بسم الله الرحمن الرحیم Brine Treatment Pilot Plant at SWWT&RP (Sulaibya Waste Water Treatment and Reclamation Plant) Imad AL-Maheimid & Ahmed Kh. Al-Jasmi Research & Technology Group, KOC Surface Team
Introduction Arid and semi-arid climate areas such as Kuwait are affected by water shortages, especially shortage in the water intended for industrial applications. So in this particular climatic context, treating and reuse of any available source of wastewater will partially overcome the industrial water shortage problem. The available water sources for KOC/ HO industrial applications is: 1. Desalted Sea Water, the discussion was mad to treat 60,000 bbls/day to produce low salinity water for HO applications, this option is not an optimal one due to the low recovery, environment protection issues and logistic problems. 2. Brackish water, this also not an optimal option due to the limited reserve of brackish water in North Kuwait, also brackish water in NK is considered as strategic reserve for the state of Kuwait. 3. KNPC effluent treated water from MAB & MAA refineries is not feasible option due to the long distance and logistic problems. 4. RO treated water from SWWT&RP, this treated water is mainly used for agricultural purposes in AL-Abadaly and AL-Waffra farms. 5. RO reject (Brine) from SWWT&RP which is sustainable source water for KOC. Historical Brine specifications and fresh Brine samples specifications has been studied by KOC, numerous reputed companies were approached to explore the feasibility of treating this second generation of waste (Brine) and the conclusion mad by few companies that this water can be treated to a desired specifications.
Sulaibya WWT&RP Overview
Diagram of the general layout of the SWWT&RP
KOC Pilot Plant Location in SWWT&RP PRELIMINARY TREATMENT PLANT ARDIYA SCREENS GRIT & FOG REMOVAL MAIN PUMPS BIOLOGICAL TREATMENT PLANT SULAIBIYA 25 km MIXING SECONDARY CLARIFIERS AERATION BASINS PIPE LINE TO SLUDGE TREATMENT RECLAMATION PLANT SULAIBIYA CHLORINE REVERSE OSMOSIS TO OFF-TAKER CHLORINE CLEAR WELL ULTRA-FILTRATION RO Reject, 15% KOC Pilot Plant
Scope of Work A scope of work has been created by KOC to construct two pilot plant to explore the feasibility of treating RO Brine in order to achieve a treated water suitable for KOC industrial applications. The main objectives of the scope of work is to treat RO Brine to a desired specifications. The selected technologies were integrated with ZLD to avoid any generation of waste water (third generation of waste), by this integration, recovery ratio designed to exceed 98%. Implementing ZLD concept will reflect KOC contribution and responsibility to the community. The plant will not generate any liquid waste; hence it will provide a good opportunity to safe Kuwaiti marine life and environment. The major part of the scope covers design, construction, operation and troubleshooting of the Brine treatment pilot Plant. The feed water to Brine treatment pilot Plant were supplied from MPW (Ministry of Public Work) from Sulaibya Waste Water Treatment and Reclamation Plant (SWT&RP) RO reject.
Invited Companies More than 12 companies which shows their interest to treat this Brine were invited and the tender was released, more than 12 companies were participated in pre-tender meeting and sit visit. Due to a challenging scope of work only three companies passed the technical evaluation and the contracts were awarded to two companies.
SWWT&RP, Brine Specifications (RO Reject) Type of Analysis Effluent Water Anions NO3 Total PO4 Total Alkalinity as CaCo3 (TA) Alkalinity as HCO3 Alkalinity as Co3 ClSO4 F Total Anions as CaCo3 Cations N-NH4 K Na Mg Ca Sr Ba Fe++ Li Total Hardness as CaCo3 (TH) Total; Cations as CaCo3 Inert Species Unit Average Maximum 34.97 12.75 269.54 328.70 0.00 12 1259 0.79 3431 66.00 100.00 600.00 732.00 0.00 3000 3000 1.44 8165.3 26.50 77.80 804.1 82.20 646.0 5.50 0.05 0.21 0.03 1498 3431 75.00 127.40 2444.4 134.50 759.5 9.10 0.09 0.70 0.06 2452 5663 B SiO2 Other Quality Parameters TDS ph Temperature H2S Color Total Coliform 0.26 3.64 0.49 10.00 C Pt-Co Unit Colonies/100 ml 4306 7.24 30 0.003 137.4 787.4 7166 8.4 <40 0.10 182 38000 BOD Conductivity TSS COD Grease Residual Free Chlorine μs/cm 5.52 6535 2.05 156.3 <0.1 0.09 23.9 10890 50 1157 <6.0 19.5
SWWT&RP RO Reject Data Interpretation Careful inspection of the data reveals that 55% of the ions on the reported average Brine specifications are notorious scale species (Sulfate, Magnesium, Bicarbonate, Phosphate.Transition metals and Silica), while 66% of ions in the maximum Brine constitutes are such notorious species. The remaining ions in the Brine are mainly Sodium & Chloride (Sodium Chloride). Moreover, there are a major parameters that have the greatest impact on selecting design options and treatment equipments like, TH, TDS, Sulfate, Iron and total suspended solids. Therefore, The selected Brine treatment technology shall be: 1. Focused on proper conditioning (effective de-scaling & desalting) of Brine. 2. Integrated with Zero Liquid Discharge, ZLD.
Produced Water Specifications KOC Pilot Plant Produced Water Identified Specifications Important Parameters Concentration Unit Total Hardness (as CaCO3) <0.5 Silica (SiO2) <50 Oil & Grease <5.0 Total Dissolved Solids (TDS) 2500 ±10% Total Suspended Solids (TSS) <0.1 Dissolved Oxygen (DO) <7 PPb Sulfate Concentration <10 Iron <0.2
Why De-salting, De-scaling and Zero Liquid Discharge ZLD Since any further liquid waste generation will: 1. Reduce the quantity of the treated water from Brine (300 bbls/day) to meet the required amount of treated water for KOC industrial applications. 2. Is an environmentally prohibited because of the disposal of third generation of concentrated liquid stream is not an option. The blow down (concentrate) stream from Once Through Steam Generators OTSG or any other types of Steam Generator, which constitutes a significant amount of the conditioned feed water shall be of a sufficient quality (readily desalted and de-scaled) to be efficiently reutilized without further treatment to: 1. Recover its inherited thermal energy to pre-heat the OTSG conditioned feed water without causing any scaling problems within heat exchanger, and then, 2. Partially recycle it to supplement the OTSG feed water, and /or 3. Directly reuse for other oil fields activities such as crude oil washing and de-salting or injected into crude reservoirs for pressure maintenance (pressure support) without formation of scale deposition problems.
Contractor -1 Pilot Process Flow Diagram Brine feed water (RO reject) will be collected in storage tank prior to mix it with treatment chemicals. The precipitation step is the main one that aims at the efficient removal of the bulk of notorious species (Sulfate, Magnesium, Phosphate, Silica and Transition metals including Iron)., this invented crystallization step is based on inter-mixing brine with a suitable additives at ambient temperature and low pressure to form selective precipitation of targeted notorious species. This step is followed by press filter which is operated in low pressure (less than 100 PSI) to remove all precipitates which formed in the previous step. The calcium polishing step is based on exchanging calcium with sodium and recycling the recovered calcium to the second step to bring the total hardness in the treated water to the TH desired level, sodium chloride or sodium hydroxide can be used to regenerate the exchange of ions. TDS polishing step is based on using low-pressure loose membrane to control the TDS (2250 2750 iters) between their permeate and concentrate stream. Removal of Oxygen in the pilot plant is based on the patented membrane gas separation unit. The design of this pilot is that a recovery ratio of more than 98% have been achieved.
Contractor - 2 Pilot Process Flow Diagram Brine will be softened by using a cold lime soda ash softening process., this to promote the precipitation of Calcium Carbonate & Magnesium Hydroxide, also organic matter will be incorporated in the scale and eventually will be lowered significantly, organisms will be inhibited due to high ph. Softened/clarified effluent water ph will be adjusted by dosing suitable acid. MMF is a foreseen to insure that the feed water quality for reverse osmosis is meet. A set up of reverse osmosis consist of feed pumps, cartridge filters and anti scalant addition before the water inters the 2-stages high recovery RO system. The recovery of RO system designed to be 95% of treated water meeting KOC specifications. The remaining 5% Brine will be subjected to further treatment to achieve ZLD. The design of this pilot is that to achieve recovery ratio of 98%.
KOC, KISR and Contractor Samples Results Parameters Specifications Number of Samples Total Dissolved Solids 2250 2750 Exceeding the expectation Silica (SiO2) < 50 - Within the specifications Exceeding the expectation Oil & Grease < 5.0 - Exceeding the expectation Dissolved Oxygen, (On-line DO) < 7 PPB - - Exceeding the expectation Sulfate Concentration < 10 Exceeding the expectation Iron < 0.2 Exceeding the expectation Total Hardness (as CaCO3) < 0. 5 73 % <10 84 % < 10 Good Achievement Total Suspended Solids (TSS) < 0.1 24 % is 0 ppm 59 % < 2 ppm 33 % is 0 ppm 30 % < 2 ppm Good Achievement KOC Results KISR Results Contractor Results Overall Remarks
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