Classifications

• • 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
  • C02F1/02—Treatment of water, waste water, or sewage by heating
  • C02F1/025—Thermal hydrolysis
• • 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
  • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
  • C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
  • C02F1/5245—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents using basic salts, e.g. of aluminium and iron
• • C—CHEMISTRY; METALLURGY
  • C05—FERTILISERS; MANUFACTURE THEREOF
  • C05B—PHOSPHATIC FERTILISERS
  • C05B7/00—Fertilisers based essentially on alkali or ammonium orthophosphates
• • C—CHEMISTRY; METALLURGY
  • C05—FERTILISERS; MANUFACTURE THEREOF
  • C05C—NITROGENOUS FERTILISERS
  • C05C3/00—Fertilisers containing other salts of ammonia or ammonia itself, e.g. gas liquor
• • 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
  • C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2101/00—Nature of the contaminant
  • C02F2101/10—Inorganic compounds
  • C02F2101/16—Nitrogen compounds, e.g. ammonia
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2101/00—Nature of the contaminant
  • C02F2101/30—Organic compounds
  • C02F2101/38—Organic compounds containing nitrogen
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
  • C02F2103/18—Nature of the water, waste water, sewage or sludge to be treated from the purification of gaseous effluents
• • 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

Definitions

• the invention concerns a method and an apparatus for purifying a polluted medium containing ammonium, where the medium in a first chemical process may be supplied with a first reagent, causing a chemical reaction between the ammonium in the medium and added reagents, which may result in precipitation of at least a first ammonium- containing salt, where a subsequent second mechanical process can separate medium from precipitation products, where precipitation products in a third chemical process may be decomposed into a precipitate and ammonium.
• From EP 490 396 is known a method and an apparatus for purifying polluted medium containing ammonium, where the medium is supplied with a first reagent in a first chemical process, where the first reagent may contain magnesium.
• the process causes a chemical reaction between the ammonia of the medium and added reagents.
• at least a first ammonium-containing salt is precipitated, and by a subsequent sec- ond mechanical process medium is separated from precipitation products.
• the precipitation products are decomposed into a precipitate and ammonium, and the precipitate is recirculated to the first chemical process, where it is used as the first chemical reagent.
• the decomposition of precipitation products into precipitate and ammonium occurs at a high temperature, where ammonium together with water vapour is separated by drying or by steam stripping.
• the object of the invention is to achieve an effective and cheap removal of ammonium from a polluted medium and at the same time to produce a nitrogenous product that may be recycled.
• the third chemical process is effected as a liquid based thermo- chemical process in which the precipitate and ammonium are released to the surrounding liquid, where the precipitate is recirculated to the first chemical process, where the precipitate is used as reagent and where the ammonium content of the surrounding liquid may be discharged for subsequent utilisation.
• reagents are supplied in dependence of the actual need for increasing the concentration of a certain reagent.
• resource savings simultaneously with the chemical processes running optimally.
• the first reagent may advantageously contain at least one salt at least containing phos- phate and a metal.
• at least one salt at least containing phos- phate and a metal.
• the invention may advantageously be performed by the metal containing magnesium. Hereby may be achieved precipitation of a magnesium salt.
• the invention may be performed by the metal containing manganese.
• precipitation of a manganese salt may be achieved.
• the ammonium of the liquid surrounding the regenerating unit may be released by heating and be supplied to an ammonia washer, where ammonia vapours may react with an ammonium sulphate solution, whereby supersaturation of ammonium sulphate occurs, crystallising as a salt.
• a fertiliser product which advantageously may be used in agriculture.
• excess sulphuric acid from e.g. smoke purification in power plants together with nitrogen removed from a polluted medium may react into a fertiliser product.
• the invention also concerns an apparatus for purifying a polluted medium
• the apparatus can contain a first precipitation unit where the medium is advantatageously admixed with at least a first reagent, where subsequently the medium may be supplied to a separation unit separating purified medium from precipitation products, where precipitation products may be supplied to a regenerating unit in which reagents may be regenerated, and where the regenerated reagents may be added to the first precipitation unit
• the first precipitation unit advantageously may include at least one pipe system in which flowing through of a polluted medium occurs, where reagents may be supplied through at least one branch of the pipe system, where the addition of reagents are timely controlled by a control unit
• the separation unit may include means for separating at least one liquid
• the regenerating unit may include at least one thermal heating unit, where precipitation products go through a liquid based thermo- chemical process, whereby a precipitate and ammonium can be released to the surrounding liquid, from which the precipitate
• the separation unit may include at least one hydrocyclone.
• the separation unit may include at least one hydrocyclone.
• the regenerating unit may include an ammonia washer where at least a pipe connection between heating unit and ammonia washer conducts ammonium vapours to the ammonia washer, where a pump pumps air from the ammonia washer to a ventilation system included in the heating unit, where the ammonia washer transforms ammonium into salt by a chemical process.
• the ammonia washer there may be achieved a very rapid and efficient reaction between am- monium and sulphuric acid, whereby ammonium is bound in a salt which advantageously may be used as fertiliser.
• the invention may advantageously be designed with means for measuring the ammonia contents of the medium in the medium supply, where reagents are dosed to the first reaction tank on the basis of the ammonium content of the supplied medium.
• the apparatus may include means for measuring the phosphate content of the medium in the medium inlet, where reagents are dosed on the basis of the phosphate content of the supplied medium.
• a demand dependent dosing of the amount of phosphate added Reduction of the used amount to the actual need in the chemical reactions chemical bonding secures the added phosphate, and thus ensures against unnecessary discharge of excess amounts.
• the apparatus may contain means for measuring the pH value of the medium in the first reaction tank, where the first reaction tank includes means for pH regulation. Optimal precipitation conditions for ammonium are hereby achieved, whereby up to 99% of the ammonium content in sewage water reacts, with the possibility of later separation.
• the apparatus may include means for adding at least one polymer to the first reaction tank in dependence of the measured value of ammonium in the medium supply. Hereby, better separation properties are attained.
• the apparatus may advantageously include means for measuring and regulating the pH value in the thermal reactor.
• means for measuring and regulating the pH value in the thermal reactor may be achieved that the pH value in the thermal reactor is optimised.
• Fig. 1 shows a first possible embodiment of the invention seen from the side, where
• Fig. 2 shows the same invention from above, where
• FIG. 3 shows a schematic drawing of a first possible alternative embodiment
• Fig. 4 shows the chemical reactions schematically, where
• Fig. 5 shows a schematic drawing of a second possible alternative embodiment of the invention.
• Figs. 1 and 2 show a possible embodiment of the invention, designed for placing in a low container, i.e. a compact and highly efficient plant which efficiently removes am- monium from a polluted medium.
• a supply pump 1 for the untreated polluted medium On Fig. 1 is shown a supply pump 1 for the untreated polluted medium.
• the pump 1 has connection to a reaction tank 2, from which the medium is conveyed to a precipitation tank 3. From here the medium is pumped to a separation unit 4.
• a supply pump 5 for chemical sludge conveys the sludge further on to a regenerating and heating unit for chemical sludge 6.
• a supply pump 7 performs chemical pumping of sludge (2 MgHPO 4 ) to reaction tank 2. All components of the plant may advantageously be incorporated in a standard container.
• the flow of the polluted medium and the effect is shown on Fig. 3.
• the polluted medium with a high content of ammonium e.g. percolate from fillings, waste water from sludge concentrations or highly polluted industrial waste water
• a pump 29 may accurately dose the amount of polluted medium.
• the concentration of ammonium in the medium is measured on-line by a spectropho- tometer 55.
• the measured concentration of ammonium (mg/1) is multiplied with the supplied amount of medium (1/min) in order to reach the value of supplied ammonium per time unit (mg ammonium/min).
• a phosphate of e.g. PO 4 and a metal (Me: e.g. Mg, Mn, Fe, K, Ca) is added for achieving a 1 : 1 :1 ratio between NH4, Me and PO 4 . When this ration is present, a precipitate will appear:
• Dosing pumps 30 and 31 connected to the pipe system 34 add the metal 23 and phosphate 24 to the medium.
• the processed medium is discharged into a double tank system.
• This system consists of an internal reaction tank 22a and an external precipitation tank 22b.
• the medium is conducted to the centre oaf the bottom of the internal tank 22a.
• base 26 or acid is supplied to the tank by means of a dosing pump 32.
• a pH sensor 38 that automatically regulate the dosing from the pump 32 measures the pH-value.
• the internal tank 22a and the external tank 22b are mutually connected by means of holes in the upper tank section. By means of the force of gravity, a flow of medium from the internal tank 22a to the external tank 22b thereby oc- curs for further chemical reaction.
• the medium in the internal tank 22a and the external tank 22b is carefully stirred by an air mixing unit 57.
• This unit consists of a blower and membrane making small air bubbles in the medium.
• the sludge/water mixture is conducted out of the outer tank 22b and into the separation unit 28, e.g. a precipitation tank, a louver separator, a decanting unit, a bag filter or the like, which separates the precipitation product from the water.
• the precipitation product in the form of sludge is removed from the plant by a volumetric pump 36.
• An automatic valve system 37 con- trols discharging the sludge either into a container 47 for fertiliser purposes or into the regenerating unit 42.
• the sludge is automatically conducted to the regenerating unit 42, either continuously or at preselected intervals.
• the discharged sludge is mixed inside the tank by a stirrer 43 and is heated by a heating unit 46.
• the sludge is heated to about 70°C.
• the first sludge PO 4 MgNH 4 , 6 H 2 O
• MeHPO 4 second sludge
• the second sludge may be used in the first reaction 1 as substitution for PO 4 24 and metal 23 supplied from pump 30 and pump 31.
• the second sludge is taken out of the regeneration unit 42 by means of a volumetric pump 48 and is conducted either to a tank for storage or for recycling to the supply unit.
• base/acid may be added to tank 42 from a pump 41 communicating with a tank 40.
• Ammonium-containing water is discharged via a pipe 54 disposed in the upper part of the tank 42.
• Fig. 4 shows the chemical reactions schematically.
• Fig 5 shows a draft in principle of a possible alternative embodiment of the invention.
• the plant is divided into a precipitation unit 100 and a regenerating unit 200.
• the medium 101 is firstly supplied to the precipitation unit 100.
• the precipitation unit 100 is divided into three operation units: a precipitation section containing a pipe 102, a tank
• Polluted medium 101 is supplied to the precipitation unit 100 by means of a pump 109, whereby a medium flow can be controlled. Detectors 122 and 124 determine the chemical content in the polluted medium 101.
• the me- dium 101 is supplied to the pipe 102.
• a reagent 217 is added to the pipe 102 through a pipe branch 114 by means of a pump 216.
• a magnesium containing reagent 103 may be added by means of pump 110 through a pipe branch 115 to the pipe 102.
• a phosphate-containing reagent 104 may be added by means of a pump 111 through a pipe branch 116 to the pipe 102.
• the medium 101 is supplied to a tank 105 where a detector determines the chemical composition of the medium.
• a control unit 130 has at least connection to detectors (122,
• control unit both in precipitation unit 100 and in regenerating unit 200, where the control unit at least controls the pumps 109, 110, 111, 112, 113, 213, 214, 215, 216 both in precipitation unit and in regeneration unit 200.
• the function of the precipitation unit 100 is, by means of the additives 217, 103, 104,
• ammonium magnesium phosphate PO ⁇ MgNHU, 6 H 2 O
• This chemical process has already been described previously and is prior art.
• the function of the plant is to precipitate ammonium magnesium phosphate optimally and so that this precipitate subsequently may be separated from the liquid phase of the medium so that ammonium is removed from the medium.
• the first part of the precipitation section is formed in that the reaction chamber is designed as a pipe system 102 through which the flow occurs with a speed enabling that particles/precipitation products are not precipitated in the pipe system.
• the system is made as a "plug-flow" system so that the addition of additives 21, 103, 104, 106 may be controlled in time and in relation to the most optimal sequence for adding the additives: Mg 3 (PO 4 ) 2 217, Mg 103, PO 4 104, NaOH 106.
• the addition of NaOH 106 either occurs lastly in the reaction chamber or outside the "plug-flow" system in a fully stirred tank 105.
• the additive magnesium 103 is added at first in the said sequence, in the form of e.g. MgO or MgCl 3 , then the additive phosphate 104 in the shape of e.g. H 3 PO 4 or KH PO 4 to the medium, and the additives react before pH regulation by means of NaOH 106. After pH regulation, ammonium magnesium phosphate (PO 4 MgNH4, 6 H 2 O) is crystallised and subsequently separated off in the separator 107.
• the function of the separator 107 is to separate the precipitate (PO 4 MgNH4, 6 H O) from the liquid phase of the medium.
• the unit is formed as a hydrocyclone which, by means of the centrifugal force (50-300 G) induced by the pressure of the medium pumped in, brings the particles/precipitation products out at the sides of the cyclone and down into the bottom, where they are concentrated and wherefrom the parti- cles/precipitation products are taken out.
• the precipitation product normally constitutes between 0.1 and 3 % of the inlet flow, depending on the ammonium concentration.
• the function of hydrocyclones is known from other sides.
• the precipitation product (PO ⁇ MgNFLt, 6 H O) removed has resulted in removing 90 - 99% of the ammonium nitrogen of the medium in laboratory and full scale experiments.
• the total hydraulic stay time in the precipitation unit 100 is 3 - 7 minutes.
• the precipitation product (PO ⁇ gNFLt, 6 H 2 O) may subsequently be dried and used as fertiliser product in agriculture or be added to the regenerating unit 200 of the plant, so that magnesium and phosphate may be reused in the precipitation unit 100.
• the regeneration unit 200 is made up of a thermal heating unit 209 and an ammonium washer 212.
• the pipe 120 adds precipitation products to the heating unit 209 containing a stirrer 210, where air is supplied through a ventilation system 211 that communi- cates with an air pump 215 sucking from the ammonia washer 212.
• Above the liquid level of the heating unit there is a pipe 218 that forms connection to the ammonia washer 212.
• a detector 220 determines the chemical composition of the content of the heating unit. Ammonia vapour together with air are conducted through the pipe 218 to the ammonia washer 212.
• a pump 213 pumps sulphuric acid from the bottom of the ammonia washer 212 to a sprinkler 221 at the top of the ammonia washer. Sulphuric acid may be supplied to the ammonia washer with a pump 214.
• a fertiliser salt may be taken out at the bottom 219 of the ammonia washer.
• the function of the regeneration unit 200 is, by means of a thermal process to regenerate magnesium and phosphate from the precipitation product (PO 4 MgNH 4 , 6 H 2 O) produced in the precipitation unit 100.
• the purpose of the regenera- tion unit 200 is to attain a substantial improvement of the economy of the entire process by regenerating magnesium 103 and phosphate 104 from the precipitation product 6 H 2 O) produced in the precipitation unit 100, so that it may be reused in the precipitation unit 100.
• thermal heating unit 209 which is a closed container designed so that addition of precipitation product from the separator 107 to the heating unit 209 occurs continually or intermittently.
• the aqueous solution of precipitation product is kept in suspension in the heating unit 209 by means of partly by a mechanical stirrer 210 with scrapers fitted, continuously scraping deposits off the inner sides of the tank, and partly by a ventilation system 211 which is connected to the ammonia washer 212.
• the heating unit may heat the aqueous solution of precipitation products to 70°C whereby ammonium is released to the ambient liquid. At high temperatures, ammonium has a very low solubility in water why it will further evaporate to the ambient atmosphere.
• the stirring system and the ventilation system will accelerate evaporation of ammonia from liquid to the atmosphere since the contact liquid/atmosphere will be multiplied by this stirring/ventilation.
• the air leaving the heating unit for the ammonia washer has a high content of ammonium.
• the heating unit 209 is connected in a closed circuit with the ammonia washer 212 so that the air ventilated over into the heating unit 209 from the ammonia washer 212 is returned to the ammonia washer 212 via a pipe 218.
• the ammonium evaporation process may be accelerated by adding NaOH, whereby pH is increased and the solubility of ammonium in the liquid is further reduced. Simultaneously with ammonium being released from the precipitation product (PO ⁇ MgNHt, 6 H 2 O), a secondary salt Mg 3 (PO ) 2 is formed, which is continuously or intermittently removed from the heating tank 209 by a pump 216 and supplied to the precipitation unit 100.
• a secondary salt Mg 3 (PO ) 2 is formed, which is continuously or intermittently removed from the heating tank 209 by a pump 216 and supplied to the precipitation unit 100.
• the ammonia washer 212 is designed as a closed container containing a liquid with a solution of ammonium sulphate.
• the lower half of the tank contains this liquid.
• a sprinkling system 221 which is used for discharging the sulphate liquid over the incoming ammonia gas from the heating unit.
• ammonia sulphate is formed and dissolved in the liquid.
• the sprinkling system operates by the solution at the bottom of the tank being pumped up to the sprinklers 221 at the top of the tank by means of the pump 213.
• the solution may attain supersaturation of ammonium sulphate so that this will be crystallised, and a salt is formed which can be extracted, dried and used a fertiliser in agriculture and horticulture.
• the washed air is returned via the air pump 215 to the heating unit.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Hydrology & Water Resources (AREA)
• Engineering & Computer Science (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Inorganic Chemistry (AREA)
• Removal Of Specific Substances (AREA)

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• 2002
  • 2002-07-12 EP EP02762266A patent/EP1414751A1/de not_active Withdrawn
  • 2002-07-12 WO PCT/DK2002/000494 patent/WO2003006384A1/en not_active Ceased

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