Scale Sequencing Batch Reactor Research Articles

Physical Characteristics and Removal Performance of Aerobic Granular Sludge in Biological Treatment of Domestic Wastewater

This study aims to demonstrate the formation of aerobic granular sludge (AGS) for domestic wastewater treatment applications in hot climate and low humidity conditions (e.g. Saudi Arabia) as well as to characterize and examine the bioreactor performance in removing organic matter and nutrients. Based on the study, aerobic granular sludge (seeded with domestic activated sludge from Al-Madina Wastewater Treatment Plant and fed with synthetic wastewater with an organic loading rate (OLR) of 1.6 kg COD m−3d−1) was successfully cultivated with average size ranging from 1 to 2 mm in a laboratory scale sequencing batch reactor (SBR) system operated at 30 days with a complete cycle time of 3 h and at the working temperature of 30 ± 1°C. Results also showed that the aerobic granular sludge formed had excellent settling ability (settling velocity, 38.98 mh−1 and MLSS, 7.8 gL−1) and great removal performance of COD and nutrient (i.e. more than 90%).

Anammox-Based Processes for Mature Leachate Treatment in SBR: A Modelling Study

Mature landfill leachates are characterized by high levels of ammoniacal nitrogen which must be reduced for discharge in the sewer system and further treatment in municipal wastewater treatment plants. The use of anammox-based processes can allow for an efficient treatment of ammonium-rich leachates. In this work, two real scale sequencing batch reactors (SBRs), designed to initially perform partial nitritation/anammox (PN/A) and simultaneous partial nitrification and denitrification (SPND) for the treatment of ammonium-rich urban landfill leachate, were modelled using BioWin 6.0 in order to enable plant-wide modelling and optimizing. The constructed models were calibrated and validated using data from long- and short-term (one cycle) SBR operation and fit well to the main physical-chemical parameters (i.e., ammonium, nitrite and nitrate concentrations) measured during short-term (one cycle) operations. Despite the different strategies in terms of dissolved oxygen (DO) concentrations and aeration and mixing patterns applied for SBR operation, the models allowed for understanding that in both reactors the PN/A process was shown as the main contributor to nitrogen removal when the availability of organic carbon was low. Indeed, in both SBRs, the activity of nitrite oxidizing bacteria was inhibited due to high levels of free ammonia, whereas anammox bacteria were active due to the simultaneous presence of ammonium and nitrite and their ability to recover from DO inhibition. Increasing the external carbon addition, a prompt decrease of the anammox biomass was observed, with SPND becoming the main nitrogen removal mechanism. Models were also applied to estimate the production rates of nitrous oxide by aerobic ammonia oxidizing bacteria and heterotrophic denitrifiers. The models were found to be a robust tool for understanding the effects of different operating conditions (i.e, temperature, cycle phases, DO concentration, external carbon addition) on the nitrogen removal performances of the two reactors, assessing the contribution of the different bacterial groups involved.

Determining the effects of Class I landfill leachate on biological nutrient removal in wastewater treatment

The disposal of landfill leachate is a chronic problem facing the municipal solid waste industry. The composition of landfill leachate is highly variable and often dependent on site-specific conditions. Due to the potentially disruptive impact on wastewater treatment processes, wastewater treatment plants (WWTP) are reluctant to accept landfill leachate for co-treatment. To improve the ability of WWTPs to screen the impact of landfill leachate and reduce landfill owners’ cost of disposal, two bench scale methods were evaluated. First, six landfill leachates were screened with the specific oxygen uptake rate (SOUR) test, and second, the effect of leachate on the efficacy of activated sludge processes using lab scale sequencing batch reactors (SBRs) was determined with volumetric loading rates ranging from 5% to 20%. Results suggested that these tools can be used to estimate the impacts of leachate loading on biological processes. Both tools were able to identify loadings where biological activity was increased and inhibition of biological processes was minimized. The loading that maximized microbial activity was leachate specific and typically ranged from 5% to 10%. Taken together, these results suggest that improved landfill leachate screening and testing may improve outcomes at WWTPs by identifying a “Goldilocks” loading rate that increases biological activity. Nevertheless, our results also demonstrated that the effluent quality was degraded even at loading rates that increased biological activity. It is uncertain at this time if biological acclimation can remedy increased effluent nutrient mass loadings, suggesting further research is needed.

Effects of pharmaceutical load on the effluent quality using sequencing batch reactor

The effect of pharmaceutical load on the performance of laboratory scale sequencing batch reactor (SBR) in terms of effluent quality and sludge settling ability was studied. The SBR was operated using low-strength domestic wastewater and spiked with a unique combination of drugs namely atenolol, gliclazide and prazosin after 21 days of reactor operation. Atenolol and gliclazide were spiked at concentration of 1000 µg/l while 100 µg/l for prazosin. Several parameters were observed which includes concentration of COD, ammonia, MLSS and SVI30. The effluent quality and sludge settling ability before and after drugs introduction were compared. The average COD removal efficiency before and after the introduction of pharmaceutical was 85% and 74%, respectively. The average ammonia removals were 84% and 62% before and after addition of pharmaceutical respectively. MLSS and SVI30 values was successfully maintained within desired value at the end of experiment indicating good sludge accumulation and sludge settling ability.

Establishment of Biological Nitrogen Removal Process for Drinking Water Treatment in Malaysia

Eutrophication arises from human activities has been recognized globally as an environmental issue. Human activities have greatly increased the input of phosphorus and nitrogen into the water bodies which place a heavy pressure on clean water resources. There are limitations in the conventional water treatment processes, where phosphorus and nitrogen could not be removed efficiently. For nitrogen removal, biological method emerges as a sustainable and economically feasible alternative in recent years. Though the biological nitrogen removal (BNR) method is widely recognized in developed countries with temperate climate, knowledge and expertise on the application of this treatment process is relatively limited in developing countries, so as Malaysia in tropical region. Thus, this research aims to provide a preliminary view on the establishment of the BNR process for drinking water treatment in the local context. A lab scale sequencing batch reactor (SBR) seeded with fish pond sludge and activated sludge in the volume ratio of 1:1 was operated for the BNR process. After four weeks of sludge cultivation, the characteristic of simultaneous nitrification-denitrification was observed. The removal of total nitrogen (TN) was found exceeding 60% and little nitrate-nitrogen (NO3̄-N) concentration was observed at the end of the process. Besides, the reduction in orthophosphate (PO43--P) concentration in a BNR system has indicated the process was able to perform nitrogen and phosphorus removal simultaneously. These findings suggest that the establishment of BNR is feasible in Malaysia.

Insights into the acute effect of anti-inflammatory drugs on activated sludge systems with high solids retention time

ABSTRACT The increase in the occurrence of the pharmaceuticals in the environmental compartments is becoming emerging concern as it reflects their inefficient treatment in the wastewater treatment plants which are the main sources of these micropollutants. Non-steroidal anti-inflammatory drugs (NSAIDs) are one of the most commonly prescribed and frequently detected pain medications in wastewater treatment plants. A lab scale sequencing batch reactor (SBR) was operated for seven months and acute inhibitory effect of NSAIDs on activated sludge was tested with respirometry. Culture amendment with different concentrations of NSAIDs in the presence as well as absence of nitrification inhibitor resulted in considerable variation in the oxygen uptake rate (OUR) profiles. The decrease in OUR and nitrate production rate governed with reduced heterotrophic and nitrification activity. The kinetics of half saturation for growth and maximum autotrophic growth rates are determined to be affected negatively by the acute impact of anti-inflammatory pharmaceuticals even at the environmentally relevant concentrations. High removal of tested NSAIDs was observed even for the first time introduce with these compounds.

Determination of the potential of pickle wastewater as feedstock for biopolymer production.

Food industry wastewater (FIWW) streams with high organic content are among the most suitable and inexpensive candidates for polyhydroxyalkanoate (PHA) biopolymer production. Due to its high organic acid content, pickle industry wastewater (PIWW), can be considered as one of the prospective alternatives to petroleum-based polymers for PHA production. In this context, this study aimed to investigate the production of PHA with enriched microbial culture using PIWW. Two laboratory scale sequencing batch reactors (SBRs) were operated under aerobic dynamic feeding conditions at a sludge retention time of 8 days, with a total cycle duration of 24 hours. SBRs were fed with peptone mixture and PIWW. In-cycle analysis and batch respirometric tests were performed to evaluate PHA storage together with biodegradation kinetics. In-cycle analysis showed that maximum PHA content was 1,820 mgCOD/L, corresponding to 44% in the biomass (ratio of chemical oxygen demand (COD) to volatile suspended solids) for PIWW. Experimental results were also confirmed with activated sludge model simulations. As for the PHA composition, hydroxybutyrate was the major fraction. Model simulations proposed a unique conversion-degradation-storage pathway for the organic acid mixture. This paper presents a novel insight for better understanding of PHA biopolymer production using high saline FIWW.

Performance assessment of aerobic granulation for the post treatment of anaerobic effluents

Abstract Present study investigates the formation of aerobic granular biomass and its comparative performance in treatment of anaerobic effluents using two lab scale sequencing batch reactors (SBR), (Reactor 1 and 2) fed with medium strength synthetic wastewater and anaerobic effluent respectively. The granulation was better in reactor 1 with biomass concentration of 7014 mg/L while in reactor 2 it could reach only 3910 mg/L. Reactor 1 showed good organic and nitrogen removal performance. The COD removal efficiency in reactor 1 was more than 90% (average ∼ 94 ± 2%) reaching to a maximum of 98% with influent concentration of 1400 ± 12 mg/L. While in reactor 2, it was only 55 ± 9% reaching to a maximum of 64% with influent concentration of 213 ± 47 mg/L. Total nitrogen removal efficiency with influent of 140 ± 3 mg/L in reactor 1 was more than 90% compared to average removal efficiency of 78 ± 7% with influent of 84 ± 25 mg/L in reactor 2. Reactor 1 showed better nitrate removal of 91 ± 9%(influent nitrate concentration of 53 ± 6 mg/L) while as reactor 2 showed better ammonia removal of 87 ± 25% with influent concentration of 67 ± 29 mg/L. Sludge characterization by Scanning Electron Microscopy and Fourier Transforms Infrared Spectroscopy revealed bacterial morphologies of rod, coccus and filament coexisted in the granules. The preliminary findings in this study may supplement insights about application of aerobic granulation in post treatment of anaerobic effluents.

Impact of food-to-microorganisms ratio on the stability of aerobic granular sludge treating high-strength organic wastewater

This work investigated the long-term stability of aerobic granular sludge treating high-strength organic wastewater in a semi-pilot scale sequential batch reactor (SBR). The reactor was operated for 316 days under different operational conditions. It was found that the F/M ratio is an important parameter affecting granules formation and stability. Three selection mechanisms were investigated: (1) cultivation and maturation at moderately high influent COD concentration (2500 mg/L) followed by increase in influent COD concentration to 7500 mg/L; (2) stressed cultivation and operation at high influent COD concentration of 4500 mg/L; and (3) alternate feed loading strategy (variable influent COD concentration across the daily schedule of cycles at 50%, 75%, and 100% of the peak concentration of 5000 mg/L). It was found that adopting high OLR at the reactor start-up accelerated the formation of granules. However, the overgrowth of biomass under high organics concentration negatively affected the stability of granules and led to disintegration due to the presence of methanogens in the granule core. Cultivation at high organics concentration resulted in a rapid loss of microbial diversity and reactor failure. Under alternate feed loading, adequate selection of microbial community was maintained and resulted in stable reactor performance. Moreover, a strong correlation between F/M ratio and the granules settling ability was observed. When F/M ratio exceeded 1.5 gCOD/gSS.d, granules showed poor settleability and under very high sludge loading rates (above 2.5), sludge bulking occurred and led to washout of sludge due to the strong selection pressure of short settling time. Operating the reactor at F/M ratio of 0.5–1.4 gCOD/gSS.d appears to favor stable long-term granule stability.

Effect of air flow rate on development of aerobic granules, biomass activity and nitrification efficiency for treating phenol, thiocyanate and ammonium

The impact of air flow rate on aerobic granulation was evaluated for treating toxic multiple pollutants; phenol (400 mg L−1), thiocyanate (100 mg L−1) and ammonia nitrogen (100 mg L−1) by using three lab scale sequencing batch reactors (SBRs) (R1, R2 and R3). Larger granules (2938.67 ± 64.91 μm) with higher biomass concentration (volatile solids of 4.17 ± 0.09 g L−1), higher granule settling velocity (55.56 ± 1.36 m h−1) and lower sludge volume index (35.25 ± 1.71 mL gTSS−1) were observed at optimal air flow rate of 2.5 L min−1 (R2). Confocal laser scanning microscopic images illustrated the extended fluorescence for extracellular polymeric substances in R2. In R2, partial nitrification was achieved. Phenol was completely removed in all the reactors while partial removal of SCN− and no nitrification were observed with a decrease (1.5 L min−1) and an increase (3.5 L min−1) in air flow rates (R1 and R3, respectively). This study provides an experimental contribution to examine the effect of optimal combination of aeration and toxic multiple pollutants, governing characteristics and nitrification efficiency of granules along with SBR performance in an economic way in terms of optimal air supply.

Treatment of Slaughterhouse Effluent Using Sequencing Batch Reactor

Three bench scale sequencing batch reactor (SBRs) were set up with a manual control mechanism for the treatment stages to evaluate the effects volumetric exchange rate oneffectiveness of SBR in treating effluent from the slaughterhouses. The average raw slaughterhouse wastewater concentrations for COD, MLSS, NH4-N, NO3-N and TP were 11947 ± 2; 8233 ± 2025; 1,400 ±787; 70.3 ± 49.0; 65.2 ± 9.2 and 261 ± 39 mg/L respectively. Volumetric exchange rate (VER) in the 30 - 50 % range did not show significant difference in the SBR treatment. Therefore, the higher VER of 50% was recommended because it gives higher of volumetric turnover compared to the lower VERs. The SBR treatment process achieved average reductions of 59, 61, 54 and 35% for chemical oxygen demand (COD), ammonia nitrogen (NH4-N) and total phosphorus (TP) respectively.

Aerobic Granular Sludge: an Advanced Technology to Treat Oil Refinery and Dairy Wastewaters

Aerobic granular sludge (AGS) is an emerging and an advance technology for intensive and high-rate biological nutrient removal from wastewater that may play as important role in industrial wastewater treatment strategy in Iraq. Lab scale sequential batch reactor (SBR) operated with selected operation cycle was used to cultivate granular sludge for each of dairy and oil refinery wastewaters. Successful granulation process in each reactor was achieved after 72 day of operation. The results of experimental work proved the flexibility of AGS technology to treat refinery and dairy wastewater and withstand fluctuated load. The COD and NH4 removal efficiencies for oil refinery wastewater were 86% and 92%, respectively, with sludge volume index (SVI) of 50 ml/g and granules size distribution of (0.3-3) mm. While COD and NH4 removal efficiencies for dairy wastewater were 80% and 82%, respectively, with SVI of 70 ml/g and the large percentage of its granules were ranged between 0.3 and 0.5 mm and the other smaller percentage were ranged between 0.75 and 2 mm. In addition microbiology observations showed high diverse in microorganisms communities which indicated the presence of stabilized sludge in both reactors.

Traditional Nitrogen Removal Coupled with SND to Meet Advanced WWTP Standards at a Full Scale SBR Wastewater Treatment Facility

A Florida wastewater treatment facility studied how Simultaneous Nitrification Denitrification (SND) coupled with traditional nitrogen removal would be used to meet the state’s current advanced wastewater treatment nutrient criterion. This study examined the effect of these combined processes on the fate and transport of the nitrogen species during the treatment process. The effectiveness of nitrogen removal within the full scale sequential batch reactor system (SBR) and the extent of SND compared to nitrification and denitrification in the nitrogen removal process was also evaluated. Finally, the overall performance of the municipal wastewater treatment facility utilizing these combined processes was evaluated. Overall, this application reduced the total nitrogen to almost 6% of the permitted concentration of 3.0 mg/L. The combination of both processes also resulted in an actual concentration 93.7% lower than the acceptable theoretical concentration, which also resulted in effluent Total Inorganic Nitrogen nearly 80% lower than the permitted 3.0 mg/L effluent concentration. Further, the process produced a composite Total Nitrogen concentration that was 74% lower than the permitted concentration. This coupling of SND with traditional nitrogen removal resulted in a highly effective process to reduce nitrogen in the municipal wastewater effluent which is also attractive for potential implementation due to the low cost expenditure incurred in its utilization.

Effect of a static magnetic field on activated sludge community

ABSTRACTThe aim of this study was to determine the effect of a static magnetic field (SMF) on the composition of activated sludge biocenosis. The experiment was carried out in two parallel bench scale Sequencing Batch Reactors (SBRs). Both SBRs were treated with dairy wastewater. The activated sludge in the first SBR was exposed to an SMF via the induction of a 0.6 T magnetic field generated by four magnetic liquid activators. The second reactor (control reactor) was operated at the same operational parameters but the activated sludge was not exposed to the SMF. The mean length of the bacterium Eikelboom Type 0092 was lower in the SMF-exposed reactor than in the control reactor. Different activated sludge morphologies in SBRs were reflected in the values of the sludge volume index and sludge biotic index calculated on the basis of the microfauna composition.

Microbial mediated anoxic nitrification-denitrification in the presence of nanoscale oxides of manganese

The present study investigates the feasibility of anoxic nitrification-denitrification in the presence of nanoscale oxides of manganese (NSOM). A template-assisted co-precipitation method was employed to synthesize NSOM. XRD and FESEM data reveal that the composite is amorphous in nature, and the particles are in nano regime (15–28 nm). The use of NSOM as an electron acceptor for the microbial mediated anoxic nitrification and the feasibility of re-oxidation of reduced NSOM coupled to denitrification was demonstrated by laboratory scale sequencing batch reactor (SBR). SBR operation lasted for 343 days in 9 different phases by varying the initial NH4+-N (100–500 mg l−1) and cycle time (0.5–2.0 d). Maximum removals of NH4+-N and total nitrogen were 126.2 ± 11.3 mg l−1 d−1 and 109.8 ± 10.9 mg l−1 d−1 respectively, in 0.5 d cycle time. Separate batch experiments were conducted to study the effect of time, pH, temperature, COD/NH4+-N ratio, and inhibitory concentrations of NH4+-N, NO2−-N, and S2−, on the anoxic nitrification process. The developed process is economical as it works in the absence of external supply of aeration and alkalinity, and reduces 70% of the requirement of COD compared to conventional nitrification-denitrification.

Disinfection performance of adsorption using graphite adsorbent coupled with electrochemical regeneration for various microorganisms present in water

The disinfection performance of the process of adsorption using a graphitic material combined with electrochemical regeneration for a range of microorganisms including bacteria, fungi, yeast and protozoa in a laboratory scale sequential batch reactor is demonstrated. The bacterial species studied were Pseudomonas aeruginosa, Staphylococcus aureus and Legionella pneumophila. A 3.0 log10 reduction in the concentration of P. aeruginosa cells was achieved with the adsorbent that was regenerated at 30mAcm−2 with 100% regeneration on each adsorption cycle. The process was quite effective in removing S. aureus present in water with a significantly higher reduction in the number of cells (ca. 9-log10 reduction) at relatively low current density (10mAcm−2). Similarly, L. pneumophila were removed from water with a ca. 7.5-log10 reduction in the number of bacterial cells. The SEM images confirmed the adsorption of L. pneumophila onto the adsorbent and its electrochemical regeneration at 20mAcm−2 that is considered a refractory pathogen against chlorination. The process was also found to be suitable for disinfecting fungal spores, Aspergillus awamori and yeasts including Saccharomyces cerevisiae and Rhodosporidium turoloides However, the removal of Cryptosporidium parvum from water was not demonstrated successfully. The preliminary results suggest that using a chloride free environment and a relatively high current density could be useful in disinfecting C. parvum.

Contamination level of four priority phthalates in North Indian wastewater treatment plants and their fate in sequencing batch reactor systems.

The contamination level of four phthalates in untreated and treated wastewater of fifteen wastewater treatment plants (WWTPs) and their fate in a full scale sequencing batch reactor (SBR) based WWTP was evaluated in this study. The four phthalates were diethyl phthalate (DEP), dibutyl phthalate (DBP), benzylbutyl phthalate (BBP) and diethylhexyl phthalate (DEHP). All compounds were present in untreated wastewater with DEHP being present in the highest mean concentration of 28.4 ± 5.3 μg L(-1). The concentration was in the range of 7.3 μg L(-1) (BBP) to 28.4 μg L(-1) (DEHP) in untreated wastewater and 1.3 μg L(-1) (DBP) to 2.6 μg L(-1) (DEHP) in treated wastewater. The nutrient removal process and advance tertiary treatment based WWTPs showed the highest phthalate removal efficiencies of 87% and 93%, respectively. The correlation between phthalate removal and conventional performance of WWTPs was positive. Fate analysis of these phthalates in a SBR based WWTP showed that total removal of the sum of phthalates in a primary settling tank and SBR was 84% out of which 55% is removed by biodegradation and 29% was removed by sorption to primary and secondary sludge. The percentage removal of four phthalates in primary settling tanks was 18%. Comparison of the diluted effluent DEHP concentration with its environmental quality standards showed that the dilution in an effluent receiving water body can reduce the DEHP emissions to acceptable values.

Minimizing solid wastes in an activated sludge system treating oil refinery wastewater

Biosurfactants are suitable for application in wastewater treatment systems due to their biodegradability, biocompatibility and low toxicity. In activated sludge systems, they reduce coalescence and disintegrate flakes, enabling more cells to have access to oxygen. At low concentrations, they may act as growth inhibitors. In this study, rhamnolipid was added to a bench scale sequential batch reactor operating in similar conditions as oil refinery wastewater treatment plants. Concentrations from 12 to 50mg rhamnolipid/L were evaluated, the latter being the minimum concentration necessary to reduce sludge disposal. In this concentration, rhamnolipid reduces sludge disposal of up to 52%, maintaining COD removal of 81–97% and good sludge settling properties (SVI 120mL/g) and could also reduce area occupied by secondary clarifier of 39–52%. However, biosurfactant application needs to be optimized, because its cost is even higher than the savings obtained with lower waste disposal.

Free nitrous acid inhibition of biological phosphorus removal in integrated fixed-film activated sludge (IFAS) system

Free nitrous acid (FNA) inhibition of anoxic and aerobic phosphorous removal in an integrated fixed-film activated sludge (IFAS) system with different FNA adaptation was investigated. A bench scale sequencing batch reactor (SBR) with plastic media was operated in an anaerobic/anoxic/aerobic sequence. During the anoxic period, nitrite was fed into the reactor at different concentrations to select for biomass adapted to 0.06 and 0.4μg HNO2-NL−1 of FNA during anoxic stage in Phase I and II, respectively. Long term anoxic/aerobic phosphorus removal was achieved in the IFAS reactor in both phases. In Phase I, aerobic phosphorous uptake was inhibited at higher level compared with anoxic phosphorus uptake. In Phase II, DPAO in both suspended and attached forms could adapt and were not inhibited at FNA level four times higher than the adapted concentration. The PAO’s aerobic activity in Phase II, did not show significant adaptation and was inhibited at slightly lower level compared with that in Phase I. The FNA inhibition of aerobic phosphorous uptake rate in attached biomass was 20% of that in suspended forms. In batch testes with the FNA level was raised to three times the adapted concentration, the contribution of attached biomass to overall anoxic and aerobic phosphorus uptake increased by 20% and 39%, respectively. The attached biomass could allow an IFAS system to be less inhibited and better maintain phosphorous removal at sudden FNA inhibition events.

Continuous flow aerobic granular sludge reactor for dairy wastewater treatment.

The focus of this study was to assess the treatment performance and granule progression over time within a continuous flow reactor. A continuous flow airlift reactor was seeded with aerobic granules from a laboratory scale sequencing batch reactor (SBR) and fed with dairy wastewater. Stereomicroscopic investigations showed that the granules maintained their integrity during the experimental period. Laser diffraction investigation showed proof of new granules formation with 100-500 μm diameter after only 2 weeks of operation. The treatment performances were satisfactory and more or less similar to the ones obtained from the SBR. Thus, removal efficiencies of 81-93% and 85-94% were observed for chemical oxygen demand and biological oxygen demand, respectively. The N-NH(+)(4) was nitrified with removal efficiencies of 83-99% while the nitrate produced was simultaneously denitrified - highest nitrate concentration determined in the effluent was 4.2 mg/L. The removal efficiency of total nitrogen was between 52 and 80% depending on influent nitrogen load (39.3-76.2 mg/L). Phosphate removal efficiencies ranged between 65 and above 99% depending on the influent phosphate concentration, which varied between 11.2 and 28.3 mg/L.