Lei Yang,Xu-Hui Wang,Shen Cui,Yong-Xiang Ren,Jie Yu,Ning Chen,Qian Xiao,Lin-Kai Guo,Rui-Hua Wang
A novel strain NP5 with efficient heterotrophic nitrification, aerobic denitrification and phosphorus accumulation ability was isolated and identified as Pseudomonas putida strain NP5. The removed ammonium and phosphate were mainly converted into intracellular components by assimilation, and negligible nitrification intermediates and N 2 O were accumulated during heterotrophic nitrification. In addition, the optimal conditions for nutrient removal were: succinate as carbon source, C/N 10, P/N 0.2, temperature 30 °C, salinity 0% and shaking speed 160 rpm. Besides, strain NP5 possessed an exceptional heavy metal and nanoparticles resistance. Cr 6+ was found to be the most toxic among the tested metals, and it could be removed simultaneously. Moreover, an obvious phosphorus release was observed under anaerobic condition, and repeated exposure to the anaerobic/aerobic conditions could significantly improve the nutrient removal. Furthermore, the successful expression of key enzymes for nitrogen and phosphorous removal provided additional evidence for possibility of simultaneous nitrification, denitrification and phosphorus removal.
Xiuwen Qian,Xiaoyu Ji,Chunni Yan,Juan Huang,Yufeng Wu,Xinyue Wang
Modified basalt fiber (MBF) has been employed as biological carrier to strengthen wastewater treatment. However, few studies focused on the superiority of different MBFs and their microbial mechanisms. In this study, after surface coating and chemical grafting, four MBFs and BF were applied as carriers in contact oxidation reactors. Surface roughness and area of MBFs increased in relation to original BF. Compared to BF group, MBFs could improve nutrients removal performance and stability, probably owing to impacts on microbial community structure. Specifically, calcium coating (Ca-MBF) contributed to the highest ammonium removal in average (72.25%), due to the relative more stimulation on Nitrosomonas and Nitrospira . Improvement on nitrification in Ca-MBF group resulted in the most significant increase of total nitrogen removal by 9.72% (p < 0.05) compared to BF. In contrast, chemical grafting was more inclined to enhance denitrification, particularly in PEI-MBF group, which was 34.62% higher (p < 0.05) than BF. The most enrichment on denitrification bacteria was also observed in PEI-MBF group (51.29%), including Zoogloea , Flavobacterium , and Acinetobacter , causing promotion on microbial denitrification. Besides, chemical grafting brought about more phosphate accumulating organisms like Thauera , Acinetobacter , and Pseudomonas , increasing total phosphorus removal compared to BF by 4.27–18.53%. Nevertheless, the highest phosphorus removal was discovered with Ca modification, inconsistent to the lowest microbial abundance, suggesting that more physical absorption sites by Ca modification was the major reason for enhancement on phosphorus removal. This work provided insights into application potential of different modified BFs for wastewater treatment.
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