Innovation, Excellence and Sustainability in Refinery Waste Water Management

Carlo Zaffaroni CH2M

Jitendra Patel Bapco, Bahrain

MERTC 2017, Bahrain January 2017

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Why Talking about a Waste Water Treatment?

• Importance of water in the overall Oil & Gas value chain • Specific importance of water cycle

(needs/treatment/uses/consumption/quality) in Downstream & Refining operations

• Looking for new solutions/technologies: – «Trouble-free», affordable and effective – Sustainable (from $ and Environment standpoint)

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• Bapco WWTP is a new benchmark in industrial waste water treatment At Global Water Summit 2014 held in Paris (7 April 2014), received the “Distinction Award for Industrial Water Project of the Year” competing against similar relevant and innovative projects commissioned in 2013 all over the world.

• Bapco WWTP is an example of high quality sustainable approach At MEED Awards in Dubai (12 May 2014), the project won the “Quality Project of the Year” and was named “Sustainable Project of the Year 2014” for Bahrain nation and for the entire GCC region.

A New Benchmark in Refinery Waste Water Treatment

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• Bapco - unwavering commitment to protect the environment - need for secondary waste water treatment identified

• Secondary treatment facilities - improve quality of the waste water discharge

• Earlier only primary WW treatment - API oil separators plus IAF

• Bapco’s waste water – a real treating challenge: – high temperature (up to 48°C) – high and variable salinity (TDS above 30,000 mg/l)

Introduction

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• The plant manages the spent caustic waste water (90.000 mg/l COD, 30.000 mg/l H2S, 2.500 mg/l TKN)

• Comply with challenging discharge limits, especially for nitrogen and phosphorus

• Feasibility study and Front End Engineering Design (FEED) done by CH2M, USA

• Commissioned early 2014 • CH2M started 5 year Operations & Maintenance of this unique WWTP in

May 2014, executing a win-win cooperation between Bapco & CH2M

Introduction (cont’d)

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• No large MBR for a Refinery WWTP risk of membrane fouling due to oil carryover

• BAT (Best Available Technologies) WWTP chemical sector: not possible to achieve stable nitrification if Cl- > 10,000 wppm

• Need for exotic material, seawater like, few applications in WWTP • Spent Caustic treatment: Wet Air Oxidation or other • No indirect cooling applicable for WW (fouling of HE); • Discharge limit 10 mg/l TN and/or 5 wppm TKN - challenging but feasible • Lack of flexibility of biological WWTP if load compositions change

Need to find a suitable technological solution, develop and prove it!

Context

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CH2M has been working together with BAPCO since 2008 through the following project phases: • WWTP:

– Study phase and pilot plant testing – Front End Engineering Design (FEED) – EPC package – Owner’s engineer during plant construction, startup and PGTR – O&M for 5 years, since 1 May 2014

• Water and waste water consultancy • Pre-treatment API Separator upgrade: Study Phase & FEED

Bapco & CH2M Partnership

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API Separator - Removal of floating free oil and heavy solids Induced Air Floatation (IAF) - Removal of free and emulsified oil

Pre-MBR WWTP: Primary Waste Water Treatment

API Separator IAF

Refinery oily water

to the Sea

Sludge

Skimmed oil

WWTP

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Refinery Waste Water

Parameter Minimum Average Max Month Max Day

COD kg/d 1,655 3,445 4,776 4,819 mg/L 110 181 218 201 BOD kg/d 857 1,295 1,735 1,799 mg/L 57 68 79 75 TKN kg/d 517 987 1,294 1,576 mg/L 35 52 59 66 NH3 kg/d 324 493 648 749 mg/L 22 26 30 31 TSS kg/d 150 647 1,435 1,247 mg/L 10 34 66 52 TDS kg/d 389,153 548,079 678,023 852,347 mg/L 22,837 28,786 32,758 35,550 O&G mg/L 1.5 15 29 57 H2S mg/L 0.06 9 22 54 Total Phosphate kg/d 60 76 87 96 mg/L 4 4 4 4 Ortho Phosphate kg/d 45 57 66 72 mg/L 3 3 3 3 Temperature °F 77 99 119

WWTP Influent Water Characteristics

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Parameter Monthly Average(a) Maximum(b)

COD mg/L 150 350 BOD mg/L 25 50 TKN mg/L 5 10 TSS mg/L 20 35 O&G mg/L 8 15 pH 6 to 9 Not specified Turbidity NTU 25 75 Phenols mg/L 0.5 1 Total Coliforms MPN/100ml 1,000 10,000 TOC mg/L 50 Not specified Fluorescent Petroleum Matter as MBAS mg/L 0.1 0.1

Temperature ∆T ±3ºC (±5.4 ºF) of receiving water

Environmental Specifications for Final Effluent Refinery Waste Water

(a) Average reading during 30 days (b) Maxuimum value which must not be exceeded at any time

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Plant Overview 3D Image of the WWTP

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Plant Overview (cont’d) Block Flow Diagram

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Plant Overview (cont’d) Photos

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Flow rate COD TKN WW SC IN ww IN sc IN tot OUT IN ww IN sc IN tot OUT USgpm m3/h USgpm m3/h mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l

Average 3292 ± 470 749 ± 107 2.8 ± 0.9 0.6 ± 0.2

120 ± 20

48252 ± 9748 162 ± 27 78 ± 25 14 ± 7 2688 ± 780 17 ± 7 2.8 ± 2.5

Median 3304 751 2.8 0.6 119 47516 160 76 14 2633 15 2 Max Month 3973 904 4 0.9 147 61305 198 98 22 3563 25 8

Max Day 4320 982 4.8 1.1 203 93220 287 150 55 4676 60 14

O&G NH3-N NO2-N NO3-N TDS TP IN OUT IN OUT OUT OUT IN OUT IN OUT mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l

Average 17 ± 35 0.1 ± 1 7 ± 4 0.4 ± 0.3 0.1 ± 0.2 2.6 ± 1.2 33120 ± 3318 32136 ± 2991 1 ±

2.9 0.5 ± 0.3

Median 11 0 7 0.3 0.02 2.4 31700 31735 0.6 0.5 Max Month 26 0 12 0.7 0.53 4.3 37377 36510 1.5 1.1 Max Day 445 10 37 2.9 0.78 9.3 45780 50942 9.9 1.9

Abbreviations: WW= waste water from Refinery sewer SC= spent caustic

WWTP Performance Influent and Effluent Concentration Data

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Pictures shows COD concertation, inclusive of spent caustic, in the influent and effluent of the plant.

The COD removal efficiency is:

• Average: 53%.

WWTP Performance (cont’d) COD Concentration

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The TKN removal efficiency is:

• Average: 85%.

WWTP Performance (cont’d) Influent TKN and Effluent N-NH3

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The influent O&G concentration varies mainly according to the pre-treatement unit condition.

The effluent is ultra-filtered water with very low (about zero) concetration of O&G.

WWTP Performance (cont’d) O&G Concentration

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Key aspect is the managment of incoming phosphorus variability:

• Pre-alert from Refinery process units;

• On-line analyzer monitoring.

WWTP Performance (cont’d) Total Phosphorous

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Median values:

• Sludge cake dry content: 19%;

• Total sludge produced: 8.7 ton/month;

• COD removed: 47.8 ton/month;

• Sludge Growth: 0.23 KgTSS/Kg COD rem.

WWTP Performance (cont’d) Sludge Production

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Membrane

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new membrane

Membrane (cont’d)

after 2 years of operation

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1. Maintenance Cleaning • Performed once per week, for each train • A clean-in-place process (no draining of the membrane volume) • Citric is added first, and membranes are soaked for 2 hours • After recirculation, the train is isolated again and membranes are soaked in

sodium hypochlorite for 1 hour, and then placed back on-line

Membrane (cont’d) Cleaning Cycles

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2. Short Recovery Cleaning • Performed on each train every 2-4 weeks • was introduced when the maintenance cleaning was not effective (due to high

salinity) in order to reduce the frequency of long recovery cleaning • The mixed liquor is drained and sent to the other working membrane trains • The membrane tank is filled above the membrane level using the back-pulse

pump, and membranes are then soaked in a citric acid solution for at least 2 hours

• The acid solution is drained and sent back to the equalization tank, and the membrane train is then back-pulsed to remove all the citric acid solution

• The back-pulse process is repeated using sodium hypochlorite, and membranes are soaked for 1 hour

• The sodium hypochlorite solution is drained and sent back to the equalization tank and the membrane train is put back on-line.

Membrane (cont’d) Cleaning Cycles

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3. Long Recovery Cleaning • Performed every two months, on each train • Procedure is similar to that applied for the short recovery cleaning, soaking in

citric acid is for 8 hours. • Concentration and pH are checked every 2 hours and, if needed, more acid is

added to control them • Usually during this soaking time (8 hours) other maintenance activities are

carried on e.g. inspection of the chamber, pipes, bolts and nuts

Membrane (cont’d) Cleaning Cycles

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Citric Acid Soaking Sodium Hypochlorite Soaking

Volume Concentration Time Volume Concentration Time

Litres wppm hours Litres wppm hours Maintenance Cleaning 1000 2000 2 1000 200 1

Short Recovery Cleaning

1000-1500 depending on permeability

2000-2200 ≥2 1000-2000

depending on permeability

≥200 1

Long Recovery Cleaning 1000-2000 2000-2200 >8 1000-6000 1000-1200 >8

• During cleaning, pH varies between 2.5 and 10.5

Membrane (cont’d) Cleaning Cycles

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The vertical lines indicates that recovery cleaning was performed.

Membrane (cont’d) Cleaning Cycles

Permeability Trend - Membrane Train 3

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• High peak of oil concentration was one of the main concerns, especially because of the old upstream pre-treatment.

• The incoming oil and TSS concentrations causes fouling of the plate heat exchangers A project is ongoing to replace the old API separator with a new design.

• O&M issues have been encountered with the Lithium Bromide adsorption chiller unit as vacuum holding issues and other intensive maintenance required activities

Major O&M Challenges

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• The variability in the load and other constituents in the waste water result in foaming in the biological system, especially if additional air is required to handle a heavy influx of TKN. In these cases significant amounts of anti-foam must be added and installation of an antifoam spray system is being considered to improve its actual distribution

Major O&M Challenges (cont’d)

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• Bapco WWTP with MBR as a core treatment process is operating successfully for more than 2 years, and the final effluent meets all the discharge limits since the unit startup in 2014.

• Despite several issues faced in the beginning, the robust design and the conservative cleaning schedule allowed meeting the treatment target and to run the WWTP successfully within the normal operating conditions.

• Spent caustic is not only being treated successfully in the MBR, but it also provides alkalinity for nitrification and organic carbon for denitrification.

• Membrane cleaning procedures were slightly modified to restore the flux. A third short recovery cleaning was also implemented for efficient membrane operation.

Concluding Remarks

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• The observed WWTP sludge yield for the two year period was approximately 0.23 kg TSS/kg COD removed.

• The dewatered cake solids concentration using the centrifuge for the two year period was approximately 19%.

Concluding Remarks (cont’d)

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Thank You.