Formation and Characterization of Aerobic Granules in a Sequencing Batch Reactor Treating Soybean-Processing Wastewater

Abstract

Aerobic granules were cultivated in a sequencing batch reactor (SBR) fed with soybean-processing wastewater at 25+/-1 degrees C and pH 7.0+/-0.1. The granulation process was described via measuring the increase of sludge size. The formation of granules was found to be a four-phase process, that is, acclimating, shaping, developing, and maturated. A modified Logistic model could well fit with the granule growth by diameter and could be employed to estimate the maximum diameter, lag time, and specific diameter growth rate effectively. Both normal and log-normal distributions proved to be applicable to model the diameter distribution of the granules. The granule-containing liquor was shear thinning, and their rheological characteristics could be described by using the Herschel-Buckley equation. The suspended solids concentration, pH, temperature, diameter, settling velocity, specific gravity, and sludge volume index all had an effect on the apparent viscosity of the mixed liquor of granules. The matured granules had fractal nature with a fractal dimension of 1.87+/-0.34. Moreover, 83% of matured granules were permeable with fluid collection efficiencies over 0.034. As compared to activated sludge flocs, the aerobic granules grown on the soybean-processing wastewater had better settling ability, mass transfer efficiency, and bioactivity.

Microbial and Physicochemical Characteristics of Compact Anaerobic Ammonium-Oxidizing Granules in an Upflow Anaerobic Sludge Blanket Reactor

“…A plexiglass UASB reactor (2.1 liters; 10 cm in inner diameter) and a gas-solids separator portion (2.6 liters) was used in this study. The seeding aerobic granular sludge was taken from a lab-scale sequencing batch reactor treating soybean-processing wastewater (21 , was used as the feed for the enrichment culture described in the present study. The influent pH value was adjusted to 7.0 by adding 3 M NaOH or 3 M HCl.…”

Microscale Hydrodynamic Analysis of Aerobic Granules in the Mass Transfer Process

“…In this study, the mean porosity of granules was estimated as 0.16 and 0.53, respectively, for the combined model and the protein model. Previous studies showed that the porosity of microbial aggregates with a diameter ranging from 1.0 mm to 10.0 mm could reach up to 80-90% (1,9,24). For these studies, the porosity of the microbial aggregates was calculated based on the following equations: …”

Comparison of performance, microorganism populations, and bio-physiochemical properties of granular and flocculent sludge from denitrifying phosphorus removal reactors

“…The protein and humic substances in EPS were measured using the modified Lowry method [14]. Image analysis, granule size, and specific gravity of granular sludge were determined using the method described by Su et al [15].…”

“…Su et al [15] reported that the settling velocity and specific gravity were 37 m/h and 1.017, respectively, for an aerobic granular sludge. For this study, the settling velocity and specific gravity were 241 ± 29 m/h and 1.171, respectively, in G-SBR.…”