PeCOD: The New Way to Measure True COD for Laboratory or On-Line Monitoring

Transcription

1 PeCOD: The New Way to Measure True COD for Laboratory or On-Line Monitoring SAVES TIME REDUCES COST GREEN TECHNOLOGY

2 Importance of Measuring OD Oxidizable organic material in water; A food source for micro-organisms depletes oxygen, water unfit for flora and fauna A source of information for plant operators plant process operating improvement A source for uncontrolled chemical reactions may alter production processes and product quality

3 Background: COD & BOD 5 Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) are ubiquitous measurements of overall water quality Among the most diagnostic parameters for the determination of water quality in natural waterways and waste streams. COD measures the equivalent amount of oxygen required to chemically oxidize the organic compounds in water BOD measures the equivalent amount of oxygen required to biologically (microbes) oxidize the organic compounds in water

4 Background: COD & BOD 5 COD & BOD 5 expressed as mg/l O 2 (or ppm ) The standard BOD test requires five days to complete - unable to provide continuous monitoring of organic load. COD is often used for BOD screening. BOD COD (sample matrix dependant)

5 Background: COD & BOD 5 Regulatory: EPA s regulate environmental compliance of industry and public utilities (WWTP s) to water pollution limitations using COD or BOD 5 Non-regulatory: Industry uses COD & BOD 5 internally for process monitoring and process refinement

6 The Measurement of COD & BOD Both COD & BOD involve a 2 step process; Step 1 - Oxidation of organic matter BOD 5 days with biological matter COD 2 hr Wet chemistry (acid, heat, pressure, catalyst with E o = +1.9v) PeCOD COD 5 to10 min Photocatalyst (UV excited semiconductor with E o = +3.2v)

7 The Measurement of COD & BOD Step 2 - Measurement of extent of oxidation BOD 5 Direct measurement of uptake of O 2 by micro-organisms over 5 days COD Wet Chemistry indirect measurement of OD via electrons consumed in reducing Cr 6+ to Cr 3+ PeCOD COD Electrochemistry direct measurement of OD via in situ measurement of electrons generated during oxidation process

8 Dichromate Method (conventional) for COD Analysis ~100 year old wet chemical process Oxidant: conc. Sulphuric acid & Dichromate Silver Sulphate (catalyst), Mercury Sulphate (chloride removal, provided chloride < 1000 ppm) Heat at 150 C, 2-3 hour process Overall measurement uncertainty, ±20-30 % as estimated by bodies such as EPA, Standard Methods many common compounds not fully oxidized Expensive: $1.50/analysis, plus disposal costs (often $2 per vial) totaling ~ $3.50 per sample slow, hazardous, inaccurate, expensive

9 Method for COD Analysis is a new technology Oxidant: UV-illuminated titanium dioxide Green & Safe : uses only an electrolyte no silver, mercury, dichromate or conc. acid Fast : 5-10 minute analysis Accurate : uncertainty < 10 % (typically < 5%) Low Cost: ~ $0.60/analysis, no disposal costs fast, green, accurate, inexpensive

10 COD vs. Theoretical Oxygen Demand (ThOD) The ThOD for complete oxidation of a given organic species can be determined from the stoichiometry of the mineralisation equation. In an ideal world, a method of COD analysis would conform to the constraint that COD/ThOD = 1. In the real world, a COD measurement method may yield a response function (COD vs. ThOD equation) with a gradient that differs significantly from unity depending on the organic species.

11 COD vs. Theoretical Oxygen Demand (ThOD) C r Comparison of COD vs ThOD for the Dichromate method (left) and UVilluminated TiO 2 (right) From Kim et al., Analyst, 2000, 125,

12 COD vs. Theoretical Oxygen Demand (ThOD)

13 COD vs. Theoretical Oxygen Demand (ThOD)

14 COD vs. Theoretical Oxygen Demand (ThOD) COD measuring techniques are not exact. This is important to consider when choosing a reference or standard. The ideal standard should closely match the sample composition or be close to the median response of the particular COD technique to a range of chemicals. A standard that is suitable for one technique may not be optimal for another.

15 PeCOD Technology TiO 2 is a well established (1967), powerful and versatile photocatalyst (3.2 V) Photoelectrochemistry - The combination of Photochemistry = the study of the interactions between atoms, small molecules, and light (or electromagnetic radiation) Electrochemistry = studies chemical reactions which take place in a solution at the interface of an electron conductor and an ionic conductor (the electrolyte), and which involve electron transfer between the electrode and the electrolyte or species in solution

16 Sensor The core of the technology

17 PeCOD Technology Uses a titanium dioxide sensor Titanium dioxide is illuminated with UV light, and becomes a powerful oxidant Oxidizes the organics in a sample, and directly measures the amount of oxidation

18 PeCOD Technology PeCOD measures soluble COD, which does not include proteins, macromolecules or cellulose. Most treatment processes do not break up these molecules - they are released with the effluent stream. Soluble COD is therefore a better measure of the treatment process! Dichromate COD provides total COD, so differences can be observed for certain samples (mainly influent). Good correlation is observed for effluent and industrial samples.

19 UV LED turns on UV 400nm Oxidation of organics begins Electron (e - ) promoted to conduction band, creating photohole(h + ) which is a powerful oxidant (3.1V) UV LED Sensor Titanium Dioxide nano particle UV activation of titanium dioxide, making it a powerful oxidant h + e - e - Oxidation complete Charge transfer (Q) measured until all organics oxidized COD=Q/(4FV) x Cell with transparent window Conducting layer ITO (Indium Tin Oxide) Titanium Dioxide nano particles Glass substrate Sample+Electrolyte Cross Section

20 Blank Sample 100 mg/l COD Time 4 min Area under curve = Q net COD = k (Q net Q blank )

21 Laboratory Analyser Stand Alone Automated (PeCOD AssayPlus, Multi-Parameter, PC- BOD/Titrate Duo) Near-Line Portable Field Analyser On-line Analyser PeCOD Products

22 Laboratory/Portable Unit: L100 Waste (Port W ) Blank Solution (Port B ) On/Off Sample (Port A ) LCD Display Touch Panel Interface

23 ❶ ❷ ❸ ❹ ❺

24 Automated PeCOD Introducing a new addition to the Man-Tech product line: the PeCOD AssayPlus. COD analysis can now be fully automated with the integration of the laboratory unit with an autosampler, allowing multiple field samples to be set up to run unattended: AutoMax73 (up to 73 sample positions) AutoMax122 (up to 122 sample positions) AutoMax197 (up to 197 sample positions)

25 Automated PeCOD The PeCOD AssayPlus utilizes PC-Titrate software for all control and analysis functions. The prepared sample is placed in the autosampler rack, and the appropriate electrolyte solution is added via dosing pump. ph adjustment of preserved COD samples may be completed automatically. Auto-dilutions for extremely high COD samples may be performed. Constant stirring using a paddle stirrer ensures proper mixing of the sample with electrolyte.

26 Automated PeCOD Blanks are built into the program and are run automatically. The sample is automatically pumped into the L100 for analysis. Results are displayed on the unit and are exported into the software for reporting. QC results may be tracked over time and be flagged if out of range. Automatic calibration in desired COD range can be preprogrammed to occur prior to the arrival of analysts each morning.

27 Automated PeCOD: Multi-Parameter Man-Tech systems are known for their multi-parameter analysis capabilities. Common methods include ph, alkalinity, chloride, turbidity, color, and many others. With the integration of the PeCOD COD Analyzer with the Man-Tech system, these methods may be combined together. Multiple parameters may be analyzed from one single sample.

28 Automated PeCOD: PC-BOD/Titrate Duo Dual platform system that enables laboratories to prepare and analyze samples for BOD, then easily switch the system to analyze for such parameters as ph, conductivity, alkalinity, fluoride, etc. Now available with the PeCOD AssayPlus!

29 Automated PeCOD Near Line The PeCOD Assay Plus can be used in a near-line format, whereby samples flowing into the laboratory from a plant can be plumbed to the system for ongoing monitoring of COD and other parameters such as ph, conductivity, turbidity, color, etc. Sampling occurs at user-specified time intervals.

30 Automated PeCOD Near Line If a sample is found to breach its limit for any parameter, an alarm can be triggered to warn of a potential hazard: the system can automatically grab aliquots of these samples and dispense them into separate containers for further analyses Simple notification of the breach allows further action to be taken immediately

31 The laboratory unit can function as a portable system by the addition of a battery pack. Portable Field Unit

32 Portable Field Unit Accessories available for using the L100 as a field instrument: Battery Carry Case Portable Lab Kit

33 On-line Unit: P100 Sample and backflush Valves Stainless Steel Enclosure Sample Loop Calibrant Filter Unit PLC P100 Analyser Solutions: - Electrolyte - Water - Wash

34 On-line Unit: P100 Used for unattended monitoring; results communicated through standard telemetry Automatic regular calibration and sampling up to every 15 minutes Only requires replenishment of electrolyte reservoirs, and occasional replacement of sensor Only requires power ( VAC), water and compressed air Air and water used to backflush sampling probe to keep it clear and unblocked.

35 Consumables Electrolyte Calibrant Sensor Electrolyte and calibrant selection depends on the COD range you wish to analyze

36 COD Ranges The PeCOD can analyze four ranges of COD, color-coded for simplicity 0-25 mg/l = Blue mg/l = Green mg/l = Yellow mg/l = Red

37 Sensor replacement Life is ~500 samples Maintenance Sensor is easily removed and replaced by hand as it is pre-aligned New Sensor program is run on the L100 the first time a new sensor is used

38 Applications BOD Screening Process Monitoring & Control Environmental Monitoring

39 BOD Screening Real Time COD results rapidly provided by the PeCOD allows for more continuous organic monitoring to ensure constant compliance with regulations. Greatly reduces the number of dilutions required for BOD analysis. Utilize the PC-BOD/Titrate Duo to combine the PeCOD AssayPlus with PC-BOD, allowing for both the automated analysis of COD using the new PeCOD technology, as well as BOD following Standard Methods.

40 BOD Screening COD is analyzed first, with COD values reported along with the estimated BOD results. Following a batch of COD samples, the analyst simply switches the rack and probe holder, and the BOD samples are analyzed. The PC-BOD/Titrate system combines COD and BOD analysis into one efficient system providing a more effective utilization of laboratory equipment.

41 Process Monitoring & Control WWT Plant Protection and Optimization Manufacturing Plant Performance Optimization Plant Organic Source Monitor and Control Manufacturing Plant Water feedstock Monitor

42 Process Monitoring & Control: WWT Plant Protection and Optimization WWT plants vulnerable to costly process excursions when COD influent levels rise sharply beyond response capability of the plant. Real-time analysis of COD in the secondary stage influent will protect the plant from high COD events and optimize aeration requirements and power consumption used in the process for COD removal. Event monitoring will also improve environmental performance of a plant and lower discharge costs. Large plants under pressure to reduce carbon footprint

43 Process Monitoring & Control: WWT Plant Protection and Optimization Approximate energy cost of $300k p.a. for regional plant with 30,000 people Average of 10 tons of sugar per week (approx. $60k p.a.) to feed bugs for regional plant of 50,000 people keen to know when high COD available!

44 Process Monitoring & Control: WWT Plant Protection and Optimization 500 Primary Effluent COD Comparison COD / [mg/l O 2 ] PeCOD COD Dichromate COD Sample

45 Process Monitoring & Control: WWT Plant Protection and Optimization COD ppm 15 min cycles Primary Clarifier effluent

46 Process Monitoring & Control: WWT Plant Protection and Optimization 600 Wastewater Treatment Plant Influent Stream 500 Online PeCOD COD COD / [mg/l O 2 ] Sampling period = 6 days Sampling cycles = 15 min Secondary stage influent Sample

47 Process Monitoring & Control: Manufacturing Plant Performance Optimization Real-time analysis of COD on the effluent of an industrial plant will provide operational feedback necessary to optimize production processes and cleaning practices. The lowering of discharge levels of COD will reduce the consumption of raw materials and reduce sewer discharge costs or internal wastewater treatment plant costs.

48 Process Monitoring & Control: Manufacturing Plant Performance Optimization BOD 5 & Estimated BOD 5 / (mg/l) (PeCOD COD) 0.61 (Dichromate COD) BOD Day

49 Process Monitoring & Control: Manufacturing Plant Performance Optimization Online PeCOD COD, Jan 2007 PeCOD COD 1-hour Avg COD Jan 27-Jan 28-Jan 29-Jan 30-Jan COD / [mg/l O 2 ] Sampling period = 24 hr Sampling cycles = 15 min Analysis time = 4 min Note the 1-hr average COD from the standard method hides the true variability of the COD in this brewery.

50 Process Monitoring & Control: Plant Organic Source Monitor & Control Real-time COD analysis of influent and effluent of a biological nutrient removal (BNR) plant where methanol or acetic acid is being used as a food source. Direct financial benefits would be realized by increased efficiency of the nitrogen removal process through lowered nutrient discharge costs, reduced chemical costs and lowered BOD discharge payments.

51 Process Monitoring & Control: Manufacturing Plant Water Feedstock Monitor Monitoring of low levels of organics in water feed stocks by real-time COD will provide information on the organic content of the water not available from TOC analysis. This will enable improved product quality and reduced plant maintenance

52 Environmental Monitoring Plant Effluent Discharge Monitor Potable Water Monitor

53 Environmental Monitoring: Plant Effluent Discharge Monitor Cooling tower monitoring sea water Real-time COD monitoring would enable corrective action to be taken by the plant thus avoiding environmental breach penalties and the potential for bad publicity that could have a direct negative impact on perceived company value in the share market

54 Environmental Monitoring: Plant Effluent Discharge Monitor Potato plant in UK fined 50,000 pounds for breaching 4,000ppm discharge limit Thailand F&B/Pharmaceutical plant lost product calculated approx. $150k p.a.

55 Environmental Monitoring: Plant Effluent Discharge Monitor BOD(5) PeCOD Est. BOD(5) BOD 5 / [mg/l O 2 ] BOD 5 = 0.55 COD :00 11:00 12:00 13:00 14:00 15:00 16:00 Time of Day

56 Environmental Monitoring: Potable Water Monitor Similar to monitoring water feed stocks, TOC has been used for monitoring drinking water as the standard COD method is unable to provide real-time information and lacks sensitivity. TOC is unable to provide valuable information about the environmental impacts of the organics contained in the sample.

57 Summary Low Analysis costs < 1 / 3 current methodology (dichromate) No use/disposal of toxic & hazardous reagents No disposal costs, improved OH&S BOD screening Reduce BOD analysis costs, achieve fast reliable BOD estimates Avoid environmental non-compliance fines Real time monitoring allows identification of cause of breaches, and proactive remedy

58 Summary Portable In-field use for on-the-spot results Protect regional WWTP s from high COD loads Monitor incoming COD before it hits the plant Save energy in WWTP s Tune plant operation to incoming COD load

59 Thank You