Application of flotation as a pretreatment process during desalination

Combined coagulation-disk filtration process as a pretreatment of ultrafiltration and reverse osmosis membrane for wastewater reclamation: An autopsy study of a pilot plant

The development of novel reverse osmosis (RO) membranes resistant to multiple types of fouling is a need to secure clean water production and meet rising water demands. In this paper, the RO membrane surface-functionalized with antibacterial graphene oxide (GO) and antiscalant maleic acid was prepared and tested. The polymerization of maleic acid on the GO functionalized RO membrane was achieved using microwave radiation. The membrane surface characterization showed a decrease in membrane surface roughness from 74.7 nm to 69.0 nm and an increase in membrane hydrophilicity as the contact angle decreased from 41.7 ± 4.50 to 22.0 ± 1.10. The modified membrane was tested against inorganic scaling and biofouling, and the results demonstrated that the modified membrane has improved resistance to multiple fouling types as compared to the unmodified RO membrane. When tested in the presence of calcium sulfate scaling solution (inorganic fouling), the normalized permeate flux was found to be stable at 0.91 and 0.95 for 0.01 and 0.02 wt% maleic acid-modified RO membranes, respectively. Moreover, the modified membranes also demonstrated bacteriostasis rates of 96.1 %–97.1 % showing their anti-bacterial characteristics. Both types of membrane fouling (inorganic and biofouling) were also studied simultaneously, and the results showed that the RO membranes with dual capabilities can inhibit both mineral formation and biofilm growth concurrently.

Le dessalement des eaux par osmose inverse: l'expérience de Véolia Water

Manuscript for: Journal of Environmental Chemical Engineering New insights into the influence of ultrafiltration pretreatment on reverse osmosis membrane fouling during urban sewage reclamation: Interaction between extracellular polymeric substances and inorganic foulants

New pretreatment media filtration for SWRO membranes of desalination plants

Techno-economic evaluation of various RO+PRO and RO+FO integrated processes

Novel Tri Hybrid Desalination Plants

Pressure-retarded osmosis (PRO) and forward osmosis (FO) have been proposed to integrate with seawater reverse osmosis (RO) in order to reduce the overall energy consumption of desalination. However, their economic advantages in comparison to conventional RO have not been validated. This chapter aims to use well-developed mass transfer and economic models to investigate the technical and economic feasibilities of four potential RO and PRO/FO hybrid processes. They are (1) RO and open-loop PRO (referred to as RO+oPRO) to harvest the osmotic energy using energy recovery devices (ERDs), (2) RO and closed-loop PRO (RO+cPRO) to harvest the osmotic energy and recycle the pressurized and diluted brine as seawater feed to RO, (3) RO and FO post-dilution (RO+FO) to dilute and recycle the RO brine, and (4) seawater feed pre-dilution by FO before entering RO (FO+RO) to reduce the RO operating pressure. RO+oPRO takes advantage of the osmotic energy and reduces the RO operating expenditure (OpEx), but requires huge additional capital expenditure (CapEx) that renders it uneconomical. RO+cPRO reduces both OpEx and CapEx because it eliminates the need of additional ERDs and downsizes the seawater intake, pretreatment, and brine discharge units. RO+FO achieves the same CapEx saving as RO+cPRO but at an increased OpEx. FO+RO dilutes the seawater, reduces the RO operating pressure and significantly lowers OpEx, especially at a high RO recovery.

Inorganic scaling, governed by complex organic-inorganic interactions, presents a pervasive challenge in aqueous environments with broad implications for engineering systems. Using reverse-osmosis (RO) desalination as a model platform, we investigate how mixed organic foulants influence inorganic gypsum scaling at membrane-water interfaces. Representative proteins, humic substances, and polysaccharides are employed as model foulants to reveal their roles in modulating gypsum crystallization behavior. By integrating advanced in situ, time-resolved synchrotron X-ray scattering within the concentration polarization layer-a region typically inaccessible to conventional characterization techniques-with modelling, spectroscopic, and imaging analyses, we track the evolution of gypsum scaling from nanoscale precursors to mature crystals. Our findings reveal that different classes of organic foulants regulate gypsum crystallization through distinct mechanisms, ranging from inhibiting precursor aggregation in the bulk solution to altering interfacial physicochemical properties that govern the kinetics of heterogeneous nucleation and growth. These findings provide molecular-level insights into the coupled dynamics of organic fouling and inorganic scaling, advancing mechanistic understanding of crystallization at functional interfaces. Such insights offer guidance for the rational design of anti-scaling strategies in engineering systems.

Reverse osmosis on open intake seawater: pre-treatment strategy

An attempt was made to reclaim and recover palm oil mill effluent (POME) for water reuse using tubular ultrafiltration (UF) and reverse osmosis (RO) membranes. The reclaimed water was compared with the final discharged water of the local mill. The raw POME was first subjected to a physical pre-treatment process to remove the content of organic matter and suspended solids. The pre-treatment process was coupled with membrane technology (UF and RO) to reclaim the clean water from POME. From the combined techniques of UF (5 bar) and RO (30 bar) the results showed that the turbidity and BOD5 were reduced by 99% and 98.9%, respectively. Compared to the final discharged POME, this suggested method gives a significant difference in BOD5 and turbidity. The final permeate of RO was found to comply with the standards for water reuse. Therefore, the combined UF and RO method is a viable alternative and has a great potential for use in the palm oil industry.

In reverse osmosis seawater treatment process, membrane fouling can be mitigated by degrading organic pollutants present in the feed seawater. The present study evaluates the effectiveness of employing solar photocatalysis using TiO2/ZnO/H2O2 to pretreat reverse osmosis (RO) feed seawater under solar irradiation. Process optimisation and performance evaluation were undertaken using response surface methodology-desirability function and RSM integrated with genetic algorithm (RSM-GA). Statistical analysis was performed to determine the interactive relationships and main effects of input factors such as TiO2 dosage, H2O2 dosage, pH, reaction time and ZnO dosage. The performance evaluation was determined in terms of percentage removal of total organic carbon (TOC) and chemical oxygen demand (COD). The obtained optimum values using RSM-GA evaluation for TOC and COD removal were found to be 76.5% and 63.9%, respectively. The predicted RSM-GA results correspond well with the experimental results (TOC removal = 73.3%, COD removal = 61.2%). Utilization of renewable solar energy coupled with optimum utilisation of nanophotocatalysts enables this technique to be a unique treatment process for RO pretreatment of seawater and membrane fouling mitigation.

Pilot study of [formula omitted] hybrid systems

Effect of feed spacer arrangement on flow dynamics through spacer filled membranes

The effect of surficial function groups on the anti-fouling and anti-scaling performance of thin-film composite reverse osmosis membranes