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WATER SERVICES FORUM WATER QUALITY

WATER SERVICES FORUM WATER QUALITY. Title of Presentation : The importance of algae and algal monitoring at Rand Water Presenter : Dr. Annelie Swanepoel, Senior Scientist, Rand Water Analytical Services Date : 17 April 2019. Presentation overview.

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WATER SERVICES FORUM WATER QUALITY

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  1. WATER SERVICES FORUMWATER QUALITY Title of Presentation: The importance of algae and algal monitoring at Rand Water Presenter: Dr. Annelie Swanepoel, Senior Scientist, Rand Water Analytical Services Date: 17 April 2019

  2. Presentation overview • What are “algae” and “cyanobacteria” (is there a difference?) • Where can we expect to find algae? Human impact? • Why is the presence of algae (including cyanobacteria) such a challenge in drinking water production? • What risks are associated with algae/cyanobacteria? • How does Rand Water and other drinking water treatment facilities monitor and treat algae and cyanobacteria? • (2 case studies : Rand Water and Magalies Water) • How does algae research help Rand Water? • Concluding remarks

  3. 6CO2 + 6H2O C6H12O6 + 6O2 >70% of the earth’s OXYGEN

  4. Algae vs. cyanobacteria Toxic, taste and odours

  5. Where do we find algae?

  6. Introduction Indicator of water quality (very site specific)  NCIS CSI CSI Bones

  7. Human impact - eutrophication Cyanobacteria NO3 + PO4

  8. Human impact - eutrophication

  9. Human impact – flow interference

  10. Why do algae pose such a challenge?

  11. Avoiding coagulation, flocculation & sedimentation DAF: Dissolved Air Flotation

  12. Filter clogging

  13. Penetration into the drinking water

  14. Taste and Odours CH3 OH CH3 Geosmin and MIB Other

  15. Production of cyanotoxins (cyanobacteria)

  16. Hepatotoxins (liver) Other intestinal toxins Microcystin-LR Cylindrospermopsin Nodularin

  17. Hepatotoxins (liver) Other intestinal toxins Chlorine

  18. Neurotoxins (nervous system) Anatoxin-a Saxitoxin Anatoxin-aS

  19. Monitoring algae and cyanobacteria • WATER QUALITY MONITORING PROGRAM: • Chlorophyll-a(source) & Total photosynthetic pigments (potable) • Phytoplankton identification & enumeration(source & potable) • Cyanotoxin analysis (source and potable) • Microcystin 2011 and 2015 : SANS 241 drinking water std. • Taste & Odour: Geosmin & 2-MIB (source and potable) • Sampling frequency: • Site location (Katse Dam = 3 months; Vaal Dam = 2 weeks; Intakes to plants = daily) • Winter vs. Summer • Incident response (people affected  increased sampling)

  20. Chlorophyll-a / Total photosynthetic pigments [Chlorophyll-a] = [(A665 – A750) – (A665a – A750a)] x 28.66 x Ve Vm 8 [TPP] = (A665 – A750) x 133333.333 Vm 1 7 Filter Spectrophotometer 4 6 2 Ethanol or Methanol Vortex & Centrifuge 3 5 78 °C or 60 °C (depending on solvent) Chl-a = R250 per sample (150 samples p.m.) TPP= R200 per sample (550 samples p.m.)

  21. Algae identification and enumeration Species e.g. Anabaena circinalis(in cells/mL) Taxa e.g. Cyanophyceae (in cells/mL) Problems e.g. Toxins; Taste & Odours; Filter clogging (in cells/mL) ID and ENUM = R350 per sample (330 samples p.m.)

  22. Cyanotoxin analysis (Enzyme Linked Immuno Sorbent Assay – ELISA technique) Cyanotoxin = R1100 per sample (100 samples p.m.)

  23. Geosmin and MIB: Organic Chemistry Lab Solid phase extraction and Gas chromatography Geosmin/MIB = R1100 per sample (350 samples p.m.)

  24. On-line instruments • Observator Database • Accessible via www • YSI Multi-parameter Water Quality Sonde • Temperature (°C) • Turbidity (NTU) • pH (pH units) • Conductivity (mS.m-1) • O2 (% saturation and mg.-1) • Chlorophyll-a (µg.-1) • Cyanobacteria (cells.m-1/RFU – Relative Fluorescence units)

  25. What happens to the data? • LIMS (Laboratory Information Management System) • Most methods interfaced, some entries manual • Analyst  Technical Signatory  Scientist / Laboratory Supervisor / Head Biology Report out of compliance results to the applicable STATION and WQSS • Cyanobacteria Incident Management Protocols: • Cyanotoxins (Microcystin)  • Taste and Odour : Geosmin & 2-Methylisoborneol (2-MIB)

  26. Algal related guidelines and standards • IMP: Incident Management Protocols: Microcystin, Taste and Odour (and others) • WHO: World Health Organisation • SANS 241 (2015): SA National drinking water standard

  27. Cyanotoxin Incident Management Protocol ROUTINE MONITORING PROGRAMME: Cyanobacteria identification and enumeration; Chla and TPP analysis; Microcystin analysis; Frequency: At least once every 2 weeks <0.3 µg/L No Cyanobacteria > 2000 cells/mL Yes ALERT LEVEL 1:Analysis frequency 1x per day (at abstraction); Toxin analysis 1x per week on source & final water; Notification to DWTW; Application for discharge permits; Regular surveillance of source; Optional mouse test 0.3 - 0.7 µg/L No Yes No Cyanobacteria > 100 000 cells/mL? Microcystin concentration in the drinking water Yes ALERT LEVEL 2: Analysis frequency once per day (at abstraction); Toxin analysis 1x per day on source and final water; Mouse test at least once per week; Optimise DWTW; Reporting and Communication to response committee; Response Committee Meeting 0.7 - 2.5 µg/L No No Toxic bloom a real threat to consumers? Yes Yes ALERT LEVEL 3:Daily response committee meeting; Analysis 2x p.d.; Daily toxin analysis; Mouse test every 2nd day; Execute actions as per Response Committee ALTERNATIVE WATER SUPPLY: if toxin >2.5 µg/L for 8 consecutive days >2.5 µg/L

  28. Taste and Odour IMP ROUTINE MONITORING PROGRAMME: Photosynthetic Pigments, Geosmin and MIB analysis and Cyanobacteriaidentification and enumeration Frequency: At least once every 2 weeks Geosmin or MIB in the potable water <15 ng/L Consumer complaints Cyanobacteria > 2000 cells/mL Any of the above? No Geosmin or MIB in the potable water 15-30 ng/L Yes ALERT LEVEL 1: Geosmin and MIB analysis more frequently On-site inspections (e.g. boiling tests) Written and verbal, notification to production chemist Pro-active actions for incident preparation No Cyanobacteria > 50 000 cells/mL? Yes Geosmin or MIB in the potable water >30 ng/L ALERT LEVEL 2: Response Committee Meeting: decisions will be taken on treatment and other actions Daily report to Response Committee Members PRIMARY TRIGGER SECONDARY TRIGGER

  29. Case study 1 (GIMP) Vaal Dam on the Wilge River – September 2005 Delmas incident: At least 9 people died and 842 treated for Typhoid infection relating to contaminated borehole water. Microcystis sp. Anabaena sp.

  30. Drinking water at Zuikerbosch >300 consumer complaints I per week

  31. Increase sampling & notify stakeholders Source & potable lines monitored DAILY: Chl, Geosmin, 2-MIB and algae

  32. Application of GIMP

  33. High geosmin concentrations only at ZB not VG Vereeniging

  34. Water purification at Rand Water VEREENIGING and ZUIKERBOSCH Stations 1 and 2 receive water via a closed pipe system from the Vaal Dam ZUIKERBOSCH stations 3 and 4 receive water via an open canal system from the Vaal Dam

  35. A B S T R A C T I O N V A A L D A M Depth profile : cyanobacteria

  36. Optimising filtration Daily inspections of the filter houses by operators and plant managers Increased filter backwash frequency: 48h36h24h

  37. Optimising coagulant dosing

  38. Increase load from VG; decrease load from ZB Vereeniging

  39. Discard (not recycle) water from sludge plant

  40. Drain the forebay 93% compliance to <30 ng/L guideline Drain the forebay and allow fresh water to replace stagnant patches

  41. Case study 2 Penetration of cyanobacteria @ Vaalkop (Jan ‘12) • From 3 – 30 January 2012: • 12 000 – 42 000 cells/mL toxic cyanobacteriain the SOURCE WATER • >2 300 cells/mL in the DRINKING WATER • Dam replenished with water from Hartbeespoort Dam • Cyanobacteria Incident Management Protocol – all results reported to the relevant stakeholders • Investigation into the problem

  42. Depth profile at Vaalkop intake Depth profile at Vaalkop-dam intake (Jan 2012) Microcystissp. Merismopediasp. Aphanizomenonsp.

  43. Case study 2 Penetration of cyanobacteria at VK (Jan 2012) • Abstraction level changed from 0m (surface) to 4m below the surface, causing a MAJOR improvement: • 6 Feb 2012: Drinking water2 : 4 cells/mL • 13 Feb 2012: Drinking water1 : no algae detected • Drinking water2 : no algae detected • While the source water still showed concentrations of >26,000 cells/mL of cyanobacteria.

  44. Algae research at Rand Water

  45. Predicting Anabaena sp. concentration in Vaal Dam 14 days in advance • IF (Conductivity ≤ 15.2) • THEN... • Anabaena14= ((Temp*(pH + DO))*Conductivity) • Temp • ELSE… • Anabaena14= Initial Cyanobacteria inoculum • ((DO2)*(15.530 - Cond))

  46. Anabaena sp. 7 days in advance R2 value=0.81

  47. Anabaena sp. 14 days in advance R2 value=0.76

  48. Satellite remote sensing Matthews, M.W. and Barnard, S. 2015, Eutrophication and cyanobacteria in South Africa’s standing water bodies: A view from space, South African Journal of Science 111 (5/6).

  49. Conclusions: Multi-barrier approach to risk reduction • Monitor (source, treatment, distribution, final water) • React on monitored results (e.g. optimise the water treatment processes) • Incident Management Protocols • Prediction modeling of cyanobacteria blooms • React on predictions (e.g. start preparations in plant to deal with cyanobacteria blooms)

  50. Annelie Swanepoel (Pr.Sci.Nat.) aswanepo@randwater.co.za

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