A sludge purging procedure that increases the robustness of upflow anaerobic sludge blanket reactors in sewage treatment

Gonçãlves, Ricardo Franci; Louzada, L. M.; Wanke, R.

doi:10.1007/s13762-019-02397-1

Cited by 3 publications

(3 citation statements)

References 21 publications

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“…Solids breakthrough has been similarly observed in several previous studies at high sludge bed height (Gonçalves et al, 2019). Progressive development of sludge blanket height leads to greater local solids consolidation within the bed and a more tortuous path for flow such that channelling occurs, which introduces elevated local velocities at the solid-liquid interface above the sludge blanket, as visually evidenced by local jetting effects (Lester et al, 2013).…”

Section: Clarification Introduced Through Sludge Blanket Formation Reduces Solids Fraction Downstreamsupporting

confidence: 70%

“…Membrane integration and recirculation of the concentrate flow from membrane tank to UASB reactor could exacerbate solids accumulation due to the prevention of solids losses by the membrane (Gouveia et al, 2015b;Ozgun et al, 2015a). Unless process interventions are adopted, the accumulated solid phase (particulate organic fraction) will wash out from the UASB into the membrane stage, imposing a reduction in membrane permeability (Gonçalves et al, 2019;Ozgun et al, 2015a), and may offset the advantages of UASB configured AnMBR versus CSTR configured AnMBR.…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies have characterised the accumulated solids within the sludge blanket along the height of the UASB, with a specific focus on solids concentration, particle size, microbial diversity, specific methanogenic activity, biodegradability and dewaterability (Gonçalves et al, 2019;Ozgun et al, 2019). However, the novelty of this study is in seeking to understand the impact of solids accumulation on UASB solid-liquid separation, thus establishing the mechanisms responsible for solids breakthrough, which can be used to inform the engineered design of UASB configured AnMBR.…”

Section: Introductionmentioning

confidence: 99%

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Establishing the mechanisms underpinning solids breakthrough in UASB configured anaerobic membrane bioreactors to mitigate fouling

et al. 2020

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In this study, the mechanisms for solids breakthrough in upflow anaerobic sludge blanket (UASB) configured anaerobic membrane bioreactors (AnMBRs) have been described to establish design parameters for limiting membrane fouling. As the sludge blanket develops, two periods can be identified: (i) an initial progressive enhancement in solids separation provided through sludge blanket clarification, via depth filtration, which sustains downstream membrane permeability; and (ii) sludge blanket destabilisation, which imposed solids breakthrough resulting in a loss in membrane permeability. The onset of sludge blanket destabilisation was identified earlier in the flocculent AnMBR, which was ascribed to an increased gas production, caused by hydrolysis within the sludge blanket at extended solids residence time. Whilst hydrolysis also induced higher gas productivity within the granular AnMBR, solids breakthrough was not evidently observed during this period, and was instead only observed as the sludge blanket approached the UASB overflow. However, solids breakthrough was observed earlier for both reactors when treating wastewater with lower temperatures. This was explained through characterisation of the settling velocity of discrete particles from the sludge blanket of both MBRs; solids washout was evidenced to be induced by the increase in fluid viscosity with a reduction in temperature, which lowered terminal particle settling velocity. Nevertheless, particle settling velocity was comparable for particles from both sludge blankets. We therefore propose that the enhanced stability imparted by the granular AnMBR is due to the higher inertial force of the dense granular sludge. From this study, we suggest similarly low levels of membrane fouling can be achieved within flocculent AnMBR by managing solids retention time to constrain sludge bed height and excess

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Section: Clarification Introduced Through Sludge Blanket Formation Reduces Solids Fraction Downstreamsupporting

confidence: 70%