This work first unraveled the response mechanism of marine anammox bacteria (MAB)-dominated anammox process to Zn(II) in treating saline wastewater. Low Zn(II) doses (⩽ 3 mg/L) enhanced MAB activity, with the highest total nitrogen removal rate (TNRR) of 1.33 kg/(m3·d) achieved at 3 mg/L Zn(II). Additionally, the relative abundance of MAB (Candidatus Scalindua) sharply increased from 9.2

A sequencing batch reactor was used to study long-term nitrogen removal performance of anaerobic ammonia oxidation bacteria (AnAOB) with trehalose addition treating nitrogen-rich saline wastewater. The operating temperature was controlled at 35 +/- 0.5 degrees C with influent pH of 7.5 +/- 0.1. Trehalose played a significant role in enhancing long-term nitrogen removal performance. When trehalose was 0.1, 0.2, and 0.3 mM, ammonia removal efficiency (ARE) increased by 4.9%, 16.2%, and 32.4%, and nitrite removal efficiency (NRE) improved by 7.5%, 27.9%, and 42.2%, respectively. Optimal ARE and NRE were 92.4% and 97.4% achieved at 0.35 mM trehalose. Moreover, NO2--N was removed completely within 2 hr at high trehalose content due to the synergistic effect resulting from AnAOB and heterotrophic denitrifying bacteria. Delta NO2--N/Delta NH4+-N increased with trehalose addition, while Delta NO3--N/Delta NH4+-N decreased. Compared to Delta NO3--N/Delta NH4+-N, Delta NO2--N/Delta NH4+-N fluctuated greatly. The remodified Logistic model and modified Gompertz model were suitable for describing nitrogen removal in an operating cycle with trehalose addition. Fitted ARE(max) values were consistent with experimental values. Appropriate trehalose addition could shorten the response time of AnAOB coping with hazardous environment stress. Lag time was within 1 hr and the minimal fitted lambda value got close to 0 achieved at 0.15 mM trehalose. Practitioner points Trehalose enhanced nitrogen removal of AnAOB in saline wastewater treatment. Optimal ARE and NRE were 92.4% and 97.4% achieved at 0.35 mM trehalose. Remodified Logistic and Gompertz models can analyze nitrogen removal with trehalose. Appropriate trehalose can shorten response time of AnAOB coping with salt stress.

A sequencing batch reactor (SBR) was operated more than 200 d to treat nitrogen-rich saline wastewater by anammox process. The temperature was controlled at 35 +/- 0.5 degrees C and the mixed liquor suspended solids (MLSS) was around 4000 mg TSS/L. Anammox reactor could gradually acclimate to 100% seawater. However, the long-term effects of 50% seawater not only affected nitrogen removal performance, resulting in a decrease of nitrogen removal rate (NRR) to 0.114 kg N/(m(3).d), but also weakened sludge settling ability. The effect resulting from 50% seawater was reversible and the NRR gradually increased to 0.419 kg N/(m3.d) by adding sponge carriers. Analysis of variance (ANOVA) test shown that Delta NO3-N/ANElt-N ratio was significantly different (p < 0.05) under different seawater content. After inhibition resulting from 100% seawater, the response process of anammox could be divided into three periods. At 100% seawater, nitrogen removal performance of anammox reactor was affected when influent nitrite was higher than 150 mg NIL (NO2-Nnif/NH4+-N-inf = 1.37 +/- 0.02). Luong model was suitable to analyze inhibitory effect resulting from nitrite under saline surroundings. (C) 2018 Elsevier Ltd. All rights reserved.

Rapidly growing discharge of nitrogen-rich saline wastewater has significantly affect environment. However, due to the inhibition resulting from high salinity on microbes, it is still a challenge to treat nitrogen-rich saline wastewater efficiently. Anammox process, as a cost-effective and environment-friendly nitrogen removal approach, has shown a potential in treating nitrogen-rich saline wastewater. This review is conducted from a critical perspective and provides a comprehensive overview on the performance of anammox process treating nitrogen-rich saline wastewater. Two strategies including freshwater-derived anammox bacteria acclimatization and marine anammox bacteria enrichment are evaluated. Second, effects resulting from salinity on the performance of anammox reactor, the microbial communities and sludge characteristics are discussed. Third, salinity-tolerant mechanism of anammox bacteria is analyzed. This review also reveals some critical knowledge gaps and future research needs, which benefits application of anammox process to treat nitrogen-rich saline wastewater.

"Candidatus Brocadia sinica"-dominated simultaneous anammox and denitrification (SAD) process was used to treat nitrogen-rich saline wastewater. The reactor was operated at 30 +/- 0.5 degrees C with influent pH of 7.5 +/- 0.1. 'Ca. B. sinica' could adapt to high saline surroundings after 42 cycles' operation. With 100% seawater, nitrogen removal rate and organic removal rate were 0.71 kg/(m(3).d) and 0.27 kg/(m(3).d)), respectively. Both were closed to those without seawater. Independent of salinity, percentage of nitrogen removal by anammox was higher than that by denitrification during the whole treatment period. 'Ca. B. sinica' had good tolerance to salinity. However, maximum removal rate of NH4+-N declined with growing salinity. Modified Boltzmann model was proper to analyze the effect resulting from salinity on the maximum removal rate of NH4+-N. Granular sludge characterized by anammox granule embedded in denitrifying granule might play an important role in salt tolerance of anammox bacteria.

A sequencing batch reactor (SBR) was used to investigate the performance and sludge characteristics of anammox process at moderate and low temperatures. The initial pH was 7.5 and hydraulic retention time (HRT) was 3 h. When temperature was 25-35 °C, nitrogen removal rate (NRR) fluctuated from 1.67 to 1.82 kg/m 3 ·d. However, when temperature dropped to 15 °C, NRR suddenly decreased by 0.48 kg/m 3 ·d. Larger activation energy was acquired at lower temperature, and it was difficult to achieve efficient nitrogen removal under low temperature. When temperature declined to 10 °C, ΔNO 2 − -N/ΔNH 4 + -N and ΔNO 3 − -N/ΔNH 4 + -N reached 1.02 and 0.27, respectively. Inhibition resulting from low temperature on anammox activity was recoverable, and the modified Boltzmann model was appropriate to analyze recovery feature of anammox process. Low temperature not only led to poor nitrogen removal, but also affected sludge size and feature.

Freshwater-derived anaerobic ammonia oxidation (anammox) bacteria ("Candidatus Brocadia sinica") were investigated to remove nitrogen from high-salinity and low-temperature wastewater with glycine addition. The reactor was operated at 15 +/- 0.5 degrees C with influent pH of 7.5 +/- 0.1. When glycine were 0.2, 0.4, and 0.6 mM, respectively, nitrite removal rate (NRR) increased by 27.7%, 47.3%, and 70.4% accordingly. Optimal ammonia removal rate (0.32 kg/(m(3).d)) and NRR (0.45 kg/(m(3).d)) were achieved at 0.8mM glycine. Effect resulting from glycine on nitrite reductase was higher than hydrazine synthase. Moreover,. Delta NO2--N/Delta NH4+-N increased with glycine addition while Delta NO3--N/Delta NH4+-N first increased and then decreased. The remodified Logistic model and modified Boltzmann model were appropriate to describe nitrogen removal with glycine addition. Kinetic parameter lambda achieved through the remodified Logistic model revealed that "Candidatus Brocadia sinica" had a shorter lag phase than that of marine anammox bacteria.

A sequencing batch reactor (SBR) was used to study nitrogen removal performance of marine anammox bacteria (MAB) with Mn(II) and Ni(II) addition. The reactor was operated at 25 +/- 0.5 degrees C with influent pH of 7.5 +/- 0.1. Optimal ammonium removal efficiencies (AREs) were 93.95% and 93.18% with 0.05 mM Mn(II) and 0.025 mM Ni(II), respectively. Both Mn(II) and Ni(II) played key roles in treating nitrogen-rich saline wastewater. However, the effect resulting from Ni(II) was far stronger than Mn(II). With optimal Ni(II) addition (0.025 mM), maximal nitrogen removal rate (NRR) and specific anammox activity (SAA) increased by 14.64% and 57.88%, respectively. Modified Boltzmann model was appropriate to describe nitrogen removal at low Mn(II) and Ni(II) concentrations while remodified Logistic model could be used at high Mn(II) and Ni(II) concentrations. Mn(II) and Ni(II) dosage should be controlled within 0.075 mM to achieve good nitrogen removal in nitrogen-rich saline wastewater treatment.

As an efficient and cost-effective nitrogen removal process, anaerobic ammonium oxidation (ANAMMOX) could be well operated at suitable pH condition. However, pH shock occurred in different kinds of wastewater and affected ANANNOX process greatly. The present research aimed at studying the performance and kinetics of ANAMMOX granular sludge with pH shock. When influent pH was below 7.5, effluent \({\text{NH}}_{4}^{ + }\)–N and \({\text{NO}}_{2}^{ - }\)–N increased with decreasing pH. At Ph 6.0, effluent \({\text{NO}}_{2}^{ - }\)–N approached 100 mg/L, and the ratios of \(\Delta {\text{NO}}_{2}^{ - } - {\text{N}}:\Delta {\text{NH}}_{4}^{ + } - {\text{N and }}\Delta {\text{NO}}_{3}^{ - } - {\text{N}}:\Delta {\text{NH}}_{4}^{ + } - {\text{N}}\) approached 2.2 and 1.3, respectively. Both greatly deviated from theoretical values. When influent pH was above 7.5, effluent \({\text{NH}}_{4}^{ + }\)–N and \({\text{NO}}_{2}^{ - }\)–N increased with increasing pH. At pH 9.0, ammonium removal rate (ARR) and nitrite removal rate (NRR) decreased to 0.011 ± 0.004 and 0.035 ± 0.004 kg/(m3·d), respectively. Besides, \(\Delta {\text{NO}}_{2}^{ - }\)–N:\(\Delta {\text{NH}}_{4}^{ + }\)–N deviated from theoretical value. Longer recovery time from pH 9.0 than from pH 6.0 indicated that alkaline surroundings inhibited anaerobic ammonium oxidizing bacteria (AAOB) greater. The sludge settling velocity was 2.15 cm/s at pH 7.5. However, it decreased to 2.02 cm/s when pH was 9.0. Acidic pH had little effect on sludge size, but disintegration of ANAMMOX granule was achieved with pH of 9.0. The Bell-shaped (A) model and the Ratkowsky model were more applicable to simulate the effect resulting from pH shock on ANAMMOX activity (R2 > 0.95), and both could describe ANAMMOX activity well with pH shock. They indicated that qmax was 0.37 kg \(\Delta {\text{NH}}_{4}^{ + }\)–N/(kgMLSS·d) at the optimum pH value (7.47) in present study. The minimum pH during which ANAMMOX occurred was 5.68 while the maximum pH for ANAMMOX reaction was 9.26. Based on nitrogen removal performance with different pH, strongly acidic (pH ≤ 6.5) or alkaline (pH ≥ 8.5) inhibited ANAMMOX process. Besides, ANAMMOX appeared to be more susceptible to alkaline wastewater. Compared to extremely acidic condition (low pH), extremely alkaline condition (high pH) affected ANAMMOX granules much more.

Sequencing batch reactors were used to study anaerobic ammonium oxidation (anammox) process under temperature shock. Both long-term (15–35 °C) and short-term (10–50 °C) temperature effects on nitrogen removal performance were performed. In reactor operation test, the results indicated that ammonium removal rate decreased from 0.35 kg/(m3 day) gradually to 0.059 kg/(m3 day) when temperature dropped from 35 to 15 °C. Although bacteria morphology was not modified, sludge settling velocity decreased with decreasing temperature. In batch test, apparent activation energy (Ea) increased with decreasing temperature, which suggested the activity decrease of anaerobic ammonium oxidizing bacteria (AAOB). Low temperature inhibited AAOB and weakened nitrogen removal performance. The cardinal temperature model with inflection was first used to describe temperature effect on anammox process. Simulated results revealed that anammox reaction could occur at 10.52–50.15 °C with maximum specific anammox activity of 0.50 kg/(kg day) at 36.72 °C. The cold acclimatization of AAOB could be achieved and glycine betaine could slightly improve nitrogen removal performance at low temperature.

Effect of influent substrate ratio on anammox process was studied in sequencing batch reactor. Operating temperature was fixed at 35 ± 1 °C. Influent pH and hydraulic retention time were 7.5 and 6 h, respectively. When influent NO2 −-N/NH4 +-N was no more than 2.0, total nitrogen removal rate (TNRR) increased whereas NH4 +-N removal rate stabilized at 0.32 kg/(m3 d). ΔNO2 −-N/ΔNH4 +-N increased with enhancing NO2 −-N/NH4 +-N. When NO2 −-N/NH4 +-N was 4.5, ΔNO2 −-N/ΔNH4 +-N was 1.98, which was much higher than theoretical value (1.32). The IC50 of NO2 −-N was 289 mg/L and anammox activity was inhibited at high NO2 −-N/NH4 +-N ratio. With regard to influent NH4 +-N/NO2 −-N, the maximum NH4 +-N removal rate was 0.36 kg/(m3 d), which occurred at the ratio of 4.0. Anammox activity was inhibited when influent NH4 +-N/NO2 −-N was higher than 5.0. With influent NO3 −-N/NH4 +-N of 2.5–6.5, NH4 +-N removal rate and NRR were stabilized at 0.33 and 0.40 kg/(m3 d), respectively. When the ratio was higher than 6.5, nitrogen removal would be worsened. The inhibitory threshold concentration of NO2 −-N was lower than NH4 +-N and NO3 −-N. Anammox bacteria were more sensitive to NO2 −-N than NH4 +-N and NO3 −-N. TNRR would be enhanced with increasing nitrogen loading rate, but sludge floatation occurred at high nitrogen loading shock. The Han-Levenspiel could be applied to simulate nitrogen removal resulting from NO2 −-N inhibition.

A sequencing batch reactor (SBR) was used to test the simultaneous anammox and denitrification process. Optimal nitrogen removal was achieved with chemical oxygen demand (COD) of 150mg/L, during which almost all of ammonia, nitrite and nitrate could be removed. Organic matter was a key factor to regulate the synergy of anammox and denitrification. Both experimental ΔNO2(-)-N/ΔNH4(+)-N and ΔNO3(-)-N/ΔNH4(+)-N values deviated from their theoretical values with increasing COD. Denitrifying bacteria exhibited good diversity and abundance, but the diversity of anammox bacteria was less abundant. Brocadia sinica was able to grow in the presence of organic matter and tolerate high nitrite concentration. Anammox bacteria were predominant at low COD contents, while denitrifying bacteria dominated the microbial community at high COD contents. Anammox and denitrifying bacteria could coexist in one reactor to achieve the simultaneous carbon and nitrogen removal through the synergy of anammox and denitrification.

Herein, a new integrated membrane coagulation reactor (IMCR) was developed to effectively treat synthetic wastewater containing Reactive Black W-2N. The optimal operation conditions were determined as follows: influent pH 5.5, polyferric sulfate (PFS) dose 1.2 mmol/L, and hydraulic retention time 3 h, under which a nearly complete decolorization was achieved and chemical oxygen demand removal reached 92%. Membrane fouling experienced three phases as reflected by different increment rates of the trans-membrane pressure. A high PFS dose aggravated the membrane fouling. The fractal dimension value of flocs increased with the increasing coagulant dose. In comparison to the control experiment, ferrate addition significantly increased the mean size and porosity of the floc particles formed. Because ferrate addition could reduce the trans-membrane pressure increment rate, the steady-state performance of the IMCR process was improved. (C) 2014 Elsevier B.V. All rights reserved.

An upflow anaerobic sludge blanket reactor was employed to treat saline sulfate wastewater. Mesophilic operation (35 ± 0.5 °C) was performed with hydraulic retention time fixed at 16 h. When the salinity was 28 g L −1 , the chemical oxygen demand and sulfate removal efficiencies were 52 and 67 %, respectively. The salinity effect on sulfate removal was less than that on organics removal. The methane productions were 887 and 329 cm 3 L −1 corresponding to the NaCl concentrations of 12 and 28 g L −1 , respectively. High salinity could stimulate microbes to produce more extracellular polymeric substances (EPSs) and granulation could be performed better. Besides, with the high saline surroundings, a great deal of Na + compressed the colloidal electrical double-layer, neutralized the negative charge of the sludge particles and decreased their electrostatic repulsion. The repulsion barrier disappeared and coagulation took place. The maximum size of granules was 5 mm, which resulted from the coupled triggering forces of high EPSs and Na + contents. Sulfate-reducing bacteria (SRB) were dominant in the high saline surroundings while the methane-producing archaea dominated in the low saline surroundings. The SRB were affected least by the salinity.

An integrated membrane coagulation reactor (IMCR) was employed to treat textile wastewater. Color could be removed almost completely and chemical oxygen demand (COD) removal efficiency could reach 88% with polyaluminum chloride (PACl) dose 1.2 mmol/L, influent pH 5.5 and hydraulic retention time (HRT) 3 h. Membrane fouling experienced three phases and a higher PACl dose aggravated the membrane fouling. The contact angle of new membrane was 52.5 degrees while the fouled ones’ were around 81 degrees. The fractal dimension of floc formed with PACl 1 mmol/L was 1.88 while it reached 2.22 with PACl 1.4 mmol/L. A more permeable filter cake was formed with PACl 1 mmol/L and could alleviate the membrane fouling effectively. Both the trans-membrane pressure (TMP) and TMP increment were greater when the IMCR was equipped with larger molecular weight cutoff (MWCO) membrane. The physically reversible and irreversible filtration resistances (Rf) of the IMCR with membrane MWCO 50, 100 and 150 kDa were 3.2, 9.1 and 31.4 times of there intrinsic membrane filtration resistances, respectively. Membrane was fouled more seriously when the higher MWCO membrane was used during the IMCR process. Independent of the membrane MWCO, lower molecular weight (MW) fractions resulted in the irreversible membrane fouling.

A submerged membrane bioreactor was used to treat wastewater containing 50% seawater with the conditions as follows: chemical oxygen demand (COD) was 300–2600 mg/L, ammonium-N was 50–300 mg/L, pH was 6.0–9.0, mixed liquor suspended solids (MLSS) was 7,000 mg/L, dissolved oxygen (DO) was 2–4 mg/L, temperature was 20–25°C. The results showed that both COD and ammonium-N removal efficiencies could reach 90%with the optimal conditions as follows: organic loading rates and ammonium-N loading rates were less than 3.2 kg COD m-3 d-1 and 0.35 kg N m-3 d-1, respectively, pH value was between 7.5 and 8.5, hydraulic retention time (HRT) was more than 12 h. Membrane fouling was aggravated because the viscosity of high saline wastewater was higher than that of fresh water. The trans-membrane pressure (TMP) increased from 5 to 44 kPa during first 180 days but dropped dramatically to 8 kPa after the chemical and physical cleaning, and the filtration capacity of the membrane was almost recovered normally.