Hybrid osmotically assisted reverse osmosis and reverse osmosis (OARO-RO) process for minimal liquid discharge of high strength nitrogenous wastewater and enrichment of ammoniacal nitrogen

Ralph Rolly Gonzales; Keizo Nakagawa; Kazuo Kumagai; Susumu Hasegawa; Atsushi Matsuoka; Zhan Li; Zhaohuan Mai; Tomohisa Yoshioka; Tomoyuki Hori; Hideto Matsuyama

doi:10.1016/j.watres.2023.120716

Hybrid osmotically assisted reverse osmosis and reverse osmosis (OARO-RO) process for minimal liquid discharge of high strength nitrogenous wastewater and enrichment of ammoniacal nitrogen

Water Res. 2023 Nov 1:246:120716. doi: 10.1016/j.watres.2023.120716. Epub 2023 Oct 9.

Authors

Affiliations

¹ Research Center for Membrane and Film Technology, Kobe University, Kobe, Japan.
² Research Center for Membrane and Film Technology, Kobe University, Kobe, Japan; Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan. Electronic address: k.nakagawa@port.kobe-u.ac.jp.
³ Research Center for Membrane and Film Technology, Kobe University, Kobe, Japan; Department of Chemical Science and Engineering, Kobe University, Kobe, Japan.
⁴ Research Center for Membrane and Film Technology, Kobe University, Kobe, Japan; Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan.
⁵ Environmental Management Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan.
⁶ Research Center for Membrane and Film Technology, Kobe University, Kobe, Japan; Department of Chemical Science and Engineering, Kobe University, Kobe, Japan. Electronic address: matuyama@kobe-u.ac.jp.

PMID: 37837900
DOI: 10.1016/j.watres.2023.120716

Abstract

Ammoniacal nitrogen (NH₄N) is a ubiquitous nitrogen pollutant found in wastewater, which could cause eutrophication and severe environmental stress. It is therefore necessary to manage NH₄N by enrichment and recovery for potential reuse, as well as to regulate the amount of environmental discharge. Hybridization of membrane-based processes is an attractive option for further enhancing water and nutrient reclamation from waste streams; thus, in this present work, a hybrid osmotically assisted reverse osmosis (OARO) and reverse osmosis (RO) process was demonstrated for subsequent ammoniacal nitrogen enrichment and wastewater discharge management. Using a commercially-available cellulose triacetate membrane module, model and real wastewater containing approximately 4,000ppm NH₄N were effectively dewatered and enriched to a final NH₄N content of 40,300ppm. This corresponds to enrichment of around 10 times and approximately 90% pure water recovery. The effective combination of both processes resulted in high efficiency, as well as economical and energy-saving benefits, as shown by the process performance and our preliminary techno-economic analysis. The specific energy consumption of the hybrid process projected to operate at a capacity of 2,000 m³h^-1 was determined to be 8.8kWh m^-3, or 0.56kWh kg^-1 NH₄Cl removed/recovered for an initial feed solution containing around 15,300ppm NH₄Cl. Hybrid OARO and RO operation was able to achieve satisfactory enrichment by the OARO process and obtaining clean water by the RO process. The hybrid OARO-RO process has shown great potential as a suitable end-stage membrane-based process for wastewater dewatering and NH₄N enrichment and recovery toward a circular economy and environmental management, as well as clean water recovery.

Keywords: Ammoniacal nitrogen; Minimal liquid discharge; Osmotically assisted reverse osmosis; Resource recovery; Reverse osmosis; Wastewater treatment.

MeSH terms

Membranes, Artificial
Nitrogen
Osmosis
Waste Disposal, Fluid / methods
Wastewater*
Water
Water Purification* / methods

Substances

Wastewater
Nitrogen
Membranes, Artificial
Water