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Soil oil‐pollution is one of the most severe environmental issues at present. Shifts of soil metallome and microbiome are essential indicators for risk assessment and remediation of field soil pollutions. However, how soil metallome and microbiome react to petroleum‐contamination is not well studied. In this research, soil samples were collected from a short‐term and long‐term petroleum‐contaminated oil field. The soil physicochemical properties, metallome, microbiome, and soil microbial networks were investigated. Results showed that the contents of soil total petroleum hydrocarbon, total carbon, total nitrogen, total sulfur, total phosphorus, calcium, copper, manganese, lead, and zinc were increased by petroleum‐contamination because petroleum is rich in these elements. In contrast, the soil pH was lowered resulting from soil sulfur oxidation regardless of the petroleum pollution duration. Petroleum‐contamination also reduced bacterial and fungal α‐diversity indices because of the selective pressure of petroleum. Furthermore, bacterial α‐diversity was negatively correlated with soil total petroleum hydrocarbon content and electrical conductivity, and fungal α‐diversity was negatively correlated with soil electrical conductivity. Moreover, the relative abundances of Proteobacteria, Ascomycota, Oleibacter, and Fusarium in soil were increased by petroleum‐contamination. Network analysis showed that number of links, modules, and the network invulnerability decreased in short‐term contaminated soil, followed by the long‐term contaminated group, and the main reason should be the environmental disturbance caused by petroleum‐contamination. These results demonstrate that short‐term heavy petroleum contamination can cause shifts in soil physicochemical properties, metallome, and microbiome and assemble a less complex and vulnerable soil microbial network. Moreover, natural restoration can hardly amend soil properties and microbial network structure. This research emphasizes that the uncommonly studied soil metallome may play a vital part in the reaction of microbial communities to petroleum‐contamination. [ABSTRACT FROM AUTHOR]

[Display omitted] • The biofilm reactor maintained a high NH 4 +-N removal efficiency at 3 %–6 % salinity. • Salinity mediated the differentiation of microbial communities of biofilm and flocs. • Diffusion limitation drove microbial community assembly of the biofilm and flocs. • Positive interactions facilitated community robustness under the elevated salinity. • N conversion-related genes showed different preferences under the salinity gradient. Understanding the different biological responses to salinity gradient between coexisting biofilm and flocs is crucial for regulating the ecological function of biofilm system. This study investigated performance, dynamics, and community assembly of biofilm system under 3 %–7% salinity gradient. The removal efficiency of NH 4 +-N remained stable and exceeded 93 % at 3 %–6% salinity, but decreased to below 80 % at 7 % salinity. The elevated salinity promoted the synthesis of extracellular polymer substrates, inhibited microbial respiration, and significantly regulated the microbial community structure. Compared to flocs, biofilm exhibited greater species diversity and richer Nitrosomonas. It was found diffusion limitations dominated the microbial community assembly under the salinity gradient. And microbial network revealed positive interactions predominated the microbial relationships, designating norank Spirochaetaceae , unclassified Micrococcales , Corynebacterium, and Pusillimonas as keystone species. Moreover, distinct salinity preferences in nitrogen transformation-related genes were observed. This study can improve the understanding to the regulation of biofilm systems to salt stresses. [ABSTRACT FROM AUTHOR]

• High salinity OPWs effectively treated by pyrite-PMS coupled HAA system. • Pyrite sustained-release Fe2+ activates PMS to produce SO 4 •− and •OH to pretreat OPWs. • Ammonia and small molecular DOM were removed by heterotrophic assimilation. • FT-ICR MS revealed degradation of long-chain hydrocarbons and aromatics. • Pre-oxidation alleviated the toxicity inhibition of HAA sludge caused by OPWs. Existing conventional biological treatment techniques face numerous limitations in effectively removing total petroleum hydrocarbons (TPHs) and ammonia (NH 4 +-N) from oilfield-produced water (OPW), highlighting the pressing need for innovative pre-oxidation and biological treatment processes. In this study, a pyrite-activated peroxymonosulfate (PMS)-coupled heterotrophic ammonia assimilation (HAA) system was established to achieve satisfactory system performance for OPW treatment. Pyrite sustained-release Fe2+-activated PMS was used to produce SO 4 •− and •OH, and 71.0 % of TPHs were effectively removed from the oil wastewater. The average TPHs and NH 4 +-N removal efficiencies in the test group with pre-oxidation were 96.9 and 98.3 %, compared to 46.5 and 77.1 % in the control group, respectively. The maximum fluorescence intensities of tryptophan protein and aromatic protein in the test group declined by 83.7 %. Fourier transform ion cyclotron resonance mass spectrometry revealed that pre-oxidation degraded more long-chain hydrocarbons and aromatic family compound, whereas the HAA process produced more proteins and carbohydrates. Pyrite-PMS promoted the enrichment of ammonia-assimilating bacteria, alleviating the explosive increase in extracellular polymeric substances and reducing sludge settleability. The low cost, efficiency, green chemistry principles, and synergies of this approach make it a powerful solution for practical OPW treatment to reduce environmental impacts and promote sustainable wastewater treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Both systems achieved high N removal efficiency under varying salt ion composition. • Increasing SO 4 2− proportion improved sludge settleability, CSH and EPS content. • Increasing SO 4 2− proportion enriched AOB, genes hao and amoA in the AN system. • The dominant heterotroph in the HAA system varied with changes in salt composition. • Higher robustness and microbial cooperation in HAA system compared to AN system. The concentration and proportion of chlorine (Cl−) and sulfate ions (SO 4 2−) in actual high salinity wastewater exhibit significant fluctuations due to their diverse sources. This study compared the response of halophilic autotrophic nitrification (AN) and heterotrophic ammonia assimilation (HAA) sludges to changes in salt composition. The results demonstrated that both the AN and HAA systems maintained high ammonia removal efficiency even when exposed to mixed salt ions or pure sulfate conditions. Increasing the concentration of SO 4 2− resulted in an increase in extracellular polymeric substances content, sludge settleability, sludge hydrophobicity, and the relative abundance of Nitrosomonas in the AN system (from 2.3% to 10.4%). The dominant heterotrophic bacteria in the HAA system underwent turnover in response to changes in salt composition conditions. The robustness and the cooperation between microorganisms of the HAA system surpassed those of the AN system. This study provides scientific foundation for treating multi-ion high salinity wastewater. [ABSTRACT FROM AUTHOR]

High salinity seriously inhibits the growth and metabolism of microorganisms, resulting in poor settleability, excessive biomass loss and low treatment efficiency of biological wastewater treatment systems. The development of halophilic aerobic granular sludge (HAGS) is a feasible strategy for addressing this challenge. However, there are problems with the granulation of HAGS and the stability of granules at decreasing temperatures. In this study, granular activated carbon (GAC) with a large specific surface area and good biocompatibility was used to enhance the robustness of HAGS. The results showed that the addition of GAC shortened the granulation time from 60 d (control system) to 35 d (GAC-addition system). The proteins contents of extracellular polymeric substances (EPS) in the GAC-addition system was significantly higher (p < 0.05) than that in the control system during granulation. Satisfactory NH 4 +-N and chemical oxygen demand (COD) removal efficiencies reached more than 96% in both systems at 18–26 °C. When the operating temperature was lower than 15 °C, the GAC-addition system exhibited better NH 4 +-N removal performance (>80%) than the control system (<60%). Moreover, the abundance of almost all nitrogen metabolism-related genes in the GAC-addition system was higher than that in the control system. During the granulation process, the enrichment of functional microorganisms, including family Flavobacteriaceae , Rhodobacteraceae , and Cryomorphaceae , may promote the production of EPS by significantly upregulating (p < 0.05) the metabolic pathway "Signaling Molecules and Interaction" in the GAC-addition system. The overexpression of the nitrogen assimilation gene glnA in heterotrophic bacteria (Halomonas and Marinobacterium) may promote the conversion of inorganic nitrogen to extracellular proteins to adapt to the decreased operational temperature. Our findings confirm that GAC addition is a simple but effective strategy to accelerate granulation and enhance the robustness of HAGS in saline wastewater treatment. [Display omitted] • GAC accelerated granulation by providing carrier and increasing proteins in EPS. • The experimental system has better performance at 13–15 °C than the control system. • GAC enriched microorganisms Flavobacteriaceae , Rhodobacteraceae and Cryomorphaceae. • GAC up-regulated the metabolism pathway of "Signaling Molecules and Interaction". • High glnA abundance and robust network help HAGS adapt to decreasing temperature. [ABSTRACT FROM AUTHOR]