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Water scarcity is the next coming problem for human beings. Organics and nutrients from wastewater treatment plants, water flushing, agricultural waste, etc., causes water pollution, which leads to eutrophication of water bodies. Emerging technologies to remove and recover nutrients from wastewater and waste sludge have been widely investigated in wastewater treatment plants. The recent application of membrane technologies allows the possibility of removing and recovering nutrients to be used for sustaining agricultural yields. Several types of membranes exist, and their performances vary depending on their properties such as pore size, wettability, surface charge, etc. This chapter will highlight the applications and performances of different types of polymeric membrane processes, namely pressure-driven membranes (reverse osmosis, nanofiltration, and membrane bioreactors), osmotically driven membranes (forward osmosis), and thermally driven membranes (membrane distillation) on nitrogen and phosphorus removal and recovery. The development of hybrid systems and future membrane perspectives will also be discussed. more...

In this paper, the green synthesis of reduced graphene oxide (r-GO) nanomaterials using Callistemon viminalis leaf extract as a reducing and stabilizing agent is reported for the first time. The synthesized r-GO nanomaterials were characterized using UV–Vis, XRD, FE-SEM, TEM, and energy dispersive X-ray (EDX) analyses. The nanofilter membrane was prepared by varying the amounts of r-GO nanomaterials in a Polysulfone-N,N-dimethyl formamide (DMF) solution. The nanofilter membrane was characterized by the contact angle, atomic force microscopy (AFM), UV–Vis, and FTIR. The results confirm the formation of r-GO nanomaterials. Higher amounts of r-GO nanomaterials in the membrane show a lower contact angle, thus confirming their hydrophilic nature. Iron water filtration was performed with different amounts of r-GO nanomaterials in the membrane filter, and the water flux was smooth over an increased time period. Inductively Coupled Plasma (ICP) analysis showed a higher percentage of iron rejection (95.77%) when higher amounts (0.10 g) of r-GO nanomaterials were used in a mixed membrane (i.e., sample C). In conclusion, the findings illustrate that Callistemon viminalis mediates the synthesis of r-GO nanomaterials, which is useful in water filtration, and can be incorporated into membrane filters, since it removes iron. more...

Anaerobic membrane bioreactor was used to treat the effluent from an industrial UASB reactor receiving seafood processing wastewater. Operation in liquid circulation (LQ) was compared with the addition of granular activated carbon (LQ+GAC) and the introduction of biogas to partially replace the liquid recirculation flow (LQr+GAC+G). In all treatments, COD was removed to well under the secondary effluent standard of 120 mg/L. HRT did not cause much difference in performance but GAC addition provided superior performance in membrane fouling control. Fouling rate, the transmembrane pressure developed over time in mbar/d, was reduced by 90%, 93%, and 87% in LQ+GAC, and the additional of 54%, 55%, and 90% with biogas circulation at HRT 4, 6, and 8 h, respectively. Minimal substitution of liquid with biogas in circulation with GAC was effective and less energy intensive. SEM image showed that GAC and partial biogas supply could shift the fouling behavior. more...

The aim of this study was to compared the effect of two plasma gases, Argon (Ar) and carbon dioxide (CO2), in the acrylic acid (AAc) grafting modification of a commercial cellulose triacetate (CTA) membrane to improve water flux and anti-protein fouling properties in forward osmosis (FO) for protein recovery application. The successful grafting polymerization was evaluated by measuring the grafting yield and water contact angle, X-ray photoelectron spectroscopy (XPS) analysis, Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR) analysis. The contact angle of the CTA membrane was decreased from 64.0° to 37.1° and 36.4° by CO2 and Ar plasma gas treatment, respectively, which indicated an increase in hydrophilicity. The FO experiments were carried out in a lab-scale filtration apparatus. The effects of interfacial characteristics between membrane surfaces and model protein and polysaccharide foulants on flux decline and reversibility of foulants were compared. Ar gas was able to provide more free radicals and plasma electrons on the membrane surfaces, thus it was more effective than CO2 in increasing water flux and also decreased reverse salt flux and fouling tendency. The modified membranes had excellent anti-protein fouling properties, which makes them suitable for protein recovery applications. Using the Ar plasma modified membranes, tuna protein was concentrated from 4.5 % to 10.7 %, and excellent maintenance of water flux was achieved. more...

The present study reports the performance of a novel PVDF–Cloisite 15A hollow fiber composite membrane for the treatment of effluents containing dyes and salts through a direct contact membrane distillation (DCMD) process. The performance of the membrane was evaluated by varying several important parameters during the DCMD process which included feed properties (type of dyes, dye and salt concentration) and process conditions (feed temperature and flow rate). The experimental results showed that the in-house made membrane was able to achieve stable fluxes and excellent dye rejections (>97%) when tested with feed solutions containing dyes of different classes and molecular weights (MW), except crystal violet (CV) dye. The lower rejection resulting from a CV-containing feed is likely due to its small MW coupled with its high diffusion rate in aqueous solution. With respect to feed concentration, it is found that an increase in salt concentration in the feed solution had a negligible effect on the membrane separation performance. Increasing the dye concentration in the feed however led to lower membrane water flux owing to the deposition of dye particles on the membrane surface which resulted in severe fouling. Meanwhile, increasing the feed temperature and its flow rate could improve the membrane flux without affecting the permeate quality. When tested using a dyeing solution containing 50 ppm acid red and 1.0 M NaCl, the membrane flux was reported to enhance by 200% and 25% on increasing the feed temperature from 50 to 90 °C and the flow rate from 0.010 to 0.023 m s−1, respectively. more...

Direct contact membrane distillation (DCMD) process was applied for brine solution recovery. The energy consumption of the process was evaluated as varying feed temperature and cross flow velocity (CFV). The evaporation efficiency and energy consumption were also studied. The experiments was carried out using a hollow fiber PVDF membrane with pore size of 0.1 μm and NaCl 3.5 %wt as feed solution. The operating feed temperature and CFV were in range of 40 °C-70 °C and 0.14-0.42 m/s (laminar and transition flow region), respectively. The temperature and CFV of permeate were fixed at 20 °C and 1.97 m/s respectively. It was found that the flux rate was in function with the temperature, CFV and temperature polarization coefficient (TPC). The best result in terms of energy consumption and evaporation efficiency were obtained at CFV and temperature of 0.28 m/s and 70 °C about 188.6 W and 41.1 %, respectively. more...

The aim of this research was to examine the influence of CO2 plasma activation on CTA membrane in order to improve its the hydrophilicity. This research also investigated the enhancement of CTA membrane whether it could increase the anti-fouling in FO process. The plasma power was used varied in the range of 10-50 W and the exposure time was employed at 5-25 min, respectively. The contact angle and hydrophillicity of samples were reduced after CO2 plasma treatment. The reduction of the contact angle was presented from 64.04º to 9.38º. The optimum condition of plasma power was 20 W with the exposure time at 10 min. The result suggested that the CO2 plasma etched and changed the functional group of CTA membrane to carboxylic group and their derivative as indicated by FTIR-ATR. The results showed the decreased water flux after the treatment by CO2 plasma and the high salt leakage. Filtration experiments of BSA solution and demonstrated the low water flux fouling due to the surface roughness of modify CTA membrane. The hydrophilic membrane treatment plasma surface could reduce interactions and decreases protein absorption. more...