Evaluation Of Processes Available For Removal Of Phosphorus From Wastewater

Author : Rania Bashar
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (19 download)

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Download or read book Evaluation of Phosphorus Removal/recovery Processes During Municipal Wastewater Treatment written by Rania Bashar and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: With growing emphasis on environmental and economic sustainability worldwide, modern municipal wastewater treatment plants (WWTPs) are striving to reduce consumption of resources and ensure increased recycling and reuse of nutrients and energy contained in the wastewater. In a trade-off between enhanced P removal (to meet stringent effluent limits) and increased resource (e.g., energy, chemical) usage, it is critical for the treatment plants to be able to select the most appropriate technology. To this end, this study has combined mathematical modeling and experimental data from recent literature to perform a comprehensive evaluation of established/emerging P recovery/removal technologies considering technical, economic and energy sustainability aspects. For technical evaluations, full-scale designs of high performing P removal technologies (e.g., Modified University of Cape Towne process, Bardenpho process, membrane bioreactors, IFAS-EBPR, struvite recovery, tertiary reactive media filtration) were developed and simulated using a widely-used Windows-based process model simulating software BioWin v. 5.3 (EnviroSim Associates Ltd., Canada). The treatment configurations were evaluated in terms of performance and cost effectiveness ($/lb of P removed). Results show that the unit cost for P removal in different treatment alternatives range from $42.22 to $60.88 per lb of P removed. The MUCT BNR+ tertiary reactive media filtration proved to be one of the most cost effective configurations ($44.04/lb P removed) delivering an effluent with total P (TP) concentration of only 0.05 mg/L. Although struvite recovery resulted in significant reduction in biosolids P, the decrease in effluent TP was not sufficient to meet very stringent discharge standards. Emerging low energy mainline (LEM) treatment layouts consisting of energy efficient and innovative technologies has the potential to improve the overall sustainability of WWTPs. To evaluate the LEM treatment schemes, a configuration consisting of fine screen pretreatment, anaerobic membrane bioreactor (AnMBR) for BOD and TSS removal, reactive filter media for adsorptive P removal, and cold partial nitritation/Anammox process for N removal was simulated using operational conditions that are typical for a mid-size WWTP in the US. Our simulation results indicated that the LEM scheme could reduce the net energy requirement for treatment by about 0.46 kWh/m3 (~ 94%) compared to a conventional activated sludge system. The removal efficiencies of TN, TP and TCOD in the effluent were 93%, 90% and 94%, respectively. One-at-a-time (OAT) sensitivity analysis indicated that dominant parameters controlling energy production and consumption include temperature, wastewater influent COD, and electric efficiency of combined heat and power (CHP) engine. The LEM treatment scheme reached a break-even point (energy-self-sufficiency) at 544 mg/L COD and 38% electric efficiency of the CHP engine. The OAT analysis was further expanded using global sensitivity analysis (GSA) techniques to identify the within parameter interactions. The GSA revealed CHP efficiency has a predominantly linear (non-interacting with other inputs) impact on the net energy requirement and has the potential to be a very good control parameter in achieving energy self-sufficiency. In addition, a solution space for energy-positive operation was also identified in this study where minimum non-linear interaction between input parameters is present. Therefore, operating the treatment plant within this linear region ensures maximum control over net energy requirement, while staying within the energy positive range. The results of this study will provide guidance for researchers, municipalities, government agencies and decision-makers, and other stake-holders in choosing the most appropriate P removal option that offer the possibility to move wastewater treatment towards a sustainable, energy- and resource-positive direction.