The University of Southampton
University of Southampton Institutional Repository

Fast formation of aerobic granules by combining strong hydraulic selection pressure with overstressed organic loading rate

Fast formation of aerobic granules by combining strong hydraulic selection pressure with overstressed organic loading rate
Fast formation of aerobic granules by combining strong hydraulic selection pressure with overstressed organic loading rate
The combined strong hydraulic selection pressure (HSP) with overstressed organic loading rate (OLR) as a fast granulation strategy was used to enhance aerobic granulation. To investigate the wide applicability of this strategy to different scenarios and its relevant mechanism, different settling times, different inoculums, different exchange ratios, different reactor configurations, and different shear force were used in this study. It was found that clear granules with a size of 624 ?m were formed at 72 h with steady state reached within three days when the fast granulation strategy was used in a lab-scale reactor seeded with well settled activated sludge (Reactor 2). However, granules appeared after 2-week operation and reached steady state after one month at the traditional step-wise decreased settling time from 20 to 2 min with OLR of 6 g COD/L·d (Reactor 1). With the fast granulation strategy, granules appeared within 24 h even with bulking sludge as seed to start up Reactor 3, but 6-day lag phase was observed compared with Reactor 2. Both Reactor 2 and Reactor 3 experienced sigmoidal growth curve in terms of biomass accumulation and granule size increase after granulation. In addition, the reproducible results in pilot-scale reactors (Reactor 5 and Reactor 6) with diameter of 20 cm and height/diameter ratio (H/D) of 4 further proved that reactor configuration and fluid flow pattern had no effect on the aerobic granulation when the fast granulation strategy was employed, but biomass accumulation experienced a short lag phase too in Reactor 5 and Reactor 6. Although overstressed OLR was favorable for fast granulation, it also led to the fluffy granules after around two-week operation. However, the stable 6-month operation of Reactor 3 demonstrated that the rapidly formed granules were able to maintain long-term stability by reducing OLR from 12 g COD/L·d to 6 g COD/L·d. A mechanism of fast granulation with the strategy of combined strong HSP and OLR was proposed to explain results and guide the operation with this fast strategy.
aerobic granule, hydraulic selection pressure, organic loading rate, start-up, long-term stability, SBR
0043-1354
256-266
Liu, Yong-Qiang
75adc6f8-aa83-484e-9e87-6c8442e344fa
Tay, Joo-Hwa
1bd3ce87-355e-460f-835b-56cb81f3a1b0
Liu, Yong-Qiang
75adc6f8-aa83-484e-9e87-6c8442e344fa
Tay, Joo-Hwa
1bd3ce87-355e-460f-835b-56cb81f3a1b0

Liu, Yong-Qiang and Tay, Joo-Hwa (2015) Fast formation of aerobic granules by combining strong hydraulic selection pressure with overstressed organic loading rate. Water Research, 80, 256-266. (doi:10.1016/j.watres.2015.05.015).

Record type: Article

Abstract

The combined strong hydraulic selection pressure (HSP) with overstressed organic loading rate (OLR) as a fast granulation strategy was used to enhance aerobic granulation. To investigate the wide applicability of this strategy to different scenarios and its relevant mechanism, different settling times, different inoculums, different exchange ratios, different reactor configurations, and different shear force were used in this study. It was found that clear granules with a size of 624 ?m were formed at 72 h with steady state reached within three days when the fast granulation strategy was used in a lab-scale reactor seeded with well settled activated sludge (Reactor 2). However, granules appeared after 2-week operation and reached steady state after one month at the traditional step-wise decreased settling time from 20 to 2 min with OLR of 6 g COD/L·d (Reactor 1). With the fast granulation strategy, granules appeared within 24 h even with bulking sludge as seed to start up Reactor 3, but 6-day lag phase was observed compared with Reactor 2. Both Reactor 2 and Reactor 3 experienced sigmoidal growth curve in terms of biomass accumulation and granule size increase after granulation. In addition, the reproducible results in pilot-scale reactors (Reactor 5 and Reactor 6) with diameter of 20 cm and height/diameter ratio (H/D) of 4 further proved that reactor configuration and fluid flow pattern had no effect on the aerobic granulation when the fast granulation strategy was employed, but biomass accumulation experienced a short lag phase too in Reactor 5 and Reactor 6. Although overstressed OLR was favorable for fast granulation, it also led to the fluffy granules after around two-week operation. However, the stable 6-month operation of Reactor 3 demonstrated that the rapidly formed granules were able to maintain long-term stability by reducing OLR from 12 g COD/L·d to 6 g COD/L·d. A mechanism of fast granulation with the strategy of combined strong HSP and OLR was proposed to explain results and guide the operation with this fast strategy.

Text
Liu_Fast.pdf - Accepted Manuscript
Download (4MB)

More information

Accepted/In Press date: 4 May 2015
e-pub ahead of print date: 14 May 2015
Published date: 1 June 2015
Keywords: aerobic granule, hydraulic selection pressure, organic loading rate, start-up, long-term stability, SBR
Organisations: Faculty of Engineering and the Environment

Identifiers

Local EPrints ID: 377095
URI: http://eprints.soton.ac.uk/id/eprint/377095
ISSN: 0043-1354
PURE UUID: b3189073-5ee9-4137-8279-8d9810f1e5f2

Catalogue record

Date deposited: 19 May 2015 12:47
Last modified: 26 Nov 2019 06:50

Export record

Altmetrics

Contributors

Author: Yong-Qiang Liu
Author: Joo-Hwa Tay

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×