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The need for multifunctional, robust, reusable, and high-flux filters is a constant challenge for sustainable water treatment. In this work, fully biobased and biodegradable water purification filters were developed and processed by the means of three-dimensional (3D) printing, more specifically by fused deposition modelling (FDM).The polylactic acid (PLA) – based composites reinforced with homogenously dispersed TEMPO-oxidized cellulose nanofibers (TCNF) or chitin nanofibers (ChNF) were prepared within a four-step process; i. melt blending, ii. thermally induced phase separation (TIPS) pelletization method, iii. freeze drying and iv. single-screw extrusion to 3D printing filaments. The monolithic, biocomposite filters were 3D printed in cylindrical as well as hourglass geometries with varying, multiscale pore architectures. The filters were designed to control the contact time between filter’s active surfaces and contaminants, tailoring their permeance.All printed filters exhibited high print quality and high water throughput as well as enhanced mechanical properties, compared to pristine PLA filters. The improved toughness values of the biocomposite filters clearly indicate the reinforcing effect of the homogenously dispersed nanofibers (NFs). The homogenous dispersion is attributed to the TIPS method. The NFs effect is also reflected in the adsorption capacity of the filters towards copper ions, which was shown to be as high as 234 and 208 mg/gNF for TCNF and ChNF reinforced filters, respectively, compared to just 4 mg/g for the pure PLA filters. Moreover, the biocomposite-based filters showed higher potential for removal of microplastics from laundry effluent water when compared to pure PLA filters with maximum separation efficiency of 54 % and 35 % for TCNF/PLA and ChNF/PLA filters, respectively compared to 26 % for pure PLA filters, all that while maintaining their high permeance.The combination of environmentally friendly materials with a cost and time-effective technology such as FDM allows the development of customized water filtration systems, which can be easily adapted in the areas most affected by the inaccessibility of clean water.

Azo dyes and Chlorinated Organic Compounds (COCs) like trichloroethylene (TCE) are environmental contaminants found in textile industry effluents and groundwater sites respectively. Both compounds are carcinogenic to humans and hazardous to the environments they contaminate and are difficult to treat by conventional wastewater processes. In this study, electrocatalytically active nanocomposite membranes were fabricated and evaluated for their ability to remove azo dyes. Nano zero-valent iron (nZVI) particles were grown and stabilized within a network of dispersed single and double-walled carbon nanotubes (SW/DWCNTs), and this mixture was filtered onto the surface of a microfiltration polyethersulfone (PES) support membrane to form a porous, conductive, reactive surface nanocomposite. These catalytic surface nanocomposites were tested as a cathode alongside a graphite anode with -2 V applied for their ability to remove methyl orange (MO) dye in both a batch system and a continuous dead-end filtration system. In a well-mixed batch, it was found that complete removal of 0.25 mM MO (7.5 mMoles in 30 mL) by the charged membranes occurred within 2–3 h of operation. The performance of these nZVI-SW/DWCNT cathodes alongside controls suggests that the application of an applied current regenerates the spent reactivity of the embedded iron nanoparticles. Systems using nZVI-SW/DWCNT membranes achieved ∼ 87 mol % removal of methyl orange and demonstrated a 2.7 times greater removal rate than batch tests of analogous parameters, and 1.6 times greater than other continuous tests using membrane surface composites that lacked nZVI. Furthermore, the application of voltage to the membrane thin film surface composite increases the transmembrane flux through system, allowing for increased throughput at a given feed pressure. The results of these experiments show promise in the continuous removal of contaminants from wastewaters through reductive degradation, such as azo dyes and chlorinated organic compounds. Continuous regeneration of nZVI reactivity on a membrane surface offers substantial advantages over single-use approaches for the treatment of azo dyes and COCs in solution.