FR2812627A1 - CONTINUOUS INDUSTRIAL WASTEWATER TREATMENT PROCESS AND DEVICES FOR ITS IMPLEMENTATION - Google Patents

Abstract

Process for the continuous purification of industrial wastewater and devices for its implementation, based on the combination of different processes: an aerobic biological treatment, a physico-chemical process, an evaporation process and a membrane technique by tangential filtration , arranged in this order to constitute a wastewater treatment plant of all kinds, allowing the transformation of these polluted aqueous effluents into recyclable water in an industrial process. Adapted to the specific needs of many industries and adaptable to existing aqueous effluent treatment plants in order to optimize their performance, this process of continuous purification of industrial wastewater makes it possible to treat one or more different effluents according to their degree of biodegradability and is particularly suitable for variations in volume and polluting load of effluents.

Description

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The present invention relates to a process for the continuous purification of industrial wastewater and devices for its implementation.

The treatment of industrial wastewater is based on one and / or two main processes: a physico-chemical treatment and / or a biological treatment.

 -The physico-chemical treatment consists in adding chemical additives helping to coagulate then decant the impurities contained in the water. This allows to get out on one side, highly charged sludge difficult to revalorize, requiring high subsequent treatment costs, on the other, water. The purification rates in this type of process are limited.

-Biological treatment consists in developing an endogenous bacterial fauna capable of breaking down polluting molecules in a basin. The effluent is admitted at a regular rate. The size of the pelvis is conditioned by the time necessary for bacteria to digest polluting molecules. A decanter then separates the biological sludge from the treated water.

The biodegradability ratio of the effluent is decisive for the choice of the treatment process. When the two processes are combined, the physico-chemical treatment always comes before the biological treatment.

In some industries, the effluents are very complex and come from several workshops. Their complex composition often limits the performance of the biological treatment plant due to the presence of non-precipitable COD and biological inhibitors, etc., which adversely affect the functioning and efficiency of the biomass.

To remedy these drawbacks, the process according to the invention makes it possible to treat one or more different effluents according to their degree of biodegradability and makes it possible to transform highly polluted waste water into recyclable clear water by limiting the production of waste such as sludge.

Adapted to the specific needs of many industries, this continuous purification process allows a particularly high effluent treatment capacity (expressed in COD / day). In addition, its modularity allows it to be adapted to existing effluent treatment installations in order to increase their efficiency.

It is characterized by the means used, and more particularly, by the combination of different processes: an aerobic biological treatment, a physicochemical process, an evaporation process and a membrane technique by tangential filtration, arranged in this order to constitute a continuous treatment and depollution station of aqueous effluents of all kinds. The single figure shows by way of nonlimiting example; a diagram of an embodiment according to the invention where the effluent A, after neutralization of the pH (3) by diffusion in the liquid and absorption of the neutralizer (4), arrives in a biological reactor (1). It is in this tank, in suitable material, sized according to the time necessary for endogenous or exogenous bacteria, selected and seeded with nutrients at frequencies and determined quantities to digest the polluting molecules and according to the variations in volume and polluting load. of the effluent, that this effluent A is brought to a temperature of 25-30 C. It is agitated (6) and permanently aerated by the blown air produced by a compressor (7) and injected by an aeration ramp (5), through fine nozzles. This blown compressed air is a function of the volume of the reactor and of the effluent and allows evaporation of this effluent.

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 This oxygenation is necessary for the maintenance and development of endogenous or exogenous bacteria specific to the effluent, making it possible to digest the biodegradable materials of this effluent A. Each day, a determined volume of effluent from the bioreactor (1) passes through the physico-chemical treatment consisting of several compartments, in order to allow the molecules of effluent A, dispersed in the solutions (8, 9, 10 and 11) and partially biodegraded, to be added with chemicals which coagulate them roughly water-insoluble flocs. These flocs are raised to the surface of the water by blowing pressurized water: the fine air bubbles attaching to the flocs, entrain them towards the surface of the water which is mechanically skimmed. These liquid skimmed sludges (13) are sent (14) to a bioreactor (2), while the water (12) is directed to a storage tank (18) to undergo a final membrane treatment by tangential filtration when the chemical parameters of water impose it, especially in terms of residual COD, conductivity, chlorides etc ..., for the purpose of recycling treated water in the industrial process.

In the reactor (2.) the sludge is stored. This bioreactor (2) is also designed to receive an effluent B, which may consist of several effluents, the degree of biodegradability of which is slower than that of effluent A. The dimensioning of this reactor is conditioned by the volume of the effluent B, by the time necessary for its biodegradation as well as the volume of the liquid sludge from the physico-chemical treatment and the retentate produced by the membrane process by tangential filtration.

This reactor (2) of suitable material, the internal face of which is treated with thermal and anti-corrosion protection, can, by a heating system, in particular by recovering calories from the industrial process, be brought to a temperature of 50 to 70 C. This temperature, combined with the permanent injection of compressed air, allows significant evaporation of this effluent without atmospheric pollution. Indeed, effluent B, agitated (6) and aerated (5), is mixed with liquid sludge (13) which gradually become biologically inactive but remain chemically active for the absorption of pollutants from this effluent B. This characteristic allows trapping volatile organic compounds and polluting vapors. An injection of compressed air, through nozzle nozzles, of the order of 130 m3 / hour, makes it possible to evaporate, at the abovementioned temperature, about 10 m3 / day (effluent. The evaporation caused in the bioreactors (1 ) and (2) allows an optimization of the process according to the variations in volume and polluting load of the incoming flow.

Periodically, the contents of the reactor (2) are directed to a neutralization tank (15) and to the compression and mechanical dewatering unit (16) in order to condition compressed sludge cakes in order to evacuate them off site for treatment. and valued. The residual water (17) from the sludge treatment is directed to the bioreactor (1) to be mixed there with the effluent A and to be treated therein biologically. A large quantity of pollutant molecules from effluent B having been digested during the stay in the bioreactor (2), after dewatering of the sludge, this effluent can join the bioreactor (1) to complete its biodegradability.

After the physico-chemical treatment, the water (12) is directed to a storage tank (18). A pump (supply (19) feeds a concentration tank (20). A recirculation pump (21) circulates the water (12), according to a determined pressure. This water (12) passes through a housing module, suitable material serving as a housing for membranes (22), of organic type or

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 or mineral, determined according to their degree of porosity. A permeate (23), freed of its impurities, is permanently evacuated to a storage tank (25). A feed pump (26) directs this treated water (23) to the industrial process. A retentate or concentrate of impurities (24) returns to the concentration tank (20) and is periodically removed to the reactor (2). The intervention of the membrane process by tangential filtration at the end of the purification process makes it possible, on the one hand, to eliminate the problems of clogging due to too high polluting loads, on the other hand, to develop a particularly precise treatment in order to '' obtain quality water that perfectly meets the requirements of an industrial process and that is not authorized by biological treatment supplemented by physico-chemical treatment. Advantageously, this additional membrane treatment makes it possible to eliminate non-precipitable COD, suspended matter, microorganisms, chlorides, etc., in order to produce recyclable water, of constant quality over time, which can meet the criteria. the most selective of an industrial process. Adapted to the specific needs of many industries and adaptable to effluent treatment plants in order to optimize their performance, this continuous purification process provides safe, economical and practical technical solutions, with reduced floor space and maintenance simplified, to industrialists who must treat their wastewater while preserving the environment.

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Claims (1)

 CLAIMS 1.- Continuous purification process for industrial wastewater, based on the combination of different processes: aerobic biological treatment, physico-chemical treatment, an evaporation process and a membrane technique by tangential filtration, allowing transform polluted wastewater into recyclable clear water, limiting the production of waste such as sludge, characterized in that an effluent A, after neutralization of the pH (3) by diffusion into the liquid and absorption of the neutralizer (4), arrives in a biological reactor (1). It is in this tank, in suitable material, sized according to the time necessary for endogenous or exogenous bacteria specific to the effluent seeded with nutrients at determined frequencies and quantities, making it possible to digest biodegradable materials and according to variations in volume. and of the pollutant load of the effluent that this effluent A is brought to a temperature of 25-30 C. It is agitated (6) and aerated continuously by the blown air produced by a compressor (7) and injected by a ramp ventilation (5). This blown compressed air, through fine nozzles, is a function of the volume of the reactor and of the effluent and makes it possible to evaporate it. 2. A process for the continuous purification of industrial wastewater according to claim 1, characterized in that each day a determined volume of effluent from the bioreactor (1) passes through the physicochemical treatment consisting of several compartments @ in order to allow the molecules of effluent A, dispersed in solutions (8, 9, 10 and 11) and partially biodegraded, to be added with chemicals which coagulate them in large coats insoluble in water. These flocs are raised to the surface of the skin by blowing in pressurized water: the fine air bubbles which are fixed on the jaws, entrain them towards the surface of the skin which is mechanically skimmed. These liquid skimmed sludges (13) are sent (14) to a bioreactor (2), while the water (12) is directed to a storage tank (18). A feed pump (19) feeds a concentration tank (20). A recirculation pump (21) circulates the water (12) at a determined pressure. This water (12) passes through a housing module, of suitable material, serving as a housing for membranes (22), of organic or mineral type, determined according to their porosity. A pinnate (23), freed of its impurities, is permanently evacuated to a storage tank (25). A feed pump (26) directs this treated water (23) to the industrial process. A retentate of impurities (24) returns to the concentration tank (20) and is periodically removed to the bioreactor (2). This additional membrane treatment by tangential filtration at the end of the purification process makes it possible to produce recyclable water, of constant quality, meeting the most selective criteria of an industrial process. 3. A process for the continuous purification of industrial wastewater according to claims 1 and 2 characterized in that the liquid sludge (13) as well as the retentate (24) are stored in the bioreactew (2). This bioreactor (2) is also designed to receive an effluent B, which may consist of several effluents, the degree of biodegradability of which is slower than that of effluent A. This bioreactor (2) made of suitable material, the internal face of which is treated with thermal and anti-corrosion protection, is sized according to the volume of the effluent B, the time required for its biodegradation as well as according to the volume of the liquid sludge (13) and of the retentate (24). This bioreactor (2), can, by a heating system in particular by recovery of the calories of the industrial process, be brought to a temperature of 50 to 70 C. This temperature combined with the permanent injection of compressed air, through fine nozzles, allows significant evaporation <Desc / Clms Page number 5>  of effluent B. The evaporation caused in the bioreactors (1) and (2) allows an optimization of the process according to the variations in volume and pollutant load of the incoming flow. Periodically, the content of the bioreactor (2) is directed to a neutralization tank (15) and to a compression and mechanical dewatering unit (16) in order to condition sludge cakes to be removed off site for treatment and recovery. The residual water (17) from the sludge treatment is directed to the bioreactor (1) to be mixed with the effluent A in order to biodegrade the polluting molecules remaining after the stay in the bioreactor (2). 4. A process for the continuous purification of industrial wastewater according to claims 1, 2 and 3, characterized in that the liquid skimmed sludge (13), mixed with the effluent B and with the retentate (24), stored in the bioreactor (2), absorb a large quantity of polluting molecules, volatile organic compounds and polluting vapors from effluent B. This characteristic makes it possible to carry out a significant evaporation of effluent B without atmospheric pollution and to allow transfer residual water (17) from the sludge treatment to the bioreactor (1) in order to complete its biodegradability. 5. A process for the continuous purification of industrial waste water according to any one of the claims, characterized in that it is adapted to the specific needs of numerous industries and adaptable to existing effluent treatment installations in order to optimize their yield and ensures the biodegradation of pollutants from one or more different effluents according to their degree of biodegradability. 6.- Wastewater treatment and depollution station characterized in that it comprises at least one device for neutralizing the pH of an effluent A, a bioreactor 1 equipped with aeration, stirring and heating systems , a physico-chemical installation, a second bioreactor 2 fitted with aeration, agitation and heating systems, the internal face of which is treated with a refractory and anti-corrosion coating, ensuring the treatment of a mixed effluent B liquid sludge 13 and retentate 24, pipes and pumps, an installation for producing and diffusing compressed air, a device for neutralizing the content of the bioreactor 2, a unit for compressing and mechanically dewatering the sludge, and a additional membrane treatment unit by tangential filtration with storage tanks, concentration tank, feed and recirculation pumps, for recycling of tra water ited.