Greywater treatment in an aerobic SBR: sludge structure and kinetics

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.

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

Water Science & Technology ◽

10.2166/wst.2010.939 ◽

2010 ◽

Vol 62 (11) ◽

pp. 2527-2535 ◽

Cited By ~ 3

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.

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

Water ◽

10.3390/w13070984 ◽

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.

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Occurrence of Microthrix parvicella in sequencing batch reactors

Water Science & Technology ◽

10.2166/wst.2014.106 ◽

2014 ◽

Vol 69 (10) ◽

pp. 1984-1995 ◽

Cited By ~ 2

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.

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Study on aerobic granular sludge formation in sequencing batch reactors for tapioca wastewater treatment

Science and Technology Development Journal ◽

10.32508/stdj.v16i1.1386 ◽

2013 ◽

Vol 16 (1) ◽

pp. 40-48

Author(s):

Phuong Thi Thanh Nguyen ◽

Phuoc Van Nguyen ◽

Anh Cam Thieu

Keyword(s):

Granular Sludge ◽

Biomass Accumulation ◽

Synthetic Wastewater ◽

Aerobic Granular Sludge ◽

Organic Loading Rate ◽

Anaerobic Sludge ◽

Batch Reactors ◽

Aerobic Granules ◽

Toxic Substances ◽

Sequencing Batch Reactors

Aerobic granular sludge has attracted extensive interest of researchers since the 90s due to the advantages of aerobic granules such as good settling ability, high biomass accumulation, being resistant to high loads and being less affected by toxic substances. Studies, however, which have mainly been carried out on synthetic wastewater, cannot fully evaluate the actual ability of aerobic granules. Study on aerobic granular sludge was performed in sequencing batch reactors, using seeding sludge taken from anaerobic sludge and tapioca wastewater as a substrates. After 11 weeks of operation, the granules reached the stable diameter of 2- 3 mm at 3.7 kgCOD/m3.day organic loading rate. At high organic loads, in range of 1.6 - 5 kgCOD/m3.day, granules could treat effectively COD, N, P with performance of 93 – 97%; 65 – 79% and 80 – 95%, respectively.

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The effect of anoxic selectors on sludge bulking

Water Science & Technology ◽

10.2166/wst.2004.0384 ◽

2004 ◽

Vol 50 (6) ◽

pp. 261-268 ◽

Cited By ~ 5

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.

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Biological treatment of pharmaceutical wastewater from the antibiotics industry

Water Science & Technology ◽

10.2166/wst.2013.729 ◽

2013 ◽

Vol 69 (4) ◽

pp. 855-861 ◽

Cited By ~ 21

Author(s):

O. Lefebvre ◽

X. Shi ◽

C. H. Wu ◽

H. Y. Ng

Keyword(s):

Loading Rate ◽

Oxygen Demand ◽

Organic Loading Rate ◽

Batch Reactors ◽

Sequencing Batch Reactors ◽

Pharmaceutical Wastewater ◽

Refractory Compounds ◽

Treated Effluent ◽

Discharge Regulation ◽

Pre Treatment

Pharmaceutical wastewater generated by an antibiotics (penicillin) company was treated by aerobic membrane bioreactors (MBRs) and sequencing batch reactors (SBRs). At a low organic loading rate of 0.22 kg-COD m−3d−1, both types of reactors were capable of treating the wastewater such that the treated effluent met the discharge regulation except for the total dissolved solids. However, when the loading rate was increased to 2.92 kg-COD m−3d−1, foaming issues resulted in unstable performance. Overall, the MBRs achieved better solid removal but the SBRs performed better in regards to the degradation of aromatic compounds, as determined by UV absorbance (UVA). Finally, ozonation was applied on two different streams and showed promise on the strong stream – that corresponds to the formulation effluent and contains most of the biorefractory compounds. Ozonation successfully reduced the UVA, lowered the pH and increased the biochemical oxygen demand : chemical oxygen demand (BOD5 : COD) ratio of the strong stream. However, it was less efficient on the effluent having undergone pre-treatment by a biofilter due to a lack of selectivity towards refractory compounds.

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

Water Science & Technology ◽

10.2166/wst.2008.675 ◽

2008 ◽

Vol 58 (2) ◽

pp. 351-358 ◽

Cited By ~ 31

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.

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

Water Science & Technology ◽

10.2166/wst.2014.209 ◽

2014 ◽

Vol 70 (2) ◽

pp. 249-255 ◽

Cited By ~ 4

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.

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