METHOD AND ARRANGEMENT FOR A WATER TREATMENT

TECHNICAL FIELD OF THE INVENTION AND PRIOR ART

The invention relates to a water treatment by oxidative proc ^¬ esses.

Water treatment by oxidative processes using oxidants, such as ozone, chlorine or chlorine dioxide, - added/applied to the water to be treated for said oxidative processes - are generally known. By said oxidative processes contaminants like residuals of pharmaceuticals or personal care products in water can be degraded and/or removed.

Within the last years many research works showed a suitabil ^¬ ity of Advanced Oxidation Processes (AOPs) for many applica ^¬ tions, especially for water treatment ("Photocatalysis with solar energy at a pilot-plant scale: an overview", Malato et al . , Applied Catalysis B: Environmental 37 (2002) 1-15; "Fig ^¬ ures of Merit for the technical development and application of Advanced Oxidation Processes", Bolton et al . , J. of Ad ^¬ vanced Oxidation Technologies, 1,1 (1996)13-17). Advanced Oxidation Processes (AOPs) for water treatment use a potential of high reactive radial species, mainly hydroxyl radicals (OH*), for oxidation of toxic or non or less biode ^¬ gradable hazardous water contaminants. Due to the high oxidation potential and low selectivity of the hydroxyl radicals, therefore reacting with almost every organic compound, the AOP can therefore be used to eliminate the contaminants, i.e. residuals of pesticides, pharmaceuti ^¬ cals, personal care products or x-ray contrast media, from (contaminated) water.

A versatility of AOPs is also enhanced by the fact that they offer different possible ways for hydroxyl radicals produc ^¬ tion, thus allowing a better compliance with specific - - treatment requirements.

A suitable, traditional application of AOP to wastewater treatments must consider that they make use of expensive re- actants/oxidants such as H ₂ O ₂ , and/or O ₃ for generating hy ^¬ droxyl radicals.

"Photocatalysis with solar energy at a pilot-plant scale: an overview", Malato et al . , Applied Catalysis B: Environmental 37 (2002) 1-15 review a use of sunlight to produce hydroxyl radicals .

At an ultraviolet driven AOP (UV AOP) UV radiation will be used to generate the hydroxyl radicals by a photolysis. Tra- ditional UV driven AOPs for water treatment can be resumed as UV/H ₂ O ₂ or UV/Ozone (UV/O ₃ ) or their combinations, since H ₂ O ₂ or O ₃ are being photolysed by UV radiation producing hydroxyl radicals . An UV driven chlorine species process as an AOP (UV/chlorine species AOP) is known from "Chlorine photolysis and subse ^¬ quent OH radical production during UV treatment of chlorinated water!, Michael J. Watts, et al . , Water Research 41, 2871 - 2878, 2007, and "Feasibility studies: UV/chlorine ad- vanced oxidation treatment for the removal of emerging con ^¬ taminants", C. Sichel, C. Garcia, K. Andre, Water Research XXX (2011) 1 -10 producing hydroxyl radicals by irradiating chlorinated solutions with UV. Growing attention is paid to an increasing number of reports of less or non-biodegradable trace contaminants, like the re ^¬ siduals of pharmaceuticals or the personal care products, in surface, ground and even drinking water. Three pharmaceuticals in focus, sulfamethoxazole, diclofenac and carbamzepine, could become most important as these three pharmaceuticals have been proposed for guideline water pa ^¬ rameters in Germany. - -

These three pharmaceuticals are found abundantly and are con ^¬ sidered harmful for an environment and a protection of drink ^¬ ing water sources. Their origin is an effluent of waste water treatment plants.

Because of their low biological degradation potential, sul ^¬ famethoxazole, diclofenac and carbamzepine are found in con ^¬ centrations up to 1 yg/L. Proposed limits in surface waters were 0,1 yg/L for sulfamethoxazole and diclofenac and 0,5 yg/L for carbamazepine .

Known degradation/removal processes for pharmaceuticals, es ^¬ pecially for sulfamethoxazole, diclofenac and carbamzepine are adsorption on activated carbon or removal/degradation by said oxidative processes using oxidants.

All these processes include relatively high costs as well as they can lack in removing/degrading several different contaminants, such as the three pharmaceuticals sulfamethoxa- zole, diclofenac and carbamzepine, at the same time, i.e. all together .

Therefore more efficient, more ecological and more economical processes, especially for removing sulfamethoxazole, di- clofenac and carbamzepine from contaminated water and/or wastewater, are desired.

Equipments for dosing as well as for a controlled dosing of chlorine species to water to be treated are known as well as equipments for irradiating water with UV, for example "Wallace & Tiernan®, Wasseraufbereitungs- und Desinfektionssys- teme, Oktober 2010.

Sensors for measuring a chlorine species concentration, an ozone concentration as well as a potassium permanganate con ^¬ centration are known, for example a membrane sensor FC1 or a membrane sensor DC7 of Wallace & Tiernan (Wallace & Tiernan, Siemens, Water Technologies, Multi-Funktions-Analysesysteme, MFA-FC1, -CD7) or a DEPOLOX-5-Messzelle ("Wallace & Tiernan® - -

Mess- und Regeltechnik MFC-DEPOLOX® 5 Multi-Funktions- Controller") .

SUMMARY OF THE INVENTION

It is a first objective of the invention to provide a method and an arrangement by which the above-mentioned shortcomings in water treatment can be mitigated. It is a second objective of the present invention to provide a method and an arrangement for an efficient, ecological and economical water treatment, especially for contaminated water and/or wastewater, further more especially said water and/or wastewater being contaminated with sulfamethoxazole, di- clofenac and carbamzepine .

These objectives are according to the invention achieved by providing a method for a water treatment by oxidative proc ^¬ esses. This method comprises adding a first oxidant and a second oxidant to water to be treated, with said first oxi ^¬ dant being a permanganate species and said second oxidant be ^¬ ing different from said first oxidant. Said first oxidant and second oxidant are treating said water by said oxidative processes .

These objects are according to the invention also achieved by providing an arrangement for a water treatment by oxidative processes . Said arrangement comprises a first dosing means arranged for dosing a first oxidant to water to be treated with said first oxidant being a permanganate species. Said arrangement fur ^¬ ther comprises a second dosing means arranged for dosing a second oxidant to said water with said second oxidant being different from said permanganate species. Said first and sec ^¬ ond oxidant dosed to the water are qualified for treating said water by said oxidative processes. - -

In other words - invention relates to a water treatment com ^¬ bining a first oxidant added/dosed to said water to be treated with a second oxidant added/dosed to said water to be treated - with said first oxidant being a permanganate spe- cies and said second oxidant being different from said first oxidant. Said first oxidant, i.e. said permanganate species, and second oxidant treating said water by said oxidative processes . The invention based on a surprising knowledge of a synergy for the combined treatment of a permanganate species, espe ^¬ cially potassium permanganate, and a - further second - oxi ^¬ dant, especially a chlorine species, as chlorine, chlorine dioxide or chloramine.

This surprising synergy effect was unforeseen as long as combined water treatment with two oxidants, like combinations of a chlorine species with persulfate salts or hydrogen perox ^¬ ide, usually reduce their oxidative strength and lower a re- moval yield of chemical substances - due to quenching ef ^¬ fects .

As for example, hydrogen peroxide is known - and explicitly used - for said quenching effects reducing chlorine for dechlorination.

The invention will be qualified for reducing pharmaceuti ^¬ cals/pharmaceutical residues, especially sulfamethoxazole, diclofenac and carbamzepine, but as well as other hazardous water contaminants by said oxidative processes performed by said inventive oxidants, especially as each of the oxidants according the invention, i.e. the permanganate species and the second oxidant, added to the water could affect different contaminants .

Hence, using said inventive combination, i.e. said synergy effect, of said two different oxidants, one of them being said permanganate species, the invention is highly qualified for removing/degrading several different contaminants at the - - same time, especially sulfamethoxazole, diclofenac and car- bamzepine .

As well as an improvement of disinfection could be achieved by the invention.

Another side effect of the invention is the removal of estro- genicity out of water to be treated. Especially potassium permanganate combined with a chlorine species can remove a hormone 17-alpha-Ethylestradiol almost completely out of wa ^¬ ter to be treated.

While being highly effective the invention will reduce strongly capital and operational cost of state of the art processes in water treatment.

Therefore, the invention provides a new, effective process as a very efficient water treatment procedure reaching a tar ^¬ geted water quality at a very economic, ecological and prac- tical way.

According to a preferred embodiment, the permanganate species can be added/dosed in liquid form. Said permanganate species, especially potassium permanganate, can also be added as a salt, especially as potassium salt.

According to a preferred embodiment, said permanganate spe ^¬ cies is potassium permanganate and/or said second oxidant is chlorine dioxide. Potassium permanganate and chlorine dioxide are accepted with German drinking water norms while these oxidants therefore can be applied for different water

sources, belong them drinking water.

According to a preferred embodiment, said permanganate spe- cies is added at a concentration of about 1 mg/L.

According to a preferred embodiment, said second oxidant is a chlorine species, especially chlorine or chlorine dioxide or chloramine, especially mono-/di-/tri-chloramine, or a hypo - - chlorite species, especially natrium/potassium/calcium hypo chlorite .

Said chlorine species can be added at a concentration of about 0 , 4 mg/L .

While adding said chlorine (CI2) or chlorine dioxide (CIO2) - for example by using a dosing means - chlorine (CI ₂ ) and chlorine dioxide (CIO ₂ ) will be dissolved in said water as free chlorine species.

Free chlorine species are known as a concentration of resid ^¬ ual chlorine in water present as dissolved gas (CI ₂ ) , hy- pochlorous acid (HOC1) , and/or hypochlorite ion (OCl ^~ ).as well as a concentration of residual chlorine dioxide in wa ^¬ ter .

The forms of free chlorine species exist together in equilib ^¬ rium - depending by a pH value and a temperature of the wa- ter.

Said second oxidant can also be ozone or a persulfate spe ^¬ cies, especially sodium/potassium/ammonium persulfate, in its peroxomonosulfate or peroxodisulfate form.

According to a preferred embodiment said permanganate species is added - by said respective dosing means - to said water before/upstream or after/downstream of said adding/dosing of said second oxidant to said water - by said respective dosing means - while said water is flowing along.

According to a preferred embodiment said water can be irradi ^¬ ated with an UV irradiation for applying an UV AOP to said water .

The irradiation of the water yields radical species, espe ^¬ cially OH* radicals, - using a potential of the high reactive radicals for - an enhanced - oxidation of contaminants in the water to be treated. - -

Further to that said UV AOP can also degrade disinfection by ^¬ products (DBPs) that are produced - especially during chlo ^¬ rine disinfection - in oxidative treated water. Said UV AOP can inactivate water-borne pathogenic microorganisms and de ^¬ stroy hazardous organic compounds in said water.

An UV source can be arranged for said irradiating, i.e. for applying said UV AOP. According to a preferred embodiment said UV source, for example an UV lamp, is arranged in a re ^¬ action chamber while said water to be irradiated is flowing through said reaction chamber.

Said UV irradiation can be applied with an irradiation dose of about 400 J/m ² - 4000 J/m ² and/or said UV irradiation having a wavelength of about 100 nm - 400 nm, especially having a wavelength of about 200 nm - 400 nm, further more espe ^¬ cially of about 250 nm - 260 nm. In a preferred embodiment said UV source will be a poly ^¬ chromatic irradiator/medium pressure UV source. Medium pres ^¬ sure UV sources/lamps provide an expanded wave length spec ^¬ trum and could be constructed more compact. Said UV source could also be a mono-chromatic irradiator/low pressure UV source, for example a low pressure amalgam UV lamp or a low pressure mercury UV lamp. Low pressure UV lamps are highly efficient while mainly providing a small spectrum by a wave length of about 257,3 nm, less energy input com- bined with less costs.

As well solar irradiance can be used as an UV source.

Further more an UV sensor (or more) - for a low pressure UV source or a medium pressure UV source - and/or a UV filter

(or more) could be used in combination with said UV irradia ^¬ tion provided by said UV source, e.g. low pressure UV source or medium pressure UV source, for controlling an irradiance - - of said UV irradiation, especially while measuring said UV irradiation filtered by said UV filter.

According to a preferred embodiment a further filter could be used - in combination with said UV source - filtering said UV irradiation to irradiate the water, e.g. to cut-off the UV irradiation at predetermined wave length. E.g., a quartz sleeve could be used to achieve cut-off of the UV irradiation at 240 nm to irradiate said water to be treated, e.g. potable water, with UV wave length longer than 240 nm.

According to a preferred embodiment said permanganate species will be added to said water first, followed by said adding of said second oxidant, further followed by said UV irradiation of said water. According to another preferred embodiment said second oxidant will be added to said water first, followed by said adding of said permanganate species, further followed by said UV irradiation of said water. As well as said second oxidant can be added to said water first, followed by said UV irradiation of said water, further followed by said adding of said permanganate species.

According to a further preferred embodiment, a concentration of said permanganate species and/or of said second oxidant, especially of said chlorine species, i.e. of said free chlo ^¬ rine species, are/is measured - especially by using a measur ^¬ ing means/measuring means, particularly a respective sensor/- s . The first and/or second dosing means could be installed in a way that allows homogenization of the added/dosed oxidant, i.e. said permanganate species and said second oxidant, be ^¬ fore said concentration measurement ( -s ) . By measuring said chlorine species concentration said measuring means can be a sensor measuring a free chlorine or chlo ^¬ rine dioxide equivalent. Such a sensor, for example a mem ^¬ brane sensor FC1 or a membrane sensor DC7 of Wallace & Tier- nan (Wallace & Tiernan, Siemens, Water Technologies, Multi- - -

Funktions-Analysesysteme, MFA-FC1, -CD7), is well known, long term stable while measuring and requires less maintenance costs . Sensors measuring said permanganate species concentration are also known, for example from "Wallace & Tiernan® Mess- und Regeltechnik MFC-DEPOLOX® 5 Multi-Funktions-Controller".

As well open cell amperiometric systems can be used for said concentration measurements.

A controller system could be used for controlling said water treatment, especially controlling said adding of said first and/or said second oxidant, i.e. said permanganate species and/or said second oxidant, and/or especially controlling said respective dosing means adding said first and/or said second oxidant. As well as said controller can control said UV irradiating of said water, i.e. said UV source irradiating said water. Said controller can also control a flow rate of said water.

Sensor signals and/or sensor data according to said measured concentration as well as signals of said UV source could also be processed by said controller to control said water treat- ment .

Especially said adding/dosing of said first and/or said sec ^¬ ond oxidant, i.e. said permanganate species and/or said sec ^¬ ond oxidant, as well as said UV AOP, i.e. said UV source/UV irradiation, could be controlled by using said measured con ^¬ centrations, especially by using said measured concentra ^¬ tion/^ of said permanganate species and/or of said second oxidant, further more measured before and after the UV AOP. According to a preferred embodiment said water to be treated flows at a flow rate of 50 m ³ /h - 1000 m ³ /h, especially at a flow rate of about 200 m ³ /h. The flow rate can be con ^¬ trolled/monitored by use of a flow control and/or of said controller. Often the flow rate is a given requirement of the - - customers and therefore the monitoring of variations in flow rate can be used to adjust said water treatment accordingly.

According to a preferred embodiment said water to be treated, for example potable water, (municipal ) waste water, indus- trial-/process water or ultrapure water, could be contami ^¬ nated water, especially contaminated with hazardous contami ^¬ nants with low or non bio degradability, further more espe ^¬ cially contaminated with residuals of pharmaceuticals and/or personal care products. Said pharmaceuticals can be sul ^¬ famethoxazole, diclofenac and carbamzepine .

Further advantages as well as advantageous features of the invention appear from the following description.

BRIEF DESCRIPTION OF THE DRAWING

With reference to the appended drawing, below follows a spe ^¬ cific description of an embodiment of the invention cited as example .

The sole figure is a schematic illustration of a water treat ment system according to an embodiment of the invention.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

The present invention is directed to an arrangement and a method for a water treatment by oxidative processes 1 - using two different oxidants 15, 16, one of them being a permanga ^¬ nate species, i.e. potassium permanganate 15, the other one being different, combined with an UV AOP 11 (cited also just as water treatment 1), as schematically illustrated in the figure .

The water treatment 1 as illustrated in the figure will be used for decontaminating water 7, for example municipal waste water or drinking water. - -

The water to be treated/decontaminated (contaminated water) 7 contains hazardous contaminants, especially residuals of pes ^¬ ticides, pharmaceuticals, personal care products which can be eliminated by the water treatment 1.

As using the combination of potassium permanganate 15 - as a first oxidant 15 - with said chlorine species 16 - as said different second oxidant 16, in this case chlorine dioxide 16, - while further more combined with said UV/chlorine spe- cies (chlorine dioxide) /potassium permanganate AOP 11, just cited only as UV AOP 11, - said water treatment 1 allows a nearly complete removal of the pharmaceuticals, especially sulfamethoxazole, diclofenac and carbamzepine, out of the wa ^¬ ter 7 at concentrations of about 0,4 mg/L chlorine dioxide and about 1 mg/L potassium permanganate.

The contaminated water 7 will flow 23 through a water circulation using a piping system 2 discharging said contaminated water 7 from the source (waste water treatment plant or drin- king water treatment plant - not shown) , pumping said dis ^¬ charged water 7 through the arrangement 1 for the water treatment 1 being decontaminated by the process for the water treatment 1 and discharging the treated and decontaminated water 8 in the water body or fresh water piping system 2.

The arrangement for the water treatment 1 comprises three sections 12, 13, 14 for treating the contaminated water 7 - arranged within a housing 22. The three sections (12, 13, 14) are arranged in flow direction 23 of the water to be treated 7 so that the water 7 can pass - fed by a pump (not shown) - the three section 12, 13, 14 of the arrangement 1.

In the first section 12 the potassium permanganate 15 is added 12 to the contaminated water 7. A dosing apparatus 3 is functionally connected to the piping system 2 arranged for adding 12 the potassium permanganate 15 to the contaminated water 7 while the contaminated water 7 is passing the first section 12. - -

The potassium permanganate 15 is added 12 as potassium per ^¬ manganate salt 12 to the water 7 to be dissolved in the water 7 as permanganate ions. A sensor 19 is arranged within the first section 12 for meas ^¬ uring 15 the concentration of the potassium permanganate 15 dissolved in the water 8.

The sensor 19 as well as the dosing apparatus 3 is connected to an analyser and controller system 18, cited as a control ^¬ ler 18, via a circuit 21 controlling the adding 12 of the po ^¬ tassium permanganate 12.

The water to be treated 7 - leaving the first section 12 - enters the second section 13.

In the second section 13 the chlorine species 15, i.e. chlo ^¬ rine dioxide 15, is added 12 to the water 7. A dosing apparatus 4 is also functionally connected to the piping system 2 arranged for adding 13 the chlorine dioxide 16 to the contaminated water 7 while the contaminated water 7 is passing 23 the second section 13. The chlorine dioxide 16 added 12 to the water 7 will be dis ^¬ solved in the water 7 as free chlorine.

A sensor 19 is arranged within the second section 13 for measuring 10 the concentration of the free chlorine in the water 7.

The sensor 19 as well as the dosing apparatus 4 is also con ^¬ nected to the controller 18, via a circuit 21 controlling the adding 12 of the chlorine dioxide 16.

The water - added (12, 13) with said potassium permanganate 15 and said chlorine dioxide 15 and leaving the second sec ^¬ tion 13 - enters the third section 14, i.e. a reaction chamber 5 with one or several low pressure, mono-chromatic amal- - - gam UV lamps 6, to be irradiated 14 with UV irradiation 14. While the water to be treated 7 being irradiated 14 with UV an UV AOP 11, i.e. an UV/potassium permanganate/chlorine di ^¬ oxide AOP 11, will be processed within the water to be treated 7.

The figure shows an UV sensor 19 and a UV filter 20 being arranged at the UV lamp 6 used for controlling 18 the irradi- ance of said UV irradiation 14 while measuring said UV irra- diation 14 filtered by said UV filter 20.

The UV sensor 19 as well as the UV lamp 6 is also connected to the controller 18 via a circuit 21. The irradiation of the water to be treated 7 - provided with an irradiation dose of about 3000 J/m ² - yields radical spe ^¬ cies 17, especially OH* radicals 17, since it is possible to generate radical species 17 from irradiation of chlorine and permanganate with UV.

The number of the radicals 17 depends, belong other parame ^¬ ters, on the (initial) permanganate concentration of the po ^¬ tassium permanganate 15 added 12, on the (initial) chlorine concentration of the chlorine dioxide 16 added 13 and the ir- radiance of the UV source/lamps 6.

Potassium permanganate 15 and chlorine dioxide 16 will be - controlled - added at concentrations of about 0,4 mg/L chlo ^¬ rine dioxide and about 1 mg/L potassium permanganate.

The UV AOP 11 uses the potential of the high reactive radi ^¬ cals 17 for oxidation of the contaminants in the water to be treated 7 while eliminating the contaminants of the water 7. The reaction chamber 5 can have varying shape and size.

The figure shows said reaction chamber 5 shaped as a cylinder being passed by the water to be treated 7. - -

Leaving the third section 14 the decontaminated water 10 will be discharged in the pool.

As an alternative for described embodiment the three sec- tions, i.e. dosing potassium permanganate 12, dosing chlorine dioxide 13 and UV irradiating 14, can also be arranged in a different order, for example dosing chlorine dioxide first 13, dosing potassium permanganate second 12 and UV irradiat ^¬ ing third 14 as well as dosing chlorine dioxide first 13, UV irradiating second 14 and dosing potassium permanganate third 12.

- -

Reference list

1 water treatment by oxidative processes using a per ^¬ manganate species and a second oxidant - in combina- tion with an UV AOP (method/arrangement )

2 piping system, water circulation

3 dosing apparatus for adding a first oxi- dant/permanganate species/potassium permanganate

4 dosing apparatus for adding a second oxidant/chlorine species/chlorine dioxide

5 reaction chamber

6 UV lamp, UV source

7 contaminated water

8 water after dosing and UV AOP, decontaminated water 9 measuring/analysing a concentration of (15)

10 measuring/analysing a concentration of (16)

11 UV/permanganate species/second oxidant AOP,

UV/potassium permanganate/chlorine dioxide AOP, 12 adding/dosing permanganate species/potassium permanganate (section)

13 adding/dosing second oxidant/chlorine spe ^¬ cies/chlorine dioxide (section)

14 irradiating with UV/applying an UV irradiation, UV irradiation (section)

15 first oxidant, permanganate species, potassium per ^¬ manganate

16 second oxidant, chlorine species, chlorine dioxide

17 OH* radicals

18 controller, controlling (1)

19 (chlorine/UV/permanganate) sensor

20 filter

21 circuit

22 housing

23 flow direction