Technique for filtering water pretreated by wastewater purification stations

Abstract

The invention relates to a novel and revolutionary method for treating wastewater by percolation filtration through an innovative filter matrix composed of sea sand, fly ash, clinker and black metallic slag. The fundamental principle of the method consists in the preliminary oxygenation of the raw wastewater before it is passed through the various layers of the filter matrix. The sea sand acts effectively to filter suspended solids, while fly ash and clinker, rich in silica, remove organic matter and heavy metals from the wastewater. Finally, the black metallic slag plays a crucial role by neutralising alkaline effluents and removing phosphorus. The results obtained from the implementing this method are highly satisfactory, with substantial reductions observed in the principal pollutants. This innovative approach enables the production of a high-quality filtrate that meets environmental standards and can be efficiently reused in processes such as irrigation or industrial cooling, while ensuring environmental protection and the sustainable use of resources.

Description

[0001] Titled

[0002] Filtration technique for water pre-treated by wastewater treatment plants.

[0003] Scope of the invention

[0004] The present invention relates to the field of water, wastewater, sewage or sludge treatment and more particularly to treatment by degassing, elimination and release of dissolved compounds.

[0005] Context of the invention

[0006] Currently, in the field of wastewater treatment, treatment plants use various filtration techniques to purify effluents before they are released into the environment. These techniques include mechanical, biological, physical, and chemical filtration, each playing a vital role in removing pollutants and contaminants from pre-treated water.

[0007] Mechanical filtration, including screening, grit removal, and oil removal, eliminates solid waste, mineral particles, and floating matter from wastewater. Biological filtration, using activated sludge, trickling filters, and lagoons, employs microorganisms to break down organic matter. Physical filtration, including automatic filters, percolation filtration, and planted filters, aims to remove suspended solids and promote the action of purifying microorganisms. Finally, chemical filtration, through flocculation and centrifugation, uses chemical reagents to precipitate pollutants.

[0008] Despite the diversity of existing filtration techniques, the challenges of wastewater management persist. Population growth, rapid urbanization, and increased industrial activity have led to growing pressure on water resources and the environment. Faced with this problem, it is imperative to develop innovative ideas and sustainable approaches to improve the efficiency of wastewater treatment, reduce environmental impacts, and ensure the availability of this vital resource for future generations.

[0009] State of the art

[0010] Patent WO2021018629 - waste water treatment plant Discloses a method for a wastewater treatment plant comprising: - means for introducing wastewater; - a pre-filter device transforming wastewater into pre-treated water which includes a pre-treatment tank internalizing lignocellulosic compounds and microorganisms; - means for evacuating pre-treated water; - at least one planted filter device transforming pre-treated water into treated water, arranged in series and positioned downstream of said pre-filter device and supplied with pre-treated water by said evacuation means, - said planted filter device comprising distribution means supplied by these evacuation means, and a filter bed constituting a culture medium for semi-aquatic plant species, - said filter bed comprising at least three layers of minerals including a filter layer, a transition layer, and a drainage layer;- means of drainage of treated water, into which the drainage layer opens, configured to drain the treated water away from said planted filter device.;

[0011] The present invention KR20190045881 relates to a purification filter for a purifier with an optimized flow path for filtering foreign substances contained in raw water, such as tap water. According to one embodiment of the present invention, the purification filter for a purifier with an optimized flow path is applied to a purification filter for a purifier that has a connector coupled to a frame and includes a filter housing coupled to the connector so that it can be replaced. The filter housing includes a pretreatment filter that removes foreign substances from the raw water introduced into the filter housing; a posttreatment filter fully connected to the upper side of the pretreatment filter and purifying the purified water introduced into the filter housing from the outside;and a multi-cell flow path switching guide, coupled to an open orifice of the filter housing and forming a raw water flow path through which the raw water is introduced, a pre-treated water flow path which is formed on an outside side of the raw water flow path and discharges the pre-treated water that has passed through the pre-treatment filter, a post-treated water flow path which is formed on an outside side of the pre-treated water flow path and discharges the post-treated water that has passed through the post-treatment filter, and a purified water flow path which is formed on an outside side of the post-treated water flow path and through which the purified water is introduced.

[0012] Summary

[0013] Our invention aims to improve the use of treated wastewater from treatment plants by reusing it instead of discharging it directly into the environment. This practice offers numerous advantages, particularly in urban settings where treated wastewater can be used for activities such as street cleaning and watering parks and gardens, thus reducing the demand for drinking water. In agriculture, treated wastewater proves to be a valuable resource, requiring less freshwater and rich in nutrients, allowing for more efficient resource use and reducing the need for additional fertilizers.

[0014] Wastewater reuse must be adapted to each region. In coastal areas, where wastewater treatment plants discharge directly into the sea, reuse is advantageous with reduced environmental impacts. Inland, treated wastewater can be reinjected into waterways, helping to maintain their levels and promoting the health of local ecosystems.

[0015] The innovation of our invention lies in filtering wastewater from treatment plants through solid adsorbents such as marine sand, fly ash, and black slag. These materials effectively purify wastewater, reducing levels of contaminants like heavy metals and producing a filtrate that meets international standards for reuse in applications such as irrigation.

[0016] The invention proposes an innovative system for the reuse of treated wastewater, offering a sustainable and efficient approach to water resource management and environmental preservation.

[0017] Description

[0018] Our invention involves using treated wastewater from treatment plants instead of discharging it directly into the natural environment, as is generally the case today. Wastewater reuse is particularly beneficial for urban applications, such as cleaning streets and sewers, or watering parks and gardens where potable water is not required. In agriculture, it allows for both reduced water consumption and, more surprisingly, the use of less fertilizer, as treated wastewater is richer in nutrients than the raw water typically used. However, reuse is not equally appropriate everywhere. In coastal areas, where wastewater treatment plants discharge water almost directly into the sea, reuse is not problematic because the environmental impact is minimal.In addition to preventing freshwater loss, this practice helps reduce groundwater withdrawals. Inland, however, water from wastewater treatment plants is reinjected into natural environments such as rivers and streams, contributing to their balance. In this context, treated wastewater from inland treatment plants, discharged directly into waterways, plays a positive role by maintaining water levels and promoting healthy ecosystems.

[0019] The principle of our invention is to filter wastewater from wastewater treatment plants (WWTPs) using adsorbents, which are solid waste products. The filter matrix we used consists of marine sand with a grain size of 120 µm, fly ash, and black slag. The fly ash comes from coal combustion in thermal power plants, and the slag from metal smelting industries. We studied, firstly, the physicochemical characteristics before and after filtration, where the parameters studied were pH, conductivity, suspended solids (SS), chemical oxygen demand (COD), biochemical oxygen demand (BOD), orthophosphates, chlorides, and ammonium; and secondly, the evolution of trace amounts of the most toxic heavy metals, namely: Cu, Pb, Co, Fe, Zn, Hg, and Cr.The results obtained are very positive as they showed spectacular reductions resulting in a filtrate that meets international standards for reuse in the field of irrigation.

[0020] Our invention consists of a high-performance system for filtering wastewater after pretreatment by wastewater treatment plants. In this context, we have developed a plant in the form of a three-stage vertical column. The purification matrix used is composed of 120 µm marine sand, ash, and black slag. The common factor among these three adsorbents is their high silica and calcite content.

[0021] The proposed treatment process is as follows: Stage 1: a bed composed of 120-micrometer marine sand. This filter bed, which has the capacity to filter solid suspended matter, must be placed first.

[0022] Stage 2: a bed composed of fly ash very rich in silica which has the capacity to filter and considerably reduce organic matter and heavy metals.

[0023] Stage 3: a bed composed of slag intended mainly for the neutralization of alkaline effluents and the removal of phosphorus.

[0024] The invention relates to a high-performance system, which we developed in the laboratory, for filtering wastewater after its initial treatment by wastewater treatment plants (WWTPs). It consists of a vertical column installed at the WWTP outlet and comprised of three stages. The purification matrix used is made up of marine sand with a grain size of 120 µm, ash, and black slag. The common factor among these three adsorbents is their high silica and calcite content. The results obtained are very positive and satisfactory, demonstrating dramatic reductions and producing a filtrate that meets the standards for reuse in irrigation and as a coolant for industrial units.

Claims

Demands: Claim 1: A wastewater treatment process for recovering a high-quality filtrate comprising the following steps: Oxygenate the wastewater beforehand; Percolate oxygenated wastewater through a filter matrix comprising at least three successive layers of: Sea Sand Fly ash Cinders Metallic black slag Claim 2: characterized in that the filter matrix comprises a first additional layer of marine sand with a grain size between 100 and 200 micrometers. Claim 3: characterized in that the filtrate obtained conforms to the standards, consisting of a second layer of fly ash rich in silica and iron oxides, and a third layer of black metallic slag with a high calcium content. Claim 4: characterized in that the filtrate is used for agricultural irrigation. Claim 5: characterized in that the filtrate is used for industrial cooling

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