The development of novel biomass carriers is an option for increasing the efficiency of processes at wastewater treatment plants (WWTPs). Biomass carriers support the adhesion of specific bacteria and the subsequent biofilm formation. As part of this work, a new type of microfibrous biomass carrier with a unique sandwich structure was developed. Technologically, the structure of the biomass carrier is based on warp knitted spacer fabric created on a double-needle bar machine. Commercially available microfiber materials were used to achieve a large specific surface area (SSA) and internal porosity of the carrier to ensure high microorganism capture. A yarn combination was chosen to reach a final carrier density slightly lower than water to float in an aqueous environment. As the first, was developed and described a three-dimensional warp knitted microfiber biomass carrier. Next, were evaluated the properties of this carrier for post nitrification on WWTPs and compared with commercially available biomass carriers. Testing biofilm (using respirometry, real-time polymerase chain reaction, and next-generation sequencing) growing on the developed carrier in a post-nitrification laboratory reactor showed excellent adhesion, stability, and abundance of microorganisms. A high rate (more than 95%) of ammonia nitrogen removal was achieved in post-nitrification, and molecular genetics methods confirmed the high concentration of nitrifying bacteria in the biofilm. The developed three-dimensional microfiber biomass carriers have proven their functionality and can be considered an advance in biofilm processes.

No abstract

This article is focused on the comparison of the reliability of the results obtained by image analysis (newly proposed evaluation method) with well-known methods of evaluation of long-term corrosion resistance of glass fibers in an alkaline environment (pH > 12). The developed method is based on the analysis of scanning electron microscopy images (diameter and structures on the fiber surface). An experiment (52 weeks) was performed to evaluate two types of glass fibers: anticorrosive glass fibers (ARGFs) and E-glass fibers (EGFs). Three media were used to treat the fibers (23 ± 2 °C): H2O, Ca(OH)2, and K2SiO3. The ARGFs’ tensile strength did not reduce; a decrease by 68% was observed for EGFs in H2O. Tensile strength decreased by 32% and 85–95% in K2SiO3; by 50% and 64% in Ca(OH)2 for the ARGF and EGF, respectively. Statistical analysis was performed to validate the reliability and plausibility of the developed method. ARGFs and EGFs did not show any relationship between the fiber diameter and weight in H2O; however, the linear trends may predict this relationship in Ca(OH)2 and K2SiO3. For the ARGF and EGF, the cubic trend was suitable for predicting the change in fiber weight and diameter over time in Ca(OH)2 and K2SiO3.

Basalt fibers are increasingly emerging as reinforcement of composite materials. Their use is purely technical, depending on the properties of the basalt fibers: thermal, chemical and electrical resistance, good mechanical properties and low environmental impact. Basalt fibers reinforced plastics penetrate to automotive, aerospace, building construction and building reparation, industrial applications, oil industry and sport tools. The topic of the paper is to find out the mechanical properties of basalt fiber reinforced plastic (BFRP) and to create a model of split pin that is originally made of steel. Basalt woven fabric was selected for this experiment. Two weave - plain and twill was available. Tensile strength test was made in three basic directions: 0°, 90° and 45°. Epoxy resin was used for production composite plates with one layer basalt reinforcement. Tensile strength test of composite plates provided input parameters for numerical model of small composite part - split pin. Real composite split pin will produced according to modeling properties. Weight decrease was supposed, this assumption was confirmed.

No abstract