WO1991004949A1 - Procede d'epuration de l'eau - Google Patents

Procede d'epuration de l'eau Download PDF

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Publication number
WO1991004949A1
WO1991004949A1 PCT/AU1990/000445 AU9000445W WO9104949A1 WO 1991004949 A1 WO1991004949 A1 WO 1991004949A1 AU 9000445 W AU9000445 W AU 9000445W WO 9104949 A1 WO9104949 A1 WO 9104949A1
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WO
WIPO (PCT)
Prior art keywords
water
particles
aluminium
filter
filter bed
Prior art date
Application number
PCT/AU1990/000445
Other languages
English (en)
Inventor
Luis Otokar Kolarik
Chee Thau Chin
Original Assignee
Commonwealth Scientific And Industrial Research Organisation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Commonwealth Scientific And Industrial Research Organisation filed Critical Commonwealth Scientific And Industrial Research Organisation
Publication of WO1991004949A1 publication Critical patent/WO1991004949A1/fr

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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
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/281—Treatment of water, waste water, or sewage by sorption using inorganic sorbents
    • 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
    • C02F1/20—Treatment of water, waste water, or sewage by degassing, i.e. liberation of dissolved gases
    • 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
    • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
    • 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
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/283—Treatment of water, waste water, or sewage by sorption using coal, charred products, or inorganic mixtures containing them

Definitions

  • This invention relates to a process for the filtration/purification of natural ground or surface waters to provide water satisfactory for general domestic use.
  • lime, aluminium or iron salts, or polyelectrolytes are used to coagulate and flocculate the colloidal dispersion.
  • the water to be treated is dosed with an optimum quantity of the above chemicals at optimum pH to achieve effective destabilization of the colloidal system.
  • the dose of the coagulant and the pH at which coagulation is performed depend upon the composition of the raw water, and must be adjusted if changes of the feed water occur.
  • the agglomerates of floes which form are settled and/or filtered out in clarifiers and filters.
  • Such prior art processes frequently require many tanks occupying many hundreds of square metres.
  • the filtration of floes formed by conventional methods must be effected at relatively low lineal flow rates such as 1-2 cm/min.
  • Hayward in South African Patent 70/2516 described the use of metallic aluminium in conjunction with sand and anthracite in one filter unit.
  • Hayward describes the use of a filter bed comprising particles consisting essentially of aluminium mixed with sand particles and covered with a layer of anthracite particles.
  • Hayward states that the aluminium particles are not dissolved during the filtration cycle and that the water borne impurities adhere to the aluminium particles.
  • South African patent 70/2516 exemplifies only separation of relatively coarse clay particles from surface water, wastewater, and sea water; removal over a prolonged time period of the colour and turbidity occurring in natural waters and the suitability of the process for providing water of potable quality were not demonstrated. It does not give any indications of the effects of pH and temperature. In practice Hayward' s process would not give water of suitable quality because at neutral pH aluminium particles will become passivated and be rendered ineffective; mechanical filtration only will result. Turner in US Patent 3,784,014 (1974) describes a complex effluent treatment device for separation of colloidal particles from a liquid medium which uses a plurality of filtration columns packed with, in sequence, aluminium powder, aluminium/granular carbon mixture, and finally activated carbon.
  • the water from this process meets physical quality guidelines for potable water but may need sterilisation to meet microbiological quality guidelines for potable water.
  • the present invention provides in one aspect a method for treating water to produce water satisfactory for general domestic use comprising:
  • step (c) filtering the water from step (b) above through a filter medium comprising particles of aluminium and/or particles of metal alloy containing aluminium, and
  • the water to be treated is less than 13°C, the water should also have its temperature raised to at least 13°C in or before step (a) of the process.
  • the process of this invention provides water which meets current world guidelines for the physical quality of potable water.
  • the residual turbidity in the treated water should be less than 5 Nephelometric Turbidity Units (NTU) and preferably less than 1 NTU.
  • Residual colour in the treated water should be less than 15 Platinum-Cobalt Units (Pt-Co), and residual aluminium should be less than 0.2 mg/1.
  • the pH after treatment should be between 6.5 and 8.5.
  • the present invention provides a method representing an integrated water treatment process.
  • the invention is based upon passing the water through the aluminium-containing filter, but to produce water of the desired quality it is essential that the water be treated prior to filtration and undergo post-filtration treatment, as described in steps (a), (b) and (d) of the first aspect of the invention.
  • Water produced by the process of the invention is suitable for general domestic use.
  • the product of the water may be used in domestic applications such as, for example, washing clothes, flushing toilets, washing cars and watering lawns.
  • the process of the invention does remove some of the microbiological material from the feed water, the product water may still contain microbiological material and may not be sterile.
  • the water be sterilized, e.g. by boiling or chlorine addition.
  • steps (a) and (b) , (c) and (d) as described in the first aspect of the invention may be described as pretreatment steps, a filtration step and a post-filtration step respectively, and these terms will be used hereinafter in this specification.
  • the feedwater which may come from a stream or a water storage or an underground aquifer, is pretreated by adjusting the pH to 4.5 or less.
  • the pH is preferably adjusted to a pH within the range of 3.5 to 4.5, more preferably 4.0 to 4.2.
  • the pH is adjusted by adding acid to the feedwater.
  • the acid may be any suitable strong acid, with hydrochloric acid being preferred.
  • Acid addition may be by any known manual or automatic means utilising any suitable pH sensing and acid addition control means.
  • the temperature of the feed water should be maintained above 13 D C, with the process preferably being operated at a temperature ranging from 15°C to 35°C.
  • the feedwater must also be treated to remove carbon dioxide formed from bicarbonate ions when the pH is lowered. Carbon dioxide removal may be achieved by any known means, with air injection or gas stripping being suitable methods.
  • the water is passed through a bed of filter medium to separate the colloidal material present in the water.
  • the water is passed through a filter bed preferably at least 200 mm deep.
  • the filter bed may consist of:
  • metallic particles of aluminium or of a metal alloy containing aluminium preferably have an average particle size in the range of from 0.252 to 1.25 mm; or
  • coal particles preferably having an average particle size within the range of 1 to 3 mm and preferably with equal volumes of coal and metallic particles.
  • the particles are preferably intimately mixed.
  • the metallic particles used should be clean and preferably be pure aluminium. If the metallic particles are passivated with an oxide or other coating their activity can be generally restored by washing the particles with dilute (0.5 - 1.0 ) hydrochloric acid.
  • the temperature for satisfactory operation of the process depends upon the filter medium chosen. If aluminium particles are used the process will operate satisfactorily at temperatures above 20°C. If metal and sand particles are used the process will also operate satisfactorily at temperatures above 20°C, while if metal and coal particles are used the process is effective at temperatures above 13°C. In contrast to conventional clarification processes the filters of this process can be operated at lineal flow rates of up to 9 m/h (15cm/min) with the preferred rate between 1.5 and 5 m/h (2.5 - 8.3 cm/min) .
  • the pretreated feed water is passed through the filter bed.
  • the waterborne impurities are coagulated/flocculated and/or electrodeposited on the filter medium and thus separated from the aqueous phase.
  • the purified water leaves the filter while the impurities are captured and retained there.
  • the filter bed will become saturated with the impurities and must be washed by reversing the flow of the water.
  • the filter may be first "airscoured” then backwashed with a small volume of suitable water. A volume of approximately 5-10% of the throughput is used in this operation.
  • the effluent from the filter is treated to neutralise the product water to the desired final pH and- to further remove aqueous aluminium species.
  • the pH of the effluent from the filter may be adjusted by any known means.
  • the effluent is treated in a bed of suitable particulate solid alkaline material, such as limestone or marble granules. If limestone is used, the limestone particles preferably have an average diameter of from 2 to 5 mm and are preferably arranged in a bed 200 - 300 mm deep.
  • the alkaline material may be mixed with or followed by an inert particulate material such as silica sand.
  • the present invention also provides an apparatus suitable for carrying out the process of the present invention.
  • the present invention includes an apparatus for treating water to produce water of potable quality comprising first pH adjustment means to adjust the pH of the water to 4.5 or less, carbon dioxide removal means to remove dissolved carbon dioxide from the water, filtration means including a filter medium comprising particles of aluminium and/or particles of metal alloy containing aluminium and second pH adjustment means to effect pH adjustment of outlet water from said filtration means to thereby produce water of potable quality.
  • the apparatus should also include means to raise the temperature of the water to at least 13°C.
  • the process of this invention has been operated under laboratory conditions and also in a full scale demonstration plant (throughput up to 2000 1/day) using feedwaters from different locations. It was surprisingly demonstrated that pH, temperature, pretreatment of the feedwater, and post treatment of the filtered water were all important parameters influencing the effectiveness of the process for the production of potable quality water.
  • Feedwater no. 4 was used in the following manner: The water was dosed with hydrochloric acid to the desired pH, heated if necessary to bring the temperature within the range 21-30°C and passed directly onto the filter bed; no attempt was made to control the alkalinity i.e. remove carbon dioxide or adjust the pH filter. Without the pretreatment specified in the process of this invention even after 17 days of operation the product water did not meet drinking water standards being high in residual aluminium. Table B presents analysis of the product water (24 h composite samples) during the operational period.
  • Feedwater No. 4 was passed at 50-100 1/h through the pilot filter with a bed consisting of 300 mm coal particles and 300 mm aluminium particles for a period of 20 days.
  • the product water was marginally acceptable for colour and turbidity but contained excessive residual aluminium.
  • Table C Analyses of composite samples of the product water after Al/Coal filter with no carbon dioxide removal or pH control of product water . Range of values over 20 days operation .
  • Table D Analyses of composite samples of the product water after Al/Coal filter with no carbon dioxide removal or pH control of product water . Range of values over 18 days operation .
  • Feedwater No. 4 was passed at 80-90 1/h through the pilot filter with a bed consisting of 600 mm of intimately mixed coal particles and aluminium particles for a period of 5 days.
  • the product water was acceptable for colour and turbidity but contained excessive residual aluminium.
  • the range of values obtained are given in Table E.
  • Feedwater No. 4 was passed at 50 1/h through the pilot filter with a bed consisting of 500 mm of aluminium particles over 300 mm coal particles and for a period of 9 days.
  • the water from this filter was post-treated by passing through a bed of 300 ram of limestone over 300 mm of sand.
  • the product water was acceptable for pH, colour and turbidity but contained reduced but still excessive residual aluminium.
  • Table F The range of values obtained are given in Table F.
  • Feedwater No. 4 was passed at 50 1/h through the pilot filter with a bed consisting of 470 mm of aluminium particles over 300 mm coal particles and for a period of 9 days.
  • the water from this filter was post-treated by passing through a bed of 300 mm of limestone over 300 mm of sand.
  • the product water was acceptable for pH only, having excessive colour, turbidity and residual aluminium.
  • the range of values obtained are given in Table G.
  • Figure 1 is a schematic representation of one embodiment of a water purification process according to the invention.
  • Figures 2A and 2B show the removal of colour and turbidity as a function of pH
  • Figure 3 shows the residual pH and residual aluminium remaining in the water after treatment according to the invention
  • Figure 4 shows the residual colour and turbidity in the product water after treatment according to the invention.
  • Figures 5 and 6 show the quality of product water after treatment according to the invention.
  • raw water 1 flows into storage tank 2 where it is mixed with pH adjusted head tank overflow water and heated if necessary to raise its temperature to a suitable value.
  • Air 7 is blown through the water in tank 2 to remove dissolved carbon dioxide.
  • air may be passed through constant head tank 4 to remove carbon dioxide (not shown) .
  • the conditioned water passes through pump 3 into constant head tank 4 where its pH is adjusted using pH control unit 5 to pH 4.5 or less.
  • the pretreated feedwater passes through valve 8 and flowmeter 9 to the filter 10.
  • the capacity of pump 3 is greater than the flow rate through valve 8 and the filter; the overflow from constant head tank 4 passes back into the raw water storage tank 2.
  • Filtered water passes through valve 11 to a holding tank 12 thence to the post-treatment unit where it passes through a bed of CaC0 3 particles 20.
  • the product water is then passed to storage and distribution.
  • the filter is backwashed when necessary by closing valve 11, opening valve 17, passing air through valve 16 to "air scour" the filter bed for a suitable time then closing valve 16 and opening valves 15 and 18 and pumping product water through filter 10 in the reverse direction to normal flow then through valve 18 to disposal.
  • the laboratory scale filter bed consisted of a 300 mm deep layer of 0.7 - 0.95 mm aluminium particles over a 300 mm deep layer of filter sand of particles size 0.5 to 1.0 mm.
  • Pretreated feedwaters 1, 2 and 3 at pH 4.2 were in turn passed for 24 h through the bed at a linear flow rate of 5-6 m/h at temperatures ranging from 22-27°C.
  • the data in Figures 5 and 6 show that after post treatment drinking quality water was consistently produced in each case.
  • aluminium alloys as filter media .
  • a variety of aluminium alloys were compared with pure aluminium eg alloy 214, extrusion alloy, and sacrificial anode alloy. The results of these comparative tests showed that each gave equivalent performance.
  • Table 3 Analyses of composite samples of the product after Al/Coal /limestone filter. Range of values over 2 days operation .

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Separation Of Suspended Particles By Flocculating Agents (AREA)
  • Water Treatment By Sorption (AREA)

Abstract

Le procédé de traitement de l'eau décrit consiste à régler le pH de l'eau à 4,5 au plus, à retirer le dioxyde de carbone de l'eau, à filtrer l'eau en la faisant passer à travers un lit filtrant contenant de l'aluminium et à régler le pH de l'eau ainsi filtrée après l'opération de filtrage. Ce procédé permet de produire de l'eau qui satisfait aux exigences actuelles quant à la qualité physique de l'eau potable. L'eau ainsi traitée est appropriée pour un usage domestique géneral mais doit être stérilisée si on veut la boire. Un appareil de réalisation de ce procédé est également décrit.
PCT/AU1990/000445 1989-09-26 1990-09-25 Procede d'epuration de l'eau WO1991004949A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AUPJ654889 1989-09-26
AUPJ6548 1989-09-26

Publications (1)

Publication Number Publication Date
WO1991004949A1 true WO1991004949A1 (fr) 1991-04-18

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ID=3774223

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Application Number Title Priority Date Filing Date
PCT/AU1990/000445 WO1991004949A1 (fr) 1989-09-26 1990-09-25 Procede d'epuration de l'eau

Country Status (1)

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WO (1) WO1991004949A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2255087A (en) * 1991-04-25 1992-10-28 Robert Winston Gillham System for cleaning contaminated water
GB2255088A (en) * 1991-04-25 1992-10-28 Robert Winston Gillham Removal of contaminants from water
US5993737A (en) * 1995-04-24 1999-11-30 Implico B.V. Stabilization of water
FR2945037A1 (fr) * 2009-04-30 2010-11-05 Captage Neutralisation Unite de traitement destinee plus particulierement au traitement de l'eau brute provenant d'une ou plusieurs chambres de captage et procede de regulation de ladite unite
EP3868467A1 (fr) * 2020-02-24 2021-08-25 Lennart Herman Simon Joos Extractions de dioxyde de carbone

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2325679A (en) * 1936-06-05 1943-08-03 Infilco Inc Stabilization of liquids
GB853464A (en) * 1957-07-05 1960-11-09 Seitz Werke Gmbh Method of obtaining service (tap) waters
AU5527269A (en) * 1968-05-21 1970-12-03 The Commonwealth Industrial Gases Limited Carbon dioxide removal from liquid
US3617580A (en) * 1968-12-16 1971-11-02 Exxon Research Engineering Co Lubricating oil treatment system
US3784014A (en) * 1970-10-15 1974-01-08 Westinghouse Electric Corp Waste and water treatment system
US4303511A (en) * 1978-08-16 1981-12-01 Kraftwerk Union Aktiengesellschaft Method of purifying tenside and detergent contaminated waste waters

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2325679A (en) * 1936-06-05 1943-08-03 Infilco Inc Stabilization of liquids
GB853464A (en) * 1957-07-05 1960-11-09 Seitz Werke Gmbh Method of obtaining service (tap) waters
AU5527269A (en) * 1968-05-21 1970-12-03 The Commonwealth Industrial Gases Limited Carbon dioxide removal from liquid
US3617580A (en) * 1968-12-16 1971-11-02 Exxon Research Engineering Co Lubricating oil treatment system
US3784014A (en) * 1970-10-15 1974-01-08 Westinghouse Electric Corp Waste and water treatment system
US4303511A (en) * 1978-08-16 1981-12-01 Kraftwerk Union Aktiengesellschaft Method of purifying tenside and detergent contaminated waste waters

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2255087A (en) * 1991-04-25 1992-10-28 Robert Winston Gillham System for cleaning contaminated water
GB2255088A (en) * 1991-04-25 1992-10-28 Robert Winston Gillham Removal of contaminants from water
WO1992019556A1 (fr) * 1991-04-25 1992-11-12 University Of Waterloo Systeme de nettoyage d'eau contaminee
GB2255087B (en) * 1991-04-25 1995-06-21 Robert Winston Gillham System for cleaning contaminated water
US5534154A (en) * 1991-04-25 1996-07-09 University Of Waterloo System for cleaning contaminated soil
US5993737A (en) * 1995-04-24 1999-11-30 Implico B.V. Stabilization of water
FR2945037A1 (fr) * 2009-04-30 2010-11-05 Captage Neutralisation Unite de traitement destinee plus particulierement au traitement de l'eau brute provenant d'une ou plusieurs chambres de captage et procede de regulation de ladite unite
EP3868467A1 (fr) * 2020-02-24 2021-08-25 Lennart Herman Simon Joos Extractions de dioxyde de carbone

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