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In order to remove nitrogen effectively from the wastewater with a low C/N ratio, the feasibility of using spent mushroom compost (SMC) hydrolysates as carbon sources for denitrification was investigated in a sequencing batch reactor (SBR). With SMCs supplement, the SBR performance was improved obviously within the 180 days of operation. The total nitrogen removal was promoted from 46.9% to 81–89.4%, and no negative impact induced by different SMCs on the SBR system was observed. The abundance of functional genes including amoA, nirS/K, norB and nosZ in the active sludge was quantified by qPCR, and most of them elevated after SMC was fed. 16S rRNA gene high-throughput sequencing showed that the significant change in microbial community not only promoted pollutants removal but also benefited the stability of the reactor. Therefore, SMC could be an extremely promising carbon source used for nitrogen removal due to its cost-effective and efficient characteristics. [ABSTRACT FROM AUTHOR]

In present study, two column-type sequencing batch reactors with alternative anoxic/aerobic phases were operated and compared under partial nitrification and full nitrification modes by controlling different dissolved oxygen (DO) conditions. During steady state, the characterizations of extracellular polymeric substances (EPS) from two reactors were qualitatively and quantitatively analyzed through chemical and spectroscopic approaches. Data implied that partial nitrification reactor had relatively higher total nitrogen (TN) removal efficiency and loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) contents. According to excitation emission matrix (EEM) spectra, LB-EPS and TB-EPS from two kinds of reactors expressed similar fluorescence peak locations but different intensities. Fluorescence regional integration (FRI) further suggested that Region IV was the main fraction in both types of EPS fractions. Moreover, TB-EPS exhibited a greater number of molecular weight fractions than those of LB-EPS. Both EPS fractions had similar functional groups, which represented the complex nature of EPS compositions. [ABSTRACT FROM AUTHOR]

The objective of this study was to characterize the composition of extracellular polymeric substances (EPS) during the achievement of partial nitrification and subsequent nitrous oxide (N 2 O) emission treating high ammonia wastewater. After operation of 120 days, the reactor achieved high ammonia removal efficiency and stable nitrite accumulation. The average size of sludge flocs in the reactor increased from 102.6 to 258.5 μm. The main compositions of EPS, including protein (PN) and polysaccharide (PS), increased to 65.46 ± 3.27 and 21.63 ± 1.08 mg/g VSS, respectively. Results of three-dimensional excitation-emission matrix spectroscopy implied that EPS transferred to tryptophan PN-like and humic acid-like substrates. N 2 O emission accounts for 11.67% of removed nitrogen during the steady state of partial nitrification reactor. The obtained results could contribute a better understanding the achievement of partial nitrification through the composition changes of EPS, and provide more information to determine nitrogen removal by considering N 2 O emission. [ABSTRACT FROM AUTHOR]

The present study illustrates the influence of microaerophilic condition on periodic discontinuous batch reactor (PDBR) operation in treating azo dye containing wastewater. The process performance was evaluated with the function of various dye load operations (50–750 mg/l) by keeping the organic load (1.6 kg COD/m 3 -day) constant. Initially, lower dye operation (50 mg dye/l) resulted in higher dye [45 mg dye/l (90%)] and COD [SDR: 1.29 kg COD/m 3 -day (92%)] removal efficiencies. Higher dye load operation (750 mg dye/l) also showed non-inhibitory performance with respect to dye [600 mg dye/l (80%)] and COD [1.25 kg COD/m 3 -day (80%)] removal efficiencies. Increment in dye load showed increment in azo reductase and dehydrogenase activities (39.6 U; 4.96 μg/ml; 750 mg/l). UV–Vis spectroscopy (200–800 nm), FTIR and 1 H NMR studies revealed the disappearance of azo bond (–N N–). First derivative cyclic voltammogram supported the involvement of various membrane bound redox shuttlers, viz., cytochrome-C, cytochrome-bc 1 and flavoproteins (FAD (H)). [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the nitrous oxide (N 2 O) emissions in partial nitrifying and full nitrifying granular sludge reactors treating ammonium-rich wastewater. During stable operation, there was no significant difference of NH 4 + -N removal efficiencies between the two granular reactors. Nitrate and nitrite were the main effluent nitrogen species of the two reactors, and nitrite accumulation rate of partial nitrifying reactor was high of 87.79 ± 2.03%. However, partial nitrifying granular-reactor had better total nitrogen removal efficiency (41.84 ± 3.35%) than that of full nitrifying granular-reactor (19.91 ± 2.12%). According to typical cycles, the N 2 O emission amount per cycle of partial nitrifying reactor account for 11.48% of the incoming nitrogen load, which was 1.5 times higher than that of full nitrifying reactor (7.47%). The obtained results could provide more information for understanding of N 2 O emission in granular sludge systems. [ABSTRACT FROM AUTHOR]

Highlights: [•] Inducing anoxic condition resulted in higher dye degradation. [•] Azo reductase and dehydrogenase activities increased with increasing anoxic/total time. [•] Higher redox catalytic currents were observed with higher anoxic phase operation. [•] Redox shuttlers facilitated enhanced electron transfer by minimization of losses. [•] Tafel analysis and bioprocess parameters correlated well with dye removal. [ABSTRACT FROM AUTHOR]

Highlights: [•] PHB-rich granules were successfully cultivated under nitrogen-limiting conditions. [•] PHB content of the aerobic granules reached 40±4.6%. [•] Effects of intracellular storages on the formation of aerobic granules were explored. [ABSTRACT FROM AUTHOR]

Highlights: [•] Aerobic granules rich in mineral P were incubated and SND via nitrite was achieved. [•] Filamentous bacteria took a critical role in mineral P accumulation in the granules. [•] The main mineral patterns formed in P-rich granules were Ca7Mg2(PO4)6 and Ca3(PO4)2. [•] Aerobic granules accumulated relatively more mineral P than sludge flocs. [Copyright &y& Elsevier]

Highlights: [•] Biofilm configured reactor documented effective azo dye removal. [•] Suspended mode operation illustrated higher substrate (COD) degradation. [•] Azo reductase activity correlated well with the dye degradation pattern. [•] Higher toxicity removal was observed with biofilm treated effluent. [•] Bio-electrochemical analysis documented good activity of biofilm system. [Copyright &y& Elsevier]

Highlights: [•] Butyrate is to be preferred over acetate as substrate for PHB production. [•] P. acidivorans dominates enrichment cultures on both acetate and butyrate. [•] Higher PHB production rate and higher PHB yield on butyrate than on acetate. [•] Accumulation of 83–85wt.% PHB in the presence of ammonium. [•] To optimize PHB production: optimize butyrate production in pre-fermentation. [ABSTRACT FROM AUTHOR]

Abstract: As a biomass carrier, mycelial pellet of Aspergillus niger Y3 was used to immobilize the aniline-degrading bacterium Acinetobacter calcoaceticus JH-9 and the mix culture of the COD rapid degrading bacteria in this study. Tourmaline was added to this system in order to improve the aniline removal performance using combined mycelial pellet. Flask experiments were performed to investigate the promotion mechanism. The results showed that the start-up time was shorted from 7 cycles to only 1 cycle. The aniline and COD concentration in effluent were much lower in the tourmaline-adding system. It was suggested that tourmaline could enhance the number and activity of the aniline-degrading bacteria immobilized on the mycelial pellet. Therefore, the performance of mycelial pellet as a biomass carrier could be improved by tourmaline. [Copyright &y& Elsevier]

Abstract: The present study investigates the formation of aerobic granular sludge in sequencing batch reactor (SBR) fed with palm oil mill effluent (POME). Stable granules were observed in the reactor with diameters between 2.0 and 4.0mm at a chemical oxygen demand (COD) loading rate of 2.5kgCODm−3 d−1. The biomass concentration was 7600mgL−1 while the sludge volume index (SVI) was 31.3mLgSS−1 indicating good biomass accumulation in the reactor and good settling properties of granular sludge, respectively. COD and ammonia removals were achieved at a maximum of 91.1% and 97.6%, respectively while color removal averaged at only 38%. This study provides insights on the development and the capabilities of aerobic granular sludge in POME treatment. [Copyright &y& Elsevier]

Abstract: Mycelial pellet of Aspergillus niger Y3 was used as a biomass carrier to immobilize the aniline-degrading bacterium, Acinetobacter calcoaceticus JH-9 and the mix culture of the COD rapid degradation bacteria. In order to investigate its removal effect on aniline and COD, the combined mycelial pellets were applied in the SBR. Comparison of the performances was conducted between another SBR inoculated with sole strain JH-9 and the above SBR. The results showed that the stable degradations of aniline and COD were observed in both reactors. In the SBR with combined mycelial pellet, the biological removal efficiency was about 0.9mg aniline/(L·d). It was much higher than that in the activated sludge reactor. Meanwhile, the performances of the sedimentation velocity, liquid–solid phase separation and the effluent quality were better in the SBR. According to SEM images and PCR–DGGE analysis, the species immobilized on the biomass carrier were more predominant in this system. [Copyright &y& Elsevier]

Abstract: In this study the evaluation of nitrogen removal in wastewater from a meat products processing company was performed, using a Sequencing Batch Reactor (SBR) at pilot scale. The phases of the SBR operation were: filling, reaction (aeration and intermittent anoxia), sedimentation and discharge. In each of these phases analyses of ammonium (), nitrite (), nitrate (), pH and dissolved oxygen (DO) were carried out to monitor the process of nitrification–denitrification. The results showed that stage IV had the best performance (2.49g CODF/Ld and ) with a removal of 71%. The transformation of much of the to gaseous nitrogen was confirmed, with the concentration of and increasing during the reaction phase but decreasing in the effluent due to its transformation to gaseous nitrogen. [ABSTRACT FROM AUTHOR]

A laboratory-scale anaerobic–anoxic/nitrification sequencing batch reactor (A2N-SBR) fed with domestic wastewater was operated to examine the effect of varying ratios of influent COD/P, COD/TN and TN/P on the nutrient removal. With the increased COD/P, the phosphorus removals exhibited an upward trend. The influent TN/P ratios had a positive linear correlation with the phosphorus removal efficiencies, mainly because nitrates act as electron acceptors for the phosphorus uptake in the A2N-SBR. Moreover, it was found that lower COD/TN ratio, e.g. 3.5, did not significantly weaken the phosphorus removal, though the nitrogen removal first decreased greatly. The optimal phosphorus and nitrogen removals of 94% and 91%, respectively were achieved with influent COD/P and COD/TN ratios of 19.9 and 9.9, respectively. Additionally, a real-time control strategy for A2N-SBR can be undertaken based on some characteristic points of pH, redox potential (ORP) and dissolved oxygen (DO) profiles in order to obtain the optimum hydraulic retention time (HRT) and improve the operating reliability. [Copyright &y& Elsevier]

Abstract: In this present study, sequencing batch reactors (SBRs) were used for biosurfactant production from Pseudomonas aeruginosa SP4, which was isolated from petroleum-contaminated soil in Thailand. Two identical lab-scale aerobic SBR units were operated at a constant temperature of 37°C, and a mineral medium (MM) with palm oil was used as the culture medium. The effects of oil loading rate (OLR) and cycle time on the biosurfactant production were studied. The results indicated that the optimum conditions for the biosurfactant production were at an OLR of 2kg/m3 days and a cycle time of 2days/cycle, which provided a surface tension reduction of 59%, a chemical oxygen demand (COD) removal of 90%, and an oil removal of 97%. Under the optimum conditions, it was found that the biosurfactant production was maximized at an aeration time of 40h. These preliminary results suggest that the SBR can potentially be adapted for biosurfactant production, and perhaps further developed, potentially for large-scale biosurfactant production. [Copyright &y& Elsevier]

Aerobic granular sludge rich in polyhydroxybutyrate (PHB) was cultivated in a sequencing batch reactor (SBR) by seeding anaerobic granular sludge. The PHB content in aerobic granules was investigated and the experimental results reveal that both influent chemical oxygen demand (COD) and ammonium concentrations had a significant effect on the morphological characteristics and the PHB production of the aerobic granular sludge. At a COD and ammonium concentration of 750mg/L and 8.5mg/L, respectively, the PHB content of the granules reached 44%, but their poor settling ability, as evidenced by a high sludge volume index, was observed. This was attributed to the outgrowth of filamentous bacteria on the granule surface. However, an increase in the ammonium concentration resulted in an elevated sludge concentration and a decrease in the PHB content in the granules. In this case, the aerobic granular sludge with a regular and compact structure was formed. The results suggest that, through controlling the COD and ammonium concentrations in the influent, the PHB-rich aerobic granular sludge with good settling ability could be cultivated. [Copyright &y& Elsevier]

Abstract: Two SBR reactors were set up to investigate the feasibility of aerobic granulation under the combined selection pressures of hydraulic shear force and substrate loading. Aerobic granulation was studied at superficial upflow air velocity of 3.2 and 2.4cm/s under an organic loading rate (OLR) range of 6.0–15.0kgCOD/m3 d. Good reactor performance and well granule characteristics were achieved in a wide OLR range from 6.0 high up to 15.0kgCOD/m3 d at 3.2cm/s. While under the velocity of 2.4cm/s, stable operation was limited in the OLR range of 6.0–9.0kgCOD/m3 d and failed to operate with granule deterioration under further higher OLRs. The optimal combination of hydrodynamic shear force and loading selection pressure was demonstrated to be an important factor that influence aerobic granulation and govern the granule characteristics and reactor performance. [Copyright &y& Elsevier]

Abstract: Acetogenic bacteria BP103 cells could be used as the absorbent for melanoidin pigment (MP) and molasses wastewater (MWW). The maximum MP adsorption yield of this strain observed from the dead (autoclaved) cell. It was two times higher than that with resting cells. However, the MP adsorption yield of the strain was 50–60% decreased by acclimatization with the media containing MP. The deteriorated cells (MP-adsorbed cells) could be recovered by washing with 0.1% SDS, 0.1% Tween 80 and 0.1mol/L NaOH solutions. Among them, 0.1mol/L NaOH solution was most suitable according to highest elution ability and no-effect to the MP adsorption capacity (The adsorption yield of deteriorated cell was reduced only 10% after washing three times with 0.1mol/L NaOH solution). In SBR system, the strain showed very low MP removal yield with both molasses wastewater (MWW) from the anaerobic pond (An-MWW) and stillage from an alcohol factory (U-MWW). However, the MP removal yield was increased by supplementation with carbon sources (glucose). Also, the MP removal efficiency was increased with the increase of supplemented-glucose concentration. The highest COD, BOD5, TKN and MP removal efficiencies of the SBR system with 10 times-diluted An-MWW solution containing 30g/L glucose under HRT of seven days were 65.2±2.5%, 82.8±3.4%, 32.1±0.8% and 50.2±3.7%, respectively. The large molecular weight fraction of MP in both U-MWW and An-MWW solutions were rapidly removed by acetogenic bacteria BP103, while the small molecular weight fractions of MP still remained in the effluent. [Copyright &y& Elsevier]

Abstract: Living bio-sludge from domestic wastewater treatment plant was used as adsorbent of heavy metals (Pb2+, Ni2+) and its adsorption capacity was about 10–30% reduced by autoclaving at 110°C for 10min. The living bio-sludge acclimatized in synthetic industrial estate wastewater (SIEWW) without heavy metals showed the highest Pb2+ and Ni2+ adsorption capacities at 840±20 and 720±10mg/g bio-sludge, respectively. The adsorbed Pb2+ and Ni2+ were easily eluted (70–77%) from bio-sludge by washing with 0.1mol/l HNO3 solution. The heavy metals (Pb2+, Ni2+) removal efficiency of both SBR and GAC-SBR systems were increased with the increase of hydraulic retention time (HRT), or the decrease of organic loading. The SBR system showed higher heavy metals removal efficiency than GAC-SBR system at the same organic loading or HRT. The Pb2+, Ni2+, BOD5, COD and TKN removal efficiencies of GAC-SBR system were 88.6±0.9%, 94.6±0.1%, 91.3±1.0%, 81.9±1.0% and 62.9±0.5%, respectively with industrial estate wastewater (IEWW) with 410mg/l glucose, 5mg/l Pb2+ and 5mg/l Ni2+under organic loading of 1.25kgBOD5/m3 d (HRT of 3 days). The bio-sludge quality (sludge volume index: SVI) of the system was less than 80ml/g. The excess sludge from both SBR and GAC-SBR systems with SIEWW under the organic loading of 1.25–2.50kgBOD5/m3 d contained Pb2+ and Ni2+ at concentrations of 240–250mgPb2+/g bio-sludge and 180–210mgNi2+/g bio-sludge, respectively. [Copyright &y& Elsevier]

Abstract: The aim of this study was to estimate the BOD5 and COD removal efficiency and biomass yield coefficient in sequencing batch reactors (SBR) treating landfill leachate. Experiments were carried out in four SBRs at HRT of 12, 6, 3 and 2d. Two series were performed. In series 1, the reactors were operated in a 24h cycle mode (anoxic 3h, aeration 18h, settling 2.75h, and discharge 0.25h). In series 2, however, the anoxic phase was eliminated. In both series the BOD5 removal efficiency was almost identical – over 98%. On shortening HRT from 12 to 2d, COD removal efficiency decreased from 83.1% to 76.7% (series 1). In series 2, efficiency ranged from 79.6% to 75.7%. In the reactors working with the anoxic phase the observed biomass yield coefficient (Y obs) was nearly constant (0.55–0.6mgVSS/mgCOD). Upon elimination of the anoxic phase, the Y obs was observed to decrease from 0.32mgVSS/mgCOD (HRT 2d) to 0.04mgVSS/mgCOD (HRT 12d). [Copyright &y& Elsevier]

Abstract: Both resting (living) and autoclaved (dead) bio-sludges showed almost the same Cu2+ and Zn2+ adsorption capacities with synthetic industrial estate wastewater (SIEWW). The resting bio-sludge showed not only Cu2+ and Zn2+ adsorption abilities but also organic matter adsorption ability. But, the organic matter (COD and BOD5) adsorption ability of bio-sludge with SIEWW containing 60mg/L Cu2+ was about half of that with SIEWW containing 60mg/L Zn2+. The adsorbed Cu2+ and Zn2+ were easily eluted (70–75%) from bio-sludge with 0.1N HNO3 and 0.1M EDTA solutions. Bio-sludge from a wastewater treatment plant could be used as an adsorbent for metal ions (Cu2+ and Zn2+). Cu2+ and Zn2+ could repress the SBR system efficiency but its efficiency could be increased with the increase of mixed liquor suspended solids (MLSS), and Cu2+ had more effect than Zn2+ to repress the system efficiency. The SBR system showed very low removal efficiencies of the pollutants with industrial estate wastewater (IEWW), but its pollutant removal efficiencies with IEWW could be increased with the addition of glucose. The Zn2+, Cu2+, BOD5, COD and TKN removal efficiencies of the system with IEWW containing 1.27g/L glucose, 10mg/L Cu2+ and 10mg/L Zn2+ under MLSS of 4500mg/L were 92.61±0.28%, 83.77±0.93%, 98±0%, 92±0% and 78.1±0.1%, respectively. [Copyright &y& Elsevier]

Abstract: COD, nitrogen, phosphate and para-chlorophenol (4-chlorophenol, 4-CP) removal from synthetic wastewater was investigated using a four-step sequencing batch reactor (SBR) at different sludge ages and initial para-chlorophenol (4-CP) concentrations. The nutrient removal process consisted of anaerobic, oxic, anoxic and oxic phases with hydraulic residence times (HRT) of 1/3/1/1h and a settling phase of 0.75h. A Box–Wilson statistical experiment design was used considering the sludge age (5–25days) and 4-CP concentration (0–400mgl−1) as independent variables. Variations of percent COD, NH4-N, PO4-P and 4-CP removals with sludge age and initial 4-CP concentration were investigated. Percent nutrient removals increased with increasing sludge age and decreasing 4-CP concentrations. Low nutrient removals were obtained at high initial 4-CP concentrations especially at low sludge ages. However, high sludge ages partially overcome the adverse effects of 4-CP and resulted in high nutrient removals. COD, NH4-N, PO4-P and 4-CP removals were 76%, 72%, 26% and 34% at a sludge age of 25days and initial 4-CP concentration of 200mgl−1. Sludge volume index (SVI) also decreased with increasing sludge age and decreasing 4-CP concentrations. An SVI value of 104mlg−1 was obtained at a sludge age of 25days and initial 4-CP of 200mgl−1. [Copyright &y& Elsevier]

Abstract: An anaerobic–anoxic sequencing batch reactor (A2 SBR) coupled with a fixed-bed nitrification reactor for simultaneous carbon, nitrogen and phosphorus removal was evaluated using slaughterhouse wastewater. Whereas the treatment could not be successfully carried out on the raw wastewater, the process showed very good nutrient removal performances after prefermentation. The removals of COD, N-NH4 and P-PO4 achieved were 99%, 85% and 99%, respectively. The increase in volatile fatty acid (VFA) and phosphate concentrations in the effluent after prefermentation may explain the high levels of biological carbon, nitrogen and phosphorus removal observed. A simple prefermentation is, therefore, necessary but sufficient to ensure good performances of the denitrifying enhanced biological phosphorus removal (EBPR) process. [Copyright &y& Elsevier]

Nitrate can affect phosphate release and lead to reduced efficiency of biological phosphorus removal process. The inhibition effect of remaining nitrate at the anaerobic/anoxic phases was investigated in a lab scale sequencing batch reactor. In this study the influence of denitrification process on reactor performance and phosphorus removal was examined. The experiments were carried out through simultaneous filling and decanting, mixing, mixing-aeration and settling modes. Glucose and acetate were used as carbon sources. The proposed treatment system was capable of removing approximately 80% of the influent PO4-P, 98% NH4-N and 97% COD at a SRT of 25 days. In the fill/decant phase, anoxic and anaerobic conditions prevailed and a large quantity of nitrate was removed in this stage. In the anoxic phase the remaining nitrate concentration was quickly reduced and a considerable amount of phosphate was released. This was attributed to the availability of acetate in this stage. For effective nitrogen and phosphate removal, a short anoxic phase was beneficial before an aerobic phase. [Copyright &y& Elsevier]

• Stress response of aerobic granular sludge to alkalinity was revealed. • Alkalinity slightly stimulated the COD and NH4+-N removal, boosted TIN removal efficiencies. • Up to 500 mg/L fortified alkalinity reduced the bacterial richness and diversity sharply. • Extra addition of alkalinity suppressed GAOs in competition with PAOs, and promoted growth of Thiothrix and Acinetobacter. Effects of additional alkalinity on the performance of aerobic granular sludge (AGS) in sequencing batch reactors (SBR) performing simultaneous nitrification, denitrification, and phosphorus removal (SNDPR) were evaluated. Results showed that COD and ammonia-N ( N H 4 + -N) were slightly stimulated and remained high and stable with the increase of alkalinity up to 750 mg/L, while denitrification was boosted and total inorganic nitrogen (TIN) removal efficiency increased from 60.46% to 98.62% with an additional alkalinity of 750 mg/L. However, total phosphorus (TP) removal stayed unaffected and efficient. Illumina MiSeq sequencing revealed that microbial diversity and richness shifted mostly with 500 mg/L exterior alkalinity addition. Additional alkalinity altered the bacterial compositions within aerobic granules at various levels and the enrichment of Thiothrix and Acinetobacter was accounted for the promotion of COD and TIN removal. [ABSTRACT FROM AUTHOR]

• Impacts of acetate/oleic acid ratio on SBR were studied for the first time. • The average removal of PO3− 4 -P was greater than 96% in reactor with less than 60% oleic acid. • Growing ratio of oleic acid led to serious bulking, which was related to PN/PS. • Microbial community shifted significantly with varying acetate/oleic acid ratios. • The correlations among SBR operation, QS and microbial community were obtained. This study comprehensively investigated the impact of acetate/oleic acid ratios (80%/20%, 60%/40%, 40%/60%, and 20%/80%) on sequencing batch reactor (SBR) with respect to the variations in performance, quorum sensing (QS), and microbial community. Results showed that NH+ 4 -N removal was not affected by the acetate/oleic acid ratios, while the COD, total nitrogen (TN), and PO3− 4 -P removal was considerably affected. The increasing oleic acid ratios led to severe sludge bulking, which was significantly positively correlated with proteins/polysaccharides (p < 0.001). The correlation of QS with the performance and sludge properties was also observed. High-throughput sequencing demonstrated that microbial compositions considerably shifted with varying acetate/oleic acid ratios. Moreover, the potential correlation of bacterial genera with the SBR performance and QS was proposed. This study elucidated the effect of acetate/oleic acid ratios on SBR from microbial viewpoint, which provided insights into fully understanding the essential roles of carbon source on wastewater treatment. [ABSTRACT FROM AUTHOR]