Enhancement of peak flux capacity in membrane bioreactors for wastewater reuse by controlling the backwashing strategy

Significance 

Extensive research has led to the development and increased use of membrane bioreactors in wastewater treatment. Going with the current global trends, future demands are expected to escalate due to the numerous advantages including small footprint, high-quality effluent and flexible design that allows for upgrading. Generally, wastewater treatment constitutes depth filtration, physicochemical treatment, and disinfection. On the other hand, dissolved solids and organic contaminants require additional reverse osmosis to eliminate. However, membrane bioreactors, which were chosen to replace direct membrane filtration, are limited to specific cases. Consequently, their expensive operational costs and high energy requirements, determined by the types of fouling control, are significant disadvantages in their applications.

In a recently published literature, several methods including dynamic control systems have been developed to reduce energy consumption in membrane bioreactors. Alternatively, fouling control through automatic backwashing have been used to improve process productivity. Therefore, researchers have identified controlling the backlash frequency as an efficient way of controlling the residual fouling in membrane bioreactors.

To this end, University of La Laguna researchers: Dr. Enrique González, Dr. Oliver Díaz, Elisabet Segredo-Morales, Dr. Luis Rodríguez-Gómez, and Dr. Luisa Vera recently developed a backwashing control system for effective control of the peak flow capacities in submerged membrane bioreactors. In particular, they investigated the possibility of monitoring the conditions of the peak flux using the developed membrane bioreactors. Their work is currently published in the research journal, Industrial and Engineering Chemistry Research.

Briefly, the research team initiated their experimental work by cross-examining the influence of transmembrane setpoint value on residual and reversible fouling. Consequently, the experimental tests were carried out in different unit sizes and peak conditions. To actualize their study, a case study was performed to compare the results of the developed backwash mode to its conventional counterparts. Eventually, the new control system was validated by testing the optimal conditions and comparing to the long-term in a pilot-scale membrane bioreactor.

The authors observed that the alternative operation mode demonstrated the feasibility of its efficiency in controlling the fouling as compared to the conventional methods. This further resulted in higher process productivity ranging from 14-16%. In addition, from the long-term tests, it was worth noting that the controlled mode was capable of achieving sustainable operation at high peak flux and peak periods which were recorded as 70 L/h m2 and 6 hours respectively. However, during the short-term tests, low transmembrane set-point values resulted in insignificant effects on process performance.

In summary, the study successfully presented an efficient automatic backwashing control system for enhancing the process performed in a membrane bioreactor. It enables determination of the degree of the membrane fouling by adjusting the filtration length in relation to the transmembrane setpoint value. Altogether, the proposed framework offers immense promises in advancing the design and operation of membrane bioreactor for efficient and effective treatment of wastewater.

Enhancement of peak flux capacity in membrane bioreactors for wastewater reuse by controlling the backwashing strategy - Advances in Engineering

About the author

Enrique González

Assistant professor in Chemical Engineering at the Chemistry Section of Faculty of Science, La Laguna University since February 2017. 10 years of post-doctorate experience in academic and industrial research in wastewater treatment technology. Co-investigator on two Spain research council-sponsored programs on membrane bioreactors. Research member in 7 contracts or research agreements with other local institutions or water companies. Key research topics have concerned biological and membrane processes applied to wastewater treatment and reuse. Most research papers have been focused in developing membrane bioreactor technology, through the development of new operating strategies, advanced understanding of fouling mechanisms and application of rotating membranes.

Email: [email protected]

About the author

Oliver Díaz López

Since January 2017, Plant manager to SUEZ WTS in the “Sistema Comarcal de Abastecimiento Urbano del NorOeste de Tenerife”. External collaborator of Department of Chemical Engineering at the Chemistry Section of Faculty of Science, La Laguna University. Key research topics have concerned biological and membrane processes applied to tertiary wastewater treatment. Most research papers have been focused in developing membrane bioreactor technology, through the development of new operating strategies and advanced understanding of fouling mechanisms.

Email: [email protected]

About the author

Elisabet Segredo Morales

Technologist in the Radioactive Installation of the Anchieta Campus of the University of La Laguna since June 2018. Pre-Doctoral researcher in the PhD program in health sciences since 2016. Research focused on the field of formulation of injectable systems for the improvement of bone regeneration in osteoporotic conditions and in the release of bioactive substances (marked with radioactive isotopes or not) inside these systems. Member of the working team on one Spain research council-sponsored programs in injectable systems for bone regeneration in osteoporosis.

Email: [email protected]

About the author

Luis E. Rodríguez-Gómez

Luis E. Rodríguez-Gómez is Associate Professor of Chemical Engineering at Universidad de La Laguna since 2003, where he obtained his PhD in 1998. His doctoral thesis about processes occurring during reclaimed wastewater transportation was awarded for the Chemistry faculty and Universidad de La Laguna. He currently teaches courses on the environmental sciences and chemical engineering undergraduate programs. He has been a researcher at the Technological Institute of the Canary Islands between 2000 and 2002.

He has been an active member of the Water Treatment and Reuse Research Group at Universidad de La Laguna since 1993, where he has been involved in several research projects on strategies for the inhibition of sulfide generation during reclaimed wastewater transportation and membrane technologies for wastewater reclamation and reuse. He also acts as scientific reviewer of several specialized journals and is co-author of several indexed scientific papers and international conferences in this area.

Email: [email protected]

About the author

Luisa Vera

Dr Luisa Vera is associate professor of University of La Laguna (Tenerife- Canary Islands), Spain. She is a Chemist (1993) and Doctor in Chemistry (1998) from Universidad de La Laguna (ULL). Her doctoral thesis about microfiltration membranes as tertiary treatment of secondary effluent from activated sludge wastewater treatment plant received two awards from ULL. She currently teaches at the Chemical Engineering department of Universidad de La Laguna (ULL) since 2003. Her contractual relationship with ULL was part-time until 2011, and then she moved to full time dedication. Her professional experience has been especially related to the Research and Development (R&D) Division of Technological Institute of the Canary Islands (ITC); first, as Project Technician and Head Section of Water Department (2002-2009) and later as Head of the Department of Promotion of Research and Technological Development (ITC) (2009-2011).

The main research areas of Prof. Vera are membrane technologies as advanced treatment and membrane bioreactors for wastewater treatment and reuse. Especially, she is focused on understanding membrane fouling mechanisms, modelling and to design novel strategies for membrane fouling control. She has published more than 32 scientific papers (27 Q1, h-index 13), 13 book chapters and contributed to more than 50 communications to specialized conferences. She has also participated in 14 competitive R&D&I projects and has supervised 4. In addition, she has been involved in 12 contracts with public and private institutions and water enterprises.

Email: [email protected]

Reference

González, E., Díaz, O., Segredo-Morales, E., Rodríguez-Gómez, L., & Vera, L. (2018). Enhancement of Peak Flux Capacity in Membrane Bioreactors for Wastewater Reuse by Controlling the Backwashing Strategy. Industrial & Engineering Chemistry Research, 58(3), 1373-1381.

Go To Industrial & Engineering Chemistry Research

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