Water recovery from sewage using forward osmosis

Abstract

This research is part of the Sewer Mining project aimed at developing a new technological concept by extracting water from sewage by means of forward osmosis (FO). FO, in combination with a reconcentration system, e.g. reverse osmosis (RO) is used to recover high-quality water. Furthermore, the subsequent concentrated sewage (containing an inherent energy content) can be converted into a renewable energy (RE) source (i.e. biogas). The effectiveness of FO membranes in the recovery of water from sewage has been evaluated. Stable FO water flux values (>4.3 LMH) were obtained with primary effluent (screened, not treated) used as the feed solution. Fouling of the membrane was also induced and further investigated. Accumulated fouling was found to be apparent, but not irreversible. Sewer Mining could lead to a more economical and sustainable treatment of wastewater, facilitating the extraction of water and energy from sewage and changing the way it is perceived: not as waste, but as a resource.

Processing municipal wastewaters by forward osmosis using CTA membrane

“…As shown in Figure 6a and 6b, the initial membrane flux of AL-DS is 7.4 L m -2 h -1 , being 7.5% higher than that of AL-FS. These results are consistent with other FO membrane studies [14,17]. [17].…”

“…The rejection rates of various pollutants in wastewater by FO membrane have been reported in some recent publications [14,15,25,26]. The present study aimed to investigate the feasibility of FO of concentrating the organic matters from energy recovery points of view.…”

“…The FO membrane was a cellulose triacetate (CTA) membrane from Hydration Technology Innovations (HTI). It has an asymmetric structure comprised of a dense functional layer and a porous support layer with an embedded polyester mesh [14,21]. The sewage was collected from sewer lines at the St Lucia Campus of The University of Queensland, which contained 400-800 mg/L of total suspended solid (TSS) and 300-600 mg/L of chemical oxygen demand (COD).…”

“…Several studies have also demonstrated the process advantages of FO in wastewater treatment. For instance, Lutchmiah et al investigated water recovery from primary effluent of WWTP by FO and found that it was technically feasible to effectively remove most of the pollutants for clean water production [14]. Cath et al studied FO filtration of secondary and tertiary treated effluent and claimed that FO could be an alternative process for water production [15].…”

Effects of Transmembrane Hydraulic Pressure on Performance of Forward Osmosis Membranes

“…TMP effects on FO membrane fouling were previously explored; however, they only supplemented a study on water recovery from sewage − it lacked a methodical experimental investigation and laboratory analyses. 11 The current study focuses on water flux, reverse salt flux (RSF), inorganic and organic feed ion rejection, and bidirectional solute flux, all of which have been thoroughly investigated in the past; 1,19−22 however, prior studies have not considered membrane performance under elevated TMPs. Three commercial membranes were tested and experimental conditions followed standardized methods whenever possible while still addressing the objectives of this study.…”