Abstract
Chemicals of emerging concern (CEC) in pig farm breeding wastewater, such as antibiotics, will soon pose a serious threat to public health. It is therefore essential to consider improving the treatment efficiency of piggery wastewater in terms of microorganisms. In order to optimize the overall piggery wastewater treatment system from the perspective of the bacterial community structure and its response to environmental factors, five samples were randomly taken from each area of a piggery’s wastewater treatment system using a random sampling method. The bacterial communities’ composition and their correlation with wastewater quality were then analyzed using Illumina MiSeq high-throughput sequencing. The results showed that the bacterial community composition of each treatment unit was similar. However, differences in abundance were significant, and the bacterial community structure gradually changed with the process. Proteobacteria showed more adaptability to an anaerobic environment than Firmicutes, and the abundance of Tissierella in anaerobic zones was low. The abundance of Clostridial (39.02%) and Bacteroides (20.6%) in the inlet was significantly higher than it was in the aerobic zone and the anoxic zone (p < 0.05). Rhodocyclaceae is a key functional microbial group in a wastewater treatment system, and it is a dominant microbial group in activated sludge. Redundancy analysis (RDA) showed that chemical oxygen demand (COD) had the greatest impact on bacterial community structure. Total phosphorus (TP), total nitrogen (TN), PH and COD contents were significantly negatively correlated with Sphingobacteriia, Betaproteobacteria and Gammaproteobacteria, and significantly positively correlated with Bacteroidia and Clostridia. These results offer basic data and theoretical support for optimizing livestock wastewater treatment systems using bacterial community structures.
Highlights
Wastewater from livestock and poultry breeding is rich in conventional pollutants like chemical oxygen demand (COD), total nitrogen (TN), ammonia nitrogen (NH4 + -N), and total phosphorus (TP), it contains a large number of chemicals of emerging concern (CEC), as well as antibiotics and various pathogens, all of which pose a serious threat to both public health and ecological security [1]
Huang et al created a single-stage biofilm process coupled with anammox and intracellular carbon metabolism (SAIC) for the treatment of swine wastewater after simulated digestion; the removal rate of TN in their SAIC system was 12.77% higher than it was in the reference system, and the removal rate of TP was as high as 83.7% [25]
We selected the ten most abundant phyla for analysis, as shown in Figure 5A, in our study of the wastewater treatment systems in pig farms, we found that the dominant bacteria in activated sludge were Proteobacteria, Chlorolipid, Bacteroidetes, Spirochetes, and Firmicutes, which is consistent with previous studies
Summary
The most commonly used biological treatments are the aerobic method, the anaerobic method, and the aerobic–anaerobic mixed method. In aerobic biological treatment, sequencing batch-activated sludge (SBR) is used to treat livestock and poultry wastewater; this process is commonly chosen because of its simplicity, effectiveness in Microorganisms 2021, 9, 2134. Microorganisms 2021, 9, 2134 removing COD, NH3 -N, and phosphorus, good sludge sedimentation performance, and strong adaptability to water quality and quantity changes [2]. The A/O process offers strong resistance to hydraulic shock and adapts well to high amounts of COD. It has a good removal effect on chemical oxygen demand and NH3 -N, and the effluent quality can meet the discharge standard
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