Reduction of excess sludge production in sequencing batch reactor (SBR) by lysis–cryptic growth using homogenization disruption

With new EEC regulations, alternative treatment and disposal techniques of the excess sludge produced by Activated Sludge (AS) wastewater treatment plants have to be performed. In order to reduce the excess sludge produced, experiments have been carried out with a Membrane BioReactor (MBR) to study the maintenance and cryptic growth phenomena of Pseudomonas fluorescens culture taken as a model when grown on a limiting substrate complex medium similar to a synthetic urban wastewater. Experiments with various imposed wasting rates showed that viability and sludge production yield decreased when sludge age increased. Same variations were observed on the cell content ratio protein/polysaccharide by analysis of the cell lysis products released after discontinuous thermal treatment. Biomass growth on these cell lysis products was achieved to characterize cryptic growth and its impact on sludge production yield. Finally, a continuous sludge thermal treatment system was operating with MBR to amplify sludge breakage and consequently biomass growth on the lysis products. With the promising results obtained, this work gives a new outlook on the AS process and leads to the development of processes with control and reduction of sludge production.

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Modelling of sequencing batch reactor operating at various aeration modes

MATEC Web of Conferences ◽

10.1051/matecconf/201925205013 ◽

2019 ◽

Vol 252 ◽

pp. 05013

Author(s):

Grzegorz Łagód ◽

Adam Piotrowicz ◽

Piotr Gleń ◽

Jakub Drewnowski ◽

Fabrizio Sabba

Keyword(s):

Sequencing Batch Reactor ◽

Batch Reactor ◽

Significant Degree ◽

Excess Sludge ◽

Effluent Quality ◽

First Case ◽

Treated Sewage ◽

Do Concentration ◽

Reactor Operating ◽

Operation Cycle

The presented study involved designing a computer model of a sequencing batch reactor (SBR) at laboratory scale. The data pertaining to the technical aspects of the bioreactor and quality indicators of wastewater constituted the input for the employed simulation tool, i.e. GPS-X software package. The results of a simulation involving a 12-hour operation cycle are presented in this work; each cycle included 6 phases: filling, mixing, aeration, settling, decantation and idling (wasting of excess sludge). The simulations were carried out using two different modes of aeration. Concentration of dissolved oxygen (DO) was maintained at constant level of 2 mgO2/L using the PID controller in the first case. On the other hand, variation of DO concentration was employed in the aeration stage of the second variant, which was achieved using appropriately elaborated set point of oxygen concentration, considering the specific intervals in oxygen supply. The changes observed in DO concentration varied from 0.5 to 2.5 mgO2/L. This research proved that the second variant, involving variation of DO concentration, was characterised by reduced levels of pollution indicators in treated sewage, as well as lower consumption of electricity, both of which contributed towards improving the effluent quality and resulted in significant degree of dephosphatation.

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Enhanced reduction of excess sludge and nutrient removal in a pilot-scale A2O-MBR-TAD system

Water Science & Technology ◽

10.2166/wst.2011.201 ◽

2011 ◽

Vol 63 (8) ◽

pp. 1547-1556 ◽

Cited By ~ 4

Author(s):

J. S. Ventura ◽

S. Seo ◽

I. Chung ◽

I. Yeom ◽

H. Kim ◽

...

Keyword(s):

Organic Carbon ◽

Nutrient Removal ◽

Domestic Wastewater ◽

Pilot Scale ◽

Excess Sludge ◽

E Coli ◽

Effluent Quality ◽

Cryptic Growth ◽

A2o Process ◽

Sludge Production

In this study, a pilot scale anaerobic-anoxic-oxic (A2O) process with submerged membrane (MBR) in the oxic tank was coupled with thermophilic aerobic digestion (TAD) reactor and was operated for longer than 600 days to treat real domestic wastewater. Regardless of the varying conditions of the system, the A2O-MBR-TAD process removed MLSS, TCOD, BOD, TN, TP, and E. coli about 99%, 96%, 96%, 70%, 83%, and 99%, respectively. The additional TP removal of the system was due to the precipitating agent directly added in the oxic reactor, without which TP removal was about 56%. In the TAD reactor, receiving MLSS from the oxic tank (MBR), about 25% of TSS and VSS were solubilized during 2 days of retention. The effluent of the TAD reactor was recycled into the anoxic tank of A2O-MBR to provide organic carbon for denitrification and cryptic growth. By controlling the flowrate of wasting stream from the MBR, sludge production decreased to almost zero. From these results, it was concluded that the A2O-MBR-TAD process could be a reliable option for excellent effluent quality and near zero-sludge production.

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