You cant see Dissolved Organics ( but we can )

Transcription

1 You cant see Dissolved Organics ( but we can ) A short presentation from Sigrist SWIG monitoring organics meeting 24 th Sept 2014 Hilton Hotel Glasgow Presenter John Kupczak Page. 1

2 Challenges for water suppliers Pollution of water resources Changing climatic conditions, e.g. heavy rainfall and floods Threats of bacteria, e.g. Cryptosporidium and other factors such as improved quality standards

3 Problems for Optical Instrumentation» < Lower Turbidity's down to 10 m FNU» Higher Turbidity's beyond 4000 FNU >

4 First some basics?

5 Light» What is light? Electromagnetic waves with» Wavelength λ (m)» Frequency f (s -1 )» Speed of light c (m/s)» Relation c λ = f 400nm 700nm Spectrum Page. 5

6 Photometer With Spectrum as Light Source Light Source Optical Filter Light detector Sample -) Page. 6

7 Wavelength / Spectrum - Overview Optical range used in SIGRIST instruments 254nm 880nm Page. 7

8 Spectrum of the Mercury Lamp» Spectral lines at: 254, 313, 366, 436 & 546nm» Several other minor peaks UV VIS Page. 8

9 Measuring Principles UV Fluorescence Scattered light Absorption Page. 9

10 Absorption A (E) Input light Transmitted light Absorption A (E) 100% 10% 1 100% 1% 2 100% 0.1% 3 Page. 10

11 So why cant we see Dissolved Organic Material People cannot perceive UV light directly since the lens of the human eye blocks most light in the wavelength range of nm; shorter wavelengths are blocked by the cornea As always there are certain exceptions Page. 11

12 Some uses of Ultraviolet Light Commercial germicidal lamp in butcher shop A 380 nanometre UV LED makes some common household items fluoresce. A bottle of Tonic Water, showing the familiar UVF, most of us have seen, and not because of the alcohol. The effect is due to the quinine content A bird appears on many Visa credit cards when they are held under a UV light source Page. 12

13 Some effects of Ultraviolet Light Fluorescent rocks include fluorite, calcite, gypsum, ruby, talc, opal, agate, quartz, and amber. Minerals and gemstones are most commonly made fluorescent or phosphorescent due to the presence of impurities. The Hope Diamond, which is blue, phosphoresces red for several seconds after exposure to shortwave ultraviolet light. Page. 13

14 Practical applications of a UVA monitor in Water Treatment 1. Continuous monitoring of 254nm in water, can be a useful method for the immediate recognition and determination of increasing or decreasing organic load at WTW intakes 2. We also know various process steps can be optimised by monitoring the sum total of UV absorption at 254nm, such as chemical dosing for instance, or controlling Ozone treatment and more 3. TOC, BOD, DOC and other established methodologies of course have a role to play, but measurement of 254 nm will provide real time results and contribute to a optimised treatment regime and save costs 4. UV254 has a greater affinity, towards reactive or aromatic organic matter which has double bonded ring structures and are typically the most problematic form of organics in water such as those which form THM complexes upon Chlorination Page. 14

15 Practical Applications of a UV A monitor in Water Treatment Real-time organic monitoring is invaluable for optimizing and controlling coagulant dose; monitoring performance and condition of activated carbon filters; determining UV dose; indicating potential formation of disinfection byproducts (DBPs) for chlorination applications; indicating biofilm formation potential in distribution systems; determining plant efficiency and effectiveness; monitoring pollution; and more. Page. 15

16 The problem of micro pollutants 1. The use of various pharmaceuticals, detergents, pesticides and cosmetics such as shower gel, shampoo etc., has greatly increased over the past decade 2. These substances, termed micro pollutants, either cannot, or are only partly biodegraded in waste water treatment plants and adsorption onto the sewage sludge is only partially effective. 3. The elimination or the retention of these trace substances, respectively, is therefore only slight or insufficient 4. As a result, contaminants reach the surface water where they can have a negative influence on the ecosystem. 5. Currently there are over 70,000 chemical substances in use today, of course its impossible to monitor all of these 24/7 Page. 16

17 Elimination of micro pollutants The list of micro pollutants in waste water is extremely extensive The compositions differ with differing waste waters,which aggravates the situation There are classification lists that exist for each category, within European countries A Switzerland specific list of micro pollutants has been derived from this European list and some of these are shown in the chart below Two methods that exhibit reasonable elimination of micro-pollutants are : 1. The use of Ozone to oxidise the substances 2. The use of powered activated carbon (PAC) for absorbing and subsequently filtering out the substances 3. Both of these method require monitoring with UV absorption instruments Page. 17

18 Testing for MP removal effectiveness Based on the numerous experiences and examinations of recent years, a practical test was carried out using ozone on a pilot plant at the Eawag in Dübendorf, nr Zurich. The proof of micro pollutant elimination was to be made using on-line and a control strategy was simultaneously researched which guarantees optimum ozonation. A reliable control is desirable for keeping the energy consumption as low as possible. ( optimisation of the ozone generator ) The basic idea: was to measure the difference in UV absorbance before and after ozonation with various light sources. All considerable and undesirable influences such as existing nitrite, nitrate, DOC were examined. In addition, the available measuring technology was tested as to its suitability. Page. 18

19 Elimination of micro pollutants List of micro pollutants in waste water at the waste water plant of Dubendorf, Zurich ( source eawag) Page. 19

20 Use of powdered activated carbon (PAC) With PAC, a wide range of micro pollutants, and their effects, can largely be removed from municipal waste water. One idea involves the dosing of the PAC directly into the biological treatment basin. The subsequent Dynasand filter ensures that no PAC can reach the environment It is under evaluation if the ColorPlus could be used before or after the Dynafilter for measuring the elimination performance on-line. The absorbance measurement is a sum signal which does not allow identification of individual substances. This demands correlating the measured absorbance at 254nm with a number of pre-determined reference substances to finally optimize the PAC dosage. Page. 20

21 Functions of the SIGRIST ColorPlus For the testing Phase two ColorPlus instruments (Pict. 2) were used with identical light sources 254nm, 366nm & 700nm. Pict.2: Absorptionmeter ColorPlus One special feature of the measuring cell used is the function of compensating window soiling. For this, the measuring beam is directed through the medium and again through the medium and through an additional glass (Pict. 3). From this, the influence of window soiling is calculated within the instrument and compensated correctly. As a result, the user is provided with accurate measurements all of the time In addition, the instrument will activate an alarm as soon as window soiling becomes to intense. The alarm is used to initialise cleaning of the measuring cell. Which can be done in a few minutes, via removal of the front cover of the flowcell. Therefore no fixed cleaning interval is required,which contributes to lower maintenance costs Pict. 3: Measuring cell with compensation glass Page. 21

22 Functions of the SIGRIST ColorPlus Pict. 4: Examination of soiling compensation in two instruments (source: eawag) In Picture 4, the function of window soiling compensation is illustrated using the light source 254 nm. The left scale shows the absorbance/m and the right scale the degree of soiling (%). Two instruments (S1&S2) were compared and the sample water was filtered differently (5µm and 20µm). After about 13 days of operation, soiling at the windows begins to accelerate.. Cleaning has to be carried out at a degree of soiling of 40% in the case of this waste water. Page. 22

23 ColourPlus UV-VIS Shown here with Pre-Filter package Shown here with new Sicon Controller Page. 23

24 ColorPlus DOC (UV absorption) USP & Product Features» Customer Benefits

25 Cover of the cell The measuring cell is designed with a cover that can be opened without any tools:» Allows simple access for cleaning of the cell inside» The cleaning effort is little Page 25 Doc. No E/3

26 Compensation glass Window fouling is determined with the use of a compensation glass:» The measured values are more precise as the influence of window fouling is eliminated (compensated)» The instrument issues an alarm when fouling compensation is out of range and the cell has to be cleaned» No predefined cleaning interval has to be introduced Page 26 Doc. No E/3

27 Many different device configurations Apart from the light source for DOC (UV absorption) measurement, two additional light sources can be integrated in the instrument:» Optional: Compensate for the influence of solid particles (light scatter) to achieve more precise DOC (UV Absorption) values» Optional: Measure Colour (Hazen) A reference beam is created and permanently measured internally :» The degradation of the light source is eliminated Page 27 Doc. No E/3

28 Various checking units Checking units for different absorption values are available:» One checking unit is built in to control high absorption values» Several other checking units are available to control the instrument in different operation points Page 28 Doc. No E/3

29 Control Unit SICON control unit with state-of-the-art technology and colour display:» Values, graphs, alarm- and status messages can be presented upon customer desire» An internal data logger allows recalling and displaying measured data of the last 32 days» Password protection avoids unauthorized access» Various means of communication including an integrated web server offer flexibility in data transfer Page 29 Doc. No E/3

30 Cost of ownership Next to technical features, the product design was focused on long live time of the instrument and low maintenance needs:» The maintenance work is very low» The cost for consumables during 10 years of operation is at CHF (main part is the mercury vapor lamp)» The cost for spare parts is low» After the commissioning and training, no service contract is necessary Page 30 Doc. No E/3

31 DOC (UV absorption measurement System )» The installation is simple» Filtration of the sample can be foreseen or retrofitted upon necessity Page 31 Doc. No E/3

32 An Interesting Example for UV Monitoring UV E/m Page. 32

33 Pilot Plant Tests <<Eawag>>, Dubendorf,CH» The name «Eawag» was originally a German acronym, standing for «Eidgenössische Anstalt für Wasserversorgung, Abwasserreinigung und Gewässerschutz» (Federal Institute of Water Supply, WASTEWATER TREATMENT and Water Pollution Control). This designation is still used in legal documents. Dübendorf - Zurich Eawag s headquarters is at Dübendorf (near Zurich), where around 300 people work. The Forum Chriesbach building with offices, training and seminar rooms, the Library Lib4RI and a cafeteria serves as a meeting place. The other buildings include laboratories, offices and testing facilities. Since 2008, the headquarters of the Swiss Centre for Applied Ecotoxicology, Eawag- EPFL has also been located at the Dübendorf site. Page. 33

34 So in Summary 1. UV 254nm provides a good method to measure Sum total of species that absorb at that wavelength 2. We ve shown information on two methods which have some potential to eradicate MP S 3. Both of those methods can use UV 254 nm as means of monitoring and optimising performance 4. We ve introduced and shown that the Sigrist ColourPlus is a very versatile, stable means of monitoring 5. UV 254 nm levels in many other applications within the water industry 6. We ve shown some special features and USP s to support the ColourPlus 7. We ask to take a look at the instruments on the ProcessPlus Stand here today 8. We ask you to pick up our short form brochure on the Elimination of micro pollutants We thank you for your attention John Kupczak BDM Sigrist ; Tel ; johnkupczak@photometer.com Web ; Page. 34