MBBR TO MBR â€“ UNIQUE PROCESS CONFIGURATION FOR ...

MBBR TO MBR – UNIQUE PROCESS CONFIGURATION FOR 

PHARMACEUTICAL WASTEWATER TREATMENT/REUSE 

ABSTRACT 

Daniel B. Wilkinson * , Dewberry, dwilkinson@dewberry.com 

Katie L. Jones, Dewberry 

Angela J. Walsh, Dewberry 

Laura R. Crisman, Dewberry 

Dewberry performed a three month pilot study of a membrane bioreactor (MBR) for the treatment of 

wastewater generated at a pharmaceutical manufacturing facility. The purpose of the pilot study was to 

evaluate the performance of the MBR for full-scale installation in support of the planned wastewater 

treatment plant (WWTP) expansion from 0.5 million gallons per day (MGD) to approximately 1 MGD. 

The objectives of the MBR pilot study were to: (1) Evaluate membrane compatibility with the waste 

stream, (2) Evaluate membrane compatibility with MBBR technology, (3) Evaluate permeate quality, (4) 

Evaluate flux degradation and cleaning requirements, (5) Confirm membrane sizing requirements for the 

full-scale system. The General Electric (GE) ZeeWeed ® hollow-fiber membrane was selected for pilot 

testing. 

The results of the pilot study indicate that the unit process configuration of MBBR to MBR is technically 

feasible for full-scale treatment at an industrial pharmaceutical facility. 

KEYWORDS 

Membrane Filtration, Pilot Study, Wastewater Treatment, Pharmaceutical, MBR, MBBR, Aerobic 

Treatment 

INTRODUCTION 

Dewberry performed a three month pilot study of a membrane bioreactor (MBR) for the treatment of 

wastewater generated at a pharmaceutical manufacturing facility. The purpose of the pilot study was to 

evaluate the performance of the MBR for full-scale installation in support of the planned wastewater 

treatment plant (WWTP) expansion from 0.5 million gallons per day (MGD) to approximately 1 MGD. The 

existing treatment steps at the industrial WWTP include two equalization (EQ) tanks, two moving bed 

biological reactor (MBBR) tanks, a suspended growth aeration basin, and biosolids removal in a dissolved 

air floatation (DAF) unit. Effluent from the WWTP is discharged to a Publicly Owned Treatment Works 

(POTW). 

To support the WWTP upgrade under future loading conditions, a technology evaluation was performed 

in which several suspended growth activated sludge treatment technologies were considered, including 

sequencing batch reactor (SBR) technology, gravity clarification, DAF, and membrane filtration 

(ultrafiltration). For each of the technologies, the biological unit process configuration was similar, with 

discharge from the MBBRs sent to a suspended growth reactor prior to the solids separation step. 

Conceptual designs and cost estimates were developed as part of the evaluation. 

Based on the life cycle costs comparison, the MBR technology appeared to be comparable to the 

conventional technologies. This was due, in part, to the high operating cost associated with historical 

polymer use in the clarifiers. From an effluent performance perspective, MBR technology offers a higher 

confidence level that effluent contaminant concentrations will be achieved and provides high quality 

MBBR TO MBR: A UNIQUE PROCESS CONFIGURATION FOR 

PHARMACUETICAL WASTEWATER TREATMENT/REUSE

effluent for water reuse onsite. Because the MBR technology appeared to offer advantages over other 

technologies in this application, the MBR pilot study was conducted. 

The objectives of the MBR pilot study were to: (1) Evaluate membrane compatibility with the waste 

stream, (2) Evaluate membrane compatibility with MBBR technology, (3) Evaluate permeate quality, (4) 

Evaluate flux degradation and cleaning requirements, (5) Confirm membrane sizing requirements for the 

full-scale system. In order to accomplish the objectives of this pilot study, the General Electric (GE), 

ZeeWeed ® (GE Water and Process Technologies, Ontario) hollow-fiber membrane was selected for pilot 

testing. 

METHODOLOGY 

GE supplied the ZeeWeed® 10 MBR Pilot unit, which is rated at 100 gallons per day (gpd) of wastewater. 

The skid-mounted pilot system included a suspended growth reactor tank, followed by a membrane tank, 

both equipped with air blowers and a diffusion plate, a feed tank, a permeate collection tank, various 

pumps, and a PLC. The pilot unit’s components are pictured in Figure 1 and Figure 2. 

Figure 1: MBR Pilot Unit Bioreactor (left), Membrane Tank (center), and Supplemental Feed Tank (right). 



Figure 2: MBR Pilot Unit PLC Control Panel (left) and Bioreactor (right). 

The pilot unit was continuously fed wastewater from two locations in the existing treatment train: (1) Raw 

wastewater from the EQ tanks, and (2) Treated wastewater from the MBBR effluent. A process flow 

diagram for the MBR pilot unit is presented below in Figure 3. 

Plant 

Water 

F/S 

Effluent 

MBBR 

Effluent 

Transfer line with 

shutoff valve 

Transfer line with 

throttling valve 

(50-‐200 gpd)and 

rotameter 

Supplemental 

Feed Tank 

(120 gallons) 

Overflow 

to Drain 

Feed Pump 

(0 -‐ 760 gpd) 

air blower 

(5 cfm ) 

ZeeWeed®10MBR Pilot Skid 

ReactorTank 

(100 gallons) 

Figure 3: Process Flow Diagram of Membrane Bioreactor (MBR) 

Permeate 

Collection 

tank 

(5 gallons) 

ZeeWeed® 

MBR 

(10 ft 2 of membrane 

in 

5.3 gal tank) 

air blower 

(5 cfm ) 

Reversible 

gear drive pump 

MBR 

Permeate 

Discharge 

(access to drain) 

Waste 

Sludge 

Discharge 

(access to drain) 

The study was completed in the following four phases: (1) Acclimation Phase during which MLSS was 

increased to target ~8,000 mg/L in the membrane tank; (2) Phase I, intermediate F:M conditions ; (3), 

Phase II, low F:M conditions, consisting of Phase IIA, low DO conditions to promote SNdN, and Phase 

Overflow 

to Drain 

Overflow 

Transfer 

Pump 


PHARMACUETICAL WASTEWATER TREATMENT/REUSE 

PI 

CIP 

Chemicals

IIB, high DO conditions to discourage SNdN; and (4) Stress Test, low F:M and high mixed liquor 

suspended solids (MLSS) conditions. Table 1 provides study setup data. 

Table 1: MBR Pilot Study - Average Operating Conditions 

Parameter Units Acclimation Phase I Phase II A & B Stress Test 

Dates of Operation 

F/S Effluent Feed 

Rate 

MBBR Effluent 

Feed Rate 

Reactor Tank 

MLSS 

Influent soluble 

COD loading to 

Reactor Tank 

F:M 

July 26 – 

Aug 7 

Aug 8 – 

Aug 29 

Aug 30 – 

Sept 27 

Oct 6 – 

Oct 18 

gpd 104 90 - 180 0 0 

gpd 0 180 - 90 260 280 

mg/L 6,400 7,200 8,900 13,400 

lb 

COD/day 

lb 

sCOD/lb 

MLVSS-d 

Reactor Tank DO mg/L 2.5 4.2 

Membrane Flux 

Rate 

2.3 1.2 0.3 0.3 

1.5 0.5 0.09 0.06 

2.2 (Phase IIA) 

5.3 (Phase IIB) 

gpd/ft 2 10 10 10 10 

Operating parameters were monitored on a daily basis, including: flow rates to and from the system, 

MLSS and dissolved oxygen (DO) concentration in the suspended growth reactor, pH, temperature, 

trans-membrane pressure (TMP), COD in the influent and permeate. Four membrane cleaning 

mechanisms were utilized on the pilot system: (1) continuous scouring via the air blower/diffuser system, 

(2) backpulsing of the membrane by reversing the permeate pump, (3) maintenance cleaning cycle with 

dilute chemical solution, (4) recovery cleaning cycle with more concentrated chemical solution once 

during the study. 

RESULTS 

The MBR pilot system was operated successfully for the three month duration of the pilot study, 

maintaining high quality permeate with no indication of significant or irreversible membrane fouling. 

Table 2 presents selected indicators of system performance for each phase of the study. Average 

parameter results during the three month study (excluding acclimation phase) are highlighted below: 

• Permeate COD = 55 mg/l 

• Permeate BOD5 = 12 mg/l 

• Permeate TSS < 3 mg/l (all samples were below the detection limit) 

• TMP = -0.8 psi (average of before and after backpulse) 

• Average hydraulic flux rate through the membrane was 10 gallons per day per square foot of 

membrane area (gfd); 

• MLSS in the reactor tank = 9,171 mg/L (maximum MLSS in the reactor tank was 17,700 mg/L) 

• F:M = 0.26 lb sCOD/lb VSS-d (F:M varied between 0.03 and 1.2) 

• Specific substrate utilization rate = 0.25 lb sCOD/lb VSS (rate varied between 0.02 and 1.1) 

• NH3-N < 0.5 mg/l; NO3-N = 4.2 mg/l; TP = 3.8 mg/l. 

2.1 



Table 2: MBR Pilot Results - Average Performance Parameters 

Units Acclimation* Phase 

I 

Phase IIA Phase IIB 

Stress 

Test 

Permeate Quality 

COD mg/L 84 64 58 42 46 

BOD5 mg/L 11.7 11.6 5.2 2 31 

TSS mg/L BDL BDL BDL BDL BDL 

Ammonia (NH3-N) mg/L Limited data 0.6 0.6 0.1 0.8 

Nitrate (NO3-N) mg/L No data 2.3 3.4 5.3 2.8 

Total Phosphorous mg/L 0.4 3.9 8.3 3.6 1.2 

Other Key Parameters 

MLSS mg/L 6,438 7,238 9,540 8,121 13,381 

Before Backpulse TMP psi -0.6 -0.6 -0.8 -1.0 

During Backpulse TMP psi 1.4 1.7 2.1 7.1 

After Backpulse TMP psi 

lb sCOD/lb 

-0.2 -0.3 -0.6 -0.4 

F:M 

MLVSS-d 1.2 0.5 0.08 0.09 0.06 

Specific Substrate 

Utilization Rate 

lb sCOD/lb 

MLVSS-d 1.1 0.5 0.06 .08 0.05 

Reactor Tank 

Dissolved Oxygen (DO) mg/L 2.3 4.2 2.2 5.3 2.1 

* After July 27, 2011 

Biological performance results 

The pilot study phases were established to evaluate the MBR system for COD removal under varying F:M 

conditions. During the acclimation phase, there was potential to observe high residual COD in the 

permeate as the reactor was operated at high F:M (1.5 lb sCOD/lb VSS-d) conditions to simulate biomass 

growth. Despite the high F:M conditions, the average permeate COD during the acclimation phase after 

July 27 was 84 mg/l and the specific substrate utilization rate averaged over 1 lb sCOD/lb MLVSS-d. This 

data indicates that the F/S effluent was readily biodegradable under the conditions of the acclimation 

phase. 

During the intermediate F:M conditions of Phase I (0.5 lb sCOD/lb MLVSS-d), a higher permeate effluent 

quality was observed, as COD averaged less than 64 mg/L. Phase II, which operated at low F:M 

conditions (0.09 lb sCOD/lb MLVSS-d), produced the highest quality permeate, with effluent COD 

average of 50 mg/l. 

Figure 4 presents permeate COD, specific substrate utilization rate, and F:M ratios for the study. In 

general, the substrate utilization rate corresponded well with the F:M ratio, which is as expected given the 

consistently low residual COD in the permeate throughout the study period. It is interesting to note that, 

excluding the first day of acclimation, the permeate COD did not exceed 150 mg/l during the study. Given 

this data, the F/S and MBBR effluents appear to be very readily biodegradable at the conditions observed 

in the study. 



800 

700 

600 

500 

Permeate COD, mg/L 

400 

300 

200 

100 

0 

Permeate COD 

Reactor Tank F:M 

Substrate Utilization Rate 

Mechanical Upset Period 

7/16/11 7/26/11 8/5/11 8/15/11 8/25/11 9/4/11 9/14/11 9/24/11 10/4/11 10/14/11 10/24/11 

Figure 4: Permeate COD, Substrate Utilization Rate, and F:M Ratio 

Phase IIA operated at an average dissolved oxygen (DO) concentration of 2.2 mg/L in order to provide 

conditions in the reactor for SNdN to occur; Phase IIB operated at an average DO of 5.3 mg/L to 

discourage SNdN and to observe nitrate concentrations in the permeate. Nitrate concentration in the 

permeate is dependent on a number of factors, including DO concentration, F:M, and influent nitrogen to 

COD ratio (N/COD). The higher the influent N/COD ratio, the greater the potential is to generate nitrate. 

Lower F:M conditions can also lead to an increase in nitrate formation. 

Figure 5 presents the nitrate data for Phase II. Since the influent N/COD during Phase IIA was higher 

than during Phase IIB, and the F:M for Phase IIA was lower than Phase IIB, it is expected that more 

nitrate was generated during Phase IIA than during Phase IIB. The average permeate nitrate 

concentrations for Phase IIA and Phase IIB were 3.4 mg/l and 5.3 mg/l respectively. This data indicates 

that it is likely that SNdN was occurring at a higher rate in Phase IIA. 

1.80 

1.55 

1.30 

1.05 

0.80 

0.55 

0.30 

0.05 

-‐0.20 



Food-‐to-‐Biomass Ratio, lb sCOD/lb MLVSS-‐d 

Specific Substrate Utilization Rate, lb sCOD/lb MLVSS-‐d

Nitrate in Permeate,mg/l 

10 

9 

8 

7 

6 

5 

4 

3 

2 

1 

0 

PHASEIIAAverages: DO = 2.2 mg/l, 

F:M= 0.08, Nitrate = 3.4 mg/l 

8/25/11 8/30/11 9/4/11 9/9/11 9/14/11 9/19/11 9/24/11 9/29/11 

Figure 5: Phase II SNdN Evaluation Nitrate Results 

Membrane performance results 

Nitrate NH3-‐N/sCOD Ratio 

PHASEIIB Averages: DO = 5.3 mg/l, F:M = 0.10, 

Nitrate = 5.3 mg/l 

A plot of the transmembrane pressure (TMP) throughout the course of the study is presented in Figure 6. 

We observed excellent membrane performance during the study. The after backpulse TMP averaged - 

0.5 psi, which is well below the trigger level for a recovery clean. We consistently observed pressures 

after backpulse that were lower than pressures before backpulse, which is indicates that the backpulse 

was providing an effective membrane cleaning mechanism by scouring the solids off of the surface of the 

membrane. 



0.18 

0.16 

0.14 

0.12 

0.11 

0.09 

0.07 

0.05 

0.04 

0.02 

0.00 

Influent NH3-‐N/sCOD Ratio

TMP, psi 

12.0 

10.0 

8.0 

6.0 

4.0 

2.0 

0.0 

-‐2.0 

-‐4.0 

-‐6.0 

Before Backpulse Pressure 

During Backpulse Pressure 

After Backpulse Pressure 

Recovery clean 

Stress Test 

Replaced Pressure Gauge 

7/16/11 7/26/11 8/5/11 8/15/11 8/25/11 9/4/11 9/14/11 9/24/11 10/4/11 10/14/11 10/24/11 

Figure 6: Transmembrane Pressure (TMP) Results 

Although TMPs above the recovery clean trigger level were not observed, a recovery clean was 

performed to evaluate if membrane fouling was reversible. Just prior to the recovery clean, the TMP had 

increased to -5 psi before backpulse and -2 psi after backpulse. 

Figure 7 shows the TMP of the initial membrane condition (at the beginning of the pilot study), and the 

TMP immediately before and after the recovery clean cycle with each chemical. The results indicate that 

citric acid proved the more effective cleaning chemical during the recovery clean, as TMP was decreased 

to the initial membrane condition (~-0.3 psi) after cleaning with this chemical. The TMP recovery 

suggests that the membrane fouling was largely reversible. It should be noted that the difference in TMP 

during the clean water tests before and after citric and hypo cleans was very small, which indicates that 

the membrane fouling was minimal. 



Transmembrane Pressure (TMP), psi 

0.0 

-‐0.1 

-‐0.2 

-‐0.3 

-‐0.4 

-‐0.5 

Initial Condition (July-‐26) Before recovery clean (Oct-‐4) After Hypo recovery clean (Oct-‐4) After Citric recovery clean (Oct-‐5) 

Figure 7: MBR Pilot Recovery Clean - Flux Test Results 

During the stress test phase, the MLSS was increased to ~ 13,400 mg/l in the reactor tank to observe the 

impacts on membrane performance. As expected, the TMP during backpulse increased, up to 7 psi, and 

the TMP before backpulse increased to -2 psi. Yet the TMP after backpulse was in line with the study 

average, at less than -0.5 psi. This data indicates that while the high MLSS concentration in the 

membrane tank was causing additional solids deposition on the membrane surface, the backpulse 

cleaning mechanism was effective in scouring the solids off of the surface. A picture of the membrane 

unit after the pilot test is presented below in Figure 8. 

Figure 8: Membrane Unit at the Conclusion of Pilot Testing 

Mixed Liquor Test 

Clean Water Test 



DISCUSSION AND CONCLUSIONS 

The results of the pilot study indicate that the unit process configuration of MBBR to MBR is technically 

feasible for full-scale treatment at an industrial pharmaceutical facility. We do not find it likely that this 

configuration will be widely installed because of capital cost considerations. However, in this application, 

the MBR technology is economically feasible because the owner was willing to perform the evaluation 

based on a life cycle cost analysis. 

On a capital cost basis, MBR technology is more expensive than conventional solids separation 

technologies for this application (including the cost credit for a smaller reactor). However, when taking 

into account life cycle costs, the MBR technology in this application would allow for an estimated 

$272,000 per year savings related to clarifier polymer costs. 

In this case, the MBR would be added to an existing treatment plant with MBBR technology. The drivers 

for selection of MBR technology in this application is the owner’s desire to: 

• Avoid any permit compliance issues, 

• Install a technology that facilitates on-site effluent reuse, and 

• Reduce chemical and polymer costs which are historically high, 

Because we are not aware of other full scale installations with this configuration we wanted to rigorously 

test membrane flux degradation rates and membrane recovery post cleaning to confirm membrane life 

cycle estimates. We operated the MBR reactor in a stress test mode with MLSS values well above the 

recommended concentration of 8,000 mg/l. Test results showed that we could successfully clean the 

membrane without any visible deposition or TMP increase after the stress test. This increased our 

confidence level that we would not have rapid flux degradation at the full scale and that the membrane life 

would be satisfactory. 

A preliminary design is currently being developed for a full-scale system at this pharmaceutical 

manufacturing facility.

MBBR TO MBR â€“ UNIQUE PROCESS CONFIGURATION FOR ...

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