Search

Titanium salt coagulant, as a new type of water treatment agent, has been widely studied, but most researches do not consider its effect on the biological treatment. In this study, different doses of TiCl 4 were added to the biological phosphorus removal (BPR) system to investigate the impact of TiCl 4 on BPR. The results showed that the addition of TiCl 4 not only significantly reduced the phosphorus concentration in effluent (below 0.5 mg/L), but also kept it stable. Moreover, the sedimentation performance of activated sludge was improved, which was superior to the control group. According to the results of flow cytometry (FCM), a small amount of TiCl 4 significantly improved the bioactivities, but excessive dosage caused inhibition. When the dosage of TiCl 4 below 20 mg/L, polyphosphate accumulating metabolism (PAM) was strengthened. In addition, the richness of microbial community and the relative abundance of Candidatus Accumulibacter clades also increased. However, when the dosage reached 60 mg/L, the relative abundance of Candidatus Competibacter increased and the BPR system was deteriorated. This study suggests that the addition of appropriate concentration of TiCl 4 can realize the synergistic enhancement of biological and chemical phosphorus removal in sewage treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Tetrasphaera are polyphosphate accumulating organisms (PAOs) that play an important role in enhanced biological phosphorus removal (EBPR) from wastewater. The effect of a wide range of temperature changes (1-30 °C) on phosphorus removal, metabolism and clade-level community structure of Tetrasphaera-dominated PAOs was investigated. At 10 °C, the bioactivities of Tetrasphaera-dominated communities were obviously inhibited and the EBPR efficiency was only 73 %. Yet at 20-30 °C, EBPR efficiency reached 99 % and the relative abundance of Tetrasphaera was up to 90 %. The temperature variation changed the community distribution of Tetrasphaera clades, which was possibly a main reason for EBPR performance. Amino acids and PHA with different contents were intracellular metabolite of Tetrasphaera-dominated communities during phosphorus release and uptake at different temperatures. Moreover, Tetrasphaera fermented protein and amino acids and released VFAs. The outcomes suggested the great potential of Tetrasphaera-PAOs in the treatment of wastewater with varying temperatures and limited carbon sources., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Achieving enhanced biological phosphorus removal dominated by Tetrasphaera utilizing waste activated sludge (WAS) as carbon source could solve the problems of insufficient carbon source and excessive discharge of WAS in biological phosphorus removal. Up to now, the sludge reduction ability of Tetrasphaera remained largely unknown. Furthermore, the difference between traditional sludge fermentation and sludge fermentation dominated by Tetrasphaera was still unclear. In this study, two different sequencing batch reactors (SBRs) were operated. WAS from SBR-parent was utilized as sole carbon source to enrich Tetrasphaera with the relative abundance of 91.9% in SBR-Tetrasphaera. PO 4 3- -P removal and sludge reduction could simultaneously be achieved. The effluent concentration of PO 4 3- -P was 0, and the sludge reduction efficiency reached about 44.14% without pretreatment of sludge. Cell integrity detected by flow cytometry, the increase of DNA concentration in the sludge supernatant and decrease of particle size of activated sludge indicated that cell death and lysis occurred in sludge reduction dominated by Tetrasphaera. Stable structure of activated sludge was also damaged in this process, which led to the sludge reduction. By analyzing the excitation-emission matrix spectra of extracellular polymeric substances and the changes of carbohydrate and protein concentration, this study proved that slowly biodegradable organics (e.g., soluble microbial byproduct, tyrosine and tryptophan aromatic protein) could be better hydrolyzed and acidized to volatile fatty acids (VFAs) in sludge fermentation dominated by Tetrasphaera than traditional sludge fermentation, which provided carbon source for biological nutrients removal and saved operation cost in wastewater treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Polyaluminium chloride (PAC) was added into the biological phosphorus removal (BPR) systems to investigate the populations of polyphosphate and glycogen accumulating organisms (PAOs and GAOs). Typical BPR performed under Al:P of 1:1, while BPR almost disappeared at Al:P of 4:1. Even with high PAC addition, PAOs still existed in systems. Compared to the BPR with no PAC addition, the relative abundance of Accumulibacter, Tetrasphaera and Commnadaceae slightly increased with PAC addition. The relative abundance of Dechloromonas was improved from 0.87% to 3.82%, becoming the most dominant PAOs. The specific structures of Accumulibacter and Tetrasphaera changed little, but that of Dechloromonas and Comamonadaceae significantly altered. Regarding the GAOs, the relative abundance of Competibacter and Defluviicoccus significantly declined. Additionally, PAC addition effectively inhibited the proliferation of filamentous bacteria, indicating its potential in inhibiting the sludge filamentous bulking. This study provided guidance for the selection of the phosphorus removal process and operational conditions., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Many of the most invasive plants are clonal, and clonal integration has been proposed as an important mechanism promoting invasiveness. When the availabilities of two essential resources are negatively correlated in space, clonal integration may benefit clonal plants through division of labor. We hypothesized that environments with reciprocal patchiness of light and soil water may induce division of labor, and nutrient addition may increase both the division of labor and the benefits of clonal integration. To test this, we grew pairs of connected and disconnected ramets of the clonal invader Mikania micrantha under negative spatial covariance of light and soil water such that the proximal ramets were grown under high light and low soil water conditions and the distal ramets were grown under low light and high soil water conditions. In half of the ramet pairs, both ramets of a pair received a nutrient addition treatment. The results showed that connection decreased the root to shoot ratio in proximal ramets and increased it in distal ramets, indicating that division of labor was induced. In addition, connection increased the root to shoot ratio of distal ramets more under high soil nutrient conditions than under low soil nutrient conditions, indicating that nutrient addition increased the division of labor. Connection increased plant biomass at the whole clonal fragment level, and this increase was larger under high soil nutrient conditions than under low soil nutrient conditions. This study showed, for the first time, that in environments with reciprocal patchiness of two essential resources, the capacity for division of labor and its influence on plant performance may depend on the availability of a third essential resource. Because invasive plants often can acquire a larger amount of soil resources than native plants, our study may also contribute to the understanding why clonality is related to invasiveness., (Copyright © 2018 Elsevier B.V. All rights reserved.)

• Dynamic response of Accumulibacter to environmental conditions was established. • Transcriptional activity of Accumulibacter clades was related to EBPR performance. • Variable Accumulibacter clades functioned with different response duration in EBPR. • Transcriptional analysis could ensure the genes and bacteria that really worked. The dynamic response mechanism of Candidatus Accumulibacter clades to environmental factors in enhanced biological phosphorus removal (EBPR) was unclear. This study investigated the relationship between the transcriptional responses of Candidatus Accumulibacter clades and environmental dynamics. Results suggested that Candidatus Accumulibacter clade IIA only responded in initial 20 and 30 min of P-release and P-uptake stage, respectively, and was also the first clade to stop responding among the six Candidatus Accumulibacter clades. Clade IIC and IID responded at rising stage of P-release and P-uptake rate. Clade IA and IIB responded at decreasing stage of P-release and P-uptake rate. The transcriptional response duration of clade IIF was the longest, which constantly responded throughout anaerobic, anoxic and oxic phase. The transcriptional responses of Candidatus Accumulibacter clades to environmental dynamics revealed the microorganisms actually working in P-release and P-uptake, and gave a new insight into the transcriptional responses related to the EBPR performance. [ABSTRACT FROM AUTHOR]