Influence of mixed feeding rate in a conventional SBR on biological P-removal and granule stability while treating different industrial effluents

About one third of the industrial activated sludge (AS) plants worldwide suffer from bad settling sludge, often caused by filamentous bulking phenomena. The present study investigated the effectiveness of a sludge granulation/densification strategy, based only on a metabolic selection mechanism, to eliminate sludge bulking in a sequencing batch reactor (SBR) treating real industrial wastewater. The wastewater originated from a tank truck cleaning company transporting chocolate and beer. The proposed strategy involved the introduction of a slow unaerated/anaerobic feeding step in the SBR operation. On lab-scale, the new feeding strategy resulted in (1) excellent settling with a sludge volume index (SVI) decreasing from more than 300 mL·g−1–100 mL·g−1 and lower, (2) the elimination of sludge bulking genera and (3) the significant enrichment of glycogen-accumulating organisms (GAO), mainly Defluviicoccus and Candidatus Competibacter, and this in less than 80 days. The feeding strategy was then applied to the full-scale installation, yielding similar results: a stable average SVI of 37 mL·g−1 was reached after approximately 150 days. Full granulation was however not reached, which warrants further optimization. The present study shows that the proposed strategy can easily be applied in existing SBR systems to solve the problem of sludge bulking.

Section: Discussionmentioning

confidence: 99%

“…Regarding industrial wastewater treatment by AGS, most lab studies report the application of a pulse feed of wastewater to build up substrate during the first minutes of a cycle, followed by prolonged anaerobic mixing phase to promote PAO/GAO metabolism (e.g. Caluwé et al 2017;Stes et al 2019;De Vleeschauwer et al 2021).…”

mentioning

confidence: 99%

Granulation strategies applied to industrial wastewater treatment: from lab to full-scale

Caluwé

Goossens

Suazo

et al. 2022

“…In this study, the volume exchange rate was only 9%. The sludge settling selection pressure was 0.13 m/h during the whole study making the selection of slow-growing carbon-storing microorganisms the main selection criterion for AGS formation (de Kreuk & van Loosdrecht 2004;Stes et al 2019;Dobbeleers et al 2020).…”

Section: Granulationmentioning

confidence: 99%

A dynamically controlled anaerobic/aerobic granular sludge reactor efficiently treats brewery/bottling wastewater

Vleeschauwer

Caluwé

Dobbeleers

et al. 2021

Self Cite

This study investigated the application of a dynamic control strategy in an aerobic granular sludge (AGS) reactor treating real variable brewery/bottling wastewater. For 482 days, the anaerobic and aerobic reaction steps in a lab-scale AGS system were controlled dynamically. A pH-based control was used for the anaerobic step, and an oxygen uptake rate (OUR) based control for the aerobic step. Additionally, the effect of an elongated aerobic step, and the effect of the removal of the suspended solids from the influent, on AGS formation were also investigated. In comparison to a static operation, the dynamic operation resulted in similar reactor performance, related to effluent quality and the anaerobic dissolved organic carbon (DOC) uptake efficiency, while the organic loading rate was significantly higher. The removal of suspended solids from the influent by chemical coagulation with FeCl3 turned hybrid floccular-granular sludge into fully granular sludge. The granulation coincided with a significant increase in the abundance of the glycogen-accumulating Candidatus Competibacter and an increase in the content of gel-forming EPS to respectively around 14% and 30%. In conclusion, this study showed the successful application of a dynamic control strategy based on common and low-cost sensors for AGS treatment of industrial wastewater.

“…A longer feeding time would enable denitrification and increase acetate production via fermentation ensuring anaerobic feeding conditions for Bio-P (Stes et al, 2019). Also, selectively remove microorganisms by wasting the lighter solids fraction through shorter settling time, SRT control, or implementation of a dedicated selective waste system has shown to enhance Bio-P and reduce effluent solids concentration (Henriet et al, 2016).…”

Section: Design Considerationsmentioning

confidence: 99%

Aerobic granular sludge treating anaerobically pretreated brewery wastewater at different loading rates

Biase

Corsino

Devlin

et al. 2020

In this study, three different aerobic granular sludge (AGS) reactors fed with anaerobically pre-treated brewery wastewater were studied. The AGS reactors were operated under different conditions including organic loading rates (OLR) between 0.8 and 4.1 kg COD m−3 d−1, C:N:P ratios (100:10:1 and 100:6:1) and food to microorganism ratios (F/M) between 0.8 ± 0.6 and 1.2 ± 0.5 and 0.9 ± 0.3 kg-TCOD kg-VSS−1d−1. Stable granulation was achieved within two weeks and the size of the granules increased according to the OLR applied. The results indicated that low C:N:P and F/M ratios were favorable to achieve stable aerobic granules in the long term. The carbon removal rate was load-independent in the range examined (TCOD removal >80%), whereas TN removals were inversely proportional to the OLRs. Overall, a longer aeration reaction time with a lower OLR was beneficial to granular structure which exhibited a compact and defined architecture. Performance results within the other conditions studied further indicated that microbial community and its complex functionality in nutrient removal was efficient at operational parameters of OLR at 0.8 ± 0.2 kg-TCOD m−3d−1 and F/M ratio at 0.5 ± 0.2 kg-TCOD VSS−1d−1. Moreover, the protein to polysaccharide ratio increased as OLR decreased, leading to a stable granular structure.