Synchronous removal of ammonia nitrogen, phosphate, and calcium by heterotrophic nitrifying strain Pseudomonas sp. Y1 based on microbial induced calcium precipitation

Simultaneous removal of calcium, phosphorus, and bisphenol A from industrial wastewater by Stutzerimonas sp. ZW5 via microbially induced calcium precipitation (MICP): Kinetics, mechanism, and stress response

The biological treatment of complex industrial wastewater has always been a research hotspot. In this experiment, a salt-tolerant strain Stutzerimonas sp. ZW5 with aerobic denitrification and biomineralization ability was screened, and the optimum conditions of ZW5 were explored by kinetics. The removal efficiencies of nitrate (NO3--N), bisphenol A (BPA), phosphorus (PO43--P), and calcium (Ca2+) were 94.47 %, 100 %, 98.87 %, and 83.04 %, respectively. The removal mechanism of BPA was the adsorption of microbial induced calcium precipitation (MICP) and extracellular polymeric substances (EPS). Moreover, BPA could weaken the electron transfer ability and growth metabolism of microorganisms and affect the structure of biominerals. At the same time, the stress response of microorganisms would increase the secretion of EPS to promote the process of biomineralization. Through nitrogen balance experiments, it was found that the addition of BPA would lead to a decrease in the proportion of gaseous nitrogen. This experiment offers novel perspectives on the treatment of industrial effluents and microbial stress response.

Simultaneous removal of ammonia nitrogen, calcium and cadmium in a biofilm reactor based on microbial-induced calcium precipitation: Optimization of conditions, mechanism and community biological response

With the enhancement of environmental governance regulations, the discharge requirements for reverse osmosis wastewater have become increasingly stringent. This study proposes an innovative approach utilizing heterotrophic nitrification and aerobic denitrification (HNAD)-based biomineralization technology, combined with coconut palm silk loaded biochar, to offer a novel solution for resource-efficient and eco-friendly treatment of reverse osmosis wastewater. Zobellella denitrificans sp. LX16 were loaded onto modified coir silk and showed removal efficiencies of up to 97.38, 94.58, 86.24, and 100% for NH4+-N (65 mg L-1), COD (900 mg L-1), Ca2+ (180 mg L-1), and Cd2+ (25 mg L-1). Analysis of the metabolites of microorganisms reveals that coconut palm silk loaded with deciduous biochar (BCPS) not only exerts a protective effect on microorganisms, but also enhances their growth, metabolism, and electron transfer capabilities. Characterization of precipitation phenomena elucidated the mechanism of Cd2+ removal via ion exchange, precipitation, and adsorption. Employing high-throughput and KEGG functional analyses has confirmed the biota environmental response strategies and the identification of key genes like HNAD.

Loofah sponge crosslinked polyethyleneimine loaded with biochar biofilm reactor for ecological remediation of oligotrophic water: Mechanism, performance, and functional characterization

The removal of complex pollutants from oligotrophic water is an important challenge for researchers. In this study, the HCl-modified loofah sponge crosslinked polyethyleneimine loaded with biochar (LS/PEI@biochar) biofilm reactor was adapted to achieve efficient removal of complex pollutants in oligotrophic water. On the 35 d, the average removal efficiency of chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), calcium (Ca2+), and phosphate (PO43--P) in water was 51, 95, 81, and 77 %, respectively. Additionally, it effectively used a low molecular weight carbon source. Scanning electron microscopy (SEM) results showed that the LS/PEI@biochar biocarrier had superior biofilm suspension performance. Meanwhile, analysis of the biocrystals confirmed Ca2+ and PO43- removal through the generation of CaCO3 (calcite and vaterite) and Ca5(PO4)3OH. This study demonstrated that the system has great efficiency and application prospect in treating oligotrophic water on the laboratory scale, and will be further validated for practical application on large-scale oligotrophic water.

The Effect of Bacteria-to-Calcium Ratio on Microbial-Induced Carbonate Precipitation (MICP) under Different Sequences of Calcium-Source Introduction

To explore the effects of the introduction order of calcium sources and the bacteria-to-calcium ratio on the microbially induced calcium carbonate precipitation (MICP) product CaCO3 and to achieve the regulation of CaCO3 crystal morphology, the mineralisation products of MICP were compared after combining bacteria and calcium at ratios of 1/9, 2/9, 3/9, 4/9, 5/9, and 6/9. A bacterial solution was combined with a urea solution in two calcium addition modes: calcium-first and calcium-later modes. Finally, under the calcium-first addition method, the output of high-purity vaterite-type CaCO3 was achieved at bacteria-to-calcium ratios of 2/9 and 3/9; under the calcium-later addition method, the output of calcite-type CaCO3 could be stabilised, and the change in the bacteria-to-calcium ratio did not have much effect on its crystalline shape.

Cyanobacterial blooms control with CaO2 in different stages: Inhibition efficiency, water quality optimization and microbial community changes

This study explored the feasibility of calcium peroxide (CaO2) to inhibit cyanobacterial blooms of the outbreak and dormancy stages. Our previous studies have found that CaO2 has a high inhibitory effect on cyanobacteria. In order to explore the application effect of CaO2 in actual cyanobacteria lake water, we conducted this study to clarify the effect of CaO2 on inhibiting cyanobacteria in outbreak and dormancy stages. The results showed that CaO2 inhibited the growth of cyanobacteria in the outbreak and dormancy stages by 98.7% and 97.6%, respectively. The main inhibitory mechanism is: (1) destroy the cell structure and make the cells undergo programmed cell death by stimulating the oxidation balance of cyanobacteria cells; (2) EPS released by cyanobacteria resist stimulation and combine calcium to form colonies, and accelerate cell settlement. In addition to causing direct damage to cyanobacteria, CaO2 can also improve water quality and sediment microbial diversity, and reduce the release of sediment to phosphorus, so as to further contribute to cyanobacterial inhibition. Finally, the results of qRT-PCR analysis confirmed the promoting effect of CaO2 on the downregulation of photosynthesis-related genes (rbcL and psaB), microcystn (mcyA and mcyD) and peroxiredoxin (prx), and verified the mechanism of CaO2 inhibition of cyanobacteria. In conclusion, this study provides new findings for the future suppression of cyanobacterial bloom, by combining water quality, cyanobacterial inhibition mechanisms, and sediment microbial diversity.

Simultaneous removal of ammonia nitrogen, phosphate, zinc, and phenol by degradation of cellulose in composite mycelial pellet bioreactor: Enhanced performance and community co-assembly mechanism

In this experiment, the prepared tea biochar-cellulose@LDH material (TB-CL@LDH) was combined with mycelium pellets to form the composite mycelial pellets (CMP), then assembled and immobilized with strains Pseudomonas sp. Y1 and Cupriavidus sp. ZY7 to construct a bioreactor. At the best operating parameters, the initial concentrations of phosphate (PO43--P), ammonia nitrogen (NH4+-N), chemical oxygen demand (COD), zinc (Zn2+), and phenol were 22.3, 25.0, 763.8, 1.0, and 1.0 mg L-1, the corresponding removal efficiencies were 80.4, 87.0, 83.4, 91.8, and 96.6%, respectively. Various characterization analyses demonstrated that the strain Y1 used the additional carbon source produced by the strain ZY7 degradation of cellulose to enhance the removal of composite pollutants and clarified the principle of Zn2+ and PO43--P removal by adsorption, co-precipitation and biomineralization. Pseudomonas and Cupriavidus were the dominant genera according to the high-throughput sequencing. As shown by KEGG results, nitrification and denitrification genes were affected by phenol. The study offers prospects for the simultaneous removal of complex pollutants consisting of NH4+-N, PO43--P, Zn2+, and phenol.

Kinetic analysis and mechanism of nitrate, calcium, and cadmium removal using the newly isolated Pseudomonas sp. LYF26

The co-existence of heavy metals and nitrate (NO3--N) pollutants in wastewater has been a persistent global concern for a long time. A strain LYF26, which can remove NO3--N, calcium (Ca(II)), and cadmium (Cd(II)) simultaneously, was isolated to explore the properties and mechanisms of synergistic contaminants removal. Different conditions (Cd(II) and Ca(II) concentrations and pH) were optimized by Zero-, Half-, and First-order kinetic analyses to explore the environmental parameters for the optimal effect of strain LYF26. Results of the kinetic analyses revealed that the optimal culture conditions for strain LYF26 were pH of 6.5, Cd(II) and Ca(II) concentrations of 3.00 and 180.00 mg L-1, accompanied by Ca(II), Cd(II), and NO3--N efficiencies of 53.10%, 90.03%, and 91.45%, respectively. The removal mechanisms of Cd(II) using strain LYF26 as a nucleation template were identified as biomineralization, lattice substitution, and co-precipitation. The differences and changes of dissolved organic matter during metabolism were analyzed and the results demonstrated that besides the involvement of extracellular polymeric substances in the precipitation of Cd(II) and Ca(II), the high content of humic acid-like species revealed a remarkable contribution to the denitrification process. This study is hopeful to contribute a theory for further developing microbially induced calcium precipitation used to treat complex polluted wastewater.

Urea addition as an enhanced strategy for degradation of petroleum contaminants during co-composting of straw and pig manure: Evidences from microbial community and enzyme activity evaluation

Alterations in microbial community succession patterns and enzyme activities by petroleum pollutants during co-composting of straw and swine manure with the supplementary nitrogen source are unclear. In this study, urea was added into co-composting systems, and the removal performance of petroleum, microbial enzyme activity and community changes were investigated. Results showed that the polyphenol oxidase and catalase activities which were both related to the degradation of petroleum contaminants were accordingly increased from 20.65 to 30.31 U/g and from 171.87 to 231.86 U/g due to urea addition. The removal efficiency of petroleum contaminants in composting with urea increased from 45.06% to 82.29%. The addition of urea increased the diversity and abundance of petroleum-degrading microorganisms, and enhanced microbial linkages. This study provides a novel strategy for the degradation of petroleum hydrocarbon as well as a new insight into the effect of urea on both microbial processes and composting phases.

Mechanisms of ammonia, calcium and heavy metal removal from nutrient-poor water by Acinetobacter calcoaceticus strain HM12

An Acinetobacter calcoaceticus strain HM12 capable of heterotrophic nitrification-aerobic denitrification (HN-AD) under nutrient-poor conditions was isolated, with an ammonia nitrogen (NH4+-N) removal efficiency of 98.53%. It can also remove heavy metals by microbial induced calcium precipitation (MICP) with a Ca2+ removal efficiency of 75.91%. Optimal conditions for HN-AD and mineralization of the strain were determined by kinetic analysis (pH = 7, C/N = 2.0, Ca2+ = 70.0 mg L-1, NH4+-N = 5.0 mg L-1). Growth curves and nitrogen balance elucidated nitrogen degradation pathways capable of converting NH4+-N to gaseous nitrogen. The analysis of the bioprecipitation showed that Zn2+ and Cd2+ were removed by the MICP process through co-precipitation and adsorption (maximum removal efficiencies of 93.39% and 80.70%, respectively), mainly ZnCO3, CdCO3, ZnHPO4, Zn3(PO4)2 and Cd3(PO4)2. Strain HM12 produces humic and fulvic acids to counteract the toxicity of pollutants, as well as aromatic proteins to increase extracellular polymers (EPS) and promote the biomineralization process. This study provides a experimental evidence for the simultaneous removal of multiple pollutants from nutrient-poor waters.

Immobilized bioreactor for enhanced ammonia, phosphorus, and phenol removal and effects of phenol on microbial communities, potential functions, and nitrogen metabolism

In the present study, an immobilized bioreactor was established to remove ammonia (NH4+-N), phosphate (PO43--P), and phenol using composite mycelium spheres (CMP) as the immobilization material in combination with Pseudomonas sp. Y1. Under optimal operating conditions, the bioreactor achieved 98.07, 91.71, and 92.57 % removal of NH4+-N, PO43--P, and phenol, respectively. The results showed that the bioreactor removed PO43--P by biomineralization and co-precipitation. Phenol removal relied on a Fenton-like reaction achieved by CMP-induced quinone redox cycling. High-throughput sequencing analysis and functional gene prediction indicated that Pseudomonas was the dominant genus and that the bioreactor had much potential for nitrogen removal, respectively. In addition, phenol affected the performance of functional genes and the associated enzymes, which influenced the nitrogen metabolism process in the bioreactor. This work serves as a guideline for the development of more stable and sustainable composite pollution removal technologies and fungal-bacterial symbiotic systems.

Microbial induced calcium precipitation by Zobellella denitrificans sp. LX16 to simultaneously remove ammonia nitrogen, calcium, and chemical oxygen demand in reverse osmosis concentrates

In recent years, with the rapid development of industrial revolution and urbanization, the generation and treatment of a large number of salt-containing industrial wastewater has attracted wide attention. A novel salt-tolerant Zobellella denitrificans sp. LX16 with excellent nitrogen removal and biomineralization capabilities was isolated in this experiment. Kinetic experiments were conducted to determine the optimal condition. Under this condition, chemical oxygen demand (COD) can be entirely removed together with ammonia nitrogen, and the removal efficiency of calcium was 88.09%. Growth curves and nitrogen balance tests showed that strain LX16 not only had good HNAD and MICP capabilities, but also had high nitrite reductase and nitrate reductase activities during this process. Three-dimensional fluorescence results reflected that when external carbon sources were lacking or salinity was high, humic acid could effectively enhance the metabolic activity of heterotrophic nitrifying aerobic denitrifying microorganisms through extracellular electron transfer, and the substances produced in the metabolic process could promote biommineralization. Moreover, combined with SEM, SEM-EDS, XRD and FTIR analysis, it is concluded that the microbial surface can provide nucleation sites to form calcium salts, and with the increase of alkalinity to generate Ca5(PO4)3OH. The theoretical basis for the use of biological treatment in reverse osmosis wastewater have been proved by this experiment.

Improvement of the specific surface area of biochar by calcium-precipitated nanoparticles synthesized by microbial induction as a template skeleton: Removal mechanism of tetracycline in water

The template method is an effective means to improve the specific surface area and porosity of biochar, but the synthesis of template agents and the way they are integrated with biomass materials still need further development. Therefore, the free Pseudomonas sp. Y1 was used to synthesize calcium-precipitated nanoparticles (CPN) on sludge as a fused template skeleton to enlarge the surface area of sludge biochar facilitating the adsorption of tetracycline (TC) in this work. The modified biochar (FBC) showed excellent specific surface area (448.55 m2 g-1) and porosity (0.0053 cm³ g-1), stable morphological structure, abundant active functional groups, and appreciable adsorption capacity (65.43 mg g-1) based on several characterization and adsorption experiments. Moreover, the adsorption model postulated that the removal of TC is mainly a chemisorption-based heat-trapping, disordered multilayer interaction. In detail, this process involved the joint contribution from electrostatic interactions, ligand exchange, hydrogen bonding, π-π bonding, complexation, and pore filling. Meanwhile, the adaptability and stability of FBC were examined by pH and coexisting substances. This template skeleton induced by microorganisms can provide new insight into the modification of biochar with the template method.

Simultaneous removal of phosphorus, zinc, and lead from oligotrophic ecosystem by iron-driven denitrification: Performance and mechanisms

Based on the current situation of complex pollution caused in surface water by oligotrophic condition and heavy metal release from river and lake bottom sediments. This study aimed to achieve the simultaneous removal of nitrate, phosphorus, Zn2+ and Pb2+ through microbial approach. At nitrate concentration of 4.82 mg L-1, carbon to nitrogen ratio of 1.5, pH of 6.0, and Fe2+ concentration of 5.0 mg L-1, the nitrate removal efficiency of Zoogloea sp. FY-6 reached 95.17%. The addition of pollutants under these conditions resulted in 88.76% removal of total phosphorus at 18 h, and 85.46 and 78.59% removal of Zn2+ and Pb2+ respectively, and there was competition for adsorption between Zn2+ and Pb2+. Extracellular polymers and fluorescence excitation-emission substrates confirmed that Fe2+ reduced heavy metal toxicity through promoting bacterial production of secretions and promotes denitrification as a carbon source. Meanwhile, contaminant removal curves and Fourier transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy demonstrated the synchronous removal of Zn2+ and Pb2+ mainly through biological action and the formation of nanoscale iron oxides. Biological-iron precipitation also provided adsorption sites for phosphorus. This research provides the theoretical foundation for applying microorganisms to restore oligotrophic source water (rivers and lakes) containing complex pollutants.

Enhanced ammonia nitrogen and phenol removal by immobilized bacteria through composite mycelium pellet-driven quinone redox cycle

The composite mycelium pellet (CMP) was coupled with Pseudomonas sp. Y1 (CMP-Y1) to remove phenol and ammonia nitrogen (NH4+-N). The CMP was formed by the self-assembly of fungal mycelium with sponge iron (SIO), gallic acid (GA), and oxalic acid. The results showed that CMP with abundant pore size and successful internal loading of sponge iron containing iron nanoparticles. CMP could induce GA redox cycle to form Fenton-like reaction and thus achieve efficient phenol removal (93.32%, 24 h). Meanwhile, the removal efficiencies of phenol, NH4+-N, and chemical oxygen demand (COD) using CMP-Y1 at 12 h were 93.71, 92.40, and 89.00%, respectively. The increase in the electron transfer activity of strain Y1 by the addition of CMP could facilitate the nitrogen removal processes. In addition, high-throughput sequencing results indicated the abundance of antioxidant and repair genes was increased, which might be a strategy of strain Y1 to cope with oxidative stress. This strategy provided the possibility for the practical application of the combination of advanced oxidation and biological treatment, and offered new insights into the symbiotic system of fungi and bacteria.

The performance and mechanism of tetracycline and ammonium removal by Pseudomonas sp. DX-21

To remove ammonium and tetracycline (TC) from wastewater, a new strain, DX-21, was isolated and exhibited simultaneous removal ability. The performance of DX-21 in TC removal, its removal mechanism, and the potential toxicities of the degradation products were investigated with genomics, mass spectrometry, density functional theory calculations, quantitative structure-activity relationship analyses, and Escherichia coli exposure experiments. DX-21 exhibited removal of ammonium (9.64 mg·L-1·h-1) via assimilation, and TC removal (0.85 mg·L-1·h-1) primarily occurred through cell surface bio-adsorption and biodegradation. Among the 12 identified degradation products, the majority exhibited lower toxicities than TC. Moreover, potential degradation pathways were proposed, including hydroxylation and deamination. Furthermore, DX-21 possessed TC resistance genes, various oxygenases and peroxidases that could potentially contribute to TC degradation. DX-21 colonized activated sludge and significantly enhanced the biodegradation of TC. Therefore, DX-21 showed potential for treating wastewater containing both ammonium and TC.

Simultaneous removal of phosphate, calcium, and ammonia nitrogen in a hydrogel immobilized reactor with bentonite/lanthanum/PVA based on microbial induced calcium precipitation

In recent years, it is urgent to solve nitrogen and phosphorus pollution in domestic wastewater. The target strain Pseudomonas sp. Y1 was immobilized using polyvinyl alcohol (PVA) matrix coupled with bentonite and lanthanum (La), respectively, to fabricate four hydrogel materials that used to construct bioreactors. The optimal operating parameters and dephosphorization mechanism were discussed, and the effects of hydrogel materials and different loads on the performance of the bioreactor were contrastively analyzed. The results manifested that when the hydraulic retention time (HRT) was 6.0 h, the C/N was 6.0, and the Ca²⁺ concentration was 100.0 mg L^-1, the bioreactors had the best heterotrophic nitrification-aerobic denitrification (HNAD) and biomineralization capacity, and the maximum removal efficiencies of Ca²⁺, PO₄^3--P, and NH₄⁺-N were 82.57, 99.17, and 89.08%, respectively. The operation data indicated that the addition of bentonite significantly promoted HNAD, and the bioreactor had stronger dephosphorization ability in the presence of La. The main phosphorous removal mechanisms were confirmed to be adsorption and co-precipitation. Finally, high-throughput sequencing results indicated that Pseudomonas accounted for the paramount proportion in the bioreactor, and the prediction of functional genes indicated that the C/N of 6.0 is more favorable for the expression of nitrogen removal-related functional genes in the bioreactor system. This study highlights the superiority of microbial induced calcium precipitation (MICP) combined with PVA hydrogel, and provides a theoretical basis for simultaneous nitrogen and phosphate removal of wastewater.

Simultaneous removal of ammonia nitrogen, recovery of phosphate, and immobilization of nickel in a polyester fiber with shell powder and iron carbon spheres bioreactor: Optimization and pathways mechanism

Composite pollutants are prevalent in wastewater, whereas, the simultaneous accomplishment of efficient nitrogen removal and resources recovery remains a challenge. In this study, a bioreactor was constructed to contain Pseudomonas sp. Y1 using polyester fiber wrapped with shell powder and iron carbon spheres, achieving ammonia nitrogen (NH₄⁺-N) removal, phosphate (PO₄^3--P) recovery, and nickel (Ni²⁺) immobilization. The optimal performance of bioreactor was average removal efficiencies of NH₄⁺-N, PO₄^3--P, calcium (Ca²⁺), and Ni²⁺ as 82.42, 96.67, 76.13, and 98.29% at a hydraulic retention time (HRT) of 6 h, pH of 7.0, and influent Ca²⁺ and Ni²⁺ concentrations of 100.0 and 3.0 mg L^-1, respectively. The bioreactor could remove PO₄^3--P, Ca²⁺, and Ni²⁺ by biomineralization, co-precipitation, adsorption, and lattice substitution. Moreover, microbial community analysis suggested that Pseudomonas was the predominant genus and had possessed tolerance to Ni²⁺ toxicity in wastewater. This study presented an effective method to synchronously remove NH₄⁺-N, recover PO₄^3--P, and fix heavy metals through microbially induced carbonate precipitation (MICP) and heterotrophic nitrification and aerobic denitrification (HNAD) technology.

Effect of dissolved oxygen on high C/N wastewater treatment in moving bed biofilm reactors based on heterotrophic nitrification and aerobic denitrification: Nitrogen removal performance and potential mechanisms

In this study, it was investigated the nitrogen removal (NR) performance and potential mechanism for high C/N wastewater treatment under different dissolved oxygen (DO) concentrations. The results showed that DO concentration significantly affected the removal efficiency of total nitrogen (TN). When the initial DO increased from 0.5 to 1.5 mg/L, TN removal efficiency significantly increased from 65 % to 85 %. However, a further DO increase did not promote TN removal, and the NR was only 80 % with an initial DO concentration of 3.5 mg/L. The effect of DO concentration on NR was influenced by the combined action of functional bacteria and electron flow. Excessive DO concentration did not positively affect NR efficiency but promoted electron utilization and respiratory proliferation. When the DO concentration was 1.5 mg/L, more electrons generated by sodium acetate metabolism were transferred to the aerobic denitrification process, compared to when the DO concentration was 3.5 mg/L.

Six complex microbial inoculants for removing ammonia nitrogen from waters

To determine the effect of microbial inoculants on the removal of ammonia nitrogen (NH₄ ⁺ -N), six different complex microbial inoculants were studied. In this study, their effectiveness on NH₄ ⁺ -N removal was compared, and their microbial community composition was determined. High-throughput sequencing results showed that Proteobacteria and Firmicutes were the dominant phyla in six samples. Before the reaction, Bacillus, Cyanobacteria, and Mitochondria genera were the dominant genera. The dominant genera were significantly different after the reaction with the addition of bacterial agents. The six water samples were Massilia, Escherichia-Shigella, Brevibacillus, Mitsuaria, Bacillus, and Ralstonia. Among the six complex microbial inoculants, "Gandu nitrifying bacteria (NR₄ )" have the best removal effect on NH₄ ⁺ -N. In addition, the removal effect of six different bacterial agents on chemical oxygen demand (COD) was compared. The results showed that "Bilaiqing ammonia nitrogen removal bacteria agent (NR₅ )" has the best removal effect on COD. Single-factor experiments suggested that the optimal conditions for NR₄ bacteria were pH 7, 30°C, 1.0 g/L of bacterial agent dosage and a wide range of NH₄ ⁺ -N from 30 to 300 mg/L. PRACTITIONER POINTS: The nitrogen removal effects of six different microbial agents were compared. High-throughput sequencing provides important insights into the study of ammonia nitrogen removal by microbial communities. Analysis of six different complex bacterial agents by high-throughput sequencing. The relative abundance of microorganisms is not proportional to the ability to remove NH₄ ⁺ -N Good application effect in urban landscape water body.