Anaerobic digestion of two biodegradable municipal waste streams

Zhang, Yue; Banks, C.J.; Heaven, S.

doi:10.1016/j.jenvman.2012.03.043

Cited by 105 publications

(55 citation statements)

References 13 publications

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“…Values are closely similar to those reported elsewhere in the literature for source segregated food waste of this type [5,25,26].…”

Section: Food Waste Characteristicssupporting

confidence: 90%

“…Early digestion trials with this material, however, showed accumulation of volatile fatty acids (VFA) over extended run times in both mesophilic and thermophilic digestion systems [1]. Similar observations were made in a full-scale thermophilic digester treating source segregated restaurant and catering waste [2], and in the UK Government's food waste demonstration AD plant in Ludlow, UK [3]; and have also been demonstrated in laboratoryscale digesters [4,5].…”

Section: Introductionmentioning

confidence: 52%

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Effect of a Trace Element Addition Strategy on Volatile Fatty Acid Accumulation in Thermophilic Anaerobic Digestion of Food Waste

Yirong

Heaven

Banks

2014

Waste Biomass Valor

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Fax +44 (0)2380 677519 2 AbstractPurpose: A trace element supplementation strategy previously shown to be effective in mesophilic conditions was tested for thermophilic digestion of source segregated domestic food waste.Method: Inoculum from a mesophilic anaerobic digester treating municipal wastewater biosolids was successfully acclimated to thermophilic temperature (55 o C) with food waste as a substrate. Four laboratory-scale digesters were maintained at a loading of 2 g VS l -1 day -1 with one pair receiving trace elements (TE) supplementation. Two more pairs of digesters were incrementally loaded to 3 and 4 g VS l -1 day -1 , respectively, and also received TE.Results: All digesters performed well for the first 3-4 months of operation, but volatile fatty acid (VFA) concentrations in those without TE showed no recovery from an initial small accumulation. On continued operation, VFA concentrations increased in all digesters, especially those at higher loading rates or without TE supplementation, reaching >30 g l -1 .Under these meta-stable conditions, a deliberate disturbance to daily feeding (cessation then resumption) led to acetic acid accumulation, a fall in pH and a sharp increase in the ratio of partial to intermediate alkalinity. Increases in VFA corresponded to an increasing total ammonia nitrogen concentration which appeared to become inhibitory at ~2500 mg N l -1 . It has been shown that in mesophilic conditions accumulation of VFA can be prevented by supplementing with selected trace elements [17][18][19][20]. Mesophilic food waste digesters supplemented with trace elements have been shown to operate with good gas production and low VFA concentrations at ammonia concentrations in excess of 6000 mg l -1 , but with a purely hydrogenotrophic methanogenic population; and a mechanism by which trace element addition can prevent VFA accumulation at high ammonia concentrations has been put forward [18]. Selenium, which is present only in low concentrations in food waste, has been shown to be essential in preventing propionic acid accumulation by providing the co-enzymes 4 necessary for the reduction of formate, one of the metabolic products of propionate degradation. At higher organic loading rates (OLR) additional cobalt is also required. This is thought to be necessary as in these high ammonia conditions all of the organic carbon is converted to carbon dioxide through syntrophic acetate oxidation by the reverse WoodsLjungdahl pathway; in conjunction with the reduction of carbon dioxide to methane by the hydrogenotrophic route, this leads to an increase in co-enzyme demand. Where formate oxidation does not occur there is an accumulation of propionic acid and other longer-chain VFAs, leading eventually to a fall in pH and cessation of methanogenesis [18]. ConclusionsThe current study investigated the extent to which a trace element addition strategy successfully applied in mesophilic conditions could prevent VFA accumulation in thermophilic digesters operating on source segregated food waste, in conditions...

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“…Values are closely similar to those reported elsewhere in the literature for source segregated food waste of this type [5,25,26].…”

Section: Food Waste Characteristicssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 52%

Effect of a Trace Element Addition Strategy on Volatile Fatty Acid Accumulation in Thermophilic Anaerobic Digestion of Food Waste

Yirong

Heaven

Banks

2014

Waste Biomass Valor

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“…A proportion of this TAN, depending on temperature and pH, is present as free ammonia nitrogen (FAN). Even under mesophilic conditions this can cause operational problems during digestion [14][15][16] and in thermophilic conditions it has led to severe inhibition, accumulation of volatile fatty acids (VFA), and eventual process failure [13,17]. A substantial amount of information is now available on threshold concentrations for TAN inhibition in mesophilic conditions [18][19][20], with reported values generally in the range of 3-5 g N L -1 .…”

Section: Introductionmentioning

confidence: 99%

Influence of ammonia in the anaerobic digestion of food waste

Yirong

Zhang

Heaven

et al. 2017

Journal of Environmental Chemical Engineering

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Ammonia toxicity was investigated in mesophilic (37 o C) and thermophilic (55 o C) digesters using high and low-nitrogen food wastes (FW). Mesophilic inoculum was successfully acclimated to thermophilic conditions by a step change in temperature followed by incremental increases in organic loading rate (OLR). Digestion performance and stability were monitored via volatile fatty acid (VFA) profiles, alkalinity, specific methane production (SMP) and volatile solids (VS) destruction. High-nitrogen mesophilic digesters stabilised by day 70 and responded well to increases in OLR, with a SMP of 0.45 L CH 4 g -1 VS, stable pH, and VFA <0.2 g L -1 . Thermophilic digesters fed on high and low-nitrogen FWs showed almost identical responses to acclimatisation. Behaviour then deviated, with high-nitrogen digesters accumulating VFA. Stable pH could be maintained for up to 310 days before eventual failure at total ammonia nitrogen (TAN) concentration >5.0 g N L -1 , although accumulation of propionic and other longer-chain VFA began at TAN ~3.5 g N L -1 . The low-nitrogen digesters showed no VFA accumulation, and had a SMP of ~0.39 L CH 4 g VS L -1 day -1 with 91% VS destruction. After 384 days the TAN concentration was increased from ~0.7 g N L -1 by urea addition. This resulted in progressive VFA accumulation in one digester when TAN reached ~3.5 g N L -1 , while stable operation at very low VFA was possible at up to ~2.5 g N L -1 in the second digester. The results confirmed acclimatisation to thermophilic conditions was possible on a far shorter timescale than to high TAN concentrations.

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“…There are two potential pathways for food waste collection: (i) commingled collection, i.e., with other municipal solid waste in what is called the residual waste stream; and (ii) source-separated collection. While the latter provides a quality feedstock for AD due to a reduction in contamination, commingled collection introduces high concentrations of potentially toxic elements (PTEs) and lowers the nutrient content of food waste, which may affect the performance of AD and the quality of the biogas and digestate produced [34,35].…”

Section: Introduction To the Case Studymentioning

confidence: 99%

“…Sustainability 2017, 9, 1497 6 of 17 feedstock for AD due to a reduction in contamination, commingled collection introduces high concentrations of potentially toxic elements (PTEs) and lowers the nutrient content of food waste, which may affect the performance of AD and the quality of the biogas and digestate produced [34,35]. As such, source-separated collection of food waste is considered to be the most suitable way to access a high quality (i.e., free from physical impurities) waste stream and ensure a stable operation of the AD process [36].…”

Section: Introduction To the Case Studymentioning

confidence: 99%

A Parameter Selection Framework for Sustainability Assessment

et al. 2017

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Sustainability assessment of resource recovery from waste is an important prerequisite for informed and sound decision-making. Life Cycle Sustainability Assessment (LCSA) has been developed to support this process, yet its use is still constrained by the difficulty of identifying the most relevant impact parameters. This paper, seeks to inform LCSA for resource recovery from waste based on a parameter identification approach that uses the political, economic, social, technological, environmental and legal (PESTEL) analysis. The novelty of this approach lies in the structured conceptualisation of the resource recovery system and the context within which decisions are made. The anaerobic digestion of source-separated food waste in the UK is used as a case study to trial and demonstrate the approach. Findings suggest that a conceptual, qualitative analysis, although limited in its scope due to the lack of quantitative components, is suitable in integrating different parameters, allowing for a holistic conceptualisation of the system and capturing important issues that could be easily overlooked. This type of analysis can summarise the key interdependencies, contrast the trade-offs and provide a wider understanding of the political and legal context within which the system operates, all important in extending the implementation of LCSA towards the right direction.

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Anaerobic digestion of two biodegradable municipal waste streams

Cited by 105 publications

References 13 publications

Effect of a Trace Element Addition Strategy on Volatile Fatty Acid Accumulation in Thermophilic Anaerobic Digestion of Food Waste

Effect of a Trace Element Addition Strategy on Volatile Fatty Acid Accumulation in Thermophilic Anaerobic Digestion of Food Waste

Influence of ammonia in the anaerobic digestion of food waste

A Parameter Selection Framework for Sustainability Assessment

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