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High quality water from refinery waste
Desalination, 67 (1987) 271-282 Elsevier Science Publishers B.V., Amsterdam-Printed
271 in The Netherlands
HIGH QUALITY WATERFROMREFINERYWASTE P. Gioli, tonics
G.E. Silingardi Italia
SPA, Milan
and G. Ghiglio (Italy)
SUMMARY STANIC Industria Petrolifera of Livorno (Italy), is a major Refinery of the AGIP group which has a capacity to process 5,200,OOO tons of crude oil per year. STANIC recently decided to study the feasibility OP reclaiming the effluent from their biological waste treatment plant which is currently discharged to the sea. The reclaimed water will be used for cooling tower makeup and feed to the boiler demineralixat ion plant. ~11 refinery wastes pass thru an API separator followed by a floatation-flocculation unit. The waste is then treated in an activated sludge biological treatment plant followed by a final aeration prior to discharge. The refinery also has an existing standard clarification gravity filtration plant used to treat municipal water prior to their boiler It is anticipated that this water feed ion exchange system. treatment plant (or portions of it) will be incorporated into a waste water recovery system. Consideration was given to the use of both the reverse osmosis (RO) and the electrodialysis reversal (EDR) membrane processes. However, the demands by refinery operation on the existing water and waste treatment would result in fluctuating quality of the water available It was evident that the reclamation to feed the membrane units. plant would have to withstand short periods (up to several days) when portions of the existing treatment facilities were not available for use. These conditions could by several means: 1) 2) 3) 4) 5) 6)
result
Oil fouling Organic fouling Bacterial attack Chlorine leakage Plugging because of high Metallic precipitates.
in the possible
damage to the membranes
SD1 levels
The best chance of successful wastewater reclamation appeared to be with the EDR System which has previously demonstrated its ability to operate under several of the above conditions. Rowever, evidence did not exist of successful EDR operation under the combination of pollutants potentially existing in the Refinery’s waste water. The key unanswered question was whether the membranes had the capability of withstanding long term exposure to various pollutants. It was decided that a pilot plant study was required prior to committing to a full scale plant.
OOll-9164/87/$03.50
0 1987 Elsevier Science Publishers B.V.
212 A containerized EDR pilot plant was obtained which included a membrane module using full sized EDR components. The use of a standard sized EDR membrane stack was considered essential to develop reliable data upon which to base a full scale system. THE TEST PROGRAM is a photograph of the containerized pilot plant used at the Fig. 1. STANIC LiVOrnO refinery. The flow scheme oE the refinery's water system and the location of the EDR pilot plant is indicated in Fig. 2. Fig. 3 is the flow diagram of the pilot unit. A double filtration system was included to enable determination of the degree of pretreatment required ahead of the EDR plant to insure reliable long term operation. A multimedia, high rate filter was intended to provide general protection in the event of turbidity excursions abouve 2. JTU. The activated carbon filter was intended to remove trace hydrocarbons and other organics. The following provisions plant feed water.
were made
for chemical
dosing of the pilot
- polyelectrolyte upstream of the multimedia filter for inline flocculation if additional turbidity removal proved necessary. - sodium hypochlorite at several points upstream of the EDR unit for use as periodic shock chlorination of for continuous addition of up to 0.2 or 0.3 mg/l cl2 for bacteria control in the membrane stack. WATER
ANALYSIS
Table A. shows the typical composition biological treatment plant.
of the water
CONSTITUENT
-MAX
PH Total Hardness Calcium Total alkalinity P alkalinity Chlorides Ammonia Turbidity BOD5 COD Sulphide Total phosphate Silica Sulphate Conductivity Hydrocarbons
8.0
Organics
ppm CaC03 ppm CaC03 ppm CaC03 ppm CaC03 ppm NaCl ppm NH3 as JTU PPm PPm PPm s ppm PO4 ppm Si02 ppm so4 Micromhos/cm PP~ by IR analysis ppm KMn04
250 170 150 0 1200 10 17 -_ _0.1 0.5 14 300 2200 5 70
TABLE A. Treated
Waste Water Analysis
following AVERAGE
200 150 120 0 800/1000 2.5-3 10-14 30 50-100 -_ -_ 2-3 200-300 -2-3 50-60
the
273
1
.
214
I
, /
275
TEST RUNS It was decided to conduct three operational pilot plant tests. 1. 2. 3.
operation of biological treated effluent clarified and filtered with multimedia and activated carbon filters. operation on biological treated effluent clarified and filtered with multimedia filter only. Operation on non-clarified biological treated effluent filtered on multimedia only.
All the above was intended to check the flexibility of operation of the EDR under different realistic operating conditions, determine extent of pretreatment required and evaluate performance of the membranes under severe operating conditions due to quality of the incoming water. THE RESULTS The following columns show the summary results of the targeted tests. TEST 1 Water temperature (degree C) TDS removal (%) water yeld ($1 Energy (KWh/m3/100 mmhos removed)
18 89,2 87,0 0,027
TEST 2
TEST 3
16 91,l 86,s 0,037
23 91,9 88,O 0,041
~11 the above are average values. organics During test No. 1 NaOCl injection followed by activated carbon filtration provided an average organics reduction of 33%. NO EDR performance degradation was noted and therefore it was decided to bypass the activated carbon filter after 768 hours of operation. During test No. 2 NaOCl injection was continued but only the multimedia filter was used for pretreatment. Chlorine residual prior to the EDR unit was limited to a maximum of 0.5mg/l. The average organics level of the EDR feed increased to 54ppm and resulted in a membrane sliming tendency. A regular membrane stack flushing with a salt/caustic solution successfully controlled the slime build up and no permanent membrane degradation was noted. Test NO. 2 was ended after 1224 hours of operation. TeSt NO. 3, EDR operation with biologically treated waste but with the refinery's clarification/filtration plant bypassed, presented the most difficult operating conditions. The turbibity level at the inlet to the multimedia filter increased substantially requiring more frequent backwash. Increased sliming of the membranes was successfully controlled by stack flushing procedures. Test No. 3 lasted 576 hours.
Analyses Typical
feed and product
RAW WZR
TEST
J,4 J,2 traces none 1917 128 12 10 330 24 72 1 12,6 0.27 12 0,5 55 18 532 24 160 7
Typical
analysis
are shown
in Table
TEST 2 FEED PRODUCT 7.4
6,9 “One
1691
64 336 57 11 10,3 32 528 145
164 40 26 2,9 0,5 0,6 12,0 350 5
TABLE B EDR Feed & Product
of the brine
reject stream
B.
TEST 3 FEED PRODUCT
J,9 traces 2674 40 378 84 32 _201 694 110
7,7 none 275 24 29 4,6 1,5 _75 46 5
AnaLyses
revealed
the following:
none detected 0.01 ppm 0.05 ppm
Cr (+6) cr (t3) zn Ni CU Fe (+3) Pb Membrane
1
FEED PRODUCT
PH Hydrocarbons Conductivity Organics Na Ca Ng K HCo3 Cl so4
Typical
analyses
0.1 0.05 0.12 0.035
PPm ppm ppm ppm
Evaluation
During the pilot plant test membrane samples were removed from the stack at specified times. Samples were taken at the 500, 1500, 2200 and 2400 hour marks in order to include the effects of all three test runs. Evaluation analysis of the membranes were made on samples taken from the edge and from the flow path respectively. The results which are summarized in Table *Cm indicate that there was a small capacity loss at the beginning of the operation; such a loss is considered normal for ion exchange membranes. After 1000-1500 hours of operation the exchange capacity stabilized itselflwithout any further indication that further variation would have occured. Based on those results a projection of 5 to 7 years life for the anion membrane was considered reasonable as well as a 7 to 10 years for the cation. For reference purposes Tables *D" and "Em shows the perfomances of AR 204 anion and CR 61 cation membrane as new.
218
STANIC MEMBRANE CAPACITY SUMMARY (all as wag/dry gram or resin)
OPERATING HOlXS
Edge
1
2.61
2.26
1 3 AVG
2.24 2.46 2.35
2.01 2.19 2.10
1 3 6 AVG
2.87 2.79 2.92 2.86
2.87 2.85 2.89 2.87
1 3 AVG
2.73 2.82 2.78
2.60 2.60 2.60
500 1600
2200
2400
GRAND AVG
INFORMATION
AR204 ANION Edge F.P. DIFF
0.35
2.35
2.22
0.12
0.25
2.48 2.41 2.45
2.03 2.02 2.03
0.42
0.01
2.26 2.25 2.35 2.28
1.94 1.89 2.11 1.98
0.30
0.18
2.31 2.39 2.35
1.83 1.85 1.84
0.51
2.65
Membrane
GENERAL
CRGIAZL CATION DIFF F.P.
stage
2.36
TABLE C Analysis of Pilot Test
ON AR 204 *ANION MEMBRANES
AR 204 membranes are anion-selective membranes comprising cross-linked copolymers of vinyl monomers and containing quaternary ammonium anion The membranes are homogeneous films, cast in sheet fro exchange groups. on reinforcing synthetic fabrics. Ionics' anion-transfer membranes characteristics which is unique. Low electrical High
Rugged
of properties
and
resistance
permselectivity
High burst
have a combination This includes:
(ability
to exclude
cations)
strength
reinforced
construction
Excellent long-term stability at temperatures us to 65 C (except in hydroxide ion form and may be used for brief periods at temperatures up to 95 Cl.
279
Long term resistance to aqueous acid solutions Very high dimensional stability in solutions of different compositions. Ability to withstand harsh chemical and physical treatment to remove surface and interior deposits. (Ionics membranes may be sandpapered, steel wooled or wire-brushed, contacted with 5-10% acids, or salts and stabilized chlorine dioxide when the cleaning requirements warrant same.) Extensive use in electrodialysis installations ~11 membranes produced at Ionics are required to pass rigorous quality control examinations. Ionics membranes have been produced for more than 25 years. TYPICAL FEATURES OF 204-SXZL-386'
Reinforcing Fabric:
Weight:
Modacrylic (copolymer of vinyl chloride and acrylonitrile)
4 oz/yd2
Specific Weight:
13.7
mg/cm2
(0.5mm)
Membrane Thickness:
20 mils
Burst strength (Mullen):
100
Water content:
46% of wet resin only
capacity:
2.20 meq/dry gram resin (minimum)
psi (7.0 kg/cm21
*Terminology of Ionics, Inc. Table D contains the electrochemical properties of the anion
membrane.
OTHER PROPERTIES Water Transport:
0.120 liters per Faraday in 0.6 NaCl @ 15
sucrose
Transport:
ma/cm2
11.5
grams per Faraday from 30% sucrose in 0.2 N KC1 into 0.02 N KCL @ 16 ma/cm2.
280
VARIOUS
Concentration
Area Specific (ohm-cm2)
Specific
Resist
Conductance
ELECTROCHEMICAL
PROPERTIES
0.01. N NaCl
0.1 N NaCl
1.0 N NACl
3.0 N N&l
14.0
11
5
2
3.6 x 10-3
4.5 x lo-3
10 x lo-3
25 x 10-3
mho/cm
Current Efficiency (Fraction of current carried by anions only)
0.99
0.96
0.88
__
OTHER PROPERTIES Watert Sucrose
Transport: Transport:
0.120 liter per Faraday
in 0.6 NaCl @ 15 ma/cm2
11.5 grams per Faraday from 30% sucrose KC1 inot 0.02 N KC1 @ 16 ma/cm2.
Anion
in 0.2 N
TABLE D Membrane Prope&ies
-
281
VARIOUS
Concentration
Area Specific2Re sist. (ohm-cm 1
spec. Conductance mho/cm
Current Efficiency D+ (Fraction of current carried by cation only)
N
0.01
ELECTROCHEMICAL
NaCl
PROPERTIES
0.1 N NaCl
15
11
3.3 x 10 -3
4
4.5 x 10 -3
3.0 N NaCl
2
12.5 x 10 -3
25 x 10 -3
0.86
0.92
0.98
1.0 N NaCl
OTHER PROPERTIES
Water
Transport:
Sucrose
Transport:
0.200 liters per Faraday
in 0.6N N&l
30 grams per Faraday fray 30% sucrose into 0.2N KC1 @ 16 ma/cm
TABLE E CATION MEMBRANE
PROPERTIES
@ 16 ma/cm2 in 0.2N KC1
282 EDR WASTE Another important aspect OE this pilot study was to evaluate the composition of the EDR brine blowdown stream to see if it met the . Italian regulations for industrial waste water (LEGGE MERLI TABELLA 'A'). ~11 water analyses conducted on the brine blowdown for COD, SOD5, Coli bacteria and heavy metals indicated compliance with Table A of the regulations. Therefore the waste stream can be discharged to the sea without hazard.
CONCLUSIONS This experimentation with its highly successful result demonstrated once more the validity and flexibility of the EDR process to treat difficult water such as a biological waste from a Refinery thus opening a new application in the waste water reclamation field. ~11 the data collected during the test were used for the design of the full scale plant of 170-190 m3/h which is now under construction and expected to be on stream early 1988.
271 in The Netherlands
HIGH QUALITY WATERFROMREFINERYWASTE P. Gioli, tonics
G.E. Silingardi Italia
SPA, Milan
and G. Ghiglio (Italy)
SUMMARY STANIC Industria Petrolifera of Livorno (Italy), is a major Refinery of the AGIP group which has a capacity to process 5,200,OOO tons of crude oil per year. STANIC recently decided to study the feasibility OP reclaiming the effluent from their biological waste treatment plant which is currently discharged to the sea. The reclaimed water will be used for cooling tower makeup and feed to the boiler demineralixat ion plant. ~11 refinery wastes pass thru an API separator followed by a floatation-flocculation unit. The waste is then treated in an activated sludge biological treatment plant followed by a final aeration prior to discharge. The refinery also has an existing standard clarification gravity filtration plant used to treat municipal water prior to their boiler It is anticipated that this water feed ion exchange system. treatment plant (or portions of it) will be incorporated into a waste water recovery system. Consideration was given to the use of both the reverse osmosis (RO) and the electrodialysis reversal (EDR) membrane processes. However, the demands by refinery operation on the existing water and waste treatment would result in fluctuating quality of the water available It was evident that the reclamation to feed the membrane units. plant would have to withstand short periods (up to several days) when portions of the existing treatment facilities were not available for use. These conditions could by several means: 1) 2) 3) 4) 5) 6)
result
Oil fouling Organic fouling Bacterial attack Chlorine leakage Plugging because of high Metallic precipitates.
in the possible
damage to the membranes
SD1 levels
The best chance of successful wastewater reclamation appeared to be with the EDR System which has previously demonstrated its ability to operate under several of the above conditions. Rowever, evidence did not exist of successful EDR operation under the combination of pollutants potentially existing in the Refinery’s waste water. The key unanswered question was whether the membranes had the capability of withstanding long term exposure to various pollutants. It was decided that a pilot plant study was required prior to committing to a full scale plant.
OOll-9164/87/$03.50
0 1987 Elsevier Science Publishers B.V.
212 A containerized EDR pilot plant was obtained which included a membrane module using full sized EDR components. The use of a standard sized EDR membrane stack was considered essential to develop reliable data upon which to base a full scale system. THE TEST PROGRAM is a photograph of the containerized pilot plant used at the Fig. 1. STANIC LiVOrnO refinery. The flow scheme oE the refinery's water system and the location of the EDR pilot plant is indicated in Fig. 2. Fig. 3 is the flow diagram of the pilot unit. A double filtration system was included to enable determination of the degree of pretreatment required ahead of the EDR plant to insure reliable long term operation. A multimedia, high rate filter was intended to provide general protection in the event of turbidity excursions abouve 2. JTU. The activated carbon filter was intended to remove trace hydrocarbons and other organics. The following provisions plant feed water.
were made
for chemical
dosing of the pilot
- polyelectrolyte upstream of the multimedia filter for inline flocculation if additional turbidity removal proved necessary. - sodium hypochlorite at several points upstream of the EDR unit for use as periodic shock chlorination of for continuous addition of up to 0.2 or 0.3 mg/l cl2 for bacteria control in the membrane stack. WATER
ANALYSIS
Table A. shows the typical composition biological treatment plant.
of the water
CONSTITUENT
-MAX
PH Total Hardness Calcium Total alkalinity P alkalinity Chlorides Ammonia Turbidity BOD5 COD Sulphide Total phosphate Silica Sulphate Conductivity Hydrocarbons
8.0
Organics
ppm CaC03 ppm CaC03 ppm CaC03 ppm CaC03 ppm NaCl ppm NH3 as JTU PPm PPm PPm s ppm PO4 ppm Si02 ppm so4 Micromhos/cm PP~ by IR analysis ppm KMn04
250 170 150 0 1200 10 17 -_ _0.1 0.5 14 300 2200 5 70
TABLE A. Treated
Waste Water Analysis
following AVERAGE
200 150 120 0 800/1000 2.5-3 10-14 30 50-100 -_ -_ 2-3 200-300 -2-3 50-60
the
273
1
.
214
I
, /
275
TEST RUNS It was decided to conduct three operational pilot plant tests. 1. 2. 3.
operation of biological treated effluent clarified and filtered with multimedia and activated carbon filters. operation on biological treated effluent clarified and filtered with multimedia filter only. Operation on non-clarified biological treated effluent filtered on multimedia only.
All the above was intended to check the flexibility of operation of the EDR under different realistic operating conditions, determine extent of pretreatment required and evaluate performance of the membranes under severe operating conditions due to quality of the incoming water. THE RESULTS The following columns show the summary results of the targeted tests. TEST 1 Water temperature (degree C) TDS removal (%) water yeld ($1 Energy (KWh/m3/100 mmhos removed)
18 89,2 87,0 0,027
TEST 2
TEST 3
16 91,l 86,s 0,037
23 91,9 88,O 0,041
~11 the above are average values. organics During test No. 1 NaOCl injection followed by activated carbon filtration provided an average organics reduction of 33%. NO EDR performance degradation was noted and therefore it was decided to bypass the activated carbon filter after 768 hours of operation. During test No. 2 NaOCl injection was continued but only the multimedia filter was used for pretreatment. Chlorine residual prior to the EDR unit was limited to a maximum of 0.5mg/l. The average organics level of the EDR feed increased to 54ppm and resulted in a membrane sliming tendency. A regular membrane stack flushing with a salt/caustic solution successfully controlled the slime build up and no permanent membrane degradation was noted. Test NO. 2 was ended after 1224 hours of operation. TeSt NO. 3, EDR operation with biologically treated waste but with the refinery's clarification/filtration plant bypassed, presented the most difficult operating conditions. The turbibity level at the inlet to the multimedia filter increased substantially requiring more frequent backwash. Increased sliming of the membranes was successfully controlled by stack flushing procedures. Test No. 3 lasted 576 hours.
Analyses Typical
feed and product
RAW WZR
TEST
J,4 J,2 traces none 1917 128 12 10 330 24 72 1 12,6 0.27 12 0,5 55 18 532 24 160 7
Typical
analysis
are shown
in Table
TEST 2 FEED PRODUCT 7.4
6,9 “One
1691
64 336 57 11 10,3 32 528 145
164 40 26 2,9 0,5 0,6 12,0 350 5
TABLE B EDR Feed & Product
of the brine
reject stream
B.
TEST 3 FEED PRODUCT
J,9 traces 2674 40 378 84 32 _201 694 110
7,7 none 275 24 29 4,6 1,5 _75 46 5
AnaLyses
revealed
the following:
none detected 0.01 ppm 0.05 ppm
Cr (+6) cr (t3) zn Ni CU Fe (+3) Pb Membrane
1
FEED PRODUCT
PH Hydrocarbons Conductivity Organics Na Ca Ng K HCo3 Cl so4
Typical
analyses
0.1 0.05 0.12 0.035
PPm ppm ppm ppm
Evaluation
During the pilot plant test membrane samples were removed from the stack at specified times. Samples were taken at the 500, 1500, 2200 and 2400 hour marks in order to include the effects of all three test runs. Evaluation analysis of the membranes were made on samples taken from the edge and from the flow path respectively. The results which are summarized in Table *Cm indicate that there was a small capacity loss at the beginning of the operation; such a loss is considered normal for ion exchange membranes. After 1000-1500 hours of operation the exchange capacity stabilized itselflwithout any further indication that further variation would have occured. Based on those results a projection of 5 to 7 years life for the anion membrane was considered reasonable as well as a 7 to 10 years for the cation. For reference purposes Tables *D" and "Em shows the perfomances of AR 204 anion and CR 61 cation membrane as new.
218
STANIC MEMBRANE CAPACITY SUMMARY (all as wag/dry gram or resin)
OPERATING HOlXS
Edge
1
2.61
2.26
1 3 AVG
2.24 2.46 2.35
2.01 2.19 2.10
1 3 6 AVG
2.87 2.79 2.92 2.86
2.87 2.85 2.89 2.87
1 3 AVG
2.73 2.82 2.78
2.60 2.60 2.60
500 1600
2200
2400
GRAND AVG
INFORMATION
AR204 ANION Edge F.P. DIFF
0.35
2.35
2.22
0.12
0.25
2.48 2.41 2.45
2.03 2.02 2.03
0.42
0.01
2.26 2.25 2.35 2.28
1.94 1.89 2.11 1.98
0.30
0.18
2.31 2.39 2.35
1.83 1.85 1.84
0.51
2.65
Membrane
GENERAL
CRGIAZL CATION DIFF F.P.
stage
2.36
TABLE C Analysis of Pilot Test
ON AR 204 *ANION MEMBRANES
AR 204 membranes are anion-selective membranes comprising cross-linked copolymers of vinyl monomers and containing quaternary ammonium anion The membranes are homogeneous films, cast in sheet fro exchange groups. on reinforcing synthetic fabrics. Ionics' anion-transfer membranes characteristics which is unique. Low electrical High
Rugged
of properties
and
resistance
permselectivity
High burst
have a combination This includes:
(ability
to exclude
cations)
strength
reinforced
construction
Excellent long-term stability at temperatures us to 65 C (except in hydroxide ion form and may be used for brief periods at temperatures up to 95 Cl.
279
Long term resistance to aqueous acid solutions Very high dimensional stability in solutions of different compositions. Ability to withstand harsh chemical and physical treatment to remove surface and interior deposits. (Ionics membranes may be sandpapered, steel wooled or wire-brushed, contacted with 5-10% acids, or salts and stabilized chlorine dioxide when the cleaning requirements warrant same.) Extensive use in electrodialysis installations ~11 membranes produced at Ionics are required to pass rigorous quality control examinations. Ionics membranes have been produced for more than 25 years. TYPICAL FEATURES OF 204-SXZL-386'
Reinforcing Fabric:
Weight:
Modacrylic (copolymer of vinyl chloride and acrylonitrile)
4 oz/yd2
Specific Weight:
13.7
mg/cm2
(0.5mm)
Membrane Thickness:
20 mils
Burst strength (Mullen):
100
Water content:
46% of wet resin only
capacity:
2.20 meq/dry gram resin (minimum)
psi (7.0 kg/cm21
*Terminology of Ionics, Inc. Table D contains the electrochemical properties of the anion
membrane.
OTHER PROPERTIES Water Transport:
0.120 liters per Faraday in 0.6 NaCl @ 15
sucrose
Transport:
ma/cm2
11.5
grams per Faraday from 30% sucrose in 0.2 N KC1 into 0.02 N KCL @ 16 ma/cm2.
280
VARIOUS
Concentration
Area Specific (ohm-cm2)
Specific
Resist
Conductance
ELECTROCHEMICAL
PROPERTIES
0.01. N NaCl
0.1 N NaCl
1.0 N NACl
3.0 N N&l
14.0
11
5
2
3.6 x 10-3
4.5 x lo-3
10 x lo-3
25 x 10-3
mho/cm
Current Efficiency (Fraction of current carried by anions only)
0.99
0.96
0.88
__
OTHER PROPERTIES Watert Sucrose
Transport: Transport:
0.120 liter per Faraday
in 0.6 NaCl @ 15 ma/cm2
11.5 grams per Faraday from 30% sucrose KC1 inot 0.02 N KC1 @ 16 ma/cm2.
Anion
in 0.2 N
TABLE D Membrane Prope&ies
-
281
VARIOUS
Concentration
Area Specific2Re sist. (ohm-cm 1
spec. Conductance mho/cm
Current Efficiency D+ (Fraction of current carried by cation only)
N
0.01
ELECTROCHEMICAL
NaCl
PROPERTIES
0.1 N NaCl
15
11
3.3 x 10 -3
4
4.5 x 10 -3
3.0 N NaCl
2
12.5 x 10 -3
25 x 10 -3
0.86
0.92
0.98
1.0 N NaCl
OTHER PROPERTIES
Water
Transport:
Sucrose
Transport:
0.200 liters per Faraday
in 0.6N N&l
30 grams per Faraday fray 30% sucrose into 0.2N KC1 @ 16 ma/cm
TABLE E CATION MEMBRANE
PROPERTIES
@ 16 ma/cm2 in 0.2N KC1
282 EDR WASTE Another important aspect OE this pilot study was to evaluate the composition of the EDR brine blowdown stream to see if it met the . Italian regulations for industrial waste water (LEGGE MERLI TABELLA 'A'). ~11 water analyses conducted on the brine blowdown for COD, SOD5, Coli bacteria and heavy metals indicated compliance with Table A of the regulations. Therefore the waste stream can be discharged to the sea without hazard.
CONCLUSIONS This experimentation with its highly successful result demonstrated once more the validity and flexibility of the EDR process to treat difficult water such as a biological waste from a Refinery thus opening a new application in the waste water reclamation field. ~11 the data collected during the test were used for the design of the full scale plant of 170-190 m3/h which is now under construction and expected to be on stream early 1988.