Warp knitted spacer microfiber biomass carrier for wastewater treatment

Abstract

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.

Development of Warp Knitted-Based Filtration Media

“…Figure 7 shows the appearance of the individual structures. The hole layout in Sample 1 was similar to that of the prototype sample [45], albeit with longer holes. Sample 2 showed regularly two-sized spaced holes, that is, long holes in odd rows and short holes in even rows.…”

“…The following material composition described in the work of [45] was successful in the pilot testing and retained:…”

“…The microfiber carrier approximated their parameters in terms of dimensions (i.e., length, width, and thickness), hole presence and arrangement, and carrier's ability to float free in the bioreactor, which is directly related to the mono and multifilament densities. The original microfiber biomass pilot carrier [45] was manufactured on a double-needle bar raschel machine, FY Rius MINI-TRONIC 806, which has six GB and gauge E12. The production was performed in a narrow-width fabric, with individual carriers in the stripes having two zones and separated by a plain-pattern cutting zone (Figure 3).…”

“…Specifically, the GB threading with spacer monofilaments was 1:1. Lapping was described in detail in the study of [45], who simultaneously published results on the efficiency of processes at wastewater treatment plants (WWTP).…”