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Stable nitritation for low-strength ammonium wastewater was the key obstacle for cost-effective and low-carbon biological nitrogen removal. A zeolite biological fixed bed (ZBFB) and an anoxic sequencing batch reactor (ASBR) were successfully applied for achieving nitritation-denitrification of low-strength ammonium wastewater by adsorption, biological desorption and denitrification. Based on free ammonia inhibition on biofilm, stable nitrite accumulation could be realized with suitable operational time and aeration in biological desorption. During cycle operation, adsorption effluent NH 4 + -N kept at 3.0–4.0 mg/L, biological desorption effluent NO 2 − -N maintained at 226.8–243.2 mg/L with average nitrite accumulation ratio of 97.18%, and nitrite removal rate was about 0.628–0.672 kg NO 2 − -N·m −3 ·day −1 , revealing obvious feasibility of ZBFB and ASBR for low-strength ammonium wastewater treatment. High-throughput sequencing analysis results further presented significant microbial community variations happened after cycle operation, with ammonia oxidizing bacteria enrichment and nitrite oxidizing bacteria inhibition in ZBFB and dominance of denitrifiers in ASBR. [ABSTRACT FROM AUTHOR]

Good start-up and performance are essential for the completely autotrophic nitrogen removal over nitrite (CANON) process, and inorganic carbon (IC) is also important for this process. In this study, a lab-scale submerged aerated biological filter (SABF) was adopted for the CANON process. A 16S rRNA gene high-throughput sequencing analysis showed that the phyla Proteobacteria and Planctomycetes were the dominant microorganisms and that the genus Candidatus Brocadia functioned as the nitrogen remover. The effect of IC on the nitrogen removal was analyzed. The results showed that the optimum concentration ratio of IC to nitrogen (IC/N) was 1.2, which produced the highest average ammonium nitrogen removal rate (ANR) and total nitrogen removal rate (TNR) values of 95.5% and 80.3%, respectively. The average AOB and AnAOB activities were 2.45 mg·L −1 ·h −1 and 3.57 mg·L −1 ·h −1 , respectively. This research could promote the nitrogen removal ability of the CANON process with a SABF in the future. [ABSTRACT FROM AUTHOR]

Inorganic carbon (IC) is important for anaerobic ammonium oxidation (anammox). In this study, the effects of the IC concentration on N 2 O emissions and microbial diversity in an anammox reactor were investigated. N 2 O emissions were positively correlated with IC concentrations, and IC concentrations in the range of 55–130 mg/L were optimal, considering the nitrogen removal rate and N 2 O emissions. High IC concentrations resulted in the formation of CaCO 3 on the surface of anammox granules, which impacted the diffusion conditions of the substrate. Microbial community analysis indicated that high IC concentrations decreased the populations of specific bacteria, such as Achromobacter spanius strain YJART-7, Achromobacter xylosoxidans strain IHB B 6801, and Denitratisoma oestradiolicum clone 20b_15. D. oestradiolicum clone 20b_15 appeared to be the key contributor to N 2 O emissions. High N 2 O emissions may result from changes in organic carbon sources, which lead to denitrification by D. oestradiolicum clone 20b_15. [ABSTRACT FROM AUTHOR]

This study investigated effects of pH-depended inorganic carbon (IC) species and pH on algal growth in the sewage simulation system, and fruitfully discussed the relationships among IC, pH and algal growth by the Monod kinetics. Results showed HCO 3 − significantly increased algal growth by 3.17–6.52 times than that of CO 3 2− and/or glucose when the value of pH was in the range of 8.0–9.5, and also the preferentially utilized indicated by the affinity coefficient ( K p ) of HCO 3 − , CO 3 2− and glucose (0.17, 15.14 and 31.22, respectively). Meanwhile, the same pH range facilitated HCO 3 − to become a dominated species (e.g., 48.80–93.19% of total IC). More importantly, good linear correlations pairwise existed among pH, IC species and algae growth. These results suggested pH plays a critical role in regulation of IC species and algae growth, which would be an efficient method to control the IC discharge from sewage effluents and weaken bloom outbreak. [ABSTRACT FROM AUTHOR]

[Display omitted] • Inorganic carbon enhances macroalgae biomass and pigment production. • One g L-1 of mixed carbon provides a pH in a range for optimal algal growth. • Algae adjust allophycocyanin content to adapt to increasing daily light. • Algae adjust the ratios of phycoerythrin and allophycocyanin to adapt to added carbon. • One g L-1 inorganic carbon increased biomass by 60%. Due to an increasing CO 2 concentration leading to global warming, the techniques as carbon capture utilization and storage are currently critical issues. This study aimed to investigate a cultivation strategy using optimal inorganic carbon level, irradiance, and photoperiod for producing the highest biomass and photosynthesis pigment contents (chlorophyll and phycobiliprotein) in the macroalga Colaconema formosanum. The results revealed that adding 1 g L-1 carbon increases phycoerythrin ratio by 12.52–13.74% and decreases allophycocyanin by 10.4–9.57%. Optimal conditions can increase algal growth by 60%, providing 5–6 mg g−1 total phycobiliprotein and 650–680 µg g−1 total chlorophyll. The results in this study illustrate the sensitivity of photosynthesis pigment after treatment with carbon, and suggest a hypothesis explaining the mechanism. The results also provide a feasible use of carbon for high-value large-scale production of pigment in the macroalgae industry. [ABSTRACT FROM AUTHOR]

Abstract: This study evaluated how Synechocystis sp. PCC 6803 responds to high total dissolved solids (TDS) associated with eliminating nutrient limitation during long-term operation of a photobioreactor. The unique feature is that the TDS were not dominated by Na+ and Cl−, as in seawater, but by HCO3 − and NO3 − from nutrient delivery. The TDS-stress threshold was about 10g/L. Whereas inorganic N and P limitations slowed the rate of inorganic C (Ci) uptake in the light, TDS stress was manifested most strongly as a substantial increase of endogenous respiration rate at night. Relief from TDS stress was incomplete when lowered pH led to a HCO3 − increase (560mgC/L as a threshold). Impaired photosynthesis led to a cascade of reduced Ci-uptake, pH decrease, HCO3 − accumulation, and HCO3 −-associated stress. Thus, long-term photobioreactor operation requires balancing the delivery rates of CO2, N, P, and other TDS components to avoid general and Ci-associated TDS stresses. [Copyright &y& Elsevier]

Abstract: Anammox bacteria are chemoautotrophic bacteria that oxidize ammonium with nitrite as the electron acceptor and with CO2 as the main carbon source. The effects of inorganic carbon (IC) limitation on anammox bacteria were investigated using continuous feeding tests. In this study, a gel carrier with entrapped anammox sludge was used. It was clearly shown that the anammox activity deteriorated with a decrease in the influent IC concentration. The relationship between the influent IC concentration and the anammox activity was analyzed using Michaelis–Menten kinetics, and the apparent K m was determined to be 1.2mg-C/L. The activity could be recovered by adding IC to the influent. The consumption ratio of IC to ammonium was not constant and mainly depended on the influent ratio of the IC to ammonium concentrations (inf.IC/inf.NH4–N). The results indicated that an inf.IC/inf.NH4–N ratio of 0.2 in the anammox reactor was ideal for the anammox process using gel cubes. [Copyright &y& Elsevier]

Abstract: This study focused on high-rate nitrogen removal by the anaerobic ammonium oxidation (Anammox) process with a sufficient inorganic carbon (IC) source. Experiments were carried out in an up-flow column Anammox reactor fed with synthetic inorganic wastewater for 110days. The IC source was added into the influent tank in the form of bicarbonate. The results confirmed the positive impact of inorganic matter on stimulating Anammox activity. After the addition of sufficient IC, the nitrogen removal rate sharply increased from 5.2 to 11.8kg-Nm−3 day−1 within only 32days. NO2-N inhibition was not observed even at NO2-N concentrations greater than 460mgN/L, indicating the enriched Anammox consortium adapted to high NO2-N concentrations. The ratio of NO2-N removal, NO3-N production and NH4-N removal for the reactor was correspondingly changed from 1.21:0.21:1 to 1.24:0.18:1. Simultaneously, the sludge volume index of the Anammox granules decreased markedly from 36.8 to 21.5mL/g, which was attributed to the implementation of proper operational strategy. In addition, DNA analysis revealed that a shift from the KSU-1 strain to the KU2 strain occurred in the Anammox community. [ABSTRACT FROM AUTHOR]

• Synechocystis sp. was the most PHB productive species. • PHB and glycogen content are strongly correlated with inorganic carbon availability. • There is a carbon threshold that triggers the transformation of glycogen to PHB. • High concentration of carbon boosted both PHB and specially glycogen accumulation. The aim of this study was to investigate the PHB and glycogen accumulation dynamics in two photobioreactors inoculated with different monocultures of wastewater-borne cyanobacteria, using a three-stage feeding strategy (growth phase, feast-famine phase and feast phase). Two cyanobacterial monocultures containing members of Synechocystis sp. or Synechococcus sp. were collected from treated wastewater and inoculated in lab-scale photobioreactors to evaluate the PHB and glycogen accumulation. A third photobioreactor with a complex microbial community grown in real wastewater was also set up. During each experimental phase different concentrations of inorganic carbon were applied to the cultures, these shifts allowed to discern the accumulation mechanism of carbon storage polymers (PHB and glycogen) in cyanobacteria. Conversion of one into the other was directly related to the carbon content. The highest PHB and glycogen contents (5.04% dcw and 69% dcw , respectively) were achieved for Synechocystis sp. [ABSTRACT FROM AUTHOR]

• Partial nitrification was conducted under different influent matrix concentrations. • Carbon sequestration correlated positively with nitrogen removal (NH 4 +-N substrate). • Inorganic carbon concentration was negatively correlated with carbon sequestration. • Functional genes for the Calvin cycle carbon sequestration pathway were present. • The responsiveness of cbbL R1 gene abundance to NH 4 +-N was high. Inorganic carbon is an important carbon source of autotrophic bacteria, e.g., ammonia-oxidizing bacteria. Ammonia-oxidizing bacteria are chemoautotrophic bacteria with carbon sequestration capacity. Experiments were performed on partial nitrification sludge with different influent matrices, and optimal experimental operational conditions were established. The carbon fixation pathway of ammonia-oxidizing sludge was determined via 13C isotope tracers and qPCR. The denitrification effect was better when the NH 4 +-N, HCO 3 –, Ca2+, Mg2+, and microbial accelerant concentrations were 15, 250, 113, 100 and 1 mL/L, respectively. The nitrite accumulation rate reached 96.95%. 13C isotope tracing showed that 13C abundance in sludge increased significantly. The results showed that IC added into the influent participated in the carbon metabolism of microorganisms. The functional gene cbbL , which follows the Calvin cycle carbon sequestration pathway, was identified in the ammonia-oxidizing bacteria, and the effect of influent NH 4 +-N on the gene abundance was greater than that of other substrates. [ABSTRACT FROM AUTHOR]

• MAB had good tolerance to high IC dose and ARE was above 99% at 108–3600 mg/L IC. • Calcium carbonate crystal was formed on the surface of MAB granule at high IC dose. • Remodified Logistic and modified Boltzmann models were appropriate at low IC doses. • Modified Gompertz model was only appropriate for high IC concentrations. With different inorganic carbon (IC) doses, nitrogen removal performance of marine anammox bacteria (MAB) treating nitrogen-rich saline wastewater was investigated in a sequencing batch reactor. Ammonium removal efficiency (ARE) was above 99% at 108–3600 mg/L IC, which indicated MAB had a good tolerance to high IC dose. When IC was 108–1200 mg/L, ARE reached 90% within 2.5 h. MAB activity was greatly promoted by providing adequate IC. Besides, the maximal substrate conversion rate (3.4 kg/(m3 d)) was achieved at 180 mg/L IC. Both the modified Logistic and Boltzmann models were appropriate to describe nitrogen removal at low IC doses, while the modified Gompertz model was more accurate at high IC doses. Calcium carbonate crystal was formed on the surface of MAB granule at high IC doses, which resulted in a significant deterioration of nitrogen removal performance. [ABSTRACT FROM AUTHOR]