Pilot introduction/background

Transcription

1 Performance analysis of 20 micron self-cleaning disc filter versus cartridge filters for RO membrane protection after media filtration in a SWRO system ZIPORA TAL AMIAD WATER SYSTEMS PEACHIE MAHER HYTOWITZ AMIAD WATER SYSTEMS ADVA ZACH MAOR AMIAD WATER SYSTEMS EATAY POMERANZ AMIAD WATER SYSTEMS ERIKA BEN-BASAT AMIAD WATER SYSTEMS

2 Pilot introduction/background 20 micron cartridges are used in many RO plants as a safety stage after media filter Media being used as the main pre-filter for the RO membranes Cartridge filters act as a barrier against the sand media or other particles that may be released from the media filter Average pressure differential across the cartridge systems is about 17 PSI Range of 3 to 28.5 psi Cartridges replacement typically about 6-8 times per year

3 Pilot motivation and goals Would 20 micron self-cleaning disc filters provide system benefits? Benefits when the safety stage becomes a secondary stage Testing of effluent water quality in order to compare filtration performance Investigate OPEX reduction in SWRO plants Reduce average pressure differential from an average of 17 PSI to below 3.5 psi Eliminate replacement & disposal costs of cartridges

4 Self-cleaning disc filter system Raw water inlet Backwash water drain Disc filter Spin-Klin spine Filtered water outlet Filtration process Backwash water inlet Backwash process During backwash pressurized water spray to rotated and clean the discs

5 Pilot operation Three pilots were run over a five year period at an operating desalination plant Water source for all stages of the pilot and for all systems was the same filtered water from the plant media filter system. Pilot Operational dates Disc filter type Cartridge filter type Goals 1 03/07 to 08/08 Self-cleaning disc filter Type 1 Short term feasibility study 2 08/08 to 06/10 Self-cleaning disc filter Type 2 Long term feasibility study 3 06/10 to 12/12 Self-cleaning disc filter Type 2 Demonstration of long-term performance, sizing for final replacement in plant

6 Pilot operation Pilot 1 Pilot 2 Pilot 3 Black disc filter pod and white cartridge filter housing Operating in parallel to plant s installed cartridges

7 Performance results standard water quality tests SDI & turbidity data are very similar for both kind of filters Sample IN - Cart OUT - Cart IN - Disc OUT - Disc Turbidity 0.11 NTU 0.10 NTU 0.12 NTU 0.11 NTU SDI The main differences in filter performance were detected in large volume sampling and analysis and not in common water quality tests like Turbidity, TSS and SDI

8 Microscopic analysis Microscopic pictures of material collected from liter samples on a 5µm membrane INLET Cartridge (full scale) OUTLET Disc filter OUTLET Sample INLET Cartridge OUTLET Disc filter OUTLET TSS (mg/l) <0.2 Turbidity (NTU)

9 Diatom removal Disc filter inlet (after coagulation & media filter) o Algae, mainly diatoms, organic matter and few zooplankton present Disc filter outlet o Most diatoms removed, small algae and organic matter remain

10 Coagulated particles Coagulated particles found after sand media filter INLET Cartridge OUTLET Disc filter OUTLET

11 Zooplankton Whole zooplankton found after cartridge filter INLET Cartridge OUTLET Disc filter OUTLET

12 Cartridge fibers Fibers from cartridges found in outlet INLET Cartridge OUTLET Disc filter OUTLET

13 Corrosion particles ocoagulated particles and zooplankton found after sand media filter ocorrosion particles from cartridge vessels and fibers found in cartridge outlet INLET Cartridge OUTLET Disc filter OUTLET

14 Particle size removal Analysis of particle count by FILTREX automatic image analysis instrument o Quantifies solid colored material by size and shape, particle size refers to the length Pilot IN 20 µm disc filter OUT 20 µm cartridge OUT Particle size Contamination Level * 5µm - 15µm µm - 25µm µm - 50µm µm - 100µm µm - 150µm µm - 200µm *Contamination level refers to the ISO 4406 standard.

15 Particle size removal continued Disc filter has a higher absolute rejection percentage Statistics Pilot IN 20 µm Disc filter 20 µm Cartridge OUT OUT Population 30,426 15,844 19,148 Disc filter - average particle diameter is smaller: larger particles are removed more efficiently % Rejection Average size Standard Dev. Minimum Maximum µm 13.2µm 5µm 434µm 48% 10.7µm 7.77µm 5µm 150µm 37% 12.3µm 20.4µm 5µm 2376µm Quadratics av. 18.3µm 13.2µm 23.8µm

16 Particle size removal continued Additional testing verified the previous results larger particles are removed more efficiently by the disc filter system Particle Size Distribution, sample from: 08/05/2011

17 Dinoflagellates Dinoflagellates are a large group of marine plankton which cause red tide events Passing through the media filter even with coagulation 20µm disc filters provided better removal of these plankton 10,000 1,000 Concentration (No./100L) * Dinoflagellates Concentration IN OUT SK1 20µm OUT SK2 20µm OUT Cartridge 20µm Date

18 Filtration performance stability Cartridges demonstrated unstable filtration effectiveness over 32 months of testing 100% Filtration efficiency of disc filter and cartridge filters for particle removal >25um Removal Efficiency 90% 80% 70% 60% 50% 40% 30% 20% 10% Grey SK (20um) 20um Cartridge 0% 02/05/ /08/ /11/ /02/ /06/ /09/ /12/ /04/ /07/2012 Date

19 CAPEX calculations CAPEX Disc filters Cartridge filters Difference Total lot cost, US$ $825,000 $598,000 Equipment installation (30%), US$ $247,500 $179,400 CMU building (20%), US$ $165,000 $119,600 Civil/site work (15%), US$ $123,750 $89,700 Finishes allowance (2%), US$ $16,500 $11,960 I&C allowance (8%), US$ $66,000 $47,840 Mechanical and electrical allowance (20%), US$ $165,000 $119,600 CAPEX, US$ $1,608,750 $1,166,100 $442,650

20 OPEX calculations OPEX Disc filters Cartridge filters Difference Forward flow cost Flow rate (m3/hr) 10,000 10,000 Clean pressure differential (meter) 1 2 Maximum pressure differential (meter) 3 10 Average pressure differential (meter) 2 6 Energy consumption for pressure diff. (kwtt/year) 700,800 2,102,400 (1,401,600) Energy cost ($/kwtt) $0.068 $0.068 Differential pressure energy cost per year $47,654 $142,963 $(95,309) Backwash cost (assuming 1 backwash per hour) Backwash flow rate (m3/hr) 960 Backwash duration (seconds) 15 Backwash water volume per cycle (m3) 88 BW frequency (number/month) 720 Total energy of backwash volume per year (KWH) 152,064 Total energy of backwash volume per year ($) $10,340 n/a $10,340

21 OPEX calculations OPEX Disc filters Cartridge filters Difference HCl dosage, liter HCl/hour (4ppm of 33% solution) 40 HCl dose duration, minute 4 HCl dose frequency, x/week 0.17 HCL dosing, liter/year 23 HCl cost, $1/kg $1 Chemicals - operating cost, daily $23 Chemicals - operating cost per year $8,436 $8,436 Cartridge replacement cost New cartridge cost $13,800 Cartridge replacement frequency (number/year) 4 New cartridge cost per year $55,200 Replacement work cost (1 person per year) $170,000 Cartridge replacement cost per year total $225,200 $(225,200) Total OPEX (US$/year) $66,430 $368,163 $(301,733)

22 CAPEX CAPEX & OPEX results othe disc filter system price is approximately 40% more than the cartridge filter system OPEX oroi of 1.47 years oenergy expended overcoming the higher pressure differential of cartridges is a substantial OPEX ocartridge replacement costs (including labor of replacement) are a substantial OPEX odisposal costs of cartridges is not current included is the costs

23 Disc filters - additional benefits Disc filters provide protection against catastrophic failure during extreme loading events Protects the membranes from irreversible fouling or damage that could occur during filter failure Disc filters are polymeric construction so no special coating or materials are required for brackish or salt water use Green filtration solution energy savings and elimination of a waste stream

24 Conclusions The ROI of the disc filter system is very compelling: 1.47 years OPEX savings due to lower average pressure differential OPEX savings due to elimination of cartridge disposal The disc filter removes particles larger than 25µm more effectively than the cartridges The disc filter removes dinoflagellates (red tide causing plankton) more effectively Cartridge effluent was unstable and showed compromised effectiveness, while the disc filter performance was stable and consistent

25 System installations From piloting there have been two large systems of note designed with 20 micron disc filter systems in place of 20 micron cartridges odesalinated water for plant use, installed in January of 2013 and treating 36.6 MGD ocurrently in design by CH2M Hill, a project in Singapore for 87.4 MGD

26 Acknowledgements We would like to acknowledge Aviv Shafrir of Amiad Water Systems and Doron Yardeny (formerly of Arkal) who performed the daily work and data collection on these systems for the five years of piloting.

27 Thank you! Questions?