Novel membrane separation technologies and membrane processes

Study on the effectiveness of membrane separation + N2 deoxidation process for the treatment of bacteria in ballast water

Effects of the membrane separation + N₂ deoxidation process on the abundance and activity of bacteria were examined under two salinity conditions at Yangshan Port, Shanghai, China. Sequencing of 16S rRNA gene amplicons demonstrated a decrease in the diversity and activity of bacteria in fresh water and marine water, with a total removal rate of approximately 63 % and 69 %, respectively. Indicator bacteria decreased to 10 CFU·100 mL^-1, which met the IMO D-2 standard. A total of 13 potential pathogens were detected after treatment, indicating that there is still a risk of pathogenic bacteria invasion in the discharge water, particularly marine bacteria, and that the D-2 standard may be insufficient as a preventive measure against pathogenic bacteria transfer. The results will provide reference for government supervision, and will also be important for monitoring foreign bacteria and technology development.

A study on treatment efficacy of ballast water treatment system applying filtration + membrane separation + deoxygenation technology during shipboard testing

The efficacy of a BWMS with filtration + membrane separation + deoxygenation technology in treating ballast water was investigated under marine operational circumstances in five shipboard tests. The shipboard tests were carried out between August 2020 and March 2021 onboard a bulk carrier JIN HAI HUA, which sailed between Mawei, Qinhuangdao and Caofeidian in China throughout spring, summer, and fall season. The discharge results in all five tests met the D-2 standard in IMO BWMS Code, with the shortest holding time of less than three days. The BWMS does not involve application of chemicals or generation of by-products, and is considered to be an appropriate choice for certain types of ships.

A Comprehensive Review on Forward Osmosis Water Treatment: Recent Advances and Prospects of Membranes and Draw Solutes

Forward osmosis (FO) is an evolving membrane separation technology for water treatment and reclamation. However, FO water treatment technology is limited by factors such as concentration polarization, membrane fouling, and reverse solute flux. Therefore, it is of a great importance to prepare an efficient high-density porous membrane and to select an appropriate draw solute to reduce concentration polarization, membrane fouling, and reverse solute flux. This review aims to present a thorough evaluation of the advancement of different draw solutes and membranes with their effects on FO performance. NaCl is still widely used in a large number of studies, and several general draw solutes, such as organic-based and inorganic-based, are selected based on their osmotic pressure and water solubility. The selection criteria for reusable solutes, such as heat-recovered gaseous draw, magnetic field-recovered MNPs, and electrically or thermally-responsive hydrogel are primarily based on their industrial efficiency and energy requirements. CA membranes are resistant to chlorine degradation and are hydrophilic, while TFC/TFN exhibit a high inhibition of bio-adhesion and hydrolysis. AQPs are emerging membranes, due to proteins with complete retention capacity. Moreover, the development of the hybrid system combining FO with other energy or water treatment technologies is crucial to the sustainability of FO.

Superhydrophobic PDMS-pCA@CNWF Composite with UV-Resistant and Self-Cleaning Properties for Oil/Water Separation

Oil separation is crucial for avoiding environmental pollution originating from industrial wastewater and oil spillage; therefore, it is essential to develop techniques for oil separation. Herein, a new membrane with superhydrophilicity was synthesized by a facile, green, and low-cost method. First, cellulose non-woven fabric (CNWF) was modified by poly (catechin) (pCA), which has good antioxidant and antibacterial activities, to make it unaffected by ultraviolet light and to improve the stability of the structure. Then, hydrolyzed polydimethylsiloxane (PDMS) was coated on the pCA@CNWF surface via chemical bonding to make the composite hydrophobic. This durable superhydrophobic fabric can be used to separate various oil/water mixtures by gravity-driven forces with high separation efficiency (over 98.9%). Additionally, the PDMS-pCA@CNWF possesses the advantages of flexibility, high efficiency, and an outstanding self-cleaning performance, and demonstrates significant potential for applications in various environments, even under various harsh conditions, which make it very promising for the treatment of oil pollution in practical applications.