Post-aerobic digestion of waste sludge: performance analysis and modelling of nitrogen fate under alternating aeration

Tomei, M. Concetta; Carozza, Nicola Antonello; Angelucci, Domenica Mosca

doi:10.1007/s13762-015-0839-5

Cited by 10 publications

(3 citation statements)

References 22 publications

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“…PAD may offer other benets not discussed in detail here, including improved dewaterability, reduction of odorous compounds, and removal of pathogens and micropollutants. 31,33,59,60 These aspects will be important to study at the full-scale as well. Additionally, research is needed on the microbial communities in full-scale systems to understand the key microbes and their potential to resist perturbations.…”

Section: Comparison To Sidestream Deammonicationmentioning

confidence: 99%

Post aerobic digestion (PAD) is a solids sidestream nutrient removal process that utilizes native carbon: performance and key operational parameters from two full-scale PAD reactors

Sabba¹,

Redmond²,

Dunlap³

et al. 2022

Environ. Sci.: Adv.

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Section: Comparison To Sidestream Deammonicationmentioning

confidence: 99%

Post aerobic digestion (PAD) is a solids sidestream nutrient removal process that utilizes native carbon: performance and key operational parameters from two full-scale PAD reactors

Sabba¹,

Redmond²,

Dunlap³

et al. 2022

Environ. Sci.: Adv.

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“…Nitrification efficiency is defined by the ratio between the nitrified nitrogen (NO 3 -N and NO 2 -N) and the ammonia nitrogen (TAN) available for nitrification. The latter is either fed (with the anaerobic digestate) to the aerobic reactor or produced in the aerobic hydrolysis of VS (Tomei, Carozza, and Mosca Angelucci 2016b). According to a preliminary analysis of solid removals, the feed (digestate) is the dominating source of ammonia nitrogen (available for nitrification) in the aerobic reactor.…”

Section: Nitrogen Balancementioning

confidence: 99%

Anaerobic-aerobic sequential treatment: Temperature optimization and cost implications

Ghanimeh

Khalil

Angelucci

et al. 2019

Journal of the Air & Waste Management Association

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Traditionally, aeration units, used as a polishing stage after anaerobic digestion (AD) of wastes, are operated at ambient temperature. Yet, when effluent quality is the main design criterion, raising the temperature of the aeration stage can be justified by improved removal efficiencies. In this study, an anaerobic-aerobic sequential system (AASS) was operated to co-digest raw wastewater and food waste. The aerobic compartment was tested under psychrophilic and mesophilic temperatures. At the design loading rate of 2 g VS L −1 d −1 , the anaerobic digester achieved removal efficiencies of 85 ± 2% of volatile solids (VS), 84 ± 3% of total chemical oxygen demand (COD T ) and a biogas yield of 1,035 ± 30 mL g VSfed −1 (50% methane). The aerobic reactor achieved additional removal of 8% COD T and 7 % VS. By raising the temperature of the aerobic reactor to the mesophilic range, COD and solids concentrations of the effluent dropped to approximately half their values. This was accompanied by an increase in nitrification (from 68% to 91%) and denitrification (from 10% to 16%). The energy analysis showed that total energy consumption slightly increases (from 0.45 to 0.49 kWh kg CODfed −1) by raising the temperature of the aerobic reactor to mesophilic range. A preliminary evaluation of the sludge disposal cost, revealed a saving increase of 5-6% under mesophilic operation with respect to psychrophilic conditions.Implications: In order to cope with the globally increasing constraints on the disposal of urban wastes, efficient post-processing of effluents becomes a crucial requirement for the anaerobic digestion industry. In this context, the submitted manuscript shows that the quality of the effluent, of an anaerobic digester, treating food waste with raw wastewater, can be substantially improved by optimizing the aerobic polishing stage. Raising the temperature of the aerobic reactor to the mesophilic range resulted in a drop of solids and COD concentrations to approximately half their values. Equally important, the implications on operational costs were found to be favorable, compared to traditional psychrophilic aerobic post-treatment, when taking into consideration indirect sludge treatment costs and energy selling revenues.

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“…Shortcut nitrogen removal could be the nitrogen removal mechanism based on the presence of NO 2 − . Some research previously used the term SND but was not able to verify if shortcut nitrogen removal was occurring (Tomei et al, 2016). Due to the lower oxygen demand of shortcut N removal compared to SND, it is important to understand the nitrogen removal mechanism.…”

Section: Introductionmentioning

confidence: 99%

Lab‐scale data and microbial community structure suggest shortcut nitrogen removal as the predominant nitrogen removal mechanism in post‐aerobic digestion (PAD)

Sabba¹,

Redmond²,

Ruff³

et al. 2022

Water Environment Research

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Implementing an aerobic digestion step after anaerobic digestion, referred to as “post aerobic digestion” (PAD), can remove ammonia without the need for an external carbon source and destroy volatile solids. While this process has been documented at the lab‐scale and full‐scale, the mechanism for N removal and the corresponding microbial community that carries out this process have not been established. This research gap is important to fill because the nitrogen removal pathway has implications on aeration requirements and carbon demand, that is, short‐cut N‐removal requires less oxygen and carbon than simultaneous nitrification–denitrification. The aims of this research were to (i) determine if nitrite (NO2−) or nitrate (NO3−) dominates following ammonia removal and (ii) characterize the microbial community from PAD reactors. Here, lab‐scale PAD reactors were seeded with biomass from two different full‐scale PAD reactors. The lab‐scale reactors were fed with biomass from full‐scale reactors and operated in batch mode to quantify nitrogen species concentrations (ammonia, NH4+, NO2−, and NO3−) over time. Experimental results revealed that NO2− production rates were several orders of magnitude greater than NO3− production rates. Indeed, nitrite accumulation rate (NAR) was greater than 90% at most temperatures, confirming that shortcut nitrogen removal was the dominant NH4+ removal mechanism in PAD. Microbial community analysis via 16S rRNA sequencing indicated that ammonia oxidizing bacteria (AOB) were much more abundant than nitrite oxidizing bacteria (NOB). Overall, this study suggests that aeration requirements for post‐aerobic digestion should be based on NO2− shunt and not complete simultaneous nitrification denitrification. Practitioner Points AOB are a key feature of PAD microbial communities NOB are present, but in much lower abundance than AOB High nitrite accumulation ratio suggests shortcut nitrite as the main mechanism for nitrogen removal Nitritation in PAD reactors is sustained at temperatures as high as 40°C No ammonia oxidation occurred at 50°C implying different mechanisms of nitrogen removal including ammonia stripping

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Post-aerobic digestion of waste sludge: performance analysis and modelling of nitrogen fate under alternating aeration

Cited by 10 publications

References 22 publications

Post aerobic digestion (PAD) is a solids sidestream nutrient removal process that utilizes native carbon: performance and key operational parameters from two full-scale PAD reactors

Post aerobic digestion (PAD) is a solids sidestream nutrient removal process that utilizes native carbon: performance and key operational parameters from two full-scale PAD reactors

Anaerobic-aerobic sequential treatment: Temperature optimization and cost implications

Lab‐scale data and microbial community structure suggest shortcut nitrogen removal as the predominant nitrogen removal mechanism in post‐aerobic digestion (PAD)

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