Characterization of oligotrophic AnAOB culture: morphological, physiological, and ecological features.

Anaerobic ammonium oxidation (anammox) process is regarded as a promising nitrogen removal technology to treat ammonium wastewaters in a wide concentration range. Oligotrophic anaerobic ammonia oxidation bacteria (O-AnAOB) culture has been successfully achieved from a new anammox system to treat superlow ammonium concentration wastewaters. In this work, the O-AnAOB culture was compared with the eutrophic AnAOB (E-AnAOB) culture to reveal its physiological, morphological, and ecological features. Results showed that the specific anammox activity (SAA) of O-AnAOB culture was 0.07 kgN/(kgVSS·d) with the nitrogen removal rate (NRR) of 0.20 kgN/ (m3 d) in the reactor, while the SAA of E-AnAOB culture was 2.11 kgN/(kgVSS·d) with the NRR of 11.10 kgN/(m3 d). The hzs gene transcription levels (hzs-mRNA) of O-AnAOB and E-AnAOB cultures were 1.32 × 109 copies/gVSS and 1.51 × 1010 copies/gVSS, respectively. Morphologically, the O-AnAOB culture took on the unique brown color rather than the typical red color of E-AnAOB. The O-AnAOB cells lived in a disperse pattern in the culture. The cells were seriously deformed with deep craters on the cell wall. The size of anammoxsome and paryphoplasm compartments inside the O-AnAOB cells was smaller than that inside the E-AnAOB cells. Ecologically, the O-AnAOB culture had special microbial community with a higher bacterial diversity than the E-AnAOB. The most dominant genera in O-AnAOB were Anaerolineaceae (33.7%, fermentative bacteria), Candidatus Kuenenia (17.4%, anammox bacteria), and Nitrospira (7.3%, nitrite oxidizing bacteria). This study provided an insight into the new anammox process for deep nitrogen removal from wastewaters.

Feasibility of anaerobic ammonium oxidation process for treatment of pretreated printed circuit board wastewater.

The treatment of pretreated printed circuit board (PCB) wastewater by anaerobic ammonium oxidation (anammox) process has been rarely reported. This study sought to investigate the performance of the anammox process during various phases of pretreated PCB wastewater treatment. The nitrogen removal efficiency (NRE) reached 90 ± 10% at a Cu2+ concentration of 2.5 mg·L-1, but declined to 22 ± 11% as the Cu2+ level increased to 10.3  mg·L-1. During phase III, there was a 38% increase in the relative abundance of Candidatus Kuenenia compared to phase I. By adjusting the substrate concentration and introducing synthetic wastewater into the reactor, the anammox performance was nearly restored to that of phase I. These findings underscore the potential of the anammox process for treating pretreated PCB wastewater and expanding its practical applications to industrial wastewater treatment.

Kinetic affinity index informs the divisions of nitrate flux in aerobic denitrification.

Aerobic denitrification is attracting increasing attention since its advantage of complete nitrogen removal in a single aerobic reactor with simplified configurations. This study investigated the nitrate kinetic affinity (half-saturation index, Km) by an isolated aerobic denitrifier named P. balearica strain RAD-17. It turned out that strain RAD-17 had a high Km of 162.5 mg-N/L and maximum nitrate reduction rate of 21.7 mg-N/(L•h), enabling it to treat high-strength nitrogen wastewater with high efficiency. Further analysis illustrated that Km was the critical value for the change of growth yield rate along initial nitrate concentrations. Nitrogen balance results elucidated an opposite nitrogen flux to cell synthesis and nitrogen loss during aerobic denitrification. Moreover, the expression of functional genes provided proofs for these phenotypic results at transcriptional level. Consequently, Km could be an indicator for nitrate flux division directing to respiration and assimilation in aerobic denitrifiers, shedding light on its regulation for wastewater treatment.

Denitrification performance and microbial communities of solid-phase denitrifying reactors using poly (butylene succinate)/bamboo powder composite.

This study explored the denitrification performance of solid-phase denitrification (SPD) systems packed with poly (butylene succinate)/bamboo powder composite to treat synthetic aquaculture wastewater under different salinity conditions (0‰ Vs. 25‰). The results showed composite could achieve the maximum denitrification rates of 0.22 kg (salinity, 0‰) and 0.34 kg NO3--N m-3 d-1 (salinity, 25‰) over 200-day operation. No significant nitrite accumulation and less dissolved organic carbon (DOC) release (<15 mg/L) were found. The morphological and spectroscopic analyses demonstrated the mixture composites degradation. Microbial community analysis showed that Acidovorax, Simplicispira, Denitromonas, SM1A02, Marinicella and Formosa were the dominant genera for denitrifying bacteria, while Aspergillus was the major genus for denitrifying fungus. The co-network analysis also indicated the interactions between bacterial and fungal community played an important role in composite degradation and denitrification. The outcomes provided a potential strategy of DOC control and cost reduction for aquaculture nitrate removal by SPD.

Simultaneous ammonia and nitrate removal in an airlift reactor using poly(butylene succinate) as carbon source and biofilm carrier.

In this study, an airlift inner-loop sequencing batch reactor using poly(butylene succinate) as the biofilm carrier and carbon source was operated under an alternant aerobic/anoxic strategy for nitrogen removal in recirculating aquaculture system. The average TAN and nitrate removal rates of 47.35±15.62gNH4-Nm(-3)d(-1) and 0.64±0.14kgNO3-Nm(-3)d(-1) were achieved with no obvious nitrite accumulation (0.70±0.76mg/L) and the dissolved organic carbon in effluents was maintained at 148.38±39.06mg/L. Besides, the activities of dissimilatory nitrate reduction to ammonium and sulfate reduction activities were successfully inhibited. The proteome KEGG analysis illustrated that ammonia might be removed through heterotrophic nitrification, while the activities of nitrate and nitrite reductases were enhanced through aeration treatment. The microbial community analysis revealed that denitrifiers of Azoarcus and Simplicispira occupied the dominate abundance which accounted for the high nitrate removal performance. Overall, this study broadened our understanding of simultaneous nitrification and denitrification using biodegradable material as biofilm carrier.

Synthesis of Mesoporous Single Crystal Co(OH)2 Nanoplate and Its Topotactic Conversion to Dual-Pore Mesoporous Single Crystal Co3O4.

A new class of mesoporous single crystalline (MSC) material, Co(OH)2 nanoplates, is synthesized by a soft template method, and it is topotactically converted to dual-pore MSC Co3O4. Most mesoporous materials derived from the soft template method are reported to be amorphous or polycrystallined; however, in our synthesis, Co(OH)2 seeds grow to form single crystals, with amphiphilic block copolymer F127 colloids as the pore producer. The single-crystalline nature of material can be kept during the conversion from Co(OH)2 to Co3O4, and special dual-pore MSC Co3O4 nanoplates can be obtained. As the anode of lithium-ion batteries, such dual-pore MSC Co3O4 nanoplates possess exceedingly high capacity as well as long cyclic performance (730 mAh g(-1) at 1 A g(-1) after the 350th cycle). The superior performance is because of the unique hierarchical mesoporous structure, which could significantly improve Li(+) diffusion kinetics, and the exposed highly active (111) crystal planes are in favor of the conversion reaction in the charge/discharge cycles.

The morphological and settling properties of ANAMMOX granular sludge in high-rate reactors.

Digital macro photography and settling tests were carried out to investigate the morphological and settling characteristics of ANAMMOX granules in a high-rate reactor. The ANAMMOX granules could be divided into settling and floating granules. The settling granules with an average diameter of 2.96±0.99 mm were smaller than the floating granules with an average diameter of 4.58±1.22 mm. A settling model was established and validated to correlate the settling velocity with the density (ρG), mass shape factor (ψmass), shape-correction factor (characterized by sphericity (Φ(')) or roundness (ξ)) and projected area equivalent sphere diameter (dP) of ANAMMOX granules. The sphericity was more suitable than the roundness for describing the settling behavior. The sensitivity of four parameters was in the order of ρG,ψmass, dP and Φ('). Based on the settling model, ANAMMOX granules with diameter of 1.75-4.00 mm were supposed to be optimal for the ANAMMOX process.

[Relationship between tumorous stem mustard yield and soil fertility in Fuling, Southwest China].

By combining field investigation and indoor chemical analysis, the relationship between tumorous stem mustard yield and soil fertility factors was investigated in the main planting areas of tumorous stem mustard in Fuling, Southwest China. The results showed that available Ca, Mg, Fe, Mn, Cu and Zn in the soil were rich (3034, 260, 11.2, 26.1, 1.15 and 1.50 mg x kg(-1), respectively), available P was moderate (19.3 mg x kg(-1)), and organic matter, available N, available K and available S were deficient (9.05 g x kg(-1), 89.2 mg x kg(-1), 106 mg x kg(-1) and 27.0 mg x kg(-1), respectively). The yield of tumorous stem mustard was significantly positively correlated with soil pH and available Ca, whilst significantly (P < 0.01) negatively correlated with available Fe. The influence order of soil fertility factors on the yield of tumorous stem mustard was available Mn > available Cu > pH > available Fe > available K > available Ca > available Mg > available S > available N > available Zn > organic matter > available P. The linear equation (Y = 31636 + 3.63X(6)) of soil available Ca and the yield, was established by stepwise regression analysis.

Toxicity assessment of anaerobic digestion intermediates and antibiotics in pharmaceutical wastewater by luminescent bacterium.

In order to evaluate the effect of anaerobic digestion intermediates and antibiotics in pharmaceutical wastewaters on anaerobic digestion process, their acute toxicities were tested using the 15 min median inhibitory concentration (IC(50)) at pH 7.00 ± 0.05. The results showed that the IC(50) of ethanol, acetate, propionate and butyrate were 19.40, 20.71, 10.47 and 12.17 g L(-1) respectively, which suggested the toxicity descended in the order of propionate, butyrate, ethanol and acetate. The IC(50) of aureomycin, polymyxin and chloromycetin were 12.06, 6.24 and 429.90 mg L(-1) respectively, which indicated the toxicity descended in the order of polymyxin, aureomycin and chloromycetin. Using equitoxic ratio mixing method, the joint toxicities of five groups referred by A (four anaerobic digestion intermediates), B (four anaerobic digestion intermediates and aureomycin), C (four anaerobic digestion intermediates and polymyxin), D (four anaerobic digestion intermediates and chloromycetin) and E (four anaerobic digestion intermediates, aureomycin, polymyxin and chloromycetin) were investigated respectively. Their interactions were additive (A), synergistic (B), additive (C), synergistic (D) and synergistic (E). The investigation would lay a basis for the optimization of anaerobic biotechnology for pharmaceutical wastewater treatment.

The structure, density and settlability of anammox granular sludge in high-rate reactors.

Microscopic observation and settling test were carried out to investigate the structure, density and settlability of anammox granules taken from a high-rate upflow anaerobic sludge blanket (UASB) reactor. The results showed that the anammox granules were irregular in shape and uneven on surface, and their structure included granule, subunit, microbial cell cluster and single cell. The gas pockets were often observed in the anammox granules, and they originated from the obstruction of gas tunnel by extracellular polymer substances (EPSs) and the inflation of produced dinitrogen gas. The volume of gas pockets became larger with the increasing diameter of anammox granules, which led to the decreasing density and the floatation of anammox granules. The diameter of anammox granules should be controlled at less than 2.20mm to avoid the granule floatation. A hypothesized mechanism for the granulation and floatation of anammox biomass was proposed.