The deposition of nanofibers onto a traditional filtration medium and their effects on filtration efficiency

Traditional filtration media composed of fibers with sizes on the micrometer scale have difficulty filtering particles a little smaller than 300 nm. Even though nanofibrous materials are able to capture these particles and can have excellent filtration efficiency, their widespread use continues to be inhibited by several obstacles, particularly an excessive pressure drop and the inability to form self-supporting filtration membranes. We have prepared two types of composite materials, namely an ultra-thin nanofibrous layer made of polyurethane or nylon with various fiber diameters and pore areas. Scanning electron microscopy was used for their characterization. The nanofibrous layer was deposited directly onto a traditional melt-blown polypropylene filtration fabric with a very low area weight of 30 g/m2, which facilitates handling and bypasses the need for the layer to be self-supporting. Moreover, a fine polyethylene mesh was added as a separate layer to prevent humidity from passing through the filtration material as well as to cover fabrics. The filtration efficiency and the pressure drop of the prepared materials were determined. The results showed that the incorporation of a nylon nanofibrous layer with smaller fiber diameters and pore areas leads to a significant increase in the filtration efficiency (92%) against the most penetrating particles, the critical size of which decreased to 50 nm, while the pressure drop was comparable to the pressure drop of a commercially available FFP2 respirator. The prepared filtration material could be used to manufacture respirators.

Surface Charge Effects on Adsorption of Solutes by Poplar and Elm Biochars

Elm and poplar are two tree species that can provide a large amount of low-value feedstock for biochar production due to their rapid growth rate (poplar), and susceptibility to disease and/or infestation (both elm and poplar). Biochar has been studied recently as filtration medium for water purification, as it provides a renewable alternative to activated carbon. In this work, the adsorption efficiency of biochars made from elm and poplar as a function of pyrolysis temperature were studied by ultraviolet (UV) adsorption of dyes with positive, neutral, and negative charges to determine what factors had the greatest effect on adsorption of these dyes. It was found that conductivity of the biochars increased with pyrolysis temperature, and that this factor was more important than surface area in terms of adsorbing charged dyes. Both elm and poplar biochars were not effective in adsorbing neutral dyes. This research demonstrates that elm and poplar biochars adsorb charged (either positively or negatively) solutes more efficiently than uncharged ones because they carry both charges themselves. Therefore, these biochars would make excellent candidates as renewable filtration media for charged contaminants.

Manganese Removal by Biofiltration Using Activated Carbon-barium Alginate-entrapped Cells: Morphology, Durability, Settling Velocity, and Treatment Efficiency

Occurrence of manganese in water supplies causes colored water and pipe rusting in water treatment and distribution systems. Moreover, consumption of manganese-contaminated water may lead to neurotoxicity in humans. Biofilters have the potential to alleviate the manganese issue through bio-oxidation, particle separation, and adsorption processes. Biofiltration performance can be enhanced by augmentation of the manganese-oxidizing bacterium entrapped in polymeric materials. This study aimed to investigate the potential of barium alginate-entrapped cells supplemented with powdered activated carbon (PAC) for manganese removal. Streptomyces violarus strain SBP1, an effective manganese-oxidizing bacterium, was selected. The experiments were divided into 2 parts, including 1) characterization of barium alginate bead and 2) manganese removal testing. Effect of PAC content (1, 5, and 10% w/v) in the entrapment material on bead morphology, bead durability, and settling velocity (relative to a filtration medium) was investigated. Micro-structural observation using a scanning electron microscope showed that the PAC was distributed through intra-porous structure of the beads. The PAC-supplemented barium alginate beads improved durability (up to three-time higher Young’s modulus values). The PAC-supplemented barium alginate beads gave similar settling velocity compared to a filtration medium. The manganese removal efficiencies by the PAC-supplemented beads (no cells) ranged from 48 to 53%. Based on barium alginate bead characterization and manganese removal performance, the bead with 5% PAC content was selected for cell entrapment. The investigation revealed that the entrapped cells achieved faster manganese removal rate than free cell system. The findings from this study indicated high potential of the entrapped cells for use in future biofilter applications.

Life Cycle Assessment of Various Filtering Media for Greywater Treatment Using Greenwall Filtration System

The risk of global water crisis is becoming more evident due to the increase in overall global urban population and reduction of freshwater availability. Treated greywater using greenwall technology was identified as a potential method to produce water for non-potable applications. The filtering media in greenwall technology acts as a growing media for the plants and as a filtration medium. In this study, the pollutant removal efficiency and environmental impacts associated with two filtering medias (coir pith and perlite) were investigated. The coir pith was found to have higher removal efficiencies for both COD and TSS removal compared to perlite. Besides, the life cycle of each filtering media used for greywater treatment in greenwall technology were compared. Coir pith was found to have a higher environmental impact on global warming potential (1.19568 kg CO2 eq.) and freshwater consumption (0.00066295 m3), while perlite was found to have a higher environmental impact in terms of fossil depletion (0.045562 kg oil eq.) and terrestrial ecotoxicity (0.008508135kg 1,4-DB eq). In conclusion, this study provides a framework for in-depth data analysis of the entire life cycle of filter media and a decision-making tool for the selection of suitable filtering media for greenwall filtration system.

Geo Physicochemical Properties for Soil Base Subsurface Constructed Wetland System

Wetland land system is the natural way for the treatment of wastewater. Constructed wetland system (CWs) is a traditional way for treatment. CWs are considered as secondary or tertiary treatment systems. CWs provide good landscape and better habitat quality for the community. Various types of media are used in Constructed Wetland Systems. Literature shows that various soils have the potential to filtration medium (in substratum) in Horizontal Flow Subsurface Constructed Wetland System (HFSCWs) for wastewater treatment. Soil should have few environmental and geo tech properties. Soil provides the root zone in rhizome network for the vegetation in CWs. Soil provides the absorbent media not only in the HFSCWs but Vertical Flow Constructed Wetland system (VFCWs) also. As per Environmental Protection Agency (EPA), various properties of filter media were described. This review base on types of commonly used wetland, filter media, plant use and geo physicochemical parameters of filter media.

Study of the "aquifer-well" geotechnogenic system using precision observations at the water intakes of Tyumen region

An express research method is presented for studying the geotechnogenic system "aquifer-well" in solving problems of hydrogeology. The express method is based on the use of precision water level measurements. The scope of its application and relevance in modern conditions аre shown. Express pumping was performed at water bodies of Tyumen region, where an assessment (revaluation) of fresh underground water reserves was carried out. A comparative analysis of the results of express and traditional methods showed good convergence. The use of express pumping in the practice of hydrogeological research on small water bodies is the only tool for obtaining raw materials for the calculation (recalculation) of fresh groundwater reserves and makes it possible to reduce material costs when performing pilot filtration work. The recording of changes in the values of the conductivity coefficient by means of precision measurements of the water level during express pumping in monitoring studies allows you reliable and timely detection of changes in the filtration medium.

Removal of sewage phosphorus by adsorption and mineral precipitation, with recovery as a fertilizing soil amendment

Clear sand adsorbs 15–35% total phosphorus (P) from septic tank effluent, but P is mobilized when low-P effluent is applied. Amorphous P compounds formed by alkali aluminate chemical addition may also be subject to leaching. Crystalline mineralization is the desired end effect that isolates P thoroughly from the water resource. Using new low-energy iron electrochemistry (EC-P process), dissolved ferrous iron reacts with sewage phosphate ions (PO4) and precipitates onto filtration medium as vivianite [Fe3(PO4)2·8H2O], as identified by scanning electron microscopy and X-ray diffraction and predicted from Eh–pH–aHPO42− phase relations. Removal rates of 90–99% in sand, soil and synthetic foam filters are obtained. The precipitation of vivianite demonstrates that P can be immobilized quickly and without intermediary adsorption phases, as with Fe-rich soils. Vitreous silicate material (VSM) or rockwool that traps and precipitates mineral P after EC-P treatment was investigated as a means of P reuse as a fertilizing soil amendment. Comparative soil leaching and growth studies using corn plants demonstrate that the VSM alone reduces P losses from soils, and that VSM which has received EC-P effluent is equivalent to or better than commercial superphosphate fertilizer.