Role of sludge volume index in anaerobic sludge granulation in a hybrid anaerobic reactor

Anaerobic granules are responsible for organic degradation and biogas production in a reactor. The biogas production is entirely dependent on a mass transfer mechanism, but so far, the fundamental understanding remains poor due to the covered surface of the reactor. The study aimed at investigating the fundamental mass transfer characteristics of single anaerobic granules of different sizes using microscopic imaging and analytical monitoring under single and different organic loadings. The experiment was conducted in a micro reactor and mass transfer was calculated using modified Fick’s law. Scanning electron microscopy was applied to observe biogas production zones in the granule, and a lab-scale microscope equipped with a camera revealed the biogas bubble detachment process in the micro reactor for the first time. In this experiment, the granule size was 1.32, 1.47, and 1.75 mm, but 1.75 mm granules were chosen for further investigation due to their large size. The results revealed that biogas production rates for 1.75 mm granules at initial Chemical Oxygen Demand (COD) 586, 1700, and 6700 mg/L were 0.0108, 0.0236, and 0.1007 m3/kg COD, respectively; whereas the mass transfer rates were calculated as 1.83 × 10−12, 5.30 × 10−12, and 2.08 × 10−11 mg/s. It was concluded that higher organic loading and large granules enhance the mass transfer inside the reactor. Thus, large granules should be preferred in the granule-based reactor to enhance biogas production.

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“…Furthermore, the dark colored granules confirmed the anaerobic condition inside the bulk sample. These results were in agreement with [35].…”

Section: Morphology Of the Granulesupporting

confidence: 93%

Biogas Production and Fundamental Mass Transfer Mechanism in Anaerobic Granular Sludge

Afridi

Younas

2019

Sustainability

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“…Good sludge retention and adequate contact with feed organics are important factors that determine good performance of wastewater treatment facilities (Rizvi et al 2015). The HyVAB was operated under a constant liquid up-flow velocity of 4.4 m/h, which poses selective pressure on granular sludge, gradually washing out small particles (Hulshoff Pol et al 2004;Gupta et al 2016) and enhanced the granules development while suppling sufficient mixing (Chan et al 2012). A clear granule sludge bed (∼1.3 m in height) was observed after operating the system for 30 days with smaller particles being washing out from the reactor AD stage.…”

Section: Discussionmentioning

confidence: 99%

Efficient high strength petrochemical wastewater treatment in a hybrid vertical anaerobic biofilm (HyVAB) reactor: a pilot study

Wang

Ghimire

et al. 2017

Water Practice and Technology

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Performance of a pilot scale Hybrid Vertical Anaerobic Biofilm (HyVAB) reactor treating petrochemical refinery wastewater is presented here. The reactor is an integration of a bottom anaerobic sludge bed and a top aerobic biofilm stage and was operated continuously for 92 days at 21 ± 2 °C. Wastewater was fed continuously to the reactor with step flow increases reducing hydraulic retention time from 55 to 12 hours, increasing organic loading rate from 3 to 33 kg-COD/m3·d. The HyVAB removed on average 91% and 86% of the soluble and total feed COD, respectively, at steady state and loads up to 23 kg-COD/m3·d, of which 98% of the soluble COD removal occurred in the anaerobic stage. Methane yield ranged from 0.29 to 0.51 L/g-COD removed, including conversion of settled aerobic sludge to methane. Sludge production was low (0.04 kg-VSS/kg-COD removed) and biogas methane content high (84 ± 2%). The results demonstrated that HyVAB is an efficient, low footprint alternative for high strength wastewater treatment.

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“…3 Contrary to conventional suspended growth bioflocs, anaerobic granules have regular and well-defined shape, strong structure, and good settling velocities, which can enable high biomass retention and withstand high strength wastewater and shock loadings, and produce biogas [6,7]. The granule bed systems are usually featured with total biomass concentrations ranging from 20 to 40 g/L.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Evaluation of a sponge assisted-granular anaerobic membrane bioreactor (SG-AnMBR) for municipal wastewater treatment

et al. 2017

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This study compared a conventional granular anaerobic membrane bioreactor (CG-AnMBR) with a sponge assisted-granular anaerobic membrane bioreactor (SG-AnMBR) in terms of treatment performance, granular sludge properties, membrane fouling behaviour and biogas production. The SG-AnMBR showed better organics and nutrient removal, and enhanced methane yield at 156.3 ± 5.8 mL CH 4 (STP) /g COD removed. Granular sludge from the SG-AnMBR had superior quality with better settleability, larger particle size, higher EPS content and more granule abundance. The SG-AnMBR also exhibited slower fouling development with 50.7% lower total filtration resistance than those of the CG-AnMBR. Sponge addition effectively affected the concentration and properties of microbial products (e.g. soluble microbial products (SMP) and extracellular polymeric substances (EPS)) in granular sludge, cake layer as well as settling zone mixed liquor, thus alleviating the fouling propensity. The liquid chromatography-organic carbon detection (LC-OCD) analysis suggested that sponge

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Role of sludge volume index in anaerobic sludge granulation in a hybrid anaerobic reactor

Cited by 25 publications

References 30 publications

Biogas Production and Fundamental Mass Transfer Mechanism in Anaerobic Granular Sludge

Biogas Production and Fundamental Mass Transfer Mechanism in Anaerobic Granular Sludge

Efficient high strength petrochemical wastewater treatment in a hybrid vertical anaerobic biofilm (HyVAB) reactor: a pilot study

Evaluation of a sponge assisted-granular anaerobic membrane bioreactor (SG-AnMBR) for municipal wastewater treatment

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