(adjusted for inflation) suggest that a steady decrease has occurred in the membrane system cost of MBRs between 2000-2006. However, an opposite trend was ...
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COST TRENDS OF MBR SYSTEMS FOR MUNICIPAL WASTEWATER TREATMENT James DeCarolis*, Samer Adham **, William R. Pearce***, Zakir Hirani**, Stephen Lacy**, Roger Stephenson** *MWH Americas, Inc. 9444 Farnham Street, Suite 300 San Diego, CA 92123 **MWH Americas, Inc. ***City of San Diego ABSTRACT Cost estimates were developed for full-scale (1 and 5 MGD) MBR facilities designed to treat municipal wastewater. These estimates included both capital and operational / maintenance (O&M) costs related to the headworks, MBR process (biological process and membrane system), chlorine disinfection and effluent storage. The costs associated with the membrane systems were developed from budgetary cost quotes provided by suppliers which have recently introduced newly developed MBR products into the U.S. market. Each of these products offer unique design features aimed towards the reduction of capital and/or operation costs. All other costs associated with the MBR facilities were developed from previous conceptual designs performed by the project team and updated using current standard engineering cost indices. Total estimated capital plus annual costs ($/1000 gal treated) for the newly developed MBR systems (1-MGD capacity) ranged from $2.02-$2.58. The range in costs directly reflects the range in membrane system and membrane replacement costs provided by the participating MBR suppliers. Evaluation of cost estimates for 1 and 5 MGD capacity MBR facilities revealed an average economy of scale of 16.5% for the non-membrane components (i.e. headworks, process basins, buildings etc.) of the MBR facility and 23.6% for the membrane system only. Comparison of the current MBR cost estimates to historical costs estimates (adjusted for inflation) suggest that a steady decrease has occurred in the membrane system cost of MBRs between 2000-2006. However, an opposite trend was observed over the same time period for costs associated with the non-membrane components of the MBR facility. The drop in membrane system costs are attributed to advancements in manufacturing and increased competition in the market place while the increased costs of facility components are attributed to the increased cost of concrete and other raw materials used for plant construction. Results from this analysis shows these opposing trends have resulted in the overall total cost of MBR facilities to be fairly level (i.e. < 10% increase) between 2000 and 2006. KEYWORDS Membrane Bioreactor, MBR, Wastewater Reclamation, Water Reuse, Wastewater Treatment
Copyright © 2007 Water Environment Federation. All Rights Reserved
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INTRODUCTION Membrane bioreactors (MBR) are a leading-edge technology being applied worldwide for municipal wastewater treatment. The municipal MBR market has grown dramatically over the past decade with facilities increasing in number and capacity. During this time, the number of suppliers offering MBR systems within the municipal wastewater market has also sky rocketed. Though the technology has become established within the municipal wastewater treatment sector, little published information exists related to the cost of MBR systems (Churchhouse and Wildgoose, 1999; Davies et al., 1998). Due to the vast growing nature of the MBR market, it is important for the industry to have current cost information of these systems for budgeting and planning purposes. An evaluation of the historical cost trends of MBR systems would also provide useful information on how technological advancements and increased competition are impacting costs. Lastly, insight on specific applications where the implementation of MBR may be economically favorable over conventional treatment alternatives would be valuable for those considering the technology to meet their wastewater treatment goals. The project team has been evaluating MBR technology related to municipal wastewater treatment for nearly a decade. This included the completion of four consecutive projects focused on the development of various MBR systems (Adham et al., 1998, 2000, 2004; DeCarolis et al., 2007). The scope of each project also included rough order cost estimates of MBR technology based on various scenarios. Upon completion of the most recent project, focused on newly developed MBR products, the project team thought it would be useful to compare the cost information from the four projects to identify possible general trends in MBR costs for the given time period. It should be emphasized the cost estimates provided in this paper represent budgetary estimates for municipal MBR facilities based on certain assumptions; however site specific factors can significantly alter MBR costs and must be considered when performing budgetary planning. The objectives of this evaluation were: •
Perform total cost estimates (capital and annual) of new developed MBR systems recently introduced in the U.S. market for various capacities (1 and 5 MGD).
•
Assess the economy of scale of associated with 1 and 5 MGD MBR facilities.
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Compare cost estimates of MBR facilities prepared between 2000-2006 to identify possible cost trends related to the membrane component as compared to other facility system components (i.e. biological basins, pre and post treatment).
METHODOLOGY Costing Approach Cost analyses were performed to estimate the capital and operational costs of full-scale MBR water reclamation facilities for treatment capacities of 1 and 5 MGD (4,000-20,000 m3/day). Costs were estimated for MBR facilities consisting of headworks, process basins, membrane system, mechanical equipment, blower and pump building, chlorination system and effluent storage. All costs except those related to the membrane systems were derived from previous estimates (Adham et al., 2004) and updated using current Engineering News Record Copyright © 2007 Water Environment Federation. All Rights Reserved
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Construction Cost Index (ENRCCI) and Chemical Engineering Plant Cost Index (CEPCI). Costs associated with the membrane systems (i.e. membranes, pumps, blowers and miscellaneous equipment along with installation) were based on recent budgetary costs estimates provided by suppliers of the newly developed MBR systems including Koch Membrane Systems, Huber Technologies Inc., Kruger Inc. and Parkson Corporation. Table 1 provides a brief description of each of these MBR products including their unique design features which may impact capital and/or operation and maintenance (O&M) costs. In order to get comparable quotes from all suppliers, a memo was created and given to each supplier, which provided specific information related to the cost request. The cost estimates of the newly developed systems were compared to historical MBR cost estimates prepared from budgetary estimates provided by establsihed MBR suppliers including Zenon, Kubota and Memcor (Adham et al., 1998, 2000, 2004). Conceptual Design Criteria Table 2 provides the MBR design criteria used for all cost estimates. The raw water quality was assumed typical of medium strength municipal wastewater with BOD5, ammonia, and TSS of 290 mg/L, 30 mg-N/L and 320 mg/L, respectively. The membrane operating conditions and reactor design criteria were based on previous conceptual MBR designs and pilot testing conducted by the project team (Adham et al., 2004; DeCarolis et al., 2007) and consultation with participating MBR manufacturers. As indicated, the instaneuous membrane flux rates ranged from 15 – 19 gfd for submerged systems and 30 gfd for external systems. The higher flux value used for external systems is due to membrane scouring which results from high recirculation of MLSS across the membrane surface which prevents accumulation of solids on the membrane surface. As shown in Table 2, cost estimates were based on MBR systems designed for complete oxidation of biodegradable organic matter (BOD5
