Removal of Diverse and Abundant ARGs by MF-NF Process from Pig Manure and Digestate

Abstract

Antimicrobial resistances are emerging as one main threat to worldwide human health and are expected to kill 10 million people by 2050. Intensive livestock husbandry, along with biogas digestate, are considered as one of the biggest ARG reservoirs. Despite major concerns, little information is available on the diversity and abundance of various ARGs in small to large scale pig farms and biogas digestate slurry in Germany, followed by their consequent removal using microfiltration (MF)–nanofiltration (NF) process. Here, we report the identification and quantification of 189 ARGs in raw manure and digestate samples, out of which 66 ARGs were shared among manures and 53 ARGs were shared among both manure and digestate samples. The highest reported total ARG copy numbers in a single manure sampling site was 1.15 × 108 copies/100 µL. In addition, we found the absolute concentrations of 37 ARGs were above 105 copies/100 μL. Filtration results showed that the highly concentrated ARGs (except aminoglycoside resistance ARGs) in feed presented high log retention value (LRV) from 3 to as high as 5 after the MF-NF process. Additionally, LRV below 2 was noticed where the initial absolute ARG concentrations were ≤103 copies/100 μL. Therefore, ARG removal was found to be directly proportional to its initial concentration in the raw manure and in digestate samples. Consequently, some ARGs (tetH, strB) can still be found within the permeate of NF with up to 104 copies/100 μL.

Comparison of antibiotic resistance genes in swine manure storage pits of Iowa, USA

“…To survey a broad range of genes, we also used a second method, which is a relative quantification method on a HT-qPCR platform. This method has recently been used by numerous studies (Muurinen et al, 2021;Fernanda et al, 2022;Flater et al, 2022;Kasuga et al, 2022;Mware et al, 2022;Samanta et al, 2022) because it allows for simultaneous presence/absence detection of numerous genes (Stedfeld). HT-qPCR is also limiting in the volume of each reaction (6.7 x 10 -3 mL vs 2 mL in conventional qPCR), which directly influences its detection limits.…”

Removal of antibiotic resistance genes during livestock wastewater treatment processes: Review and prospects

“…In wastewater treatment, membrane separation is mainly achieved by using pressure as a driving force with the pore size, electrostatic effect, and diffusion effect of the membrane (48). These processes mainly include reverse osmosis (RO), nanofiltration (NF), microfiltration (MF), and ultrafiltration (UF), which have better removal capacities with ARGs (49)(50)(51). The removal rate of ARGs by membrane separation is inversely proportional to the membrane pore size (52).…”