Filtration Of Creek Water Using A Pall Microfiltration System For The ...

July 13, 2001 

SLS Report No. 9799SC 

FILTRATION OF CREEK WATER 

USING A PALL MICROFILTRATION SYSTEM FOR 

THE CITY OF CRESTED BUTTE AND SEAR BROWN, CO 

PURPOSE 

___________ 

To evaluate the performance of a Pall Microza 0.1 µm microfiltration (MF) system on Coal 

Creek water and for the City of Crested Butte, Colorado and Sear Brown Engineering. 

SUMMARY 

___________ 

The City of Crested Butte and Sear Brown set up a pilot study to evaluate the design and 

operating conditions of microfiltration technology in the filtration of Coal Creek water at the City of 

Crested Butte WTP. The City of Crested Butte envisions a 1.5-MGD plant to treat Coal Creek water 

using conventional treatment protocols. Pretreatment using potassium permanganate and pH adjustments 

were also evaluated. 

The Pall 0.1-µm MF system pilot test began on March 31, 2001 and ended on July 9, 2001. 

Operational fluxes up to 43 GFD were tested. The MF filtrate with respect to the turbidity was consistent 

throughout the test. The filtrate turbidity was typically 0.02 to 0.04 NTU. Manganese levels were 

consistently less than 0.05 mg/L in the filtrate. Based on the pilot test results the Pall 0.1 µm MF system 

can be designed to meet the seasonal water demands as follows: 

CIP interval of >2 weeks using a protocol of 4-hr recirculation with 1-% caustic/0.1% sodium 

hypochlorite followed by 2% citric acid. 

Ref.: TW145.00

This report is proprietary to PALL CORPORATION and is furnished in Confidence for the Private use of the intended recipient, for the sole purpose of evaluating 

PALL technology. It may not be copied nor disclosed, in whole or in part, without the prior express approval of PALL CORPORATION. 

This report is proprietary to PALL CORPORATION and is furnished in Confidence for the Private use of the intended recipient, for the sole purpose of evaluating PALL 

technology. It may not be copied nor disclosed, in whole or in part, without the prior express approval of PALL CORPORATION.

BACKGROUND 

________________ 

The City of Crested Butte processes Coal Creek water from two existing conventional treatment 

sites under the authority of the Crested Butte Water Treatment Plant. The conventional treatment utilizes 

coagulation, flocculation, sedimentation and mixed media filtration. The exiting conventional treatment 

plant produces enough potable water to meet demands with favorable raw water conditions. However, 

future expansion of the service area will require a modification of the current water treatment system. 

One proposed solution is the implementation of membrane technology 

The City of Crested Butte is interested in evaluating the Pall Microfiltation (MF) system for the 

design on a proposed 2-MGD expansion of the Crested Butte water treatment plant (WTP). The Pall 

Microfiltration system was selected for pilot testing as a viable membrane technology. The Pall pilot test 

started on March 31, 2001 and ended on July 7, 2001. Operating and performance data from the Pall 

pilot and test results from the City of Crested Butte and Sear Brown were collected and presented in this 

report. 

TEST EQUIPMENT & OPERATION: 

_____________________________________ 

A fully automated pilot system was installed at the City of Crested Butte WTP test site. The 

process flow diagram is shown in Figure I. The system was equipped with one Pall Microza MF 

membrane with the physical characteristics described in Table I. 

FIGURE I 

Schematic Pall Microza MF Pilot System 

FT 

PT 

TI 

PT 

S2 

UPPER 

RF DISCHARGE 

FT 

PT 

AIR INJ . 

RF PUMP 

S1 

FEED PUMP 

LOWER 

RF DISCHARGE 



TABLE I 

Test Module Microza XUSV-5203 

Outside Membrane Area 398 ft 2 

Module Length 

2 meters 

Module Diameter 

5 inches 

Membrane Material 

PVDF 

Housing Material 

PVC 

The Microza hollow-fiber membrane was operated in an outside-to-inside mode with periodic 

regeneration of the membrane by a simultaneous air scrubbing/reverse flow (SASRF) followed by a 

reverse flow (RF). The excess recirculation (XR) rate for this pilot study was 10% of filtrate. The pilot 

system operates at a constant filtrate flow rate. The operating conditions are shown in Table II. 

TABLE II 

Summary of Operating Conditions 

Filtrate 

Flux Based on Outside Area 

Recirculation Rate 

SASRF (frequency, duration, flowrate) 

Cycle 1 (3/30 to 4/5) 

(4/5 to 5/3) 

Cycle 2 (5/4 to 5/17) 

(5/18 to 5/21) 

Cycle 3 (5/22 to 5/30) 

(6/1 to 6/8) 

Cycle 4 (6/8 to 6/17) 

(6/19 to 7/9) 

RF (frequency, duration, flowrate) 

Cycle 1 (3/30 to 4/5) 

(4/5 to 5/3) 

Cycle 2 (5/4 to 5/17) 

(5/18 to 5/21) 

Cycle 3 (5/22 to 5/30) 

(6/1 to 6/8) 

Cycle 4 (6/8 to 6/17) 

(6/19 to 7/11) 

7.7 to 12 GPM 

27.9 to 43.4 GFD 

10% of filtrate 

30 min, (30 sec air/60 sec air + filtrate), 5 gpm 








30 min, 20 sec, 10 gpm 

30 min, 20 sec, 10 gpm 

30 min, 20 sec, 10 gpm 

30 min, 20 sec, 15 gpm 

30 min, 20 sec, 14 gpm 

30 min, 20 sec, 12 gpm 

30 min, 20 sec, 12 gpm 

30 min, 20 sec, 13 gpm 



Typically when the transmembrane pressure (TMP) reaches a maximum of 35 psid, the 

membranes are chemically cleaned in place (CIP) with a solution of 1 % NaOH and 1,000 ppm NaOCl 

followed by a solution of 2% citric acid. Makeup water was potable water. The CIP consisted of a 4-hr 

recirculation of the NaOH/chlorine followed by a 2-hr recirculation with citric acid. 

Prior to the start of the test, an integrity test was performed to ensure that the test membrane is 

integral. A pressure decay rate of

TEST RESULTS AND DISCUSSION 

_____________________________________ 

1. Pall MF Performance and Operation: 

For the duration of pilot program, the MF was evaluated under the operational parameters and 

characteristics summarized in Table III. 

TABLE III 

Date 

Cycle 

# 

Interval 

(days) 

Membrane Operational Characteristics 

TMP 

initial/final 

(psi) 

Flux 

(GFD) 

Date of 

CIP 

Temp 

Range 

(C) 

Feed 

NTU 

Recovery 

(%) 

3/30-4/5 1 7 3/7 27.9 0.7-1.2 1-4 96.2 

4/5-5/3 28 9/21 32.6 5/3 0.5-4.2 2-8 95.7 

5/4-5/18 2 14 5/33 32.6 5/18 (a) 3.0-9.4 6-8 96.4 

5/18-5/21 3 16/22 32.6 5/22 8.1-10.7 6-8 96.0 

5/22-5/30 3 8 3/8 32.6 8.3-12.8 3-6 96.2 

5/30-6/8 10 9/11 39.8 8.8-13.1 3-4 97.1 

6/8-6/12 4 12/25 43.4 6/14 (b) 11.7-14.5 2-3 97.2 

6/14-6/17 3 12/34 43.4 6/18 8.8-11.6 2-3 97.2 

6/19-7/11 4 22 5/18 (c) 39.8 97.0 

(a); (b); maintenance clean of 0.5% citric RF flush for 15 min 

(c); 2-ppm chlorine added to SASRF and RF starting on 7/2 

a. Cycle 1 (March 30 to May 3): 

The cycle started on March 30 with a flux of 27.9 GFD with an initial TMP 3 psid. 

The TMP increase was a minimal 4-psi after 7 days. The flux was increased to 32.6 GFD on 

April 5. The run continued until May 3 with a TMP increase to 21 psid. The total run time for 

cycle 1 was 35 days (Figure II). The feed turbidity was 1 to 8 NTU with a temperature range 

of 0.7 to 4.2C. The filtrate turbidity was consistently 0.02 to 0.04 NTU with a particle count 

of < 1 count/ml for particle sizes > 2µm. The pilot was CIP on May 3. 

b. Cycle 2: (May 4 to May 21): 

The cycle started on May 4 with a flux of 32.6 GFD with an initial TMP of 5 psid. The cycle 

continued for 14 days until terminal TMP of 33 psid was reached. A maintenance clean 

consisting of a 2% citric acid recirculation for 1 hour was then performed. This was successful 

in reducing the TMP to 16 psid. The microfiltration pilot was restarted and the cycle was 

continued until May 21 with a final TMP of 22 psid. The total time for cycle 2 was 17 days 



(Figure III). The feed turbidity was 6 to 8 NTU with a temperature range of 3.0 to 10.7C. The 

filtrate turbidity was consistently 0.02 to 0.04 NTU with a particle count of < 1 count/ml for 

particle sizes > 2u. The microfiltration pilot was CIP on May 22. 

c. Cycle 3 (May 22 to June 17): 

Cycle 3 started on May 22 with a flux of 32.6 GFD with an initial TMP of 3 psid. The 

TMP gradually increased to 8 psid over the next 8 days. On May 30 the flux was increased to 

39.6 GFD with an initial TMP of 9 psid. The TMP increased to 11 psid over the next 10 days. 

On June 8 the flux was increased to 43.6 GFD with an initial TMP of 12 psid. There was a 

rapid TMP increase to 25 psid in the next 4 days. A maintenance clean consisting of a 2% 

citric acid recirculation for 1 hour was performed on June 14. This produced a TMP recovery 

to 12 psid. The cycle was continued for 3 more days until terminal TMP was reached. The 

total run time for cycle 3 was 25 days (Figure IV). The feed turbidity during cycle 3 was 3 to 

6 NTU with a temperature range of 8.3 to 14.5C. The filtrate turbidity was consistently 0.02 to 

0.04 NTU with a particle count of < 1 count/ml for particle sizes > 2µm. The microfiltration 

pilot was CIP on June 18. 

d. Cycle 4 (June 19 to July 11): 

Cycle 4 started on June 19 with a flux of 39.6 GFD with an initial TMP of 5 psid. The 

TMP gradually increased to 25 psid over the next 13 days. On July 2, chemical addition of 2- 

ppm chlorine in the SASRF and RF cycles was initiated. The immediately reduced the TMP 

to 20 psid. The cycle continued for another 9 days with the TMP remaining flat at 20 psid. 

The test period was ended on July 11 without reaching TMP. The total run time for cycle 4 

was 22 days (Figure V). The feed turbidity during cycle 4 was 0.2 to 3 NTU with a 

temperature range of 13 to 19 C. The filtrate turbidity was consistently 0.02 to 0.04 NTU with 

a particle count of < 1 count/ml for particle sizes > 2 µm. 

2. Turbidity Trends: 

Raw and filtrate turbidity trends can be seen in the previous graphs. The feed turbidity 

was typically 2 to 3 NTU. During spring runoff, the turbidity was typically 6 to 8 NTU. The 

filtrate turbidity was consistently 0.02 to 0.04 NTU. 

3. Particle Count Trends: 

Raw and filtrate particle count trends can be seen in Figures VI through IX. The feed 

counts of greater than 2µm were typically 20,000 to 30,000 counts/ml. The filtrate counts of 

greater than 2µm were typically less than 1 count/ml. 

4. Manganese Results: 

This report is proprietary to PALL CORPORATION and is furnished in Confidence for the Private use of the intended recipient, for the sole purpose of 

evaluating PALL technology. It may not be copied nor disclosed, in whole or in part, without the prior express approval of PALL CORPORATION.

The manganese concentration in the filtrate were consistently < 0.05 mg/L when 

potassium permanganate was used in pretreatment of raw water and sodium hypochlorite was 

dosed into the raw water and filtrate backwash. 

5. Water Analysis Data: 

Water analysis data for Coal Creek water are summarized below in Table IV. 

TABLE IV 

Coal Creek Water 

(Courtesy of Crested Butte WTP and Sear Brown) 

Parameter 

Range 

Total Alkalinity (mg/L as CaCO 3 ) 12-26 

Bicarbonate (mg/L as HCO) 15-31 

Carbonate (mg/L as CO 3 )

______________________________ 

Scott Caothien 

Director 

Scientific and Laboratory Services 

West Coast Division 

Pall Corporation 

____________________________ 

Paul Morris 

Field Engineer 

Scientific and Laboratory Services 

West Coast Division 

Pall Corporation 

This report is proprietary to PALL CORPORATION and is furnished in Confidence for the Private use of the intended recipient, for the sole purpose of 

evaluating PALL technology. It may not be copied nor disclosed, in whole or in part, without the prior express approval of PALL CORPORATION.

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