The authors present a comprehensive numerical study on the lateral response of pile foundations in sands with a constant relative density. The influence of the pile configuration (length (L) diameter (D) and flexural rigidity), load eccentricity (h), sand type and relative density (Dr) was investigated. This discussion provides some additional insights on the lateral response of large diameter monopiles in uniform sand by combining the authors work with the observations in Wang et al. (2021) and Richards et al. (2021).

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Marine microorganisms have an inherent advantage in the treatment of saline wastewater due to their halophilic properties. Ammonium assimilation is the most important and common nitrogen conversion pathway in the ocean, which means that it may be a suitable nitrogen removal strategy under high salinity conditions. However, the targeted construction of engineering microbiomes with ammonium assimilation function for nitrogen recovery has not been realized. Here, we constructed four halophilic ammonium assimilation microbiomes from marine microbial community under varying chemical oxygen demand (COD) to nitrogen (COD/N) ratios. The regulation of COD/N ratio on microbial self-assembly was explored at the phenotypic, genetic, and microbial levels. The results of nitrogen balance tests, functional genes abundance and microbial community structure confirmed that the microbiomes regulated by different COD/N ratios all performed obligate ammonium assimilation functions. >93% of ammonium, 90% of TN, 98% of COD, and 82% of phosphorus were simultaneously removed by microbial assimilation under the COD/N ratio of 20. COD/N ratios significantly affected the self-assembly of microbiomes by selectively enriching heterotrophic microorganisms with different preference for organic carbon load. Additionally, the increase of COD/N ratio intensified the competition among species within the microbiome (the proportion of negative connections of microbial network increased from 5.0% to 24.4%), which may enhance the stability of community structure. Taken together, these findings can provide theoretical guidance for the construction and optimization of engineering microbiomes for synergistic nitrogen removal and recovery.

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The contradiction between theoretical metabolism of ammonium assimilation and experiential understanding of conventional biosystems makes the rational optimization of the ammonium-assimilating microbiome through carbon to nitrogen (C/N) ratios perplexing. The effect of different C/N ratios on ammonium-assimilating biosystems was investigated in saline wastewater treatment. C/N ratios significantly hindered the nutrient removal efficiency, but ammonium-assimilating biosystems maintained functional stability in nitrogen conversions and microbial communities. With sufficient biomass, higher than 86% ammonium and 73% phosphorus were removed when C/N ratios were higher than 25. Ammonium assimilation dominated the nitrogen metabolism in all biosystems even under relatively low C/N ratios, evidenced by the extremely low abundances of nitrification functional genes. Different C/N ratios did not significantly change the bacterial community structure of ammonium-assimilating biosystems. It is anticipated that the ammonium-assimilating biosystem with advantages of clear metabolic pathway and easy optimization can be applied to nutrient removal and recovery in saline environments.

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Wastewater with high salinity is one of the major challenges for conventional wastewater treatment. Although nitrogen management is vital for wastewater treatment, efficient strategies for nitrogen recovery and removal from saline wastewater remain challenging. Here we propose microbial ammonium assimilation to achieve efficient nitrogen removal and recovery into biomass from saline wastewater without gaseous nitrogen release opposite to the conventional wastewater treatment,. We find one marine bacterium Psychrobacter aquimaris A4N01 with the ability to form sedimentary granular biofilms that can be engineered to construct an efficient ammonium-assimilating microbiome followed the bottom-up design. We demonstrate that the microbiome removes ammonium through assimilation without reactive nitrogen intermediates and gaseous nitrogen emission, according to the functional gene abundance and nitrogen balance. More than 80% of ammonium, total nitrogen and total phosphorus are removed and recovered into biomass, with more than 98% of COD removed from saline wastewater. As one prototypic microbe to form ammonium-assimilating biofilms, Psychrobacter aquimaris A4N01 plays key role in nutrient metabolism and microbiome construction. We stress that ammonium assimilation with a clear and short pathway is a promising method in future saline wastewater treatment and sustainable nitrogen management.@en