Journal
WATER ENVIRONMENT RESEARCH
Volume 94, Issue 1, Pages -Publisher
WILEY
DOI: 10.1002/wer.1664
Keywords
activated sludge; continuous flow biological process; densification; deselection; granulation; intensification; morphology; solids residence time; SVI
Funding
- SUEZ International
- SUEZ Group
Ask authors/readers for more resources
The full-scale demonstration of activated sludge conversion into a granule-floc hybrid process in the Dijon water resource recovery facility was successful in optimizing settleability and process robustness. The densified biomass maintained stable SVIs below 100 ml/g for several months and achieved a year-round SVI below 50 ml/g, breaking the cycle of interannual bulking. Controlling granule-floc proportions allows for improved operational adjustments and design accuracy, enabling stable settling and effluent functionalities.
Full-scale demonstration of activated sludge conversion into a granule-floc hybrid process was implemented in Dijon (France) water resource recovery facility (WRRF). Biomass densification was achieved based on external gravimetric selection using hydrocyclones within continuous-flow anaerobic-anoxic-oxic (A(2)O) biological nutrient removal (BNR) bioreactor. The goal was to optimize settleability of biological sludge by lowering and stabilizing sludge volume index (SVI) to improve process robustness and resiliency. Process proved to stabilize operation and to uncouple the total solids residence time (SRT) between floc and granule morphologies. The densified biomass initially produced stable SVI < 100 ml/g for a period of 4 months and thereafter a steady state year-round SVI below 50 ml/g, including the winter period during which the control train SVI expansion >200 ml/g. The densified biomass successfully broke the vicious cycle of interannual bulking. Form and function interrelationship is proposed for the densified biomass (hybrid floc-granule). The concept of biological architecture is proposed as the purposeful control of granule and floc proportions, with a proposed form factor ratio of 1:2 granule to floc, that produce a SRT uncoupling function factor ratio of 4:1 granule to floc, further resulting in very stable settling and effluent functionalities. Practitioner Points Controlling granule-floc proportions allows for sludge volume index (SVI) operational adjustment, which further allows for increased clarified design accuracy. One-third aggregates dramatically improved settling characteristics: 20% and 35% of AGS ensures SVIs below 100 and 50 ml/g, respectively. Densified biomass enables new SRT and clarifier flux rates approaches for engineering and operation practices: Doubling typical surface loading rates from 6.0-8.5 to 15-20 kg m(-2) h(-1) and surface overflow rates from 0.6-0.8 to 1.5-2.4 m/h SRT uncoupling of 1:4 is achieved between floc and granule, enabling specific niche environment for fast and slow growing organisms.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available