Processing municipal wastewaters by forward osmosis using CTA membrane

Abstract

Direct sewage filtration by forward osmosis (FO) was investigated with the aim of concentrating organic matters in sewage into a small volume of energy source. The results showed that chemical oxidation demand (COD) in the feed sewage solution was concentrated by more than 300%. Although a gradual decline in membrane flux with filtration time occurred, a flux of 3-7.4 L m -2 h -1 was still produced satisfactorily. The membrane flux decline was caused by both membrane fouling and the decline of osmotic driving force due to the salinity change in both feed solution and draw solution. The membrane fouling analysis indicated that the fouling was mainly attributed to the formation of cake layer on the membrane surface in both membrane orientation, the active layer facing the feed side (AL-FS) and the active layer facing the draw solution side (AL-DS). However, AL-FS outperformed AL-DS in terms of membrane flux and fouling. This study may offer new insight into the development of lowenergy wastewater treatment processes and energy recovery. 2 HighlightsOrganic matters in sewage can be effectively concentrated to small volume by FO.Membrane flux decline is caused by both membrane fouling and the decline of osmotic driving force.Cake layer is the dominant contributor to the membrane fouling.This study offers new insight into the development of low-energy wastewater treatment.

Improving wastewater management using free nitrous acid (FNA)

“…Specifically, microfiltration (MF) and ultrafiltration (UF) membranes are commonly implemented in membrane bioreactors, followed by further purification by nanofiltration (NF) and reverse osmosis (RO) for water reclamation (Bartels et al 2005, Garcia et al 2013. Forward osmosis (FO) is another membrane-based treatment technology that has gained interests for its ability to pre-concentrate raw wastewater for biogas production (Ansari et al 2016, Zhang et al 2014. These membrane-based technologies apply hydraulic pressure or osmotic pressure to drive water molecules to pass across the membrane which results in the formation of fouling layer on the surface and inside the pores of the membrane (Lee et al 2010, Mi and.…”

Forward Osmosis as a Pre-Treatment Step for Seawater Dilution and Wastewater Reclamation

“…Past studies have provided a baseline information that wastewater, brackish water, and seawater have great potential to augment shortage water supply, however; the energy expenditure and equipment required for purification of such water streams has limited their potential in many parts of the world [2,5]. The reuse of wastewater for other applications rather than drinking purpose is already established and examples include the irrigation of golf courses or industrial cooling [6].…”

Microalgae (Scenedesmus obliquus) dewatering using forward osmosis membrane: Influence of draw solution chemistry

“…In comparison with pressure-driven microfiltration and ultrafiltration, FO demonstrates unparalleled advantages of lower energy consumption, superior separation efficiency, potentially lower fouling tendency and more recovery of intact algal cells due to the lack of hydraulic pressure [7]. With the development of more efficient membranes, FO has been considered for various dewatering applications, such as pre-concentration of wastewater to facilitate the subsequent anaerobic digestion [8], landfill leachate dewatering [6] and concentration of fruit juice [9].…”