scholarly journals Molecular mechanisms governing aerobic granular sludge processes

2015 ◽  
Vol 10 (2) ◽  
pp. 277-281 ◽  
Author(s):  
Yan Zhou ◽  
HuiJuan Xu ◽  
Yu Liu
Keyword(s):  
Wastewater Treatment ◽  
Quorum Sensing ◽  
Structural Stability ◽  
Significant Role ◽  
Molecular Mechanisms ◽  
Granular Sludge ◽  
Cellular Communication ◽  
Aerobic Granular Sludge ◽  
Aerobic Granules ◽  
Aerobic Granulation

The aerobic granular sludge process is a promising technology for wastewater treatment. The formation and structure of aerobic granules are traditionally thought to depend highly on selection pressures, while the underlying molecular mechanisms are unclear. It is well known that bacteria coordinate their behavior using small signaling molecules, known as quorum sensing (QS). This paper is an attempt to provide updated information on QS mechanisms governing granular sludge processes. It is shown that QS-mediated cellular communication has a significant role throughout aerobic granulation, including granule development, structural stability and integrity maintenance. Such understanding is helpful for developing novel aerobic granular sludge processes.

scholarly journals Characterizing the structure of aerobic granular sludge using ultra-high field magnetic resonance

2020 ◽  
Vol 82 (4) ◽  
pp. 627-639
Author(s):  
Catherine M. Kirkland ◽  
Julia R. Krug ◽  
Frank J. Vergeldt ◽  
Lenno van den Berg ◽  
Aldrik H. Velders ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Magnetic Resonance ◽  
Wastewater Treatment Plants ◽  
Granular Sludge ◽  
Structural Features ◽  
Aerobic Granular Sludge ◽  
Aerobic Granules ◽  
Bulk Fluid ◽  
Characterization Methods ◽  
Non Invasive

Abstract Despite aerobic granular sludge wastewater treatment plants operating around the world, our understanding of internal granule structure and its relation to treatment efficiency remains limited. This can be attributed in part to the drawbacks of time-consuming, labor-intensive, and invasive microscopy protocols which effectively restrict samples sizes and may introduce artefacts. Time-domain nuclear magnetic resonance (NMR) allows non-invasive measurements which describe internal structural features of opaque, complex materials like biofilms. NMR was used to image aerobic granules collected from five full-scale wastewater treatment plants in the Netherlands and United States, as well as laboratory granules and control beads. T1 and T2 relaxation-weighted images reveal heterogeneous structures that include high- and low-density biofilm regions, water-like voids, and solid-like inclusions. Channels larger than approximately 50 μm and connected to the bulk fluid were not visible. Both cluster and ring-like structures were observed with each granule source having a characteristic structural type. These structures, and their NMR relaxation behavior, were stable over several months of storage. These observations reveal the complex structures within aerobic granules from a range of sources and highlight the need for non-invasive characterization methods like NMR to be applied in the ongoing effort to correlate structure and function.

An Attempt to Develop Aerobic Granular Sludge in Continuous Airlift Reactors

2021 ◽  
Vol 1025 ◽  
pp. 265-272
Author(s):  
Muhammad Syafiq Mohd Shafei ◽  
Zulkifly Jemaat
Keyword(s):  
Wastewater Treatment ◽  
Operation Mode ◽  
Treatment Plant ◽  
Granular Sludge ◽  
Cod Removal ◽  
Aerobic Granular Sludge ◽  
Organic Loading Rate ◽  
Aerobic Granules ◽  
Reactor Performance ◽  
Airlift Reactors

Recent advancement on biological wastewater treatment is via granular sludge technology. It is widely known that, aerobic granular sludge has been developed in a batch operation since its discovery. Yet, most of the wastewater treatment plant (WWTP) is operated in continuous mode. Now, the real challenge is how to adopt the granular technology while maintaining present operation mode of WWTP. Thus, this study attempts to evaluate the feasibility of developing aerobic granular sludge in continuous airlift reactors feed with two different substrates, namely glucose and acetate. Two identical airlift reactors (6 L) were employed and operated at room temperature (30°C). Prior to the substrate feeding, both reactors were inoculated with seed sludge obtained from a palm oil mill anaerobic pond. One of the reactors was fed with 2000 mg COD L-1 of glucose (ALR1) and the other reactor with 2000 mg COD L-1 of acetate (ALR2). The hydraulic retention time (HRT) and organic loading rate (OLR) for both reactors were maintained at 4 days and between 0.2 to 0.5 kg m-3day-1 respectively. Dissolved oxygen was maintained between 5.0 and 6.0 mg O2L-1 and supplied by air compressor. The reactor performance was monitored based on COD removal. Aerobic granules developed throughout the study period was evaluated based on granules size and morphology, sludge volumetric index (SVI30) and SVI5/SVI30 ratio analysis. Results showed that ALR1 demonstrated the formation of filamentous-type aerobic granules with most of the SVI30 average at 100 to 190 mL g-1. Ratio SVI5/SVI30 analysis was evaluated at 0.2 and 0.5. The largest granules size obtained during the experiment was about 600 μm on day-136 and average granules size obtained at 200 to 400 μm. ALR1 able to achieve 95% COD removal. For ALR2, round shaped aerobic granules were developed with average SVI30 from 100 to 1000 mLg-1. SVI5/SVI30 analysis indicated an average ratio between 0.7 and 0.9. The average granules size was between 30 to 50 μm and the largest was 78 μm on day-60. 90% of COD removal efficiency was obtained in ALR2. In conclusion, ALR fed with acetate had indicated better aerobic granules characteristics as compared to glucose fed reactor. Furthermore, the study demonstrated that to develop aerobic granules in continuous reactors is feasible.

Textile wastewater treatment: Aerobic granular sludge vs activated sludge systems

2014 ◽  
Vol 54 ◽  
pp. 337-346 ◽  
Author(s):  
Adriana Maria Lotito ◽  
Marco De Sanctis ◽  
Claudio Di Iaconi ◽  
Giovanni Bergna
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Granular Sludge ◽  
Textile Wastewater ◽  
Aerobic Granular Sludge ◽  
Textile Wastewater Treatment ◽  
Activated Sludge Systems

Strength characteristics of aerobic granular sludge

2012 ◽  
Vol 65 (2) ◽  
pp. 309-316 ◽  
Author(s):  
A. Nor-Anuar ◽  
Z. Ujang ◽  
M. C. M. van Loosdrecht ◽  
M. K. de Kreuk ◽  
G. Olsson
Keyword(s):  
Granular Sludge ◽  
Aerobic Granular Sludge ◽  
Strength Analysis ◽  
Anaerobic Granular Sludge ◽  
Aerobic Granules ◽  
Sludge Flocs ◽  
Conventional Activated Sludge ◽  
Biomass Retention ◽  
Settling Characteristic ◽  
Fast Settling

Aerobic granular sludge has a number of advantages over conventional activated sludge flocs, such as cohesive and strong matrix, fast settling characteristic, high biomass retention and ability to withstand high organic loadings, all aspects leading towards a compact reactor system. Still there are very few studies on the strength of aerobic granules. A procedure that has been used previously for anaerobic granular sludge strength analysis was adapted and used in this study. A new coefficient was introduced, called a stability coefficient (S), to quantify the strength of the aerobic granules. Indicators were also developed based on the strength analysis results, in order to categorize aerobic granules into three levels of strength, i.e. very strong (very stable), strong (stable) and not strong (not stable). The results indicated that aerobic granules grown on acetate were stronger (high density: >150 g T SSL−1 and low S value: 5%) than granules developed on sewage as influent. A lower value of S indicates a higher stability of the granules.

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