Classifications

• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F9/00—Multistage treatment of water, waste water or sewage
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/24—Treatment of water, waste water, or sewage by flotation
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/30—Treatment of water, waste water, or sewage by irradiation
  • C02F1/32—Treatment of water, waste water, or sewage by irradiation with ultraviolet light
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
  • C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
  • C02F1/444—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by ultrafiltration or microfiltration
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
  • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
  • C02F1/463—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrocoagulation
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
  • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
  • C02F1/467—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction
  • C02F1/4672—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction by electrooxydation
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/72—Treatment of water, waste water, or sewage by oxidation
  • C02F1/722—Oxidation by peroxides
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F11/00—Treatment of sludge; Devices therefor
  • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
  • C02F11/121—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering
  • C02F11/123—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering using belt or band filters
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F11/00—Treatment of sludge; Devices therefor
  • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
  • C02F11/121—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering
  • C02F11/127—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering by centrifugation
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2209/00—Controlling or monitoring parameters in water treatment
  • C02F2209/04—Oxidation reduction potential [ORP]
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2209/00—Controlling or monitoring parameters in water treatment
  • C02F2209/06—Controlling or monitoring parameters in water treatment pH
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2209/00—Controlling or monitoring parameters in water treatment
  • C02F2209/11—Turbidity
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2209/00—Controlling or monitoring parameters in water treatment
  • C02F2209/42—Liquid level
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2303/00—Specific treatment goals
  • C02F2303/24—Separation of coarse particles, e.g. by using sieves or screens
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2305/00—Use of specific compounds during water treatment
  • C02F2305/10—Photocatalysts

Definitions

• Wastewater purification plants typically comprise a series of components adapted to remove, with a process in series, the contaminants from waste of urban and/or industrial origin.
• the products that exit from a purification plant are:
• - industrial wastewater any type of wastewater discharged from buildings or plants where commercial activities or the production of goods take place, other than domestic wastewater and runoff rainwater.
• the plants typically in use provide for chemical-physical processes, membrane separation and vacuum evaporation.
• the object of the present invention is to provide a separation technique which guarantees advantageous performance levels in terms of management, sustainability and cost effectiveness.
• Figure 1 (A) process diagram according to the present invention; (B) process diagram according to another embodiment.
• Figure 2 schematic representation of the plant according to an embodiment.
• FIG. 3 A, B, C, diagram representative of the yields of three processes implemented according to the present invention.
• Figure 4 process diagram in the embodiment comprising a photooxidation step implemented during electro-oxidation, with recovery and re-introduction into the tank of the photocatalyst crystal.
• Figure 5 schematic representation of an embodiment of a portion of the plant.
• A front view.
• B side view.
• C perspective view.
• Figure 6 schematic representation of a detail of the portion of plant in the embodiment of figure 5.
• A perspective view.
• B front view.
• C side view.
• said process further comprises:
• Step c) addition in said electro-oxidation step, of a photocatalytic semiconductor selected from the group comprising TiO2, ZnO, SnO2, WO 3 , ZnS or mixtures thereof.
• said photocatalytic semiconductor is added in an amount comprised between 0.03 and 0.30 g/l, or 0.05-0.10 g/l.
• Said step a), of electrocoagulation enables the formation of a colloid system, in which the solid phase tends to separate off forming a flocculate.
• the electrocoagulation step is performed with Iron and/or Aluminum electrodes.
• anodic oxidation takes place with the release of metal ions in the form of hydrates which absorb the pollutant material creating flocs.
• anodic reduction takes place, with the formation of hydrogen gas which keeps the flocs that has formed afloat.
• the effect of the electric field is such as to also cause the large molecules present in the water to be treated to break up into fractions with a lower molecular weight, reducing the soluble COD (chemical oxygen demand).
• This step is followed by filtration, preferably with a 0.2-micron MBR (membrane bioreactor) immersion membrane, to clarify the wastewater. Also in this case, to prevent the membranes from clogging, air-filled microbubbles are distributed from below.
• MBR membrane bioreactor
• hydrogen peroxide can be dosed into the plant to increase, in the acid environment (pH 3-5), the oxidizing power of the system through the Fenton reaction in the presence of Fe 2+ which catalyzes the decomposition the H2O2.
• This process is particularly useful for oxidizing hazardous organic molecules such as, by way of example, VOCs, BTEX, IPA, aniline.
• Step b) of electro-oxidation removes soluble CODs and a large part of the ammonia.
• exposure to UV light dissociates chlorine and hypochlorite in the form of chloride ion, neutralizing the formation of CI2 which would occur.
• said steps a) and b) are preceded by a pre-treatment for removing coarse solids suspended in the water to be treated.
• said step b), of electro-oxidation is followed by an ultrafiltration and/or reverse osmosis step and/or further filtration through nano-structured adsorbent (HTS) or zeolites.
• HTS nano-structured adsorbent
• said wet sludges are conveyed towards an appropriate drying system, e.g., a drying belt filter, or a centrifuge, or a settling vessel, to enable dehydration and hence definitive removal.
• an appropriate drying system e.g., a drying belt filter, or a centrifuge, or a settling vessel.
• the dehydration water can be appropriately reintroduced into the treatment cycle.
• Electrocoagulation step The process according to the present invention advantageously exploits the following chemical reactions: Electrocoagulation step:
• Electro-oxidation step with exposure to UV light is
• the hydrogen peroxide formed with the indicated reaction cooperates in synergy with the electrodes in the oxidation process for decomposing organic substances and microorganisms.
• the presence of Fe 2+ coming from the electrocoagulation step, in combination with the production of H 2 O 2 increases the oxidizing power of the system through the Fenton reaction.
• Step c) is optionally used in synergy with step b) by advantageously exploiting H 2 O 2 produced by electro-oxidation to amplify its oxidizing action through the following photocatalytic reactions:
• H 2 O 2 + 0’ 2 OH + OH- + O 2
• said process is implemented in a plant which, with reference to figure 2, comprises:
• At least a first electrocoagulation tank (1 ) which comprises Fe or Al electrodes. From said at least one electrocoagulation tank the water and the flocs and precipitates formed pass into a filter tank (2);
• MBR microfiltration membranes at 0.2 pm
• Said tank is preferably closed by a lid adapted to convey any vapors that are formed during oxidation.
• Said tank is illuminated with UV light, preferably high efficiency UV LED, for dissociating CI2 and hypochlorite. Where said lid is provided, said LEDs are conveniently positioned below said lid.
• a further filtration section for example a tank (4) optionally provided with MBR membranes and/or an ultrafiltration module (5);
• one or more reverse osmosis modules (7) to be activated when values above the permitted threshold of salts, especially chlorides, are measured in the liquid;
• One or more storage tanks (8) adapted to contain the water used for counter washing, e.g., for counter washing the MBR and ultrafiltration during the process and for chemical washing during maintenance.
• said process is implemented in a plant where one or more of the tanks comprised in the plant of figure 2 is replaced by a multiplicity of electric hoses.
• said electric hoses 50 are hoses 51 that comprise electrodes 52 inside. Said electric hoses are arranged in series, where said water to be treated enters into a first one of said hoses and then, passing into each of the electric hoses, exits from the last of said electric hoses.
• said electrodes 52 are easily removable from said hoses 51 , so as to facilitate the maintenance and replacement operations. The number of said electric hoses varies according to the flow rate.
• said electric hoses are arranged on top of one another, where the water to be treated enters into the first hose which is the highest one and, with a zig-zag path, crosses each of said hoses and exits from the lowest hose.
• the embodiment of figure 5 comprises 16 electric hoses and enables a flow rate of 15 m 3 /h, with an average length of time of the liquid in contact with the electrodes of about 30 minutes.
• said electric hoses occupy a surface area of about 5m 2 . This solution enables considerable savings in terms of occupied surface area, where the same flow rate and length of time are obtained in the tank with a demand of at least 12m 2 surface area.
• said plant for the purification of wastewater comprises:
• At least one filter tank that contains MBR (0.2 pm microfiltration membranes) submerged to collect suspended solids, bacteria and algae;
• hoses at least a second multiplicity of electro-oxidation electric hoses, arranged in series, each comprising Ti or graphite electrodes, adapted to oxidize soluble CODs, metals and nitrogen compounds, with an inlet hose and an outlet hose;
• one or more reverse osmosis modules to be activated when values above the permitted threshold of salts, especially chlorides, are measured in the liquid;
• one or more storage tanks adapted to contain the water used for counter washing.
• the plant also comprises process control systems, by way of example, redox sensors, level sensors, pH sensors and/or turbidimeters.
• process control systems by way of example, redox sensors, level sensors, pH sensors and/or turbidimeters.
• the plant also comprises a PLC control cabinet (9) which collects the signals from the sensors, processes them, and handles the process.
• said plant is conveniently housed on a movable unit.
• the steps that compose the process according to the present invention, depicted in figure 1A, B, are detailed below.
• Step I P re-treatment
• the incoming fluid is stored in an accumulation tank (optional).
• an accumulation tank (optional).
• This may be a reinforced concrete tank, a silo or a tank inserted especially on the skid of the plant and it is required as protection for the suction centrifugal pump.
• the presence of a tank of larger dimensions is necessary where the annual flow rate has a discontinuous trend, i.e. , with peak periods with respect to the average annual flow rate.
• the incoming fluid can pass through a grille, so as to remove any solid and/or sludgy material in the wastewater to be treated.
• the incoming fluid is then subjected to rough filtration, carried out by washable basket filters, self-cleaning hydrocyclones or cartridge filters, usually made of metal material, with a not excessively fine mesh.
• Said filters placed upstream of the charge pump, provide for the inlet of large solid particles inside the suction of the charge pump, thus protecting its impeller and auger.
• This method has lower costs for the supply of reactants but requires periodic replacement of the metal plates.
• Said flocculation step in one embodiment, takes place in an appropriately shaped tank so as to promote the precipitation of the flocs, which are then sent to the sludge line. In an embodiment, this takes place in a multiplicity of electric hoses arranged in series.
• the microfiltration step removes a significant part of the turbidity caused by suspended solids and bacteria.
• the water leaving this step is already visibly clearer without suspended solids, although it still has a characteristic color. This water moves on to step IV.
• Step IV Electro-oxidation and photo-oxidation process
• the tank or the electric hoses where said process takes place comprise non-sacrificial electrodes adapted to oxidize organic material (e.g., abatement of: COD, BOD, ammonia, plant protection products, IPA, etc..) and inorganic material (e.g., heavy metals).
• organic material e.g., abatement of: COD, BOD, ammonia, plant protection products, IPA, etc..
• inorganic material e.g., heavy metals.
• the presence of power LED UV (with radiated energy from 500 to 1000 w/m 2 ) prevents the formation of gaseous chlorine. LED light is able to activate a photocatalyst capable of eliminating microorganisms and oxidizing complex organic molecules (e.g., drugs, PFAS etc..).
• such step also makes use of a photocatalyst.
• a photocatalyst makes use of a photocatalyst in this process step, when the water is already clear and no formation of sludge is observed, guarantees maximum photocatalytic effectiveness.
• said photocatalyst is a constituent of the inner walls of said tank. In this embodiment, as the contact surface is smaller than the volume, said photocatalyst is not particularly effective.
• said photocatalyst is a constituent of the inner walls of said electric hoses.
• the ratio of the contact surface/volume is increased with respect to the tank embodiment, clearly improving the effectiveness of the photocatalyst.
• said photocatalyst is in suspension in said tank or in said electric hoses.
• Photocatalyst crystals with dimensions 1- 100 pm are introduced into the tank or into said electric hoses.
• the suspension passes through a microfiltration system (porosity 0.5 pm) where the permeate is discharged or reused in the production process whereas the photocatalyst returns into the tanks or the electro-oxidation hoses for continuing the photocatalytic action, as shown in Figure 4. This enables the reuse of the photocatalyst.
• the surfactants are removed using a foamer.
• a foamer This is an effective method which consists of insufflating air-filled microbubbles.
• the dissolved surfactants tend to form bubbles in contact with the air, and the foam thus formed is mechanically removed.
• the pH is corrected to restore the neutral level of the fluid before it passes through the osmotic membrane and also to keep the pH within the limits established by law for discharging.
• the main pollution parameters are checked on the fluid to verify its compliance with the limits established for introduction into the discharge channel.
• the measured parameters refer to:
• the sludges collected along the entire treatment line are conveyed onto a secondary plant for dehydration.
• the plant embodiment comprising electric hoses, reducing the volume with respect to the solution comprising tanks, guarantees greater interaction between electrodes and pollutants, thus increasing the efficiency of electroflocculation and electro-oxidation.
• Electrodes in hoses get less dirty than electrodes in tanks and they are easier to clean than electrodes arranged in tanks.
• the system frequently changes the polarity of the electrodes.
• the polarity change is necessary in order to eliminate any induced polarization phenomena on the electrodes which would reduce the capacity to oxidize the pollutants.
• the polarity change also eliminates the phenomenon for which one electrode releases the cation and the other reduces it reforming the metal deposited on the electrode, a phenomenon which would make the electroflocculation process absolutely inefficient.
• gas is formed which is conveniently conveyed into a trap by a valve placed in the highest portion of said system of electric hoses.
• the process according to the present invention guarantees:
• a pilot plant was built according to the present invention, adapted to treat 12 cubic meters of wastewater per day.
• said wastewater has undergone step a) of electrocoagulation.
• step b) of electro-oxidation.
• the parameters of the treated water, detected by the sensors after electro-oxidation not be compliant for the final use, the same returns to the start of the process for a further treatment.
• the sludge obtained from the process is conveyed for dehydration.
• This wet sludge can be conveyed towards a drying belt filter (example A), a centrifuge (example B), a settling vessel (example C) or towards another drying system for facilitating the dehydration and thus the definitive elimination thereof.
• the dehydration water is reintroduced into the treatment cycle.

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• Life Sciences & Earth Sciences (AREA)
• Hydrology & Water Resources (AREA)
• Engineering & Computer Science (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Water Treatment By Electricity Or Magnetism (AREA)

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• 2023
  • 2023-02-27 EP EP23712597.6A patent/EP4482799A1/de active Pending
  • 2023-02-27 WO PCT/IB2023/051791 patent/WO2023161888A1/en not_active Ceased

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