Nitrogen removal is a critical process in water treatment plants(WIPs)and wastewater treatment plants(WWTPs).The recent discovery of a novel bacterial process,complete ammonia oxidation(comammox,CMX),has refuted a cen...Nitrogen removal is a critical process in water treatment plants(WIPs)and wastewater treatment plants(WWTPs).The recent discovery of a novel bacterial process,complete ammonia oxidation(comammox,CMX),has refuted a century-long perception of the two-step conversion of NH3to NO3-.Compared with canonical nitrifiers,CMX bacteria offer undeniable advantages,such as a high growth yield propensity and adaptability to nutrient-and growth-limiting conditions,which collectively draw attention to validate the aptness of CMX bacteria to wastewater treatment.As there has been no comprehensive review on the relevance of CMX bacteria for sustainable water and wastewater treatment,this review is intended to discuss the roles and applications of CMX in the removal of nitrogen and pollutants from water and wastewater.We took into account insights into the metabolic versatilities of CMX bacteria at the clade and subclade levels.We focused on the distribution of CMX bacteria in engineered systems,niche differentiation,co-occurrence and interactions with cano nical nitrifiers for a better understanding of CMX bacteria in terms of their ecophysiology.Conceptualized details on the reactor adaptability and stress response of CMX bacteria are provided.The potential of CMX bacteria to degrade micropollutants either directly or co-metabolically was evaluated,and these insights would be an indispensable advantage in opening the doors for wider applications of CMX bacteria in WWTPs.Finally,we summarized future directions of research that are imperative in improving the understanding of CMX biology.展开更多
Comammox Nitrospira clade A and B showed contrasting responses to citrus planting.54d9-like AOA and Nitrobacter-NOB dominated in the 5Y and 10Y soils.Nitrososphaera-like AOA and Nitrospira-like NOB dominated in the 20...Comammox Nitrospira clade A and B showed contrasting responses to citrus planting.54d9-like AOA and Nitrobacter-NOB dominated in the 5Y and 10Y soils.Nitrososphaera-like AOA and Nitrospira-like NOB dominated in the 20Y and 30Y soils.Soil pH and P content were the major factors shaping nitrifying communities.展开更多
Residual ammonium is a critical parameter affecting the stability of mainstream partial nitritation/anammox(PN/A), but the underlying mechanism remains unclear. In this study,mainstream PN/A was established and operat...Residual ammonium is a critical parameter affecting the stability of mainstream partial nitritation/anammox(PN/A), but the underlying mechanism remains unclear. In this study,mainstream PN/A was established and operated with progressively decreasing residual ammonium. PN/A deteriorated as the residual ammonium decreased to below 5 mg/L, and this was paralleled by a significant loss in anammox activity in situ and an increasing nitrite oxidation rate. Further analysis revealed that the low-ammonium condition directly decreased anammox activity in situ via two distinct mechanisms. First, anammox bacteria were located in the inner layer of the granular sludge, and thus were disadvantageous when competing for ammonium with ammonium-oxidizing bacteria(AOB) in the outer layer. Second, the complete ammonia oxidizer(comammox) was enriched at low residual ammonium concentrations because of its high ammonium affinity. Both AOB and comammox presented kinetic advantages over anammox bacteria. At high residual ammonium concentrations,nitrite-oxidizing bacteria(NOB) were effectively suppressed, even when their maximum activity was high due to competition for nitrite with anammox bacteria. At low residual ammonium concentrations, the decrease in anammox activity in situ led to an increase in nitrite availability for nitrite oxidation, facilitating the activation of NOB despite the dissolved oxygen limitation(0.15–0.35 mg/L) for NOB persisting throughout the operation. Therefore, the deterioration of mainstream PN/A at low residual ammonium was primarily triggered by a decline in anammox activity in situ. This study provides novel insights into the optimized design of mainstream PN/As in engineering applications.展开更多
基金supported by the National Natural Science Foundation of China(52000185 and 51878675)Key Research and Development Program of Shandong Province(2019JZZY020308)China Postdoctoral Science Foundation,China(2017M612807)。
文摘Nitrogen removal is a critical process in water treatment plants(WIPs)and wastewater treatment plants(WWTPs).The recent discovery of a novel bacterial process,complete ammonia oxidation(comammox,CMX),has refuted a century-long perception of the two-step conversion of NH3to NO3-.Compared with canonical nitrifiers,CMX bacteria offer undeniable advantages,such as a high growth yield propensity and adaptability to nutrient-and growth-limiting conditions,which collectively draw attention to validate the aptness of CMX bacteria to wastewater treatment.As there has been no comprehensive review on the relevance of CMX bacteria for sustainable water and wastewater treatment,this review is intended to discuss the roles and applications of CMX in the removal of nitrogen and pollutants from water and wastewater.We took into account insights into the metabolic versatilities of CMX bacteria at the clade and subclade levels.We focused on the distribution of CMX bacteria in engineered systems,niche differentiation,co-occurrence and interactions with cano nical nitrifiers for a better understanding of CMX bacteria in terms of their ecophysiology.Conceptualized details on the reactor adaptability and stress response of CMX bacteria are provided.The potential of CMX bacteria to degrade micropollutants either directly or co-metabolically was evaluated,and these insights would be an indispensable advantage in opening the doors for wider applications of CMX bacteria in WWTPs.Finally,we summarized future directions of research that are imperative in improving the understanding of CMX biology.
基金supported by the National Key Research and Development Program of China(2021YFD1700900)the National Natural Science Foundation of China(42007033)+1 种基金the Scientific and Technological Key Projects of Henan Province(232102320117)the Natural Science Foundation of Henan Province(222300420464).
文摘Comammox Nitrospira clade A and B showed contrasting responses to citrus planting.54d9-like AOA and Nitrobacter-NOB dominated in the 5Y and 10Y soils.Nitrososphaera-like AOA and Nitrospira-like NOB dominated in the 20Y and 30Y soils.Soil pH and P content were the major factors shaping nitrifying communities.
基金financially supported by the Natural Science Foundation of Shandong Province, China (No. ZR2019BEE070)a Project of Shandong Province Higher Educational Science and Technology Program (No. J18KA207)。
文摘Residual ammonium is a critical parameter affecting the stability of mainstream partial nitritation/anammox(PN/A), but the underlying mechanism remains unclear. In this study,mainstream PN/A was established and operated with progressively decreasing residual ammonium. PN/A deteriorated as the residual ammonium decreased to below 5 mg/L, and this was paralleled by a significant loss in anammox activity in situ and an increasing nitrite oxidation rate. Further analysis revealed that the low-ammonium condition directly decreased anammox activity in situ via two distinct mechanisms. First, anammox bacteria were located in the inner layer of the granular sludge, and thus were disadvantageous when competing for ammonium with ammonium-oxidizing bacteria(AOB) in the outer layer. Second, the complete ammonia oxidizer(comammox) was enriched at low residual ammonium concentrations because of its high ammonium affinity. Both AOB and comammox presented kinetic advantages over anammox bacteria. At high residual ammonium concentrations,nitrite-oxidizing bacteria(NOB) were effectively suppressed, even when their maximum activity was high due to competition for nitrite with anammox bacteria. At low residual ammonium concentrations, the decrease in anammox activity in situ led to an increase in nitrite availability for nitrite oxidation, facilitating the activation of NOB despite the dissolved oxygen limitation(0.15–0.35 mg/L) for NOB persisting throughout the operation. Therefore, the deterioration of mainstream PN/A at low residual ammonium was primarily triggered by a decline in anammox activity in situ. This study provides novel insights into the optimized design of mainstream PN/As in engineering applications.
