Effect of carbohydrate and protein in the EPS on sludge settling characteristics

2001 ◽  
Vol 43 (6) ◽  
pp. 193-196 ◽  
Author(s):  
H.-S. Shin ◽  
S.-T. Kang ◽  
S.-Y. Nam
Keyword(s):  
Volume Index ◽  
Batch Reactors ◽  
Airflow Rate ◽  
Sequencing Batch Reactors ◽  
Constant Ratio ◽  
Sludge Volume Index ◽  
Protein Ratio ◽  
Sludge Settling ◽  
Precise Role ◽  
Settling Characteristics

EPSs have been believed to play a bonding role in microbial floc formation. However, the precise role is not well known. In this study, sludge settling characteristics and the carbohydrate to protein ratio in the EPS were tested at various airflow rates. Sludge was collected from three modified sequencing batch reactors (MSBRs), which were operated with airflow rates of 0.8 L/min, 2 L/min and 4 L/min, respectively. During the operation periods, the reactor operated at an airflow rate of 0.8 L/min showed a sludge volume index (SVI) of 80 to 90 mL/g and a constant ratio of carbohydrate to protein in the EPS, while a significant increase of this ratio and the SVI occurred in the other reactors. High airflow rate increased the amount of carbohydrate in the EPS, but the protein level was almost constant for reactors with airflow rates of 2 L/min and 4 L/min. The higher ratio of carbohydrate to protein caused the bulking of the sludge; hence it was not favourable for sludge settling. The ratio of carbohydrate and protein in the EPS is inferred to be essential for solid floc formation.

Effects of sludge settling characteristics in the BNR system

2000 ◽  
Vol 42 (3-4) ◽  
pp. 283-288 ◽  
Author(s):  
Z. Yun ◽  
W. Yo ◽  
Y. Yi ◽  
S. Choi ◽  
E. Choi ◽  
...  
Keyword(s):  
Settling Tank ◽  
Volume Index ◽  
Anoxic Zone ◽  
Sludge Volume Index ◽  
Analytical Accuracy ◽  
Fast Settling ◽  
Sludge Settling ◽  
Extracellular Polymer ◽  
Sludge Settleability ◽  
Settling Characteristics

Although the BNR system design assumes no sludge settling problems in the final settling tank, the fluctuation of daily loading and up to 40% of anaerobiosis in the BNR system would be considerable factors in determining the sludge settleability. The sludge volume index (SVI) is a classical parameter to examine the sludge settleability but it has a limited value to evaluate the overall settling characteristics. The extracellular polymer (ECP) content in sludge has long been considered as an indicator of biological flocculation in activated sludge process, but the skepticism on analytical accuracy limits the usage in settling study. This study focused on evaluating the BNR system performance related to the sludge settling characteristics under the controlled laboratory environment. A 5-stage BNR system (anaerobic-anoxic-3 stage oxic) was operated with the HRTs from 3.9 to 7.6 hours. In order to determine the sludge settling properties, both SVI and ECP content were monitored. The ECP contents in the sludge sample were measured by the slime-washing step followed by high-G centrifugation and sonication. The gel-electrophoresis was used to detect the DNA in the sonicated samples to determine the intracellular polymer contamination. It has been found that the anaerobiosis in the anaerobic and anoxic zone that consisted of 37% of reactor volume could not deteriorate the sludge settling properties even at the HRT of 3.9 hours. The SVI values of sludge taken from the reactor with the HRT of 7.2 hours averaged to less than 50 mL/gr. It was postulated that a fast settling sludge in the BNR system could not always ensure production of clear effluent. The sludge with very low SVI might not achieve a complete biological flocculation potential. In addition, the degree of denitrification in the BNR system could be related to the sludge settleability.

Settling Characteristics of Activated Sludge in Danish Treatment Plants with Biological Nutrient Removal

1994 ◽  
Vol 29 (7) ◽  
pp. 157-165 ◽  
Author(s):  
Gert Holm Kristensen ◽  
Per Elberg Jørgensen ◽  
Per Halkjær Nielsen
Keyword(s):  
Activated Sludge ◽  
Nutrient Removal ◽  
Volume Index ◽  
Biological Nutrient Removal ◽  
Sludge Volume Index ◽  
Filamentous Microorganisms ◽  
Best Parameter ◽  
One Year ◽  
Sludge Settling ◽  
Settling Characteristics

In 1989-91, a study was performed to investigate the settling characteristics of activated sludge in Danish treatment plants with biological nutrient removal. The study included three screening series on 38 treatment plants. Furthermore, the study included investigations during one year on seasonal variations in sludge settling characteristics at three treatment plants. The screening investigations were performed in November 1989 and May and September, 1990. Results showed that in the May-screening, 35-45% of the plants had a filament index of 2-2.5 or above, corresponding to a sludge volume index above 150 ml/g. When comparing data for diluted and non-diluted sludge volume indices, a SVI value of 150 ml/g seemed parallel to a DSVI of 110 ml/g. In the November- and September-screenings, some 30% of the plants had activated sludge showing a filament index in or above the critical area. Dominating filamentous microorganisms were found to be (in decreasing order): Microthrix parvicella, Type 0041, Type 021N, Type 0092, Type 0914, and Type 1851. A distinct variation over the year in sludge settling characteristics was found for the three plants. Sludge settling characteristics improved during summer, and deteriorated during winter. For activated sludge with a high content of filamentous microorganisms, the best parameter to follow the variations in sludge settling properties was the filament number. If the activated sludge concentration, the MLSS, varied significantly, the specific filament number was to be applied.

scholarly journals INFLUENCE OF STATIC MIXER ON THE FORMATION OF BIOGRANULES

2018 ◽  
Vol 81 (1) ◽  
Author(s):  
Suryati Sulaiman ◽  
Azmi Aris ◽  
Abdul Syukor Abd Razak ◽  
Khalida Muda ◽  
Aznah Nor Anuar
Keyword(s):  
Settling Velocity ◽  
Textile Wastewater ◽  
Suspended Solid ◽  
Volume Index ◽  
Batch Reactors ◽  
Static Mixer ◽  
Sequencing Batch Reactors ◽  
Air Velocity ◽  
Sludge Volume Index

Present study aimed at evaluating the formation of biogranules using sequencing batch reactors (SBRs) in treating textile wastewater under the influence of static mixer. Three sets of experiment were run with different superficial air velocity (SAV) of 0.5, 1.4 and 2.1 cms-1, each set consisting of two SBR one with and one without static mixer. The developed biogranules in reactors with static mixer (R1M, R2M and R3M) showed good results after approximately 70 days. The biomass in the reactor reached mix liquor suspended solid (MLSS) of 5.75 gL-1 with sludge volume index (SVI) of 107.4 mLg-1 and settling velocity (SV) of 70.3 mh-1 in R1M; MLSS of 7.18 gL-1 with SVI of 29.5 mLg-1 and SV of 80.4 mh-1 for R2M and MLSS of 7.38 gL-1 with SVI of 36.3 mLg-1 and SV of 74.2 mh-1 for R3M. The use of static mixer has contributed to biogranules development with good settling properties.

On-line measurements of settling characteristics in activated sludge

1997 ◽  
Vol 36 (4) ◽  
pp. 307-312
Author(s):  
Michael R. Rasmussen ◽  
Torben Larsen
Keyword(s):  
Activated Sludge ◽  
Settling Velocity ◽  
Continuous Measurement ◽  
Batch Reactor ◽  
Volume Index ◽  
Sludge Volume Index ◽  
Dynamic Variations ◽  
On Line ◽  
Settling Column ◽  
Settling Characteristics

An on-line settling column for measuring the dynamic variations of settling velocity of activated sludge has been developed. The settling column is automatic and self-cleansing insuring continuous and reliable measurements. The settling column was tested on sludge from a batch reactor where sucrose was added as an impulse to activated sludge. The continuous measurement of settling velocity revealed a highly dynamic response after the sucrose was added. The results were verified with simultaneous measurement of the initial settling rate. A 200 hour experiment showed variations in settling velocity, which was not apparent in the DSVI (Diluted Sludge Volume Index).

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.

Comparison and evaluation of empirical zone settling velocity parameters based on sludge volume index using a unified settling characteristics database

2003 ◽  
Vol 37 (16) ◽  
pp. 3821-3836 ◽  
Author(s):  
Dimosthenis.L Giokas ◽  
Glen.T Daigger ◽  
Marcos.von Sperling ◽  
Youngchul Kim ◽  
Panayotis.A Paraskevas
Keyword(s):  
Settling Velocity ◽  
Volume Index ◽  
Sludge Volume Index ◽  
Settling Characteristics

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.

Estimation of suspended solids concentrations in activated sludge settling tanks

1997 ◽  
Vol 35 (8) ◽  
pp. 127-135 ◽  
Author(s):  
Youngchul Kim ◽  
Wesley O. Pipes ◽  
Paul-Gene Chung
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Marked Effect ◽  
Treatment Plant ◽  
Accurate Method ◽  
Volume Index ◽  
Sludge Volume Index ◽  
Solids Concentration ◽  
Exponential Decrease ◽  
Sludge Settling

This is a report of a field study based on data from an activated sludge process in a wastewater treatment plant in Chester, Pennsylvania, USA. The objective was to develop an accurate method for estimation of the average suspended solids concentration (SSB) of the layer of sludge in the settling tanks (the “sludge blanket”). Plant operators estimated SSB by averaging the mixed liquor suspended solids (Sm) and the return sludge suspended solids (Su) concentrations. Measurement of SSB showed that averaging Sm and Su frequently overestimated SSB by a large amount. A different relationship between SSB and parameters which are normally measured for operational purposes was developed. The parameters are Su, the overflow rates and data from the sludge volume index (SVI) measurement. It was found that an increasing overflow rate will result in an exponential decrease in the ratio of SSB to Su. Also, the SVI has a marked effect on the ratio of SSB to Su and thus on the amount of suspended solids which can be stored in the settling tanks. The proposed estimation equation was found to be statistically superior to estimation by averaging the Sm and Su.

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.

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.

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