolytic reactor (3) are received, where coagulant and / or flocculant substances are added to said coagulation-flocculation reaction tank (4) to separate and eliminate the solids suspended in the leachates; v) a first tank with agitator (11) containing coagulant and / or flocculant substances, to supply them to the coagulation-flocculation reaction tank (4); vi) at least one filter car (5) to carry out a first separation of solids generated in the coagulation-flocculation reaction tank (4); where said filter car (5) has a mesh of 30 microns, to retain solid particles larger than this average particle diameter; vii) at least one clarification system (6), capable of forming aggregates of the leachates, in order to facilitate the separation of the; solids, without the need for ultrafiltration, backwashing and / or filter media changes; viii) a second agitator tank (12) that also contains coagulant and / or flocculant substances, to provide them to the clarification system (6); ix) at least one advanced ozone oxidation reactor (8), where the potent non-selective hydroxyl radical (OH*) is generated, which has a much higher oxidation potential than ozone or hydrogen peroxide; and said advanced oxidation reactor (8) comprises a flow meter (not illustrated) to monitor the amount of treated leachate; x) at least one ozone generating equipment (9) to provide ozone to the advanced ozone oxidation reactor (8); xí) at least one nanofiltration equipment (10), capable of retaining particles in the range of 0.001-0.01 pm, for the removal of hardness, TSS, TDS, COD, and BOD, which improves the removal of residual compounds from leachates, as well as the color and odor of treated wastewater; and xii) hydraulic pumps (not shown) to transfer the aqueous phases from one compartment of the system to another.

2. The system of the preceding claim, wherein the filter mesh screen (1) is a hydro-screen made of type 304 stainless steel.

3. The system of claim 1, wherein the homogenizing tank (2) is a lagoon with geomembranes, reinforced plastic, reinforced concrete or a tank made of any type of steel or corrosion-resistant coating material.

4. The system according to claim 1, wherein the agitation mechanism is a mechanical mechanism, or a mechanism by means of air.

5. The system of claim 1, wherein the electrolytic reactor (3) is constructed of reinforced plastic, using a stainless steel anode and cathode.

6. The system of claim 1, wherein the clarification system (6) is a dissolved air flotation system, which has an air microbubble generator (7) which provides air microbubbles to the leachate, which bind to the particles of the leachate to be removed, thus forming aggregates capable of floating and facilitating the separation of the solids.

7. The system of claim 1, characterized in that it comprises a first flow buffer tank (13) between the homogenizing tank (2) and the electrolytic reactor (3), to ensure water flow to the electrolytic reactor (3).

8. The system according to claim 1 and 7, characterized in that it also comprises a second flow buffer tank (14) between the filter car (5) and the clarification system (6), to ensure constant water flow, and absorb possible variations in the inlet flow to the clarification system (6).

9. The system according to claim 8, characterized in that it further comprises a third flow buffer tank (15) between the advanced ozone oxidation reactor (8) and the nanofiltration equipment (10), to ensure the constant flow of leachate and absorb possible variations in the inlet flow to the nanofiltration equipment (10).

10. The system of claim 1, characterized in that it comprises at least one sludge container (not illustrated) for containing the resulting solids or sludge. -YEAH- 11. A physicochemical process with dissolved air flotation (DAF), for the treatment of leachates from sanitary landfills, by using the system according to the previous claims, where the process is characterized in that it comprises the following steps: i) sifting the leachates in a filter mesh sieve (1), which will only allow the passage of solids with an average particle diameter < 1 mm; (i) recovering the aqueous fraction from the previous stage; (iii) homogenizing the aqueous fraction from the previous stage in a homogenizing tank (2) by stirring or bubbling air for homogenization; said homogenizing tank (2) may comprise a stirring mechanism suitable for maintaining a homogeneous mixture; (iv) electrochemically oxidizing said aqueous phase in an electrolytic reactor (3) for 4 to 120 min, to cause a first break in the chains of recalcitrant or refractory organic compounds and facilitate their separation by means of coagulation-flocculation, thereby achieving a reduction in the biological oxygen demand (BOD), the chemical oxygen demand (COD), the total organic carbon (TOC), and eliminating ammoniacal nitrogen (N-NH4). +), and degrade the color of the leachates; v) coagulate the oxidized aqueous phase from the previous stage, in a coagulation-flocculation reaction tank (4), with a cationic coagulant substance and an anionic flocculant substance, to accelerate the sedimentation of the solids, whose concentrations depend on the composition of the leachates to be treated; vi) filter the aqueous phase obtained in the previous stage, in a filter cart (5) that has a mesh to retain solid particles larger than the average particle diameter < 1 mm, to carry out a first separation of solids generated in the coagulation-flocculation reaction tank (4); vii) recover the filtered aqueous fraction from the previous stage; viii) clarify the aqueous fraction recovered in the previous stage, in a clarification system (6), which removes suspended solids, without the need to use ultrafiltration, eliminating backwashing and / or filter media changes; achieving the removal of up to 99% of the fats, oils, hydrocarbons, suspended solids and colloidal particles still present in the liquid phase of the leachate; where the suspended solids that were still dissolved in stage iv) will be removed in this stage; ix) recover the clarified aqueous fraction from the previous stage;x) oxidize the clarified aqueous fraction from the previous stage with a potent non-selective hydroxyl radical (OH*) to eliminate recalcitrant organic compounds in the wastewater, for this purpose an ozone generating equipment (9) is required to provide O3 to an advanced oxidation reactor (8) where the potent non-selective hydroxyl radical (OH*) is generated to carry out the oxidation of recalcitrant organic compounds present in the clarified aqueous fraction, by means of complex oxidation reactions with O3; in said advanced oxidation reactor (8) a flow meter (not illustrated) is also provided to monitor the amount of aqueous fraction treated, and fine bubble diffusers (not illustrated) to inject ozone;xi) nano-filter the aqueous fraction obtained from the previous stage, with a filtration system capable of retaining particles in the range of 0.001-0.01 pm, thereby removing suspended solids, remaining nitrogen, color and odor from the water; and xii) recover the filtered liquid fraction from the previous stage, which is now suitable for discharge into water bodies or for reuse since it complies with the corresponding environmental regulations.

12. The process of claim 11, wherein the filter mesh screen (1) is a hydro-screen made of type 304 stainless steel.

13. The process according to claim 11, wherein the homogenizing tank (2) is a lagoon with geomembranes, reinforced plastic, reinforced concrete or a tank made of any type of steel or corrosion-resistant coating material.

14. The process according to claim 11, wherein the stirring mechanism is a mechanical type mechanism, or a mechanism by means of air.

15. The process of claim 11, wherein the electrolytic reactor (3) is constructed of reinforced plastic, using a stainless steel anode and cathode, which may or may not be sacrificial, which are energized by an alternating current or direct current power source, which is defined according to the physicochemical characteristics of the leachate to be treated, where the current applied in the electrochemical oxidation ranges from 6 to 15 volts and 8 to 15 amperes.

16. The process according to claim 11, wherein the cationic coagulant substance is 50 ppm and is a solution of aluminum salts and the anionic flocculant substance is 10 ppm and is a water-soluble anionic polymer.

17. The process according to claim 11, wherein the mesh of the filter car (5) is 30 microns.

18. The process of claim 11, wherein the clarification time is 3 min.

19. The process of claim 11, wherein the clarification system (6) is a dissolved air flotation system, which has an air microbubble generator (7) that provides air microbubbles to the leachate, which bind to the particles of the leachate to be removed, thus forming aggregates capable of floating and facilitating the separation of the solids.

20. The process according to claim 11, wherein the oxidation time of step x) will depend on the results obtained from the analysis of the clarified leachate.

21. The process of claim 11, characterized in that it further comprises ensuring the water flow to the electrolytic reactor (3), by means of a first flow buffer tank (13) located between the homogenizing tank (2) and the electrolytic reactor (3).

22. The process according to claim 11, characterized in that it also comprises ensuring constant water flow and absorbing possible variations in the inflow to the clarification system (6), by means of a second flow buffer tank (14), placed between the filter car (5) and the clarification system (6).

23. The process according to claim 11, characterized in that it also comprises ensuring the constant flow of leachate and absorbing possible variations in the inlet flow to the nanofiltration equipment (10), by means of a third flow buffer tank (15), located between the advanced ozone oxidation reactor (8) and the nanofiltration equipment (10).

24. The process of claim 11, characterized in that it further comprises removing solid waste or sludge resulting from each filtration stage.

Images