The only uses of UV that we know of other than disinfection and dechloramination (removal of combined chlorine from swimming pool water) are removal of ozone and chlorine which is used in a very limited number of systems.

A few other uses are the UV/H2O2 advanced oxidation process that is used in a few installations for removal of pesticides etc. and then we know about less than five systems for direct NDMA photolysis.

Photochemical treatment of wastewater are:

- Photo-oxidative treatments of wastewater

* Photo-oxidative sunlight

* Photo-oxidation with use of lamps

- UV disinfection

Photochemical processes:

• Water oxidation sub / supercritical and

• Water photolysis in the vacuum ultraviolet

(UVV)

• UV / hydrogen peroxide

• UV/O3

• Photo-Fenton and related

• Heterogeneous Photocatalysis

No photochemical processes

• Ozonation in alkaline medium (O3/OH-)

• Ozonation with Hydrogen Peroxide

(O3/H2O2)

• Processes Fenton (Fe2 + / H2O2) and related

• Electrochemical Oxidation

• γ radiolysis and beam treatment electrons

• Non-thermal Plasma

• Download Electrohydraulic - Ultrasound

I am not sure I understand how your answer match my question since you mention several methods that do not use UV-lamps.

My question was about the practical applications of UV-treatment of water in applications that exists in significant numbers. This is applications that are more common than researched methods, experimental and demonstration systems.

those who do not use lamps or sunlight are not photo-chemicals.

only I mentioned to no phochemicals and all photochemical that I mentions ore advanced oxidation processes (AOPs)

All advanced oxidation processes already mentions can use lamps, since you can combine the use of sunlight in the day and the use of lights at night

I know about AOPs as processes but my question is about the use of UV based water treatment methods outside research laboratories. Which uses are there of quantitative importance in the water industry in terms of that there are many systems in use?

the paper: Treatment and Reuse of Wastewater from the Textile Wet-Processing Industry: Review of Emerging Technologies (Philippe C. Vandevivere, Roberto Bianchi & Willy Verstraete; J. Chem. T echnol. Biotechnol. 1998, 72, 289 - 302)

Addresses the status of technology (full scale plants, pilot plan or laboratory scale) but is an paper from 1998 and only includes the photocatalysis with TiO2 and UV light

There is very few information and only people with industry experience is the is adequate to answer

We used UV lamp in photo-catalytic removal of phenol from saline wastewater in industrial scale. The findings will be published in near future.

I think it is more of a survey to collect information about commercial UV applications such as this report which I'm not sure that will help:

http://www.wipo.int/export/sites/www/freepublications/en/patents/947/wipo_pub_947.pdf

Actually Dr. Boltons answer is very close to that I am interested in. It seems to indicate that we agree about the fields of use of UV that are really used so I have not overlooked any significant use.

I am still left with the question if anybody would be able to dare to say if the number of UV based AOP installations around the world are in the order of hundreds or thousands.

Dear Henrik! An interesting Q! ... and surprisingly few good A! I believe you and James have already plotted the domain of (commercial) use. Right now, we are experimenting with use of combined hydrodynamic cavitation and UV. First results are encouraging, but still a lot of work to be done.

Dear Henrik

In our studies we have achieved a removal efficiency of approximately 50% reduction of the organic load of dairy effluents using photocatalysis as pretreatment (TiO2 solar UV). If it was possible to get a good degradation efficience with solar UV, I think it might be more efficient employing UV lamp. If interested, I have some articles for free download in the researchgate

Currently there is research on the use of doped TiO2 or TiO2 photocatalysts coupled with others that can improve process efficiency.

Even in our article "Catalytic and photocatalytic performance of mesoporous CuxO-TiO2 " shows that it is possible to degradation in the dark (catalysis), although the photocatalytic process is the most efficient.

The UV filtration technique is one of the best suited treatment process in several of the wastewater treatment plants across the world, The UV filtration can able to eliminate not only the chemicals but also the pathogens such as coliform bacteria and other forms of the microorganisms which produce deleterious effects to human beings

Henrik

For potable water, UV treatment has only recently been accepted by the UK regulator as an approved treatment for protection against cryptosporidium oosysts (2010), and prior to that date there were only a small number of UV systems in use at a municipal scale for general disinfection, usually either on borehole sources or at locations where the standard practice of applying 30 minutes contact with chlorine was not practical. Since 2010 there have been perhaps 100 UV systems installed to address cryptosporidium concerns around the UK. With regard to other applications, there remains some interest in UV as part of AOP treatment but I am currently aware of only a very small number of such processes in the UK (< 5). Where used these have usually been installed as an alternative to conventional GAC treatment, where space, planning permission, backwash water disposal and / or capital costs make UV more attractive, despite increased power costs.

Thanks for the overview of the use of UV in UK.

From Danish companies I work with I know of just two swimming pools that have chloramine control by UV and one facility with two large systems for cryptosporidium in use in UK swimming pools.

Dear James,

Although the present TiO2 low quantum yield for applications photocatalised sistems containing TiO2 for treatment of gaseous and liquid waste. Technological applications of AOP photocatalised was well discussed and argued by Carp (2004). The authors note that, despite the low quantum yield, TiO2 can be potenializado to generate superoxide anions OH and efficiently when doped with a series of catalysts (see article) and depending on the type of resin that is employed to make the bed fixed

(CARP, O.; HUISMAN, CL; Reller, A. photoinduced reactivity of titanium dioxide. Progress in Solid State Chemistry, vol. 32nd, n. 1 - 2, p. 33-177, 2004)

In this sense, can ensure that it is possible to develop a system pretreatment with TiO2 photocatalysed combined with another form of treatment system.

In our study we got a mixture of polyurethane resin + additives + TiO2 ensured that the reduction of the organic load of dairy effluent and vinasse. Consequently it was possible to improve the biodegradability of pretreated waste and the conversion of organic matter remaining on treatment system with activated sludge and aeration pond.

Banu and co-works (2008) also obtained a system that combined the use of photocatalysis with UASB reactor. (BANU, JR; ANADAN, S.; KALIAPPAN, S., Yeom,IT Treatment of dairy wastewater using anerobic and solar photocatalytic methods. Solar Energy, v.32, 9, 812-819, 2008)

A couple of points:

1. Hydrodynamic cavitation has been employed commercially for ballast water treatment but was given up at least by one vendor; Sonolysis has also been tried for generation of OH-radicals and the results were not encouraging. Would cavitation+UV photolysis provide break-through?

2. No one has eluded to deactivation of TiO2 by metal ions such as iron, which can essentially reduce TiO2 photocalytic effectiveness by 100%.

I would put my money with Boris and the cavitation+UV. There is much research to do with this method yet so it may have a treatment target there it can compete.

UV/TiO2 has been the subject of hundreds of PhD and and patents during the last 30 years and it still hasn't found a treatment target there it could compete for with other treatment methods.

In my opinion,treatment and disinfect are the two aspect of one process one is by(1) use of chemicals and other is by (2) use of UV lamps,which will be sidenarrowing and harmless.

It is mainly used for dissinfection, killing bacteria

To kill the all microbes present in the water ,and some organic pollutants are also degraded

Dr.'s Saxena, Gomes and Raj,

If you read my question you should see that it is already agreed that the main use of UV lamps for water is disinfection. The question is about other used in water treatment.

I think that hydrodynamic cavitation is worth further consideration. Please take into consideration such reactor : http://hydrodynamics.com/technology/ (video)

and its description in Ultrasound Technologies for Food and Bioprocessing by Hao Feng, Gustavo Barbosa-Canovas, Jochen Weiss, (Springer 2011).

Combined with UV light irradiation, hydrodynamic cavitation may give even better efficiency due to very good mixing. It is very simple technology with a very small footprint (it can be place on a rack.

Is there literature reference on TiO2/UV photocatalysis used in membrane bioreactor at pilot scale ?

My questions are about :

- UV irradiation efficiency in a mixed liquor suspended solid concentrations at about 5-15 g/L.

- UV source existing technologies for irradiating membrane coated with TiO2 and immerged in activated sludge. Is there many types of UV lamps ?

- Air bubble interference on UV irradiation (air flow is used to control fouling of the membrane).

- I m looking for examples of module and pilot design used for this combined treatment : UV photocatalysis/Biological reaction/Membrane separation.

@Ewa, It is quite interesting question. Nobody has investigated it yet. The most important are number of cavitation bubbles formed during the processes. There is vacuum inside the bubbles, therefore the range and utilization of UV light is higher in such system. Additionally, there is sonoluminescence during collapsing of cavitation bubbles-another source of light. The releasing of high heat is associated with collapsing of cavitation bubbles that helps in photolysis, formation of singlet oxygen and other highly reactive species (hydroxyl radicals). Collapsing of cavitation bubbles results also in high concentration of radicals in a very small space.Therefore, I assume that there is a synergistic effect in combined application of hydrodynamic cavitation and UV light but this needs further investigation to confirm this. Amount of energy needed to induced hydrodynamic cavitation in such reactor is very low; however the throughput of the reactor is very high.

Dear all, and especially James, Ewa & Przemyslaw who meditate about the hydrodynamic cavitation (HDC). All said is true. In our experiments with HDC we are able to enhance degradation of some otherwise environmentally recalcitrant chemicals. On the other side, the influence on microorganisms (disinfection) is not yet positively confirmed - which is contrary to widespread ultrasound disinfection for medical instruments ... Still experimenting to see what is about!

@James: Energy recovery is quite good. If the desired (disinfection) effect is obtained, the costs will be acceptable, especially regarding that there is no use of chemicals and no formation of harmful disinfection by products.

Boris, As you know I read your paper with the use of hydrodynamic cavitation for destruction of micropolutants in wastewater.

I considered to calculate the energy use per decade removal, but in your experimental description it is dififcult to see how much energy is used for the treatment. Do you have any idea about the energy use per unit time in your experimental setup?

Dear Henrik and James ... as for now our concern is to obtain HDC that will make desired effect ... and latter on try to optimize also energy. But for your info I will check with the colleagues our setup and give you the first rough estimation of energy needs.

Dr. Bolton is right the electrical energy per order method is the most straight forward means of comparing different oxidation methods. I have used it to compare hydrodynamic cavitation and ultrasonic cavition systems for disinfection. The paper is available here https://www.researchgate.net/publication/235601488_Disinfection_of_gram-negative_and_gram-positive_bacteria_using_DYNAJETS(R)_hydrodynamic_cavitating_jets?ev=pubfeed_overview

Article Disinfection of gram-negative and gram-positive bacteria usi...

@Boris, hydrodynamic cavitation is obtained in many ways. One can use a water jet (sonic water jet), narrow tube ( high pressure change) and a spinning rotor with cavities.

It seems to me that the last solution is the best. The water jet and narrow tube systems need a high efficient pump that pumps the water with high flow and pressure. Such equipment is very expensive ( see the price of turbo pumps used in mass spectrometers); there is no such equipment which can be used in industry so far. Therefore, the reactor based on spinning rotor is only viable option for industrial application.

Of course, there is another option like electric discharge in water. But this process is a very energy intensive process.

Dear Przemyslaw! THX 4 your support on HDC. We are well aware of all possible means to obtain cavitation ... that were published sofar. We are searching for own possibilities ... with the main goal to make it industry applicable ... and not only researchers' tool for SCI paper writing. Great deal of the needed energy may be recovered - it depends on the construction of the cavitation cell - closer to the Venturi flow one gets more energy is recovered ... Still, it is true that the chemicals are so far much cheaper to do the disinfection properly ... but - there are disinfection by products and by effects which may call to physical water treatment ... Here we are!

@Boris, Sonochemistry, Fenton processes and photocatalysis are very good for scientific purposes. I used radiation methods to simulate transformation of organic compound in environment. I studied both reductive and oxidative pathway. The same purposes can be achieved by using other AOPs. BTW, radiation methods are the most efficient in disinfection but people do not like anything that is linked to ionizing radiation. Ionising radiation kills also spores and there is no chance to create mutants. Ionising damages DNA irreversibly.There is no induced radiation after the process.

See http://www.eb-tech.com/

@Przemyslaw! THX! I went through your work, seen at the RG. Your suggestion to use ionized radiation ... I must admit that I am hesitating to employ such a technology into a process which is not 105% well operated ... so for wastewater treatment this condition can hardly be true. We need robust methods with low maintenance and inexpensive and easy monitoring ... and harmful if anything goes wrong ...

@Boris. Maybe you can try fluidized bed electrodes:

http://www.wetsus.nl/research/research-themes/advanced-waste-water-treatment

Quite interesting.

@Ewa, My opinion is based on ratio of number of scientific publication to number of industrial application. Commonly used AOP, UV/H2O and Fenton processes have certain limitations. Therefore, there is a need to find other methods that do not have such limitations. However, people from industry are quite conservative and they do not want to invest millions of dollars into novel, not well-known technologies. Sometimes risk is too high for them ( whole plant should be redesign and staff retrained).

However, a comparison of novel technologies to old one can help in convincing them. This is a subject of popularization and advertisement of the technologies.

@Ewa, therefore, I wonder why there are so few large scientific projects (from inception to implementation) in this area. For example Marie Curie projects or ERC projects in. Do you know such projects in Canada, USA and Australia?

@Ewa, Scientist are also quite conservative. They like to undertake research projects which will end up with success.They need to have some preliminary information/experience about the investigated process. Starting a research from scratches is very challenging and time consuming (very expensive). There is a strong demand for success.

For example, UV/Cl is a quite capable process for destruction of organic pollutants and disinfection but what about formation of toxic chlororganic compounds and chlorine oxoanions which are toxic to aquatic organisms. Some of good ideas are rejected during preliminary selection without conducting any experimental work.

Ewa is right, but also Przemysław concerns

Anyway, time is ready for AOP's implemented to some systems.

We are working with a big dye company to implement at industrial scale, UV/H2O2 oxidation that you can find here for references (azo dyes from the Reactive series): DOI:10.1016/j.jenvman.2013.04.023 and DOI:10.1080/19443994.2013.787553

Article Response surface methodology (RSM) analysis of photodegradat...

And here the other one attached.

I repeat: with no EU financing we almost completed the implementation at industrial level.

I hope this can grew up the motivation for every scientist involved in this type of processes.

Article Evaluation of UV/H2O2 advanced oxidation process (AOP) for t...

Hi Jakob, I read the text you suggested and I cannot find the answer to my question in that text. Is there anything about use of UV for other purposes than disinfection?

More turbid water requires different design of UV reactors and more energy to deliver the desired irradiation dose regardless of the treatment target.

Is the book not just about UV for disinfection?

@Jakob & @Henrik! Clearly Henrik is asking what OTHER uses besides disinfection can UV offer. We have experimented in removal of pharmaceuticals. Our new technology involves H2O2 + UV + Hydrodynamic cavitation ... with some very interesting results, i.e. removal of target compounds below detection! The paper will be published soon. We will upload it so that anybody can get a copy. Cheers! Boris

Removal of Pharmaceuticals may to attributed more to H2O2 or effect of ozonization

It will be appreciated if a direct link can be established to UV

Uv can perhaps be acting as catalyst

The removal of chloromines by UV treatment of recycled swimming pool water may or maynot be due to UV or possibly due to the small electromagnetic radition present due to the electric energy for lighting yhe lamps

This is specific query to Henrik, James bolton, Jakob & Boris

Hello to all of you,

So far Chlorine is being prdominently used for Dis-Infection of Treated Waste Water and Yes we are all aware of the compounds being formed and the dtrimental effects etc; However, the commercial viability overrules other considerations

Now we are trying to intorduce UV and Yes we are aware of the limitations of opacity of the treated waste water and of the high replcement cost of the Lamps etc;

The Target is Pathogen Removal

but we should also hope to have other benefits mentioned here !!

Can I request you for comments ?

Thank You

Dear Yogesh! … & co.!

All you say is valid. The point is our consideration of the costs of production and treatment vs. the direct (costs) benefits of increased public health, addressable to photogenic microorganisms. If you now begin to calculate indirect costs of human health due to DBPs, the whole picture comes more clear and in favor of more costly, but healthier disinfection methods than chlorine.

BTW: Combining UV with a small dose of H2O2 may make wonders in regard to the residual DBPs and other trace compounds, now coming into consideration as health hazard substances (see new Water Framework Directive for Europe).

Cheers, Boris

Your request is not so related to my question but the question of chlorine disinfection versus UV disinfection always deserves a comment. Here in Denmark the comparison is very easy since one cannot get a permit to use chlorine on wastewater. We use UV, peracetic acid, performic acid or in many cases, there is no disinfection after the biological treatment.

We never have problems with the transparency of the water in UV systems after complete biological treatment of the wastewater followed by sand filters or proper secondary settling. I once compared the problem of transparency inhibiting UV with the occasional breakdown in nitrification that causes ammonia concentrations to increase in effluents which reduces the disinfection power of chlorine as it forms chloramine. Both systems have occasional problems.

Regarding the economy and technical feasibility of UV versus chlorine it is cheaper to use UV in many estimated if the cost estimate is made over the lifetime of the UV installation as the treatment cost per volume treated is lower with UV (power and lamp replacement) than with chlorine.

The added benefit of degrading pharmaceuticals and other chemicals in parallel to the UV disinfection is not a real benefit since the UV dose used to disinfect generally remove much less than 1% of even the photosensitive chemicals.

Some examples of the use of UV other than disinfection in water treatment:

TOC reduction in ultrapure water

UV based AOT for the enviromental remediation

UV rays could be used for the generation of free radicals in Advanced oxidation Processes AOPS. These free radicals such as OH or Cl act in degrading some organic compounds like polyphenols or pesticides

UV radiations stop and kill all germs present in water.

UV treatment in the presence of catalyst (e.g. TiO2) is very effective for the degradation of recalcitrant compounds from wastewater. This process also improves the biodegradability of wastewater after treatment.

Dr. Choudhary,

Do you know of any significant number of installations that use UV for photocatalysis in real applications?

My impression is that it is something which has been used in laboratory studies for at least 30 years, but it is not used in real water treatment applications.

In the presence of UV light the Photo degradation of the toxic substance occurs to non-toxic substances. Uv light decomposes water in to OH radical which acts as a oxidant also .

Dr. Deshmukh,

Do you know of any significant number of installations that use UV for photodegradation of toxic subscances? Which types of water is treated and where are they?

Actually my question is about uses of UV in water treatment other than disinfection and photolysis of chloramines.

Dear Tareq,

Actually my question is about uses of UV in water treatment OTHER THAN disinfection and photolysis of chloramines.

I cannot see anything else in your answer than information about disinfection which is well established.