A Bioreactor Designed for Restricting Oversize of Aerobic Granular Sludge

Hongbo Feng,Honggang Yang,Jun Li,Jianlong Sheng,Zengrui Pan

doi:10.3390/pr9020374

Abstract

Aerobic granular sludge (AGS) with oversized diameter commonly affects its stability and pollutant removal. In order to effectively restrict the particle size of AGS, a sequencing batch reactor (SBR) with a spiny aeration device was put forward. A conventional SBR (R1) and an SBR (R2) with the spiny aeration device treating tannery wastewater were compared in the laboratory. The result indicates that the size of the granular sludge from R2 was smaller than that from R1 with sludge granulation. The spines and air bubbles could effectively restrict the particle size of AGS by collision and abrasion. Nevertheless, there was no significant change in mixed liquor suspended solids (MLSS) and the sludge volume index (SVI) in either bioreactors. The removal (%) of chemical oxygen demand (COD) and ammonia nitrogen (NH4+-N) in these two bioreactors did not differ from each other greatly. The analysis of biological composition displays that the proportion of Proteobacteria decreased slightly in R2. The X-ray fluorescence (XRF) analysis revealed less accumulation of Fe and Ca in smaller granules. Furthermore, a pilot-scale SBR with a spiny aeration device was successfully utilized to restrict the diameter of granules at about 300 μm.

Highlights

Aerobic granular sludge (AGS) is a biological aggregate which is generally defined as more than 90% of sludge with particle size greater than 200 μm [1,2]
AGS has been evaluated for treatment of various industrial wastewaters such as textile [5], rubber [6], brewery [7], and petroleum [8] wastewater
The results showed that with the particle size increasing, the resistance of mass which transfers from the surface to the interior would increase so that the anaerobic zone would expand, and the lack of nutrients in the interior would further lead to the disintegration of the sludge particles, and to the failure of operation [16]

Summary

Introduction

Aerobic granular sludge (AGS) is a biological aggregate which is generally defined as more than 90% of sludge with particle size greater than 200 μm [1,2]. It was first cultured by Mishima et al [3] in an aerobic upflow sludge blanket (AUSB) with pure oxygen aeration in 1911. AGS has been evaluated for treatment of various industrial wastewaters such as textile [5], rubber [6], brewery [7], and petroleum [8] wastewater. The AGS process is considered as a promising and alternative technology for wastewater treatment. Most of the reported AGS is still at the lab or pilot-scale [9,10], with only a few reported cases at full-scale [11,12]

Methods

Results

Conclusion