The effect of anoxic selectors on sludge bulking

2004 ◽  
Vol 50 (6) ◽  
pp. 261-268 ◽  
Author(s):  
M.V. Tampus ◽  
A.M.P. Martins ◽  
M.C.M. van Loosdrecht
Keyword(s):  
Storage Capacity ◽  
Volume Index ◽  
Feeding Pattern ◽  
Batch Reactors ◽  
Substrate Uptake ◽  
Sequencing Batch Reactors ◽  
Floc Structure ◽  
Substrate Feeding ◽  
Substrate Uptake Rate ◽  
Sludge Settleability

The effect of the substrate feeding pattern on sludge settleability in denitrifying systems was investigated. The feeding pattern was simulated in two sequencing batch reactors (SBR). SBR1 simulates a system with a limiting substrate (acetate) and a non-limiting electron acceptor (nitrate), while SBR2 simulates the opposite condition. Sludge volume index (SVI) was the main observed parameter. The stoichiometry, substrate uptake rate, storage capacity as well as sludge morphology and mixed culture population dynamics were also determined. Results show that independent of the feeding pattern, the settleability of the sludge remained good (SVI ≈ 50 mL/g) and stable. Neither the concentration of the acetate nor of the nitrate offered any limitations on sludge settleability, assuring that a good bio-P activity is present in nitrate limiting systems. Filamentous bacteria belonging to the TM group were usually present, although in low numbers. Despite the diffused, irregularly shaped and open floc structure, good settleability was observed. The results obtained were in line with the hypothesis on diffusion based selection.

The impact of reduced phosphorus levels on microbial floc properties during biological treatment of pulp and paper wastewaters

2007 ◽  
Vol 55 (6) ◽  
pp. 73-79 ◽  
Author(s):  
J.R. Liu ◽  
S.N. Liss
Keyword(s):  
Extracellular Polymeric Substances ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Reactor Performance ◽  
Inorganic P ◽  
P Limitation ◽  
Floc Structure ◽  
The Impact ◽  
Sludge Settleability ◽  
Phosphorus Levels

The effect of limiting P in activated sludge was investigated in laboratory scale sequencing batch reactors (SBRs) fed effluent from a container board mill. Floc characterization included measurement of hydrophobicity, surface charge, and analysis of extracellular polymeric substances (EPS). Reactor performance was assessed by monitoring COD and inorganic P removal, MLSS, and sludge settleability (SVI and batch settling flux) over a period of eight months. Control reactors (BOD:N:P of 100:5:1) were compared to reactors run under P-limited conditions (100:5:0.3; 100:5:0.1). Reactor performance at lower temperatures (14 °C; control = 26 °C) was also studied to assess the impact of P-limitation. Changes in floc structure and the composition of EPS occurred within 1 to 3 days following a reduction in P levels. There was an insignificant increase in SVI; however, gravitational settling velocity and batch settling flux values for low P floc were consistently higher than for floc generated under control conditions. Lower temperatures (14 °C) resulted in a deterioration in floc settling properties at a BOD:N:P of 100:5:1. This impact on settling was significantly reduced at a BOD:P of 100:0.1. Reducing P concentrations in the wastewater treatment system has the potential to improve sludge settleability and reduce final P discharges.

Microbial community analysis with a high PHA storage capacity

2006 ◽  
Vol 54 (1) ◽  
pp. 183-188 ◽  
Author(s):  
L.S. Serafim ◽  
P.C. Lemos ◽  
S. Rossetti ◽  
C. Levantesi ◽  
V. Tandoi ◽  
...  
Keyword(s):  
Storage Capacity ◽  
Nile Blue ◽  
Community Analysis ◽  
Microbial Community Analysis ◽  
Fish Analysis ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
The Third ◽  
Carbon Substrates ◽  
Substrate Feeding

Activated sludge was submitted to aerobic dynamic substrate feeding for the production of biodegradable plastics. Two sequencing batch reactors were operated with acetate or propionate as sole carbon substrates. With acetate a homopolymer of polyhydroxybutyrate (PHB) was obtained and with propionate a copolymer of hydroxybutyrate and hydroxyvalerate P(HB/HV) was produced. Three main morphotypes were identified in both sludges: two belong to the Alphaproteobacteria class and the third to the Betaproteobacteria class. Bacilli belonging to Betaproteobacteria were shown by FISH analysis, applied in combination with Nile Blue post-staining, to be the main responsible for PHAs storage. The latter were affiliated to Azoarcus genus within Betaproteobacteria.

scholarly journals Effect of the famine phase length on the properties of aerobic granular sludge treating greywater

2021 ◽  
Author(s):  
U. Rojas-Z ◽  
C. Fajardo-O ◽  
I. Moreno-Andrade ◽  
O. Monroy
Keyword(s):  
Granular Sludge ◽  
High Strength ◽  
Volume Index ◽  
Aerobic Granular Sludge ◽  
Batch Reactors ◽  
Substrate Uptake ◽  
Sequencing Batch Reactors ◽  
Uptake Rates ◽  
Key Factor ◽  
Phase Length

Abstract Sequencing batch reactors (SBR) treating high-strength greywater need an aerobic granular sludge (AGS) with good properties, such as a low sludge volume index (SVI) and high settling velocities and substrate uptake rates to yield short settling and aeration stages. To promote the formation of stable granular sludge, the length of the famine phase could be a key factor. In this regard, the effect of the duration of this variable on the AGS properties was assessed by comparing a gradual versus an abrupt reduction of the famine phase in two SBR treating greywater. The initial average famine phase of 3.3 h was gradually reduced to 0.3 h over 20 weeks in one reactor, and abruptly in another one. This condition induced filamentous outgrowth, as well as the deterioration on the properties of the sludge; being more accelerated the effect when the famine periods were abruptly shortened. In both cases the reduction on the famine periods induced increased organic loading rates, which led to degranulation events when it was higher than 2.5 g-COD g-VSS−1 d−1. Afterwards, the biomass adapted to this situation, by forming new small-filamentous aggregates with similar SVI to that of the stable AGS formed with the longest famine period.

scholarly journals Influent with Particulate Substrate, Clean, Innocuous and Sustainable Solution for Bulking Control and Mitigation in Activated Sludge Process

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 984
Author(s):  
Pedro Cisterna-Osorio ◽  
Claudia Calabran-Caceres ◽  
Giannina Tiznado-Bustamante ◽  
Nataly Bastias-Toro
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Nutrient Deficiency ◽  
Microscopic Analysis ◽  
Volume Index ◽  
Favorable Effect ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Active Sludge ◽  
Chemical Reagents

This research studies the incidence of the type of substrate, soluble or particulate, in the emergence, development, and inhibition of bulking in activated sludge systems. It was evaluated using the sludge volume index (SVI), mixing liquor-suspended solids (MLSS), microscopic analysis of biomass, and effluent suspended solids (ESS). In the first experiment, four sequencing batch reactors (SBRs) were fed with soluble substrate at a fixed mass, while the mass of the particulate substrate varied, as those (saccharose mass/flour mass) ratios were 3:1, 3:2, 3:3 and 3:4., with a deficit ranging from 20 to 30% compared to the ratio recommended. The four SBRs have similar MLSS, IVL, and ESS. From day 30, with a deficit from 80 to 90%, the influents have ratios 1/1 and 1/2 until 48 days. The SBRs present IVL between 600 and 730 mL/g and ESS from 370 to 440 mg/L; unlike influents with ratios 1/3 and 1/4, they present IVL between 170 and 185 mL/g, and ESS from 260 to 270 mg/L. The favorable effect of particulate matter is categorical. In the second set of experiments, two SBRs were studied: SBR 1 fed with saccharose, and SBR 2 with flour; there is a lack of nutrients causing bulking in SBRs. Once the nutrient deficiency condition is changed in day 11 to excess, after 22 days, the SVI was 190 mL/g, ESS was 360 mg/L, and MLSS was 2000 mg/L for influents with saccharose; the influent with flour, with an SVI of 80 mL/g, ESS of 100 mg/L, and MLSS of 4000 mg/L, shows faster and more consistent recovery with the particulate substrate. Therefore, the proposal is to add particulate substrate-like flour to active sludge plants facing bulking. It is a clean, innocuous and sustainable alternative to processes that use chemical reagents.

Occurrence of Microthrix parvicella in sequencing batch reactors

2014 ◽  
Vol 69 (10) ◽  
pp. 1984-1995 ◽  
Author(s):  
Lana Mallouhi ◽  
Ute Austermann-Haun
Keyword(s):  
Activated Sludge ◽  
Municipal Wastewater ◽  
Batch Reactor ◽  
Oxygen Demand ◽  
Volume Index ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Municipal Wastewater Treatment ◽  
Nitrogen And Phosphorus ◽  
Microthrix Parvicella

Sequencing batch reactors (SBRs) are known for high process stability and usually have a good sludge volume index (SVI). Nevertheless, in many SBRs in Germany for municipal wastewater treatment, scum and foam problems can occur, and SVI can be larger than 200 mL/g. The microscopic investigations of the activated sludge from plants with nitrogen and phosphorus removal have shown that Microthrix parvicella is dominant in the activated sludge in most of them. Studies showed that the optimum growth of M. parvicella is performed at a high sludge age (>20 d) and low sludge load in the range of 0.05–0.2 kg of biochemical oxygen demand per kg of total suspended solids per day (kg BOD5/(TSS·d)). The investigations in 13 SBRs with simultaneous aerobic sludge stabilization (most of them are operated with a system called differential internal cycle strategy sequential batch reactor (DIC-SBR)) show that M. parvicella is able to grow in sludge loads less than 0.05 kg BOD5/(kg TSS·d) as well. To optimize the operation of those SBRs, long cycle times (8–12 h) and dosing of iron salts to eliminate long-chain fatty acids are both recommended. This leads to better SVI and keeps M. parvicella at a low frequency.

scholarly journals Greywater treatment in an aerobic SBR: sludge structure and kinetics

2017 ◽  
Vol 76 (6) ◽  
pp. 1535-1544 ◽  
Author(s):  
U. Rojas-Z ◽  
C. Fajardo-O ◽  
I. Moreno-Andrade ◽  
O. Monroy
Keyword(s):  
Synthetic Medium ◽  
Cell Yield ◽  
Volume Index ◽  
Organic Loading Rate ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Operation Sequencing ◽  
Efficient Operation ◽  
Conversion Rates ◽  
Granular Biomass

In order to have an efficient operation, sequencing batch reactors (SBR) must support granular biomass with high conversion rates, settling properties, and be able to deal with the inherent variability of the composition of real wastewaters. In this study, the effect of the influent composition and the specific organic loading rate (Bx) on the granulation process was evaluated in two SBRs, fed with greywater (GW) and a synthetic medium (SM). The feeding with SM led to the formation of compact granular biomass, with a sludge volume index (SVI) of 22.4 mL g−1, and a zone settling velocity (ZSV) of 13.1 m h−1. In contrast, feeding with GW induced the formation of filamentous granules, with lower settling properties (SVI = 165 mL g−1 and ZSV = 10 m h−1), when the system was operated at high Bx (4.4 kg COD kg VSS−1 d−1). However, the reduction of the average Bx to 2 kg COD kg VSS−1 d−1 induced an improvement in the morphology and properties of the granules (SVI = 98 mL g−1 and ZSV = 13 m h−1). Furthermore, the kinetic analysis indicated that granules cultivated with SM were formed by fast growing microorganisms with a high cell yield, whereas those cultivated in GW presented a much lower cell yield.

Treatment of thermomechanical pulping condensate using thermophilic and mesophilic sequencing batch reactors

2010 ◽  
Vol 62 (11) ◽  
pp. 2527-2535 ◽  
Author(s):  
S. P. Langevin ◽  
B. Q. Liao
Keyword(s):  
Removal Efficiency ◽  
Water System ◽  
Oxygen Demand ◽  
Volume Index ◽  
Organic Loading Rate ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Paper Mills ◽  
Treated Effluent ◽  
Thermomechanical Pulping

In-mill thermophilic treatment of individual wastewater streams to achieve water system closure has received much attention in pulp and paper mills. Aerobic biological treatment of thermomechanical pulping (TMP) condensate was conducted using thermophilic (55°C) and mesophilic (35°C) sequencing batch reactors (SBRs) for a period of 143 days at a cyclic time of 6, 8 and 12 h. A soluble chemical oxygen demand (SCOD) removal efficiency of 77 to 91% was achieved, given an organic loading rate of 0.7–1.3 kg/m3 d. The COD removal efficiency of the thermophilic SBR was slightly lower than that of the mesophilic SBR. Majority of the soluble COD was removed by biodegradation with a small portion (9–13%) of soluble COD stripped by aeration. The settleability (sludge volume index) and the flocculating ability (effluent suspended solids) of thermophilic sludge were comparable to or slightly poorer than that of the mesophilic sludge. The level of filaments in thermophilic sludge was usually higher than that in mesophilic sludge. The results of the study indicate that both thermophilic and mesophilic SBRs can be successfully operated for in-mill treatment of TMP condensate. The treated effluent has the potential for subsequent reuse in the mill.

Effect of salinity on the activity, settling and microbial community of activated sludge in sequencing batch reactors treating synthetic saline wastewater

2008 ◽  
Vol 58 (2) ◽  
pp. 351-358 ◽  
Author(s):  
G. Wu ◽  
Y. Guan ◽  
X. Zhan
Keyword(s):  
Microbial Community ◽  
Activated Sludge ◽  
Volume Index ◽  
Synthetic Wastewater ◽  
Utilization Rate ◽  
Yield Coefficient ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Saline Wastewater ◽  
Sludge Flocs

The effects of salinity on the activity in nutrient removal, settling and microbial community of activated sludge in sequencing batch reactors (SBRs) treating synthetic saline wastewater were investigated. Two SBRs, one treating synthetic saline wastewater (the N-Reactor, with NaCl addition) and the other treating fresh synthetic wastewater (the C-Reactor, without NaCl addition), were operated for 68 days. Three salinities (in terms of concentrations of NaCl)—10, 20 and 40 g NaCl/l—were examined. The microbial activity described with the specific glucose utilization rate, specific nitritation and nitratation rates, and specific phosphorus release and uptake rates, was inhibited in the N-Reactor, in comparison with that in the C-Reactor, except that the specific nitritation and nitratation rates were improved at the salinity of 10 g NaCl/l. The sludge yield coefficient decreased at salinities of 10 and 20 g NaCl/l but it rose at the salinity of 40 g NaCl/l. The settling of activated sludge flocs, in terms of the sludge volume index (SVI), was improved by adding NaCl. Particularly in the first 5 minutes during the SVI measurement, activated sludge flocs in the N-Reactor settled much faster than those in the C-Reactor. However, the effluent from the N-Reactor contained higher suspended solids than the effluent from the C-Reactor. The microbial diversity decreased with increasing the salinity, and the microbial community structure was greatly influenced by the salinity. Bacteriodetes and Actinobacteria were the dominant phylums detected with molecular fingerprinting techniques.

Investigating the influence of elongated anaerobic feeding strategy on aerobic sludge granulation and characteristics in sequencing batch reactor

2014 ◽  
Vol 70 (2) ◽  
pp. 249-255 ◽  
Author(s):  
S. Sadri Moghaddam ◽  
M. R. Alavi Moghaddam
Keyword(s):  
Extracellular Polymeric Substances ◽  
Feeding Strategy ◽  
Batch Reactor ◽  
Volume Index ◽  
Feeding Strategies ◽  
Batch Reactors ◽  
Aerobic Granules ◽  
Sequencing Batch Reactors ◽  
Feeding Mode ◽  
Feed Strategy

In this research, two sequencing batch reactors (R1 and R2) were operated with different feeding strategies to investigate the effects of elongated anaerobic feeding mode on the granulation process. For this purpose, R1 was operated in a short-feed strategy (5 min) as a reference, whereas an extended anaerobic feeding of 85 min was applied in R2. Results showed that aerobic granules formed in R1 were denser and more uniform with lower sludge volume index than those formed in R2. Investigation of tightly bound extracellular polymeric substances (TB-EPS) showed that aerobic granules in R1 produced lower amounts of TB-EPS than those in R2. This was due to the bigger and more compact granules cultivated in R1 in comparison with looser structure granules in R2 with higher flocculent sludge percentage. The relative hydrophobicity of granules in both reactors was increased with culture time and reached about 63 and 65% at day 70 for R1 and R2, respectively. Moreover, no significant correlation between protein/polysaccharide ratio and hydrophobicity was found, which showed that protein in loosely bound extracellular polymer substances was not the predominant hydrophobic component. Considering the outcomes of this study, it can be concluded that the elongated anaerobic feeding strategy was unfavourable for cultivating aerobic granules.

Polyhydroxyalkanoates production by activated sludge in a SBR using acetate and propionate as carbon sources

2004 ◽  
Vol 50 (10) ◽  
pp. 189-194 ◽  
Author(s):  
P.C. Lemos ◽  
L.S. Serafim ◽  
M.A.M. Reis
Keyword(s):  
Carbon Sources ◽  
Dry Weight ◽  
Operating Conditions ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Cell Content ◽  
A Value ◽  
Substrate Feeding ◽  
Commercial Applications ◽  
Processing Properties

In this work, sludge was submitted to aerobic dynamic substrate feeding. Two sequencing batch reactors were operated, with acetate or propionate as carbon substrates. When acetate was used the system only produced a homopolymer of polyhydroxybutyrate (PHB). In order to maximize the PHB production, tests with different concentrations of acetate and ammonia were preformed. The best results (67.2% of PHB by cell dry weight) were obtained for 0.7 Nmmol/l of ammonia and 180 Cmmol/l of acetate. The PHB cell content was further improved by pupulse addition of substrate, three times 60 Cmmol/l of acetate, reaching a value of 78.5%. Propionate can be used as a precursor for hydroxyvalerate. In conjunction with other substrates, it allows for the formation of copolymers, which present better processing properties on commercial applications. Tests with different concentrations of propionate and ammonia were performed. Under the operating conditions used, the maximum PHA accumulated inside cells was 34.8%, with 30 Cmmol/l of propionate and no ammonia.

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