Effect of sludge discharge positions on steady-state aerobic granules in sequencing batch reactor (SBR)

2012 ◽  
Vol 66 (8) ◽  
pp. 1722-1727 ◽  
Author(s):  
Lin Liu ◽  
Da-Wen Gao ◽  
Hong Liang
Keyword(s):  
Steady State ◽  
Batch Reactor ◽  
Oxygen Demand ◽  
Aerobic Granule ◽  
Stable Operation ◽  
Batch Reactors ◽  
Aerobic Granules ◽  
Sequencing Batch Reactors ◽  
Discharge Location

We have investigated the effect of sludge discharge location on the steady-state aerobic granules in sequencing batch reactors (SBRs). Two SBRs were operated concurrently with the same sludge retention time using sludge discharge ports at: (a) the reactor bottom in R1; and (b) the reactor middle-lower level in R2. Results indicate that both reactors could maintain sludge granulation and stable operation, but the two different sludge discharge methods resulted in significantly different aerobic granule characteristics. Over 30 days, the chemical oxygen demand (COD) removal of the two reactors was maintained at similar levels (above 96%), and typical bioflocs were not observed. The average aerobic granule size in R2 was twice that in R1, as settling velocity increased in proportion to size increment. Meanwhile, the production yields of polysaccharide and protein content in R2 were always higher than those in R1. However, due to mass transfer limitations and the presence of anaerobes in the aerobic granule cores, larger granules had a tendency to disintegrate in R2. Thus, we conclude that a sludge discharge port situated at the reactor bottom is beneficial for aerobic granule stability, and enhances the potential for long-term aerobic granule SBR operation.

Effects of long-term addition of Cu(II) and Ni(II) on the biochemical properties of aerobic granules in sequencing batch reactors

2010 ◽  
Vol 86 (6) ◽  
pp. 1967-1975 ◽  
Author(s):  
Xin-Hua Wang ◽  
Li-Hong Gai ◽  
Xue-Fei Sun ◽  
Hui-Jun Xie ◽  
Ming-Ming Gao ◽  
...  
Keyword(s):  
Biochemical Properties ◽  
Batch Reactors ◽  
Aerobic Granules ◽  
Sequencing Batch Reactors

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.

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.

The effect of upflow air velocity on the structure of aerobic granules cultivated in a sequencing batch reactor

2004 ◽  
Vol 49 (11-12) ◽  
pp. 35-40 ◽  
Author(s):  
J.H. Tay ◽  
Q.S. Liu ◽  
Y. Liu
Keyword(s):  
Shear Force ◽  
Sequencing Batch Reactor ◽  
Batch Reactor ◽  
Granular Sludge ◽  
Batch Reactors ◽  
Aerobic Granules ◽  
Sequencing Batch Reactors ◽  
Air Velocity ◽  
Hydrodynamic Shear ◽  
Biomass Retention

The effect of upflow air velocity on the formation and structure of aerobic granules was studied in three column sequencing batch reactors. Upflow aeration would be the major cause of hydrodynamic shear force in the column reactor. Results showed that high upflow air velocity resulted in more compact, denser, rounder, stronger and smaller aerobic granules, while high biomass retention in the reactor was achieved. It was found that high upflow air velocity could induce granular sludge to secrete more cell polysaccharides which in turn contributed to the compact and strong structure. It appears from this study that the structure of aerobic granules could be controlled by manipulating the upflow air velocity.

Aerobic granule formation in a sequencing batch reactor treating newsprint effluent under low phosphate conditions

2010 ◽  
Vol 62 (11) ◽  
pp. 2571-2578 ◽  
Author(s):  
Jianrong Liu ◽  
David Nguyen ◽  
Michael Paice
Keyword(s):  
Quorum Sensing ◽  
Batch Reactor ◽  
Homoserine Lactone ◽  
Phosphate Limitation ◽  
Aerobic Granule ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Granule Formation ◽  
Paper Mills ◽  
Receiving Waters

Pulp and paper mills are under increasing pressure to minimize the discharge of phosphate to receiving waters. We investigated the operation of two laboratory sequencing batch reactors (SBR) under low phosphate conditions over a period of eight months. Performance characteristics in terms of COD and TSS removal were similar to the full-scale mill activated sludge operation, but the floc density and structure was improved. Sludge yield as a result of phosphate limitation was routinely lower than 0.15 kg/kg of COD. Aerobic granule formation was established in one of the SBRs by reducing the settling time from 30 min to 2 min and by increasing stirring shear force. Once established, the brown granules which were 1–2 mm in diameter were stable over five months of operation. Extracellular polymeric substance (EPS) analysis of the granules indicated a higher galactose content and lower mannose content than in conventional flocs. The granules generated more quorum sensing compound (acyl homoserine lactone) than conventional flocs, suggesting that quorum sensing could play a role in granule formation. When compared to the conventional SBR, the aerobic granule SBR performed at a higher organic loading, at faster settling velocity, and without filamentous bulking.

Intelligent monitoring system for long-term control of Sequencing Batch Reactors

2008 ◽  
Vol 57 (3) ◽  
pp. 431-438 ◽  
Author(s):  
S. Marsili-Libelli ◽  
A. Spagni ◽  
R. Susini
Keyword(s):  
Monitoring System ◽  
Batch Reactor ◽  
Process Conditions ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Switching Sequence ◽  
Process Operation ◽  
Phase Recognition ◽  
Phase Length

This paper discusses the application of artificial intelligence (AI) concepts to the monitoring of a lab-scale Sequencing Batch Reactor (SBR) treating nitrogen-rich wastewater (sanitary landfill leachate). The paper describes the implementation of a fuzzy inferential system to identify the correct switching sequence of the process and discusses the results obtained with six months of uninterrupted operation, during which the process conditions varied widely. The monitoring system proved capable of adjusting the process operation, in terms of phase length and external COD addition, to the varying environmental and loading conditions, with a percentage of correct phase recognition in excess of 95%. In addition, the monitoring system could be remotely operated through the internet via TCP/IP protocol.

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