Sludge Sequencing Batch Reactor Research Articles

Effect of Aeration Rate on Specific Oxygen Uptake Rate (SOUR) in Treating Chemical Oxygen Demand (COD) in Domestic Wastewater

Specific oxygen uptake rate (SOUR) is significant parameter to determine the microbial activity and examined the effluent quality in biological wastewater treatment. Chemical oxygen demand (COD) is the major indicator in monitoring the effluent quality in relation on its removal mainly depends on the microbial activity in the activated sludge. So, this research is conducted to study the effect of aeration rate on SOUR and determined the best oxygen requirement in removing COD in domestic wastewater. The procedure was carried out by using domestic wastewater as the seed sludge in sequencing batch reactor. The reactor with working volume of 2L was operating 6 cycles in 24 hours with five phases (feeding, aeration, settle, draw and idle). The aeration time is fixed to 2.5 hours. The dissolved oxygen and COD readings were recorded with four types of aeration rate adjusted at 1L, 2L, 3L and 4L / min daily for 7 days. The result indicates that, 3L/min gives the highest SOUR which reflects that the high activity of microbial in this condition. Besides, the effluent also shows the highest COD removal efficiency on 3L/min of aeration rate. So, as a conclusion the best oxygen requirement for the microbial to carry out their activities on aeration rate of 3L/min.

Mesophilic, thermophilic and thermal hydrolysis process coupled anaerobic digestion of sewage sludge: Biomethane potential, pathogen removal and energy feasibility

Conventional Anaerobic digestion is one of the most preferred sludge management techniques however, it has limitations such as low hydrolysis rate, longer retention time, larger digester volume, and reduced methane generation etc., To overcome these problems, Thermal hydrolysis process (THP) has been used as an effective pretreatment method for enhancing methane generation. However, the effect of the thermal hydrolysis process in heavy metal solubilization and methane production from high SRT (solids retention time) sludge is still not clear. Anaerobic digestion of sewage sludge sourced from sequencing batch reactor (SBR) and conventional activated sludge process (CASP) systems were evaluated under mesophilic (MAD), thermophilic (TAD), and thermal hydrolysis process (THP) mediated anaerobic digestion (AD) in terms of methane generation and, VS and pathogen removal. THP resulted in almost 38% COD solubilization for SBR and CASP sludge. Anaerobic digestion of SBR sludge resulted in methane generation of 101, 166, and 390 mL/gVS under mesophilic, thermophilic, and THP pretreatment conditions, respectively. For CASP sludge, the highest methane generation was observed for THP pretreated sludge (587 mL/gVS), followed by thermophilic (298 mL/gVS) and mesophilic digestion (241 mL/gVS). The fecal coliforms in the mesophilic and thermophilic digested SBR sludge were 3000 and 620 MPN/g, respectively, while 6100 and 740 MPN/g were found in digested CASP sludge, respectively. The THP-MAD and TAD processed SBR, and CASP sludges met the Class A sludge fecal coliforms and Salmonella density criteria of <1000 MPN/g TS (dry basis) and 3 MPN/4g TS (dry basis), respectively, over MAD processed sludges. Even though THP pretreatment resulted in the release of heavy metals, the concentration of heavy metals in the THP effluent was lesser than the limits prescribed by USEPA. The energy demand of the THP unit (160 °C, 6 bar) was estimated to be 162 MJ/m3. The energy balance analysis revealed that THP pretreatment would lead to energy self-sufficiency upon integration in a wastewater treatment plant (WWTP). This study can provide an experimental basis to apply THP pretreatment to enhance hydrolysis rate in anaerobic digesters while maximizing methane production and achieving energy benefits over MAD and TAD.

Potential positive effects of natural sunlight on a biological system for landfill leachate treatment

AbstractActivated sludge filtration performance is a significant mean to evaluate membrane fouling trend for wastewater treatment. Here the impact of sunlight irradiation on activated sludge filtration performance and microbial communities in sequencing batch reactors (SBRs) when treating raw landfill leachate were studied. The sludge in photic SBR (i.e., SBR exposed to natural sunlight) exhibited better filtration performance compared to dark SBR (i.e., SBR unexposed to sunlight). The removal efficiency of COD and NH4+‐N in the photic SBR were slightly higher than those in the dark SBR. The contents of the extracellular polymeric substances (EPSs) of sludge in both SBRs initially increased and then decreased. However, in the later period, the sludge filtration performance worsened due to the fungal activity in the dark SBR. Natural sunlight irradiation promoted sludge filtration performance by affecting the microorganism structure in the photic SBR. The bacterial genus Thauera was dominant in the photic SBR (39.35%), whereas Planktosalinus and Ottowia were dominant in the dark SBR (16.84% and 12.55%, respectively). Natural sunlight irradiation had a prominent effect on the fungal diversity in the system, and filamentous bulking caused by the fungi genus Trichosporon’s proliferation was observed in the dark SBR but not in the photic SBR, which also increased the polysaccharide content.

Design Criteria for Chicken Slaughterhouse Wastewater Treatment with Granular Activated Sludge in Sequencing Batch Reactor

Chicken Slaughterhouse (RPA) is a business in the field of slaughtering and processing chicken into parts that are ready to sell to customers, where the waste water which contains high levels of organic matter can pollute the environment. Therefore, it is necessary to treat wastewater that is efficient and easy to use such as Granunlar Activated Sludge (GAS) using Sequencing Batch Reactor (SBR). The study was conducted on a laboratory scale to determine the effect of aeration time and settling time using different aeration (7 L/min and 10 L/min). The formation of GAS was cultured by reacting the activated sludge with slow stirring for 28 days, after which it was acclimatized by 50%, 75%, and 100%, then entered into the main study. The results obtained from the processing results are the level of COD removal to 25, 66 mg/L with 97.49% efficiency; BOD became 107.61 mg/L with an efficiency of 85.29%; and removal of TSS to 64 mg/L with an efficiency of 60%. The optimum processing time is 1 hour aeration with 40 minutes of precipitation using an aeration rate of 10 L/min. The design criteria obtained were BOD Load 0.671 kg BOD/m3.day, F/M ratio 0.145 kg BOD/kg MLVSS.day, HRT 26 hours, and SRT 28 days.

Roles of Granular Sludge Size Restricting and Organic Degradation in an Extended Filamentous AGS System Using Agnail Aeration Device

This work investigated the role of an agnail device (manually made from a comb) on sludge size restriction and organic degradation in extended filamentous aerobic granular sludge-sequencing batch reactors (AGS-SBRs) with artificial wastewater. Two identical SBRs (R1 and R2) were employed in this experiment. Extended filamentous AGS with a large size was achieved in both SBRs by seeding the dewatering the sludge on day 40. R1 (the control) did not use the agnail aeration device, and the extended filamentous AGS system was finally disintegrated. However, R2 promptly employed the agnail device on days 56–59, the extended filamentous AGS size obviously decreased from 4.8 mm to 2.5 mm, and the dominant filamentous species, including Proteobacteria, Acidobacteria, and Choroflexi, gradually shrank at a low level, acting as a framework for AGS recovery. This was because enough nutrients diffused into the inside of small sludge for the filamentous living. Simultaneously, the sludge volume indexes (SVI5 and SVI30) sharply decreased from 155.8–103.9 to 51.7–46.6 mL/g, and the mixed liquid suspended solids (MLSSs) and extracellular polymeric substances (EPSs) in R2 both increased and were kept at 5816 mg/L and 69.1 mg/g·MLVSS, respectively. These contributed to enhancing the sludge’s structural stability to avoid AGS failure. COD and NH4+-N in R2 were both degraded by simultaneous nitrification and denitrification (SND) processes throughout the experiment, which was not significantly influenced before or after the agnail aeration device was employed. These results indicate that the agnail device can effectively restrict AGS size and limit the extended filamentous overgrowth with nutrient diffusion into the sludge’s interior, which can prevent AGS disintegration. In addition, this device had no significant influence on organic degradation.

Results of Adding Sludge Micropowder for Microbial Structure and Partial Nitrification and Denitrification in a Filamentous AGS-SBR Using High-Ammonia Wastewater

This work investigated the roles of sludge micropowder addition in microbial structure and partial nitrification and denitrification (PND) in an extended filamentous aerobic granular sludge-sequencing batch reactor (AGS-SBR) using high-ammonia wastewater. Type 1683 Acinetobacter with a high percentage became the dominant extended filaments, remarkably shifted and remained at a low level, acting as a framework for AGS recovery after micropowder addition. The sludge volume index (SVI5) decreased from 114 to 41.7 mL/g, mixed liquid suspended solids (MLSS) and extracellular polymers (EPS) both increased and balanced at 6836 mg/L and 113.4 mg/g•MLVSS, respectively. COD and NH4+-N were degraded to certain degrees in the end. However, the effluent NO2−-N accumulated to the peak value of 97.6 mg/L on day 100 (aeration stage), then decreased and remained at 45.3 mg/L with development of the stirring and micropowder supplemented in the SBR on day 160 (anoxic stage), while the influent NO2−-N always remained at zero. Interestingly, the influent/effluent NO3−-N both remained at zero throughout the whole experiment. These results demonstrated that PND was successfully obtained in this work. Sludge micropowder addition not only restrained the extended filaments’ overgrowth, but also contributed to PND realization with carbon released. Citrobacter and Thauera played an essential role in the PND process for high-ammonia wastewater treatment. Running condition, wastewater characteristic, and sludge structure played an important role in microbial composition.

Effects of Bisphenol A Stress on Activated Sludge in Sequential Batch Reactors and Functional Recovery

This study assessed the toxic effects of bisphenol A (BPA) on the microbial community and the function of activated sludge in sequencing batch reactors (SBRs). The toxicity of BPA was mitigated through dosing sludge with Rhodococcus Req-001. BPA reduced the biomass of sludge, and the proportion of viable bacteria decreased with the aggravation of BPA pollution. BPA affected the secretion of extracellular polymeric substances (EPSs), increased the ratio of polysaccharide to protein, and deteriorated the sedimentation performance of sludge. BPA decreased the abundances of functional bacteria involved in the degradation of organic matter and water purification, including Polaromonas, Dechloromonas, and Nitrospira, and the water purification capacity of the reactor decreased. Req-001 enhanced the BPA removal efficiency by 15%, and increased ammonia nitrogen and phosphorus removal by 8.8% and 22.7%, respectively. The functional recovery ability of the sludge system and the high removal ability of Req-001 make it a promising specie for use in BPA bioremediation. This study combined the effect of BPA on activated sludge and reactor performance with the microbial community, clarified the toxic mechanism of BPA on activated sludge, and therefore provides a theoretical basis and potential solutions to help WWTPs cope with the toxic effects of BPA.

Understanding the effect of residual aluminum salt coagulant on activated sludge in sequencing batch reactor: Performance response, activity restoration and microbial community evolution

To investigate the effect of residual coagulant after coagulation pretreatment on activated sludge system of wastewater treatment plants (WWTPs), comparative evaluation of lab-scale sequencing batch reactors under different poly-aluminum chloride (PAC) concentrations (20 and 55 mg/L), presenting the performance differences of reactors. Results showed that the PAC concentration of 20 mg/L slightly enhanced the average removal efficiencies of chemical oxygen demand (COD) and total nitrogen (TN), up to 93.43% and 72.52%. Whereas, an inhibition effect was exerted at the PAC concentration of 55 mg/L, the average removal efficiencies decreased to 88.56% and 57.80% respectively. Similarly, the residual aluminum salts showed a concentration effect of low promotion and high inhibition on sludge activity index. The content of specific oxygen utilization rate (SOUR) and dehydrogenase (DHA) sharply decreased by 30.17% and 53.56% under the high PAC concentration of 55 mg/L. Activity recovery phase showed that the suppression of aluminum salt coagulant on biological system was reversible. High-throughput sequencing presented that the relative abundance of microbes showed obvious variations at different PAC concentrations, and certain bacteria in Chloroflexi and Bacteroidota exhibited better adaptability to the high PAC concentration environment. Nevertheless, the antagonism action between denitrifying genera and other genera as well as the downregulation of functional enzymes regarding nitrogen metabolism gave rise to the deterioration of denitrification under the high PAC concentration of 55 mg/L. This study revealed the influence mechanism of residual aluminum salt coagulant on activated sludge system, providing strategies for efficient decontamination and long-term stable operation of biological system in wastewater treatment plant under the condition of adding PAC.

Effect of stepwise or one-time illumination strategy on the development of algal-bacterial aerobic granular sludge in sequencing batch reactor

Algal-bacterial aerobic granular sludge (AGS) as a promising wastewater treatment biotechnology has attracted more attention in recent years. Still, limited information is available on the effect of stepwise illumination on algal-bacterial AGS. In this study, two illumination strategies, i.e., stepwise (R1) and one-time (R2) daily, were applied to cultivate algal-bacterial AGS from bacterial AGS. Results indicated that R1 holds more advantages over R2 in terms of algal-bacterial AGS formation, biomass growth, extracellular polymeric substances excretion and phosphorus (P) accumulation. Specifically, algal-bacterial AGS in R1 contained higher chlorophyll a content of 5.84 mg/g-MLVSS with the biomass yield of 0.50 g-MLVSS/g-COD in comparison to 5.04 mg/g-MLVSS and 0.43 g-MLVSS/g-COD in R2. Moreover, stepwise illumination effectively alleviated the negative effects of microalgae on anaerobic P release and P accumulation. However, no significant difference was detected between R1 and R2 regarding granule diameter and morphology in addition to organics and nutrients removal.

Influence of cell lysis by Fenton oxidation on cryptic growth in sequencing batch reactor (SBR): Implication of reducing sludge source discharge

The cell lysis-cryptic growth was implemented by Fenton oxidation in sequencing batch reactor. Optimizing sludge lysis condition could maximize the release of nutrients and sludge disintegration degree. After Fenton oxidation, the extracellular polymeric substance was obviously destroyed with the sludge average particle decreased from 64 μm to 36 μm. After 5% of the settled sludge in sequencing batch reactor (SBR) was oxidized by Fenton and then returned to SBR, the mixed liquor suspended solids (MLSS) decreased by 19.3% at the end of 35 days operation, the average mixed liquor volatile suspended solids/mixed liquor suspended solids (MLVSS/MLSS) was promoted by 13.3% during the entire operation. Returning lysed sludge had no significant influence on the organics and nitrogen removal, but the total phosphorus removal was distinctly enhanced by generating FePO4 precipitate. Additionally, returning lysed sludge suppressed nitrifying bacteria and promoted denitrifying bacteria slightly. Consequently, the cell lysis-cryptic growth for reducing sludge source discharge from wastewater biological treatment could be achieved on the premise of ensuring effluent quality.

개인하수처리시설의 배출특성 및 관리방안 연구

Individual sewage treatment process (ISTP) is classified into a sewage treatment system which treats all the domestic sewage and a water-purifier tank which treats only effluent flushing from the toilet. The granular sludge-sequencing batch reactor (GS-SBR) represent an attractive alternative to the ISTP due to their small footprint and their low energy consumption and excess sludge production. The objectives of this study is to analyze an operating factors of the ISTP for enhancing nitrogen removal and to figure out the performance of anaerobic/oxic GS-SBR as an alternative of ISTP (activated sludge process, contact oxidation process, biofiltration process). As a result, the efficiencies of the real ISTP showed a very fluctuating effluent qualities (BOD 0.5-47.6 mg/L, COD 1.4-71.1 mg/L, T-N 1.1-114.7 mg/L, T-P 0.073-15.041 mg/L). This indicates an alternative of cost-effectiveness process is needed to enhancing nitrogen removal rate despite a fluctuating influent concentration. As an alternative to the ISTP, the GS-SBR performance achieved high nitrogen efficiencies of <79.8 % at influent carbon/nitrogen (C/N) ration of 1-3, the food/microorganism (F/M) ratios of 0.25kgCOD /kgMLVSS/d, and the operation mode of aeration/non-aeration (1.5:1-3:1). This result indicates the anaerobic/oxic GS-SBR could be used as an alternative of the ISTP to improve the river water quality.

The co-effect of ampicillin and multi-walled carbon nanotubes on activated sludge in sequencing batch reactors: microbial status, microbial community structure and ARGs propagation

The co-occurrences of ampicillin and multi-walled carbon nanotubes showed a lower cytotoxicity to activated sludge compared to individual ones, but enhanced the relative abundances of antibiotic resistance genes.

Biological treatment of ranitidine and cefixime trihydrate mixed solution by activated sludge in sequencing batch reactor

Biological treatment of ranitidine and cefixime trihydrate mixed solution by activated sludge in sequencing batch reactor

Understanding the microbial trends in a nitritation reactor fed with primary settled municipal wastewater

Partial nitritation was pointed out as the key step to implement the autotrophic nitrogen removal processes at low temperature. This study investigated the initiation and maintenance of a nitritation process with simultaneous COD removal in a sequencing batch reactor (SBR) run at 15 °C and fed with primary settled urban wastewater characterized by 42 ± 10 mg TOC/L and 45 ± 4 mg NH4+-N/L. A nitrite accumulation ratio of nearly 100% was observed and the long-term (354 days) process stability was successfully maintained despite the municipal wastewater composition fluctuations. The absence of nitrite oxidizing bacteria (NOB) activity was attributed to the free nitrous acid (FNA) in-situ accumulated at high levels (0.02–0.20 mg HNO2-N/L). Despite nitrate production was not observed, the quantification of bacterial groups indicated that NOB were present in the SBR sludge throughout the entire operational period. Ammonium oxidizing bacteria (AOB) abundance and community structure were significantly influenced by the organic matter present in the feeding. Average organic matter removal efficiencies of 80% were obtained without observing any detrimental effect over the nitritation process performance, due to the functional redundancy within both the chemoheterotrophic and AOB communities.

Complex effects of pH and organic shocks on arsenic oxidation and removal by manganese-oxidizing aerobic granular sludge in sequencing batch reactors

Biological technologies are efficient and economical methods for removing toxic arsenic (As) from organic wastewaters. In this study, four sequencing batch reactors of manganese-oxidizing aerobic granular sludge (Mn-AGS) were operated in duplicate and imposed with acidic pH and high organic shocks. Batch experiments with different initial conditions were conducted to investigate the effects of pH and organic load on As(III) oxidation and removal. The results indicate that acidic pH shocks (influent pH decreased to 4.0/3.0) unexpectedly increased the As removal efficiency from 23.4–38.2% to 64.7–72.5%. The effects of high organic shocks were very complicated, as the results of the shocks were opposite twice. According to the results of the batch experiments, it was estimated that the suitable pH range for high performance was 5.0–8.5 in reaction liquid. Although acidic pH shocks initially inhibited As(III) oxidation and removal, they largely extended the reaction time of the suitable pH range and finally improved the As removal efficiency. There were many negative and positive factors affecting the As removal during the high organic shocks, leading to the unstable responses. Moreover, the microbial community was not largely changed by pH or organic shocks, and genus Hydrogenophaga (∼8%) might be responsible for the microbial As(III) oxidation. Finally, several operation strategies were proposed to obtain high performance, such as liquid pH control and aeration improvement.

Fish canning wastewater treatment in sequencing batch reactor with activated sludge

The biological performance of flocculent sludge in sequencing batch reactor for the treatment of fish canning wastewater was evaluated in terms of organic matter and nutrient removal by gradual increase of salt concentration in the nitritation-denitritation process. Salinity negatively affected the biological system performance in a way that reduced organic and nutrient removal. The removal efficiency of organic matter and nitrogen showed good performance below 20 g NaCl/L, while phosphate accumulating organisms activity was deteriorated and declined during whole experiment. Nitrogen removal occurred as ammonium oxidation with nitrite accumulation. Nitrite reduction was not affected by salt concentration.

Effect of Cycling Time Strategy on The Treatment of Industrial Latex Wastewater with Granular Sludge

Effects of cycling time on the performance of granular sludge in sequencing batch reactors (SBR) were evaluated. Two reactors, reactor 1 (R1) and reactor 2 (R2) was introduced to industrial wastewater with varying chemical oxygen demand (COD) loadings from as low as 0.01 to 0.28 kgCOD/m3/d. However granules in R1 utilizes cycling time of 24 hours whilst R2 utilizes cycling time of 4 hours. The overall performance for both reactors were excellent, where COD removal efficiency was kept at about 78 % to 98 % removal. Although higher COD removal was observed for both reactors, granulation did not occur in R1 when applying cycling time of 24 hours. In contrast to R2, decrement of cycling time to 4 hours promotes the growth of dense and structured sludge granules.

Assessment of Enhanced Biological Phosphorus Removal Implementation Potential in a Full-Scale Wastewater Treatment Plant in Croatia

The objective of this study was to assess the possibility of retrofitting an existing full-scale wastewater treatment plant (WWTP) based on a sequencing batch reactor (SBR) technology with the enhanced biological phosphorus removal (EBPR) process. Wastewater characterisation showed highly variable influent composition that fluctuated throughout the year with a rather low and unstable SBOD/TP ratio (SBOD—soluble biological oxygen demand; TP—total phosphorus), which is considered unfavourable for EBPR. Characterisation of the sludge showed that the non-EBPR SBR sludge from the WWTP Koprivnica contained no detectable phosphorus accumulating organisms (PAO), but could be transformed in a laboratory into EBPR performing sludge in less than 45 days under favourable conditions for PAOs. The microbial community composition was assessed using an FISH (fluorescence in situ hybridization) analysis, which confirmed that the original sludge from the WWTP, which did not have detectable PAOs, was transformed into the sludge enriched by PAOs belonging to the genus ‘Candidatus Accumulibacter phosphatis’ after 43 days of cultivation. A plant retrofit, based on the results of laboratory experiments, was proposed with the enrichment of the wastewater with volatile fatty acids via primary anaerobic fermentation and step feeding. Results of mathematical modelling (BioWin) showed that such strategy could lead to sufficient P removal through EBPR in this WWTP.

Rapid start-up of partial nitritation in aerobic granular sludge bioreactor and the analysis of bacterial community dynamics.

The rapid start-up of the partial nitritation process in a laboratory-scale aerobic granular sludge-sequencing batch reactor was successful by controlling low dissolved oxygen and gradually increasing the influent ammonia levels. The microbial community dynamics were analyzed by high-throughput sequencing and quantitative polymerase chain reaction. The microbial communities were significantlyaffected by the different influent NH4+-N concentrations (77.84, 119.42, 170.31, and 252.21mg/L) in Phases I, II, III, and IV. The sludge Shannon index in Phases I, II, III, and IV was 3.9, 4.39, 3.47, and 2.13, respectively, which was higher than that of the inoculated sludge (1.62). The dominant class transformed from Alphaproteobacteria and Gammaproteobacteria in Phase I to Betaproteobacteria in Phase IV. Furthermore, Sphingobacteria and Clostridia were the dominant bacteria in Phases III and IV. The quantitative polymerase chain reaction (qPCR) results suggested that Nitrosomonadaceae_uncultured belonging to ammonia-oxidizing bacterium was the dominant species, but the relative abundance of nitrite-oxidizing bacteria (mainly Nitrospira and Nitrobacter) was extremely rare in Phase IV. Furthermore, Thauera, Denitratisoma, and Planctomycetacia were the dominant functional nitrogen removal microbes in Phases III and IV. Some nitrogen removal pathways such as partial nitritation, denitrification, and anaerobic ammonium oxidation co-existed in the partial nitritation process.

Parametric optimization of domestic wastewater treatment in an activated sludge sequencing batch reactor using response surface methodology

In this work, the parametric optimization of real domestic wastewater treated in an activated sludge sequencing batch reactor (SBR) was performed by means of the response surface methodology (RSM). The influences of influent organic matter concentration as chemical oxygen demand (CODinf), biomass concentration (Xs) and aeration time (t) on the COD, organic matter removal efficiency as COD (η) and sludge volume index (SVI) were determined to evaluate the performance of activated sludge SBR. The results showed that organic matter efficiency and maximum SVI were obtained at a t of 12 h, 300 mg L−1 of CODinf and 2000 mg L−1 of Xs. The SBR-activated sludge exhibited a η of 73% and an SVI of 119 mL g−1. Both values indicated a very good performance. Furthermore, the COD of the effluent under these conditions complied with Mexican regulations for wastewater discharged into water bodies.