Sequencing Batch Reactor Mode Research Articles

Effects of contact/stabilization time ratio on organic carbon-methane conversion in high-rate contact stabilization system

The high-rate contact stabilization (HRCS) process is a promising technique for recovering carbon from wastewater. However, its practical application faces challenges due to its low chemical oxygen demand (COD) removal efficiency, which requires further optimization. The objective of this study was to investigate the optimal process conditions for enhancing COD removal efficiency and carbon recovery rate (CRR) in the HRCS process. To achieve this, a sequencing batch reactor (SBR) was utilized to maximize the feast-famine regime. Although the HRCS process exhibited a lower COD removal efficiency compared to the high-rate activated sludge (HRAS) process in SBR mode, it demonstrated a 16.3 % higher CRR. The influence of the contact time to stabilization time (tc/ts ratio) on both COD removal efficiency and CRR was investigated. The optimum condition was achieved at a tc/ts ratio of 0.18, which resulted in a COD removal efficiency of 60.2 ± 3.0 % and a CRR of 0.417 ± 0.041 g-CODCH4/g-CODinf (CODCH4: produced methane as COD, CODinf: influent COD). The microbial communities in HRAS and HRCS exhibited simplification compared to conventional activated sludge. Distinct shifts were observed in response to changes in solids retention time and tc/ts ratio. Under harsher operating conditions, Lactococcus spp. became the predominant species, achieving the greatest dominance at a tc/ts ratio of 0.18. This is because they produce more extracellular polymeric substances and polyhydroxyalkanoates, which improve organic capture. The operating conditions identified in this study are anticipated to make a significant contribution to practical applications aimed at enhancing carbon recovery.

Coexistence and competition of the nitrifying and anammox bacteria in SMBBR reactor with partial nitritation/anammox process treating synthetic low-strength ammonium wastewater

The nitrite-oxidizing bacteria (NOB) suppression largely restricts the implementation of partial-nitritation and anammox (PN/A) process for low-strength ammonium wastewater treatment. The main goal of the present study was to verify the feasibility of sequencing moving bed biofilm reactor (SMBBR) treating synthetic low-strength ammonium wastewater and the influence of operating conditions and microbial competitions on NOB suppression. The reactor was operated in sequencing batch reactor (SBR) mode with influent ammonium of 50 mg/L, in which the seeded biofilm harvested from an existing similar PN/A reactor treating high-ammonium synthetic wastewater. After increasing the dissolved oxygen (DO) from 0.50 to 1.25 mg/L-with hydraulic retention time (HRT) gradually decreasing from 15 to 5 h-stable nitrogen removal through PN/A was obtained. The long-term operation results showed nitrogen removal efficiencies of 66.23 ± 7.78 % were stably obtained at a relatively low filling ratio of 25 %. The reactor operated in SBR mode allowed NOB suppression and low effluent ammonium due to the ammonium gradient created in cycles. Further, the activity of NOB was controlled at a low level at medium DO concentration. Both ammonium-oxidizing bacteria (AOB) competition acting as DO-cut and anaerobic ammonium-oxidizing bacteria (anammox, AMX) competition acting as nitrite-sink were found to be essential for NOB suppression, and DO-cut played a dominated role. A simple hypothetical microstructure of one-stage PN/A biofilm, assuming AOB layered in the surface of the biofilm while AMX and NOB in the interior, was proposed to define the mechanism of DO-cut and Nitrite-sink. The obtained results demonstrated SMBBR could be regarded as an alternative guideline for successful operation of mainstream PN/A as compared to the integrated fixed film activated sludge (IFAS) systems.

Insights into modified sequencing batch reactor for the treatment of sugarcane vinasse: role of recirculation process

Insights into modified sequencing batch reactor for the treatment of sugarcane vinasse: role of recirculation process

Effect of increasing organic loading rate on the performance of conventional and modified sequencing batch reactors. (Dept. C)

A modified sequencing batch reactor (MSBR) was developed by installing six fiber vertical plates of specific surface area of 180 cm2/ L in conventional sequencing batch reactor (SBR), which designed for supporting the biofilm formation and increasing the system efficiency. In this study, the effect of increasing the organic loading rate of 281.25 g COD/m3. d by 33%, 67%, and 100 % on the performance of SBR and MSBR was investigated. The effluent BOD5, COD and TSS of the MSBR at high organic loading rate was 20, 32 and 27 mg /L, respectively, while for conventional SBR was 34, 58 and 45 mg /L, respectively. The total bio-sludge of MSBR was more than that of conventional SBR by about 30% resulting in a reduction of the F/M value. The sludge volume index (SVI) in MSBR was lower than that of conventional SBR by about 33%. MSBR system was able to treat municipal wastewater with high performance.

Micro-pressure swirl reactor (MPSR) for efficient COD and nitrogen removal of high-concentration wastewater.

A micro-pressure swirl reactor (MPSR) was developed for carbon and nitrogen removal of wastewater, in which dissolved oxygen (DO) gradient and internal circulation could be created by setting the aerators along one side of the reactor, and micro-pressure could be realized by sealing most of the top cap and increasing the outlet water level. In this study, velocity and DO distribution in the reactor was measured, removal performance treating high-concentration wastewater was investigated, and the main functional microorganisms were analyzed. The experiment results indicated that there was stable swirl flow and spatial DO gradient in MPSR. Operated in sequencing batch reactor mode, distinct biological environments spatially and temporally were created. Under the average influent condition of chemical oxygen demand (COD) concentration of 2,884 mg/L and total nitrogen (TN) of 184 mg/L, COD removal efficiency and removal loading was 98% and 1.8 kgCOD/(m3·d) respectively, and TN removal efficiency and removal loading reached up to 90% and 0.11 kgTN/(m3·d) respectively. With efficient utilization of DO and simpler configuration for simultaneous nitrification and denitrification, the MPSR has the potential of treating high-concentration wastewater at lower cost.

Nitrate Removal from Groundwater Using Immobilized Heterotrophic Algae

The treatment efficiency of Chlorella sorokiniana and Scenedesmus species, immobilized in sodium alginate, was evaluated for removing nitrate from groundwater. The experiments were performed initially in batch mode and the best-performing conditions were replicated in sequencing batch reactor mode. S. sp. showed a higher nitrate uptake in short term than C. sorokiniana. Immobilized S. sp. and C. sorokiniana cells showed 90% nitrate removal in 9 and 12 days, respectively. The optimal ratio of algal beads/water was found to be 12.5% (v:v). Comparatively, suspended S. sp. cells were able to remove only up to 35% of nitrate in 8 days. Alginate immobilized S. sp. beads were capable of uptaking nitrate for 100 consecutive days in sequencing batch reactor mode. When tested in actual groundwater, 90% of nitrate was eliminated in 2 days without need for any additional carbon source. Immobilized algal beads can be a low-cost alternative technique to remove nitrate from groundwater as they are water-insoluble, non-toxic, easy to harvest, and offer high removal efficiency.

Intensified nutrients removal in a modified sequencing batch reactor at low temperature: Metagenomic approach reveals the microbial community structure and mechanisms.

To achieve efficient biological nutrients removal at low temperature, a modified sequencing batch reactor (SBR) was developed at 10°C by extending sludge retention time (SRT), shortening aerobic stage and compensating anoxic stage. The average removal rates of ammonium (NH4+-N), total nitrogen (TN) and total phosphorus (TP) were 98.82%, 94.12% and 96.04%, respectively. Variation of carbon source in a typical cycle demonstrated the maximum synthesis of poly-β-hydroxybutyrate (PHB) (60mg/L) occurred after feast period. Furthermore, the TP in sludge reached 50.4mg/g mixed liquor suspended solids (MLSS) (78.4% was inorganic phosphorus and 21.6% was organic phosphorus) after 120 days of operation, indicating an excellent P-accumulating capacity was achieved in this system. Ammonia oxidizing bacteria (AOB) activity inhibition test verified both AOB and ammonia oxidizing archaea (AOA) were involved in ammonia-oxidizing process and the latter accounted for 17%-19%. Metagenomic-based taxonomy revealed the dominant genera were Candidatus Accumulibacter (12.18%), Dechloromonas (7.54%), Haliangium (6.69%) and Candidatus Contendobacter (3.40%). As described from the denitrifying genes perspective, with the exception of nitrite reduction (performed by denitrifiers), denitrifying phosphorus-accumulating organisms (DPAOs) played a leading role in denitrification pathway, showing that poly-β-hydroxyalkanoates (PHA)-driven nutrients removal was the dominate process.

Kinetics Coefficient of Palm Oil Clinker Media for an Attached Growth Media in Sequencing Batch Reactor Mode

Kinetics Coefficient of Palm Oil Clinker Media for an Attached Growth Media in Sequencing Batch Reactor Mode

Bayesian Network Based Approach for Diagnosis of Modified Sequencing Batch Reactor

Wastewater treatment is a complicated dynamic process affected by microbial, chemical and physical factors. Faults are inevitable during the operation of modified sequencing batch reactors (MSBRs) because of the uncertainty of various factors. Abnormal MSBR results require fault diagnosis to determine the cause of failure and implement appropriate measures to adjust system operations. Bayesian network (BN) is a powerful knowledge representation tool that deals explicitly with uncertainty. A BN-based approach to diagnosing wastewater treatment systems based on MSBR is developed in this study. The network is constructed using the knowledge derived from literature and elicited from experts, and it is parametrized using independent data from a pilot test. A one-year pilot study is conducted to verify the diagnostic analysis. The proposed model is reasonable, and the diagnosis results are accurate. This approach can be applied with minimal modifications to other types of wastewater treatment plants.

Variation in bacterial communities during landfill leachate treatment by a modified sequencing batch reactor (SBR)

Variation in bacterial communities during landfill leachate treatment by a modified sequencing batch reactor (SBR)

Improvement of MSBR Process for Treatment of Sand-laden Sewage

The influent of a sewage treatment plant was mainly composed of domestic sewage. Modified Sequencing Batch Reactor (MSBR) process was adopted, in order for the design effluent quality to meet the first level B criteria specified in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB18918 - 2002). High Sand content in the influent caused operational problems such as poor aeration in sequencing batch tank, high sediment content and siphon effect in the effluent of MSBR. The problems were solved by analyzing the reasons and taking improvement measures, thus ensuring the effluent quality to meet the discharge standard.

The Comparison of Different Nutrient Sources in Development of Aerobic Granular Sludge

Aerobic granular sludge (AGS) as recent biological wastewater treatment has been developed in a modified sequencing batch reactor (SBR) using real textile wastewater. This experiment focused on comparing the effects of different nutrient sources, i.e. fine chemicals and fertilizer, on the characteristics of the AGS. The development of AGS conducted in a reactor that called as aerobic up-flow fluidized bed (AUFB) reactor. AUFB reactor allows the three-steps SBR operation namely filling-and-discharging, reaction, and settling. The developed AGS was characterized through some parameters i.e. physical characteristics (morphology, size distribution, settling velocity, specific gravity), granulation profile (MLSS and SVI), and removal performances (removal of COD and colour). The results showed that the developed AGS has a slight morphological difference as the effect of each nutrient source. Interestingly, metal ions contained in the nutrient sources affect the granulation profile and removal performances. Higher metal ions in the sources tent towards better profile (higher MLSS and lower SVI) but decreased removal performance (lower colour removal). In conclusions, this experiment suggests that the use of fertilizers as the nutrient source in developing AGS is comparable to the use of fine chemicals.

RECENT STATE-OF-THE-ART LEACHATE TREATMENT PLANTS IN EASTERN ENGLAND

The paper presents detailed design and performance data for two full-scale leachate treatment plants that have been designed and operated in Eastern England during recent years, in which reliable performance has been achieved for an extended period. The first plant is a modified Sequencing Batch Reactor system, treating relatively diluted leachate (COD about 500 mg/l, ammoniacal-N about 180 mg/l) from a closed landfill site, to provide complete nitrification of ammoniacal-N and degradation of all degradable COD, in a manner requiring minimal site attendance. This is made possible by means of reliable and robust operational software, which can run the plant in a completely automated manner, but nevertheless alerts the operator to any issues. The second state-of-the-art leachate treatment plant was designed and built at the Masons Landfill Site in Ipswich. It was designed to treat 160 m 3 /day of strong methanogenic leachate, often containing more than 2000 mg/l of ammoniacal-N. Discharge of treated leachate is to sewer, under a consent in which the main parameters that are limited are ammoniacal nitrogen, and COD. Treatment comprises full biological nitrification, with ultra-filtration membranes providing additional removal of COD, to achieve challenging consent limits. Taken together, the two case studies provide valuable, robust and real, full-scale data, for the degree of treatment which can realistically be delivered, by well-designed and operated, aerobic biological leachate treatment plants, where each plant has succeeded in treating leachates to well below the consented quality limits for discharge.

Denitrification of high strength nitrate bearing acidic waters in granular sludge sequencing batch reactors

Nitrate containing acidic wastewaters are generated in nuclear fuel cycle operations. These waters are often neutralized prior to either storage or biological treatment. In this study, treatment of high strength nitrate bearing acidic waters was investigated in a sequencing batch reactor. A six liter reactor was inoculated with activated sludge and operated in sequencing batch reactor mode by feeding simulated nitrate wastewater at pH 7.5. After establishing denitrifying microbial consortia in the form of compact granules, the pH of the feed was gradually decreased to 5.0 and then to 4.0. The in situ neutralization of the feed in the reactor by the denitrification-driven alkalinity and the acclimatization strategy helped to achieve complete and stable denitrification during long term operation. The denitrifying microbial community developed in the sequencing batch reactor predominantly consisted of rod- and cocci-shaped microorganisms. This study showed that nitrate bearing acidic effluents can be directly denitrified in granular sludge sequencing batch reactors without a prior treatment. Thus, in situ neutralization and acclimatization strategy can be a potential approach to be considered for treating nitrate contaminated acidic waters.

Aerobic granulation of protein-rich granules from nitrogen-lean wastewaters

Proteins (PN)-rich granules are stable in structure in long-term reactor operations. This study proposed to cultivate PN-rich granules with PN/polysaccharides (PS) >20 from nitrogen lean wastewater, with ammonia-nitrogen as sole nitrogen source at chemical oxygen demand (COD)/N of 153.8. The yielded granules can sustain their structural stability in sequencing batch reactor mode for sufficient treatment of wastewaters up to 7000mg/L COD and with COD/N<500 and in continuous-flow reactor for successful 216-d treatment of wastewaters up to organic loading rate (OLR) of 39kg/m3-d. The produced granules were enriched with Firmicutes and β-proteobacteria as dominating strains. More than 58% of the nitrogen fed in the nitrogen-lean wastewater is converted to the PN in the granules. The replacement of ammonia by nitrate as sole nitrogen source led to granules enriched with γ-proteobacteria which are easily deteriorated at low OLR.

Simultaneous nitrification-denitrification in a sequencing batch reactor equipped with fixed Kaldnes carriers

The main aim of this study was to evaluate the performance of a modified sequencing batch reactor (MSBR) using fixed Kaldnes carriers fed with acclimated sludge for ammonium removal via simultaneous nitrification-denitrification (SND) in synthetic wastewater. The results exhibited a SND of 82.3% within a 450-minute cycle time which was higher than that of a SBR without carrier (69.83%). Nitrite accumulation rate (NAR) increased from 16.94% to 32.83% until 120 minutes of cycle time, and then, decreased to 1.17% by 450 minutes. The biomass concentration in the bio-film (674 ± 6 mg/l) was lower than suspended biomass (1984 ± 12 mg/l). However, the specific oxygen uptake rate (SOUR) of the bio-film (5.24 ± 0.28 mg O 2 /mg MLVSS.d) was greater than suspended biomass (1.89 ± 0.12 mg O 2 /mg VSS.d), indicating the higher bioactivity of the bio-film than that of suspended biomass. Up to 3% salinity had no significant effect on MSBR performance for both chemical oxygen demand (COD) and ammonium removal. These results illustrated the high efficiency of the MSBR in the treatment of wastewater containing high salinity as well as the removal of nitrogen compounds via SND.

Advanced nitrogen removal via nitrite using stored polymers in a modified sequencing batch reactor treating landfill leachate

A modified sequencing batch reactor (SBR) operated at the anaerobic-aerobic-anoxic mode was developed in this study to fully utilize the organics in landfill leachate (ammonia concentration of 1000 ± 50 mg N/L and COD/total nitrogen (TN) ratio of 1-4). The unique feature of modified SBR process was the addition of an anaerobic stage after feeding stage, so that microorganisms could store the organics during anaerobic stage and supply the carbon source for endogenous denitritation after aeration stage. The 70-day operational tests showed the effluent TN was below 10 mg N/L at C/N ratio of 4. The intracellular stored polymers were analyzed and the microorganisms were capable of storing the carbon source as polyhydroxybutyrate (PHB) and glycogen in anaerobic stage, which were the electron donors for endogenous denitritation. Fluorescence in situ hybridization (FISH) analysis showed that glycogen accumulating organisms (GAOs) account for 39.8% of microorganisms in SBR, and carried out advanced nitrogen removal.

Nitrogen and phosphorus removal in a novel extra-loop fluidized bed bioreactor (EFBBR)

AbstractThe performance of a novel extra-loop fluidized bed bioreactor (EFBBR) in sequencing batch reactor mode (total 12 h: anaerobic 1.5 h, aerobic 5 h, anoxic 4.5 h, settle 1 h, and idle 1 h) and employing a PVC tube as a carrier medium for the simultaneous carbon, nitrogen, and phosphorus removal from synthetic wastewater is discussed. The EFBBR was operated and the system commissioning and optimization lasted for about 300 d. During the operation, the EFBBR was able to achieve chemical oxygen demand (COD), ammonia nitrogen (NH4-N), and phosphorus removal efficiencies of 90, 95, and 100%, respectively. The results presented that C/N was insignificant for COD removal. At C/P = 33.2, there were productions including NO2-N and NO3-N. However, at C/P = 10.4, nitrification was restrained with TKN/COD from 0.0805 to 0.139, and phosphorus was eliminated completely. The reactor operation can achieve nitrite accumulation successfully. Therefore, the EFBBR is a novel high-powered equipment for carbon and phosph...

Aerobic sludge granulation in a full-scale sequencing batch reactor.

Aerobic granulation of activated sludge was successfully achieved in a full-scale sequencing batch reactor (SBR) with 50,000 m3 d−1 for treating a town's wastewater. After operation for 337 days, in this full-scale SBR, aerobic granules with an average SVI30 of 47.1 mL g−1, diameter of 0.5 mm, and settling velocity of 42 m h−1 were obtained. Compared to an anaerobic/oxic plug flow (A/O) reactor and an oxidation ditch (OD) being operated in this wastewater treatment plant, the sludge from full-scale SBR has more compact structure and excellent settling ability. Denaturing gradient gel electrophoresis (DGGE) analysis indicated that Flavobacterium sp., uncultured beta proteobacterium, uncultured Aquabacterium sp., and uncultured Leptothrix sp. were just dominant in SBR, whereas uncultured bacteroidetes were only found in A/O and OD. Three kinds of sludge had a high content of protein in extracellular polymeric substances (EPS). X-ray fluorescence (XRF) analysis revealed that metal ions and some inorganics from raw wastewater precipitated in sludge acted as core to enhance granulation. Raw wastewater characteristics had a positive effect on the granule formation, but the SBR mode operating with periodic feast-famine, shorter settling time, and no return sludge pump played a crucial role in aerobic sludge granulation.

Development of aerobic granular sludge for sewage treatment in a hot climate

This study is conducted to develop the aerobic granules for domestic wastewater treatment application in a hot climate (specifically at a temperature of 30oC). A 3 L laboratory scale, slightly modified sequencing batch reactor (SBR) was built and used for the experimental study. The observation shows that after 90 d of the SBR operation, stable aerobic granules with an average size of 1.1 mm were formed at 30oC (fed with acetate). The formation of the aerobic granules is also achievable with a complex influent (pre-treated sewage) after operating the SBR system for 125 days and the average size of the granules from this operation was found to be 0.8 mm. In addition, the results also proved that high temperature (30oC) did not affect the development of stable, dense and good settle able granules; thus making the granular sludge SBR system an effective technology for wastewater treatment in hot climates.