TY - JOUR
T1 - Comparison of physical characteristics and dewatering behaviour between granular and floccular sludges generated from the same sewage source
AU - Krysiak-Baltyn, Konrad
AU - Cavalida, Raul
AU - Thwaites, Ben
AU - Reeve, Petra J.
AU - Scales, Peter J.
AU - Van den Akker, Ben
AU - Ong, Lydia
AU - Martin, Gregory J. O.
AU - Stickland, Anthony D.
AU - Gras, Sally L.
PY - 2019/6
Y1 - 2019/6
N2 - Aerobic granular sludge can improve the efficacy of wastewater treatment in existing sequencing batch reactors (SBRs) compared to conventional floccular sludge. Despite the well known advantages of increased capacity, reduced reactor footprint and enhanced nutrient removal, many performance characteristics of granular and floccular sludges have not been directly compared, in particular for sludges generated from treating the same sewage source. In this study we investigated the microstructure, microbial composition, settling and dewatering properties of granular and floccular sludge generated from the same sewage sources. Cryo-scanning electron microscopy analysis indicated that the granular and floccular sludges had a significantly different internal network structure, with flocs being much more open and porous than granules. Sulphur deposits were clearly visible on the surfaces of granules, which was complemented by the enrichment of some sulphur oxidising bacterial species compared to floccular sludge, as assessed by Next Generation Sequencing (NGS). Dewatering measurements showed, as expected, that the settling velocity of granules was much faster than flocs at solids concentrations below the gel point. At at higher solids concentrations above the gel point, however, both flocs and granules form a similar gelled network structure with no significant difference in dewaterability. We used the dewatering properties in process models to predict the impact of granulation on thickener and filter throughput. Overall, this work highlights the biological, structural and physical differences and similarities between granular and floccular sludges with the outcome being improved settling for granules but no significant difference in downstream dewatering properties that pertain to filtration processes.
AB - Aerobic granular sludge can improve the efficacy of wastewater treatment in existing sequencing batch reactors (SBRs) compared to conventional floccular sludge. Despite the well known advantages of increased capacity, reduced reactor footprint and enhanced nutrient removal, many performance characteristics of granular and floccular sludges have not been directly compared, in particular for sludges generated from treating the same sewage source. In this study we investigated the microstructure, microbial composition, settling and dewatering properties of granular and floccular sludge generated from the same sewage sources. Cryo-scanning electron microscopy analysis indicated that the granular and floccular sludges had a significantly different internal network structure, with flocs being much more open and porous than granules. Sulphur deposits were clearly visible on the surfaces of granules, which was complemented by the enrichment of some sulphur oxidising bacterial species compared to floccular sludge, as assessed by Next Generation Sequencing (NGS). Dewatering measurements showed, as expected, that the settling velocity of granules was much faster than flocs at solids concentrations below the gel point. At at higher solids concentrations above the gel point, however, both flocs and granules form a similar gelled network structure with no significant difference in dewaterability. We used the dewatering properties in process models to predict the impact of granulation on thickener and filter throughput. Overall, this work highlights the biological, structural and physical differences and similarities between granular and floccular sludges with the outcome being improved settling for granules but no significant difference in downstream dewatering properties that pertain to filtration processes.
KW - Cryo-SEM
KW - Filtration
KW - Granular sludge
KW - Sedimentation
KW - Sequencing
UR - http://www.scopus.com/inward/record.url?scp=85063274176&partnerID=8YFLogxK
UR - http://purl.org/au-research/grants/ARC/LP120100304
UR - http://purl.org/au-research/grants/ARC/IH120100005
U2 - 10.1016/j.jwpe.2019.100785
DO - 10.1016/j.jwpe.2019.100785
M3 - Article
VL - 29
JO - Journal of Water Process Engineering
JF - Journal of Water Process Engineering
SN - 2214-7144
M1 - 100785
ER -