Moving Bed Sequencing Batch Reactor Research Articles

Sequential bio-treatment of ammonia-rich wastewater from Chinese medicine residue utilization: Regulation of dissolved oxygen

To effectively treat actual ammonia-rich Chinese medicine residue (CMR) resource utilization wastewater, we optimized an anaerobic-microaerobic two-stage expanded granular sludge bed (EGSB) and moving bed sequencing batch reactor (MBSBR) combined process. By controlling dissolved oxygen (DO) levels, impressive removal efficiencies were achieved. Microaeration, contrasting with anaerobic conditions, bolstered dehydrogenase activity, enhanced electron transfer, and enriched the functional microorganism community. The increased relative abundance of Synergistetes and Proteobacteria facilitated hydrolytic acidification and fostered nitrogen and phosphorus removal. Furthermore, we examined the impact of DO concentration in MBSBR on pollutant removal and microbial metabolic activity, pinpointing 2.5 mg/L as the optimal DO concentration for superior removal performance and energy conservation.

Advanced biodegradation process of atrazine in the peroxidase-mediated sequencing batch reactor (SBR) and moving-bed SBR (MSBR): mineralization and detoxification.

The advanced biodegradation process of atrazine was stimulated with hydrogen peroxide (H2O2) in a sequencing batch reactor (SBR) under different operational conditions due to in situ generation of H2O2-peroxidase. The complete biodegradation and mineralization of 50mg/L atrazine was achieved in the SBR with a biomass concentration of 328mg/L stimulated with 10mM of H2O2. The presence of H2O2 in the SBR induced the generation of H2O2-peroxidase resulted in acceleration of atrazine biodegradation. Adding moving media to the SBR system and converting it to the MSBR considerably improved the rate of atrazine biodegradation and mineralization under H2O2 mediation. The highest specific utilization rate of atrazine in the SBR operated at the biomass concentration of 55mg/L was 19.4mg/gbiomass.h, while it was 33.5mg/gbiomass.h in the MSBR operated at the biomass concentration of 37mg/L. The low ATZ removal along with no peroxidase activity in the bioreactor in absence of H2O2 clearly ideated that the biodegradation and mineralization of ATZ was considerably mediated by H2O2-peroxidase enzyme. The toxicity of atrazine solution decreased markedly when treated in the MSBR under optimum conditions. Accordingly, the MSBR stimulated with H2O2 is an efficient and thus promising process for biodegradation of recalcitrant compounds.

Factors affecting simultaneous nitrification and denitrification (SND) in a moving bed sequencing batch reactor (MBSBR) system as revealed by microbial community structures.

The effects of biological factors including dissolved oxygen (DO), pH, carbon/nitrogen (C/N) and hydraulic retention times (HRT) on the performance of simultaneous nitrification and denitrification (SND) in a moving bed sequencing batch reactor (MBSBR) were investigated. A low DO was found to be advantageous to the SND in that nitrification was not inhibited, while pH and C/N ratio were shown to have positive effects on SND, and HRT needed to be controlled in a suitable range. A desirable SND efficiency was obtained at a DO of 2.5 mg L-1, pH of approximately 8.0, C/N ratio of 10 and HRT of 10h in the MBSBR. High-throughput sequencing analysis showed that different operating conditions impacted microbial communities, resulting in different nitrogen removal mechanisms. Autotrophic and heterotrophic nitrification together contributed to the good nitrification performance, while denitrification was conducted by combined anoxic and aerobic processes. Furthermore, the results of principal component analyses (PCA) and the abundance of the predominant nitrification and denitrification genera both showed that DO and HRT might be regarded as the dominant variable factors influencing community structure analysis during SND, while the linear discriminant analysis (LDA) effect size (LEfSe) algorithm showed differences in abundance among the biofilm microbial communities with different DO. Overall, the results of this study improve our understanding of the bacterial community structure with different operating conditions in MBSBRs.

The effect of dissolved oxygen concentration (DO) on oxygen diffusion and bacterial community structure in moving bed sequencing batch reactor (MBSBR)

The effect of dissolved oxygen concentration (DO) on simultaneous nitrification and denitrification was studied in a moving bed sequencing batch reactor (MBSBR) by microelectrode measurements and by real-time PCR. In this system, the biofilm grew on polyurethane foam carriers used to treat municipal sewage at five DO concentrations (1.5, 2.5, 3.5, 4.5 and 5.5 mg/L). The results indicated that the MBSBR exhibited good removal of chemical oxygen demand (92.43%) and nitrogen (83.73%) when DO concentration was 2.5 mg/L. Increasing the oxygen concentration in the reactor was inhibitory to denitrification. Microelectrode measurements showed that the thickness of oxygen penetration increased from 1.2 to 2.6 mm when the DO concentration (from 1.5 mg/L to 5.5 mg/L) in the system increased. Oxygen diffusion was not significantly limited by the boundary layer surrounding the carrier and had the largest slope when DO concentration was 2.5 mg/L. The real-time PCR analysis indicated that the amount of the ammonia-oxidizing bacteria and nitrite-oxidizing bacteria increased slowly as DO concentration increased. The proportions of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria, as a percentage of the total bacteria, were low with average values of 0.063% and 0.67%, respectively. When the DO concentration was 2.5 mg/L, oxygen diffusion was optimal and ensured the optimal bacterial community structure and activity; under these conditions, the MBSBR was efficient for total inorganic nitrogen removal. Changing the DO concentration could alter the aerobic zone and the bacterial community structure in the biofilm, directly influencing the simultaneous nitrification and denitrification activity in MBSBRs.

Alteration of moving bed sequencing batch reactor operational strategies for the enhancement of nitrogen removal from stabilized landfill leachate

Stabilized landfill leachate is well known to contain high concentration of nitrogen particularly in the ammonium nitrogen (NH4+-N) form. Also considering of high toxicity of non-biodegradable and low proportion of biodegradable compounds in stabilized landfill leachate, the conventional biological treatment of nitrogen is usually inefficient. As such, the quest of this study was to revise the operational strategies of bioreactor, i.e. moving bed sequencing batch reactor (MBSBR), for the enhancement of nitrogen removal from stabilized landfill leachate. The performance of MBSBRs packed with 8% (v/v) of polyurethane (PU) cubes and polyethylene (PE) rings, respectively, in removing nitrogen from a combined stabilized landfill leachate and domestic wastewater in increasing leachate volumetric ratio under various operational strategies was investigated. On increasing the leachate volumetric ratio to 14%, the performance of both MBSBRs in NH4+-N removal was comparable under the continuous aeration strategy. When the aeration strategy was changed to intermittent aeration (IA), the MBSBR with PU media achieved a higher NH4+-N removal rate, while the MBSBR with PE media failed to remove NH4+-N completely. For the MBSBR with PU media, the adoption of IA coupled with step feeding strategy had yielded a removal efficiency of 80% for total nitrogen in comparison to 64% if only IA strategy was adopted at the leachate volumetric ratio of 14%. Nevertheless, further increase in leachate volumetric ratio to 20% had led to the accumulation of NH4+-N in the effluent of MBSBR under IA-SF strategy. At this stage, the MBSBR operated with IA strategy could still remove NH4+-N completely. Thus, the IA-MBSBR with PU media is the preferred operational strategy for nitrogen removal at higher leachate volumetric ratio.

Application of a New Type of Dispersed Particles-Stabilized Biomass in Aerobic Sequencing Batch Reactor (SBR) for Treating Starchy Wastewater

In this study, we present the advance in the performance of a sequencing batch reactor (SBR) by adding rubber particles to grow a new type of dispersed particles-stabilized biomass. The moving beds were tiny particles of casting rubber with density of 1.15 ± 0.03 g · cm−3. A conventional SBR was used as control, to compare the results between moving-bed SBR (MB-SBR) and SBR, hence received no moving bed. It was found that MB-SBR had acceptable resistance against the phenomena that caused rapid changes in settlement properties in comparison with SBR. The results showed that by decreasing the hydraulic retention time, the performance of MB-SBR was not influenced considerably in comparison with SBR. The performance of MB-SBR was approximately 26% and 88% higher than that of SBR for influent chemical oxygen demand of 1000 and 2000 mg · L−1, respectively. Improved resistant against organic loading shocks was observed in MB-SBR.

Alternative solid carbon source from dried attached-growth biomass for nitrogen removal enhancement in intermittently aerated moving bed sequencing batch reactor

The feasibility of using dried attached-growth biomass from the polyurethane (PU) foam cubes as a solid carbon source to enhance the denitrification process in the intermittently aerated moving bed sequencing batch reactor (IA-MBSBR) during the treatment of low COD/N containing wastewater was investigated. By packing the IA-MBSBR with 8% (v/v) of 8-mL PU foam cubes saturated with dried attached-growth biomass, total nitrogen removal efficiency of 80% could be achieved for 10 consecutive cycles of operation when the intermittent aeration strategy of consecutive 1 h of aeration followed by 2 h of non-aeration period during the REACT period of the IA-MBSBR was adopted. Negligible release of ammonium nitrogen (NH4(+)-N) and slow-release of COD from the dried biomass would ensure that the use of this solid carbon source would not further burden the treatment system. The slow-releasing COD was found to have no effect in promoting the assimilation process and would also allow the carbon source to be used for many cycles of operation. The 'carbon-spent' PU foam cubes could be reused by merely drying at 60 °C at the end of the operational mode. Thus, the dried attached-growth biomass formed on the PU foam cubes could be exploited as an alternative solid carbon source for the enhancement of denitrification process in the IA-MBSBR.

Evaluation of Aeration Strategy in Moving Bed Sequencing Batch Reactor Performing Simultaneous 4-Chlorophenol and Nitrogen Removal

The aeration strategy ranging from intermittent to continuous aeration in the REACT period of moving bed sequencing batch reactor (MBSBR) was evaluated for simultaneous removal of 4-chlorophenol (4-CP) and nitrogen. The results show that the removal rates of 4-CP and ammonium nitrogen (NH(4)(+)-N) increased with the increase of continuous aeration period. In the presence of 4-CP, NH(4)(+)-N removal was mainly by the assimilation process. The removal of NH(4)(+)-N to oxidized nitrogen via oxidation was only observed after 4-CP was completely degraded with sufficient aeration period provided indicating the inhibitory effect of 4-CP on nitrification. As the intermittent aeration strategy would lead to slower 4-CP degradation resulting in the delay of nitrification process, continuous aeration would be the preferred strategy in the simultaneous removal of 4-CP and nitrogen in the MBSBR system.

Enhancement of nitrogen removal in moving bed sequencing batch reactor with intermittent aeration during REACT period

This study was conducted to evaluate the performance of moving bed sequencing batch reactor integrated with intermittent aeration strategy (IA-MBSBR) in nitrogen removal from low COD/N wastewater. The IA-MBSBR with a packing volume of 8% (v/v) of 8-mL polyurethane (PU) foam cubes was capable of achieving a total nitrogen (TN) removal of 57% primarily via simultaneous nitrification and denitrification (SND) process. From the batch experiments, the stored carbon substrate in the biomass located inside the acclimated PU foam cubes was found to be responsible for facilitating the denitrification process. The suspended-growth biomass was found to play the major role in the process of oxidizing the ammonium nitrogen (NH4+–N) to oxidized nitrogen (NO2-–N and NO3-–N). Among the batch reactors operated with the same IA strategy and packed with 20%, 30% and 40% (v/v) of 8-mL acclimated PU foam cubes, complete TN removal was achieved in the reactor with 30% of support media concentration.

Nitrogen removal in moving bed sequencing batch reactor using polyurethane foam cubes of various sizes as carrier materials

The performance of moving bed sequencing batch reactors (MBSBRs) added with 8 % (v/v) of polyurethane (PU) foam cubes as carrier media in nitrogen removal was investigated in treating low COD/N wastewater. The results indicate that MBSBR with 8-mL cubes achieved the highest total nitrogen (TN) removal efficiency of 37% during the aeration period, followed by 31%, 24% and 19 % for MBSBRs with 27-, 64- and 125-mL cubes, respectively. The increased TN removal in MBSBRs was mainly due to simultaneous nitrification and denitrification (SND) process which was verified by batch studies. The relatively lower TN removal in MBSBR with larger PU foam cubes was attributed to the observation that larger PU foam cubes were not fully attached by biomass. Higher concentrations of 8-mL PU foam cubes in batch reactors yielded higher TN removal.

Biodegradation kinetics of a mixture of phenols in a sequencing batch moving bed biofilm reactor under starvation and shock loads

BACKGROUND: The objective of this research was to study the biodegradation kinetics of a mixture of phenol, 4-chorophenol 2,4-dichlorophenol and 2,4,6-trichlorophenol in a moving bed sequencing batch reactor (SBR) subjected to starvation and shock loads. The effect was evaluated on the degradation time and on the specific degradation rate. RESULTS: The bacteria present in the system degraded effectively the mixture of phenols. Degradation efficiencies were higher than 98% as total phenols and greater than 95% as organic carbon. It was observed that starvation and shock loads had only a transient effect on microorganisms degradation rate. The substrate removal rate decreased when the perturbations were applied, but for subsequent SBR cycles the previous activity was recovered. Results also demonstrated that suspended biomass was more sensitive to changes than the attached biomass present in the moving bed. CONCLUSIONS: The moving bed SBR presented robust performance under variable influent concentrations of a mixture of inhibitory compounds. Copyright © 2011 Society of Chemical Industry

Biological removal of phenol from strong wastewaters using a novel MSBR

In this study, the performance of a moving-bed sequencing batch reactor (MSBR) that removes phenol from wastewater is presented. The effects of phenol concentration (50–3325 mg L −1), filling time (0–4 h) and aerating time (4–18 h) on the performance of the MSBR are given in terms of phenol and COD removal efficiencies. Moreover, the effect of the moving media on the overall performance of the reactor is also determined. The reactor can completely remove phenol and COD at inlet concentrations up to 3000 mg phenol L −1 (6780 mg COD L −1), which was the inhibition concentration, and with a 24-h cycle time. The filling time range tested here did not significantly affect phenol or COD removal. The optimum hydraulic retention time (HRT) for the MSBR is 40 h and the critical phenol loading rate is 83.4 g phenol m −3 h −1, which gives a phenol removal efficiency of 99%. The reactor can also withstand shock loads from slug feeding. The moving bed contribution to phenol and COD removal efficiencies was up to 28.1 and 34.7%, respectively, at the phenol loading rate of 83.4 g m −3 h −1. The findings of this investigation suggest that MSBR can be a robust and promising process for effectively treating wastewaters containing inhibitor or recalcitrant compounds in industrial settings.

Effect of Starvation and Shock Loads on the Biodegradation of 4-Chlorophenol in a Discontinuous Moving Bed Biofilm Reactor

The influence of starvation (defined as the period without substrate) and shock loads on the performance of a moving bed sequencing batch reactor degrading 4-chlorophenol (4CP) were investigated. The biomass was acclimated to biodegrade 100 mg/L of 4CP, and the colonization of the packing material was followed. Two starvation periods and two shock loads were studied. The degradation capacity of the suspended and the attached biomass present on the moving bed was also evaluated. The experiments showed that, after the starvation period, the specific degradation rate decreased from 30.5 to 28.5 and 20 mg 4CP/gVSS/h, when starvation periods of 24 and 48 h were applied, respectively. When two concentration peaks of 500 and 1,050 mg/L were applied, a loss of 6% and 8% on the specific degradation rate, respectively, was also observed. The moving bed thus showed great robustness against starvation periods and shock loads. Suspended biomass presented higher specific degradation rates, but attached biomass did not generate a metabolite that is inhibitory when it accumulates.

Study of Nitrogen and Organics Removal in Sequencing Batch Reactor (SBR) Using Hybrid Media

The removal of nitrogen and organics in a sequencing batch reactor (SBR) using hybrid media were investigated in this work. The hybrid media was made by the use of polyurethane foam (PU) cubes and powdered activated carbon (PAC). The function of activated carbon of hybrid media was to offer a suitable active site, which was able to absorb organic substances and ammonia, as well as that of PU was to provide an appropriated surface onto which biomass could be attached and grown. A laboratory-scale moving-bed sequencing batch reactor (SBR) was used for investigating the efficiency of hybrid media. The removal of nitrogen and organics for synthetic wastewater (COD; 490–1,627 mg/L, 180–210 mg/L) were evaluated at different COD/N ratio and different anoxic phase conditions, respectively. The system was operated with the organic loading rate (OLR) of 0.1, 0.16, 0.24, and 0.28 kg COD/m3 day, respectively. Each mode based on OLR was divided as the periods of 45 days of operation time, except for third mode that was operated during 30 days. After acclimatization period, effluent total COD concentrations slightly decreased and the removal efficiency of organics increased to about 90% (COD; 70 mg/L) after 60 days and achieved 98% (COD; 30 mg/L) at the end of experiments. The organics reduction seemed to be less affected by shock loading since high organic loads did not affect the removal efficiency. The concentrations in effluent showed almost lower than 1 mg/L and concentrations were high (150 mg/L) during a very low C/N ratio (C/N = 2). Over 90% of T-N removal efficiency (T-N; 16 mg/L) was obtained during the last 20 days of the operation after controlling the COD/N ratio (C/N = 7). The mixing condition and COD/N ratio at anoxic phase were determined as a main operating factors. In future, the optimal operating conditions of SBR system with hybrid media will be investigated from the view of maintaining a sufficient biomass to the hybrid media under the vigorous mixing conditions.