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Membrane Separation of X B s from Wastewater with

SDIfs EXTRAIY, - Membrane Separation System

SUMMAR Y

Presented in this paper is a description of the use of SDI's EXTRAN, Membrane Separation technology to separate and concentrate PCBs from wastewater. Pilot testing results are presented. Commercial operational data was not available at the time this paper was submitted for publication; however, preparations are being made for a 60 gallon per minute system to separate PCBs from wastewater in a RCRA TSD facility. The use of EXTRAN,, Membrane Separation is an attractive alternative to other treatment processes like carbon adsorption because it separates and concentrates PCBs into a small liquid volume that can be incinerated at a permitted incinerator. A high quality effluent is produced that can be recycled or discharged under current standards.

EXTRAN, membranes are composed of cellulose made by a proprietary SDI process into hollow fibers (inner diameter of 400 microns), which are potted into suitable pressure vessels (modules) and incorporated into a system. EXTRAN, membrane is resistant to a vast array of hydrocarbons and organic solvents. Being a true water diffusion membrane, it has no pores to clog. These properties in combination with adequate tangential velocity through the bore of the fiber allows continuous operation with no online chemical cleaning. Periodic use of surfactant followed by biocide to kill any bacteria growing inside the EXTRAN, membrane module is practiced.

3 1.0 Introduction

Pilot testing results are presented in this paper. Data from ongoing commercial operations was not available in time to place into this report.

2.0 Pilot Testing

Two different types of testing were conducted. The first testing to be discussed was the continuous treatment of a wastewater stream during a six day period.

The other two tests were batch tests of sump water and a solvent waste.

2.0.1 Continuous Treatment

The pilot testing was performed to verify the ability of SDI's EXTRAN- Membrane Separation System to continuously remove PCBs from oily wastewater on a twenty four hour per day, seven day per week basis. The wastewater utilized in this portion of the study is generated daily during the five day work week.

2.0.2 Batch Treatment

Additionally, batch tests were performed for wastewater containing PCBs. One sample was collected from a concrete sump: the other sample was a solvent waste sample containing PCB. These tests were conducted to determine the ability of SDI's EXTRAN, Membrane Separation System to remove PCB when present in higher concentrations than the concentrations found in the wastewater treated on a continuous basis.

2.1 Pilot T e s t i n g System Description

A diagram showing the flow scheme utilized during the continuous wastewater treatability testing is shown here.

Effluent from the Dissolved Air Flotation (DAF) Unit was held in a tank, which served as the feed tank to the EXTRAN,, Membrane Separation System. After sand filtration, a 16 gallon per minute feed stream was pumped through 10 micron cartridge filters and into the SDI S-34 membrane module. The permeate (treated water) was sent to temporary tanks for collection and testing.

A total of 14 gallons per minute exited the membrane module as concentrate. Of this 14 gallons per minute, 12 gallons per minute was recycled, introduced into the sand filter effluent entering into the system. The other 2 gallons per minute were sent to the DAF Unit as blow down.

The two batch tests utilized the same flow scheme except that the waste was contained in separate, small tanks.

2.1.1 Operational Settings and System Capabilities

The data below describes the operational settings and capabilities of a full scale EXTRAN, Membrane Separation System as compared to the Pilot Test System used in this project.

Parameter Pilot Test Svstem Commercial Svstem

Number of Modules 1 Feed Flow per Module 16 gpm Blow Down 2 gpm Permeate Flow 2 gpm Filtration 10 micron ATMP* 40 psi max. PH 5 - 9 Water Temperature Max. 150 F

28 16 gpm 60 gpm 60 gpm 10 micron 40 psi max. 5 - 9 150 F

*Average Trans-Membrane Pressure (ATMP) is the average of the feed and concentrate outlet pressures minus the permeate back pressure on module.

2.1.2 Pretreatment

Incoming wastewater was filtered through a sand filter with a 30 micron particulate cutoff rating. Sand filter effluent (4 gallons per minute), combined with 12 gallons per minute of recycle water fromthe membrane system, was pumped through cartridge filters with a 10 micron cutoff rating.

The use of 10 micron filtration is SDI's standard practice for pilot testing of heavily contaminated streams: however, it should be noted that the micron cutoff for pre-filtration is a function of the solids loading and morphology of the particulate.

Pre-filter service life was monitored by measuring the pressure drop across the filter. Pre-filters were changed out when the pressure drop reached 10 psi.

2.1.3 Uembrane Separation

The EXTRAN, Membrane Separation Test System utilized in this pilot study included one six inch diameter SDI S-34 Module. It has a permeate capacity (output) of 3 gallons per minute of clean water at 77 F and 30 psi. Typically, the permeate flow is between 2 and 3 gallons per minute when treating oily wastewater under the same pressure and temperature conditions.

The EX-, membrane is 95 percent cellulose: made by a proprietary SDI process into hollow fibers (inner diameter of 400 microns), which are potted into suitable pressure vessels (modules) and incorporated into a system. EXTRAN, membrane is resistant to a vast array of hydrocarbons and organic solvents.

Being a true water diffusion membrane, it has no pores to clog. These properties in combination with adequate tangential velocity through the bore of the hollow fiber allows for continuous operation with no online chemical cleaning. Periodic cleaningwith soap and water, followed by a biocide is practiced to prevent bacteria from damaging the membrane fibers. Typically this is practiced prior to extended shutdown of the system.

2.1.4 Recycle and Blow Down Streams

EXTRAN, membrane separation concentrates the PCBs and other organic compounds by rejecting these compounds and permeating treated water from the inside of the fiber to the outside of the fiber. The rejected PCBs remain inside the bore of the hollow fiber and are swept out of the module by wastewater flow, as shown on the diagram at the end of this sub-section.

The flow schematic in Section 2.1 shows the concentrated wastewater stream being divided; a portion ( 2 gpm of blow down) is returned to the DAF Unit and a larger portion (12 gpm) is recycled to the membrane system feed.

Conmated Water Feed

Water Feed Concentrated I

Concentrated organlc Contamlnatlon

3 . 0 Analytical Results ? This section describes the influent and effluent characteristics;

comparisons are made to the facility's Industrial User Discharge Permit . 3.1 EXTRAN, - Hembrane Flow Rate Figure 1 shows the flow rate maintained during the continuous treatment test which included six days and 17 hours of operation. After an initial flow rate of 2.9 gallons per minute (normalized to 30 psi ATMP and 25 C) while treating tap water, the flow rate quickly dropped to 2.5 gallons per minute when wastewater was fed to the system. This immediate loss of flow rate is typical during the change from tap water to wastewater containing oil and grease; however, as Figure 1 indicates, flow rates rapidly stabilized with no loss of flow during further operation.

During the more than six days of operation, approximately 18,000 gallons of wastewater were treated. The normalized flow rates, excluding the tap water flow rate, averaged 2.4 gallons per minute with a range of 2.2 to 2.7 gallons per minute. As shown in Table I, the normalized system flow rate began at 2.5 gallons per minute and ended at 2.5 gallons per minute.

During batch testing, standard operating conditions were utilized, 27 psi Average Trans-Membrane Pressure, feed flow of 16 gallons per minute, blow down of 2 gallons per minute, and permeate of 2 gallons per minute. Due to the short duration of these tests, detailed flow data is not presented.

3.2 Wastewater Characteristics

Data obtained by a third party laboratory, utilizing approved EPA procedures, is presented here for both the continuous treatment test and batch tests.

3.2.1 Continuous Treatment

During the six days and 17 hours of operation, wastewater fed to the EXTRAN, Membrane Separation System had these characteristics:

Industrial User parameter Units Svstem Feed Permit Limit*

PCB (Total) PPB 0.09 - 3.41 < 0.10 Oil & Grease PPM 64 - 926 < 100 COD PPM 362 - 574 < 1000 TOC PPM TSS PPM 31 - 944 < 300

* Monthly Average established for Industrial User Permit

56 - 410 No Limit

PH su 7.5 - 8.5 5 - 9.5

This wastewater was collected in sumps, tredted by the DAF Unit, held in a storage tank, filtered through a sand filter, then pumped through 10 micron cartridge filters prior to membrane separation.

3.2.2 Batch Treatment

The wastewater treated by the EXTRAN,, Membrane Separation System after sand filtration had the following characteristics:

Param eter Units Sumx, Water Solvent Waste

PCB (Total) PPB TOC PPM TSS PPM MBAS (Surfactant) PPM

10* 430 1044 7360 12.5

* Sample taken from middle layer of wastewater had 210 PPB prior to sand filtration, 18,000 PPB in top layer of scum, and 21,000 PPB in the settled oily sludge.

3.3 Permeate Quality from EXTRANg Hembrane Separation System

This section describes the performance of SDI's EXTRAN, Membrane Separation System.

3.3.1 Continuous Treatment

PCB, Oil and Grease, and Total Organic Carbon (TOC) results are presented for the permeate samples taken during the continuous testing.

3.3.1.1 PCB

Figure 2 shows the feed and permeate PCB concentrations in parts per billion (detection limit of 0.05 PPB) for samples taken during six days of operation. While total PCB concentrations in the feed varied from 0.09 PPB to 3.41 PPB, the permeate total PCB concentrations were below detection limits on four of the six days.

The sample taken on December 7 contained 0.05 PPB which is the detection limit; however, this value is below the permit limit of 0.10 PPB. The PCB detected in this sample was interpreted by computer matching to be a PCB with Aroclor 1254 having the closest chemical structure to the contaminant measured.

The permeate sample taken on December 8, contained 0.07 PPB of PCB with Aroclor 1254 having the closest chemical structure to the contaminant measured according to automated computer matching. This value is also below the permit limit of 0.10 PPB.

Table I1 shows the PCB data collected during the six days of testing.

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3.3.1.2 Oil and Grease

iJ

Oil and Grease was reduced by as much as 92% on December 7, with a high influent value of 926 caused by an upset in the treatment plant. Reductions of 56% (117 to 51 PPM), 55% (73 to 33 PPM), and 58% (64 to 27 PPM) were accomplished on December 8, 10, and 11 respectively.

3.3.1.3 Total Organic Carbon (TOC)

Rejection of TOC by the EXTRAN, Membrane Separation System was essentially nil. The separation efficiency of SDI's membrane is a function of the solubility of the contaminant in water. The organic compounds comprising the bulk of the TOC were undoubtedly very water soluble.

SDI has developed a Hybrid Membrane Separation System for removing highly soluble compounds from water. This system utilizes the EXTRAN, membrane in series with nanofiltration followed by carbon adsorption to meet very stringent discharge limits. Nanofiltration was tested using two types of nanofiltration membranes: each receiving permeate from EXTRAN, membrane. However, since EXTRANT, membrane alone was sufficient to reduce the PCBs to below the permit limit, this data is not presented in detail in this paper. Nanofiltration membranes reduced the TOC values in EXTRAN, permeate from 480 to 48 and 21 PPM on December 7, from 166 to 40 and 16 PPM on December 8, from 52 to 12 and 7 PPM on December 10, and from 57 to 10 and 5 PPM on December 11.

3.3.2 Batch Treatment

Analytical data describing SDI's EXTRAN,, Membrane Separation System's ability to separate and concentrate PCB from sump water and a solvent waste is presented here.

3.3.2.1 Sump Water

Figure 5 shows the results of treating sump water containing 210 PPB of PCB with sand filtration and the EXTRAN, Membrane Separation System. After sand filtration, the PCB was measured to be 10 PPB. Membrane separation achieved a permeate with non-detectable concentrations, according to a third party lab which documented a detection limit of 0.05 PPB.

During this test, 1400 gallons of PCB contaminated water were reduced to 50 gallons of concentrated PCB water, a reduction of greater than 96%. PcB was not detected in the 1350 gallons of clean water produced.

3.3.2.2 Solvent Waste

Figure 6 shows the results of treating this solvent waste, which contained surfactant, emulsifier, and carrier solvents. The sand filter effluent had a TOC of 1044 PPM, a Total Suspended Solids of

-3

3

7360, and a PCB concentration of 430 PPB.' Permeate from the EXTRAN, Membrane Separation System had non-detectable PCB at a detection limit of 0.05 PPB.

The TOC was reduced by only 29%. This low removal rate is due to the presence of surfactant and soluble solvents that increase the solubility of the mixture of contaminants. EXTRAN,, membrane separates contaminants with an efficiency that is a function of the contaminant's solubility in water.

4.0 Conclusions

SDI's EXTRAN,, Membrane Separation System is an new and innovative technology that can remove PCB from wastewater to levels which meet or exceed the requirements of current discharge permit limits.

The separation of the PCBs documented in these pilot test occurred even though large amounts of soluble contaminants were present in the wastewater.

The ability of SDI's EXTRAN,, Membrane Separation System to concentrate the PCB into a much smaller volume accomplishes waste minimization. By minimizing the volume of PCB waste, this process brings industry a means to significantly reduce the costs of offsite transportation and incineration.

SDI's Environmental Contract Services Division will continue to increase their data base through commercial operations, providing both fixed base systems for continuous treatment needs and mobile treatment services for onsite volume reduction of intermittent waste generation activities.

3.5

3

2.5 n

5 n 9 2

5 3 1.5 0

1 LL

0.5

0

FIGURE 1 : EXTRAN MEMBRANE FLOW RATES NORMALIZED TO 25 C AND 30 PSI ATMP

1 .o

I

2.1 2.8 3.9 4.9

DAYS OF OPERATING TIME

EXTRAN PERMEATE FLOW RATE

6.0 6.7

EXTRAN Flow Rate

GPM

Table I: Normalized EXTRAN Membrane Flow Rates

Water Temp F

Norma 1 i ze EXTRAN

Flow Rate GPM

EXTRAN Flow Rate

GPM Water Temp F

Normalized EXTRAN

Flow Rate GPM

0.0 0.2 0.3 0.5 0.7 0.8 1.0 1.2 1.3 1.5 1.8 1.9 2.1 2.3 2.5 2.7 2.8 3.0 3.2 3.4

2.0 1.9 1.8 1.9 1.8 1.8 1.8 1.8

1.8 1.8 1.9 1.8 1.8 1.8 1.8 1.8

1.8

1.8 1.8 1.8

60 66 66 62 64 64 63 60 65 65 65 66 63 64 65 66 64 62 64 68

2.9 2.5 2.4 2.7 2.5 2.5 2.5 2.6 2.4 2.4 2.4 2.5 2.4 2.4 2.4 2.3 2.5 2.5 2.4 2.3

3.6 3.8 3.9 4.1 4.3 4.4 4.6 4.8 4.9 5.1 5.2 5.5 5.7 5.8 6.0 6.2 6.4 6.5 6.7

1.9 2.0

1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 2.0 2.0 2.0 1.8 1.9 1.9 1.9 1.9

1.8

69 71 65 68 69 70 71 71 63 68 68 70 70 68 66 66 68 70 67

2.4 2.5 2.4 2.3 2.3 2.2 2.2 2.2 2.4 2.3 2.3 2.5 2.5 2.5 2.4 2.5 2.4 2.4 2.5

Normalized Flow Rates are calculated for 25 C and 30 PSI ATMP

FIGURE 2: FEED AND PERMEATE PCB CONCENTRATIONS PERMIT LIMIT OF 0.1 0 PPB

0.7

0.6

0.5

n

E z 0

0.4

3 0.3 z 0 0 0.2 m 0 n

0.1

0

5

1214 1215 1 215 12/6 1217 12/8 12/10 SAMPLING DATES

m FEED CONCENTRATIONS @ PERMEATE CONCENTRATIONS

--c PERMIT LIMIT CONCENTRATION OF 3.41 PPB IN FEED ON 12/8 PERMEATE CONCENTRATIONS DETECTED ON 12/7 AND 12/8 ARE AROCLOR 1254

Li

Sample Date

Li

PCB Concentrations in Feed PCB Concentrations in Permeate

PCB PCB PCB PCB Aroclor Total Aroclor Aroclor Total Aroclor

1254 1242 PCB 1254 1242 PCB ( PPB 1 ( PPB 1 ( PPB 1 ( PPB 1 ( PPB 1 ( PPB 1

12/4 12/5 12/5 12/6 12/7 12/8 12/8 12/10

ND 0.09 0.09 ND ND ND ND 0.07 0.07 ND ND ND ND 0.11 0.11 ND ND ND

0.38 0.10 0.48 ND* ND* ND* 0.13 0.10 0.23 0.05 ND 0.05 ND 3.41 3.41 ND ND ND

<1. oo** ND <1. oo** 0.07 ND 0.07 ND 0.22 0.22 ND ND ND

<1.00** = Sample size was too small to analyze with 0.05 PPB detection limit. A detection limit of 1 PPB was utilized. PCB was non-detectable at this concentration.

Aroclors 1016, 1221, 1232, 1248, 1260 were not detected in any samples.

n

H n n z 0

Y

E 5 W 0 Z 0 0 W v)

U c3 d 4 0

i5

1 000

1 00

10

1

FIGURE 3: FEED AND PERMEATE OIL & GREASE CONCENTRATIONS PCB PILOT TEST

e - 117 ---

64 73

33

\__ 71 51 --- ~

27

3A\\

12/7 12/8 12/10 SAMPLING DATES

- FEED CONCENTRATIONS ---c PERMEATE CONCENTRATIONS SAMPLES TAKEN DURING PLANT UPSET CONDITION ON 12/7

12/11

600

- 500 5 n

5 400 m

E 300 2

P v

3

4 8 200 a 6 I- loo

0

FIGURE 4: FEED AND PERMEATE TOC CONCENTRATIONS PCB PILOT TEST

\ \

- \ \ 41(r\ \

\ \

. 57

56 61 i

12/7 12/8 12/10 SAMPLING DATES

12/11

- FEED CONCENTRATIONS --t PERMEATE CONCENTRATIONS TOTAL ORGANIC CARBON (TOC) IS IN SOLUBLE FORM

FIGURE 5: PCB REDUCTION BY EXTRAN MEMBRANE WITH SAND FILTRATION PILOT TEST FOR SUMP WATER

PCB REDUCTION BY SAND FILTRATION

PCB REDUCTION BY EXTRAN MEMBRANE FEED CONCENTRATION = 21 0 PPB PERMEATE CONCENTRATION = ~0.05 PPB

FIGURE 6: PCB REDUCTION BY UCTRAN MEMBRANE WITH SAND FILTFMTION PILOT TEST FOR CONCENTRATED SOLVENT WASTE

EXT" MEMBRANE

ILTRATION (35,

PCB REDUCTION BY SAND FILTRATION

PCB REDUCTION BY EXTRAN MEMBRANE FEED CONCENTRATION = 670 PPB PERMEATE CONCENTRATION = ~ 0 . 0 5 PPB

-8%)

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