Water filtration through wood with helical cross-flow

Abstract

A B S T R A C TThe use of wood as a filter element for water treatment can be an efficient, low-cost alternative because wood is a renewable material. Therefore, pioneering a study to examine the possibility of filtering water through wood was advantageous. In 2002, the first experiments with wood filtration in the perpendicular direction of fibers were conducted (Correa and Sens [1]). With the continuation of this study, a new research developed as presented in this article. This study was conducted in two steps by the construction of pilot systems. The first step studied deadend filtration and the second step studied helical cross-flow. The three species of wood studied were: caixeta (Tabebuia cassinoides Lam P. DC.), garapuvu (Schizolobium parahyba Vell. Blake), and pine (Pinus elliottii). The images obtained in the scanning electron microscope had the same approximations for all the three samples in the pores' direction as well as in the direction of fibers. The porosity of the wood fits within the size of the microfiltration. The observation of the wood's permeability revealed that the more porous the wood, the greater the permeability and the smaller the apparent mass. Filtration in the perpendicular direction of the fibers did not prove valuable because of its very low filtration rate and the need for high working pressure. Pine proved to be the superior option when considering the quality and production of water in the dead-end filtration. In this study, the value for wood density which is calculated to be 0.50 g/cm 3 and the porosity in the range of 40% proved to be significant factors for this treatment system. This implied a correlation between wood density and its porosity when choosing wood for water filtration. With respect to the observed wood, the pore diameter with higher performance was approximately 0.02 mm. The results in the helical cross-flow filtration generated an average removal of 70% to apparent color removal and 93% for average turbidity. The working pressure did not exceed 40 psi for a filtration rate of 15 m 3 /m².d. The helical cross-flow filtration tests involving coagulation showed enhanced results and higher efficiency. Fouling on the surface of the wood reached a depth of 5 mm, not found in 10 mm. In summary, this treatment system exhibited improved and cost-effective results with minimal power consumption due to low working pressures.

Enzyme immobilization inside the porous wood structure: a natural scaffold for continuous-flow biocatalysis

“…30 Wood and wood-based functional materials have therefore recently been used for various ow-through applications. They comprise membranes for water ltration, [31][32][33][34][35] oil/water-separation, [36][37][38] and membranes with tunable ux. 63 Moreover, owthrough catalysis has been performed with a wood-based material.…”

Rejection of micron-sized particles using beech wood xylem

“…29 Sens et al investigated the application of two tropical hardwoods (caixeta and garapuvu) and one softwood (pine) for the treatment of water. 30 Two setups, dead-end filtration and helical cross-flow, were examined by filtering raw surface water. In the dead-end filtration mode, the system was hindered by significant pressure loss generated by the wood.…”

Nanoscale Ion Regulation in Wood‐Based Structures and Their Device Applications

“…Such hierarchically porous wood structure provides an excellent platform for investigating multiscale ion transport and regulation through suitable physical and/or chemical modification, enabling its applications in various types of devices. Recently, multiscale‐engineered wood‐based structures for various ion‐based applications have been demonstrated, including ion‐intercalated cellulosic membrane with unconventional super high ion conductivity and charge selectivity by opening up sub‐nanometer molecular channels, [ 77 ] surface carbonized bilayer wood block for high efficiency continuous solar desalination, [ 153–155 ] metallic nanoparticle decorated wood membrane for high flux water treatment, [ 72,156–158 ] and electrode material hybridized wood for cost‐effective energy storage. [ 104,114,159–161 ] The benefits provided by the multiscale‐engineered wood‐based structures can be utilized toward developing ion‐water‐based emerging technologies ( Figure ), such as: 1) mechanically robust ion selective/regulation membranes for a range of energy applications (e.g., batteries, supercapacitors, salinity gradient power generation and thermal energy harvesting); ) wood‐based 2D and 3D devices that simultaneously ensure high flux and high ion‐removal efficiency for water filtration (with a particular focus on the removal of heavy metal ions) and water desalination (with a particular focus on salt‐rejection solar desalination devices); and ) functional wood‐based devices with targeted signaling and sensing functions (e.g., strain and humidity sensors, transistors, and biological systems).…”

“…Wood with hierarchically porous structure and lignocellulosic compositions offers new opportunities toward high‐efficiency and high‐throughput water filtration. [ 72,157,158 ] The multiscale pores form 3D interconnected pathways for water transport, whereas the abundant functional groups on the surface of the lignocellulosic cell wall could act as trapping sites for contaminants removal. Moreover, additional functional groups can be grafted on the cellulose backbone of the cell wall, allowing the design of various modified wood structures toward better contaminant trapping effect.…”