Improving hydrolysis of food waste in a leach bed reactor

Browne, James; Allen, Eoin; Murphy, Jerry D.

doi:10.1016/j.wasman.2013.06.025

Cited by 68 publications

(40 citation statements)

References 17 publications

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“…Pilot-scale studies carried out with this material in 2003 considered both mesophilic and thermophilic operation [3] and based on these studies the first full-scale commercial demonstration plant was designed as a continuously stirred tank reactor (CSTR) operated at mesophilic temperature [4]. Since then a number of alternative technologies for food waste digestion have been suggested including two phase systems [5] and leach bed reactors [6,7]. Digestion of source segregated domestic food waste is now a popular approach in many areas of the world [8,9], with 400 plants in the UK alone contributing 480 MW to the electricity grid in 2016 [10].…”

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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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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“…It is often used in co-digestion processes with WWTP excess sludge in order to improve methane production and reduce concentration of undesirable compounds frequently present in the sludge 1 . In literature a new system has been proposed, which consists of a leach bed reactor (LBR), coupled with a UASB reactor; LBR allows to extract a liquid substrate, highly soluble and readily biodegradable, suitable to undergo a high-velocity anaerobic process 10 . The coupling of a solid-treating LBR and a liquid-treating UASB has been named HASL (hybrid anaerobic solid-liquid reactor) and can be considered as a two-stage digestion 11 .…”

Section: Introductionmentioning

confidence: 99%

Characterization and BMP Tests of Liquid Substrates for High-rate Anaerobic Digestion

Mainardis

Cabbai

Zannier³

et al. 2018

Chem.Biochem.Eng.Q.

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This work was focused on the physicochemical characterization and biochemical methane potential (BMP) tests of some liquid organic substrates, to verify if they were suitable for undergoing a process of high-velocity anaerobic digestion. The selected substrates were: first and second cheese whey, organic fraction of municipal solid waste (OFMSW) leachate, condensate water and slaughterhouse liquid waste. Firstly, a physicochemical characterization was performed, using traditional and macromolecular parameters; then, batch anaerobic tests were carried out, and some continuous tests were planned.The results revealed that all the analyzed substrates have a potential to be anaerobically treated. Valuable information about treatment rate for a high-velocity anaerobic digestion process was obtained. Start-up of a lab-scale UASB reactor, treating diluted cheese whey, was successfully achieved with good COD removal efficiency. These preliminary results are expected to be further investigated in a successive phase, where continuous tests will be conducted on condensate water and OFMSW leachate.

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“…However, leachbeds have been mostly used for the organic fraction of municipal solid waste (OFMSW) and energy crops (Vandevivere et al, 2003;Deublein and Steinhauser, 2011), and minimal studies have investigated their use with solid manure residues (Vandevivere et al, 2003;Deublein and Steinhauser, 2011). In general, leachbeds have been prone to relatively poor performance with low methane yield (Kusch et al, 2008;Lehtomaki et al, 2008;Xu et al, 2011;Browne et al, 2013). There appears to be considerable opportunity to improve the performance of leachbeds via systematic research and development.…”

Section: Research Motivationmentioning

confidence: 99%

“…Batch systems also give variable biogas flow and composition, due to the batch operation. To provide more consistent biogas production, multiple leachbeds can be setup and operated in parallel as single stage, or fed to a single methanogenic reactor in dual stage configuration Browne et al, 2013). Safety measures need to be closely observed during the loading and emptying of the batches, because personnel performing the unloading/loading could be exposed to hazardous conditions.…”

Section: Anaerobic Digestion Technology Options For Solid Manure Resimentioning

confidence: 99%

“…Unfortunately, the performance of leachbeds have been often suffer from inhibition problems due to lack of control (Jha et al, , 2011), resulting in only 20 -30 % of methane recovery (Kusch et al, 2008;Lehtomaki et al, 2008;Xu et al, 2011;Browne et al, 2013). This results in large digester sizes and low biogas yield, affecting technical and economic feasibility of the leachbed technology.…”

Section: Anaerobic Digestion Technology Options For Solid Manure Resimentioning

confidence: 99%

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Anaerobic treatment of solid manure residues

Yap¹

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Spent bedding, which is a mix of bedding stubble, faeces, urine, spilt water and animal feed, is a major by-product of livestock farming in Australia and the United States. In Australia, such residues are stockpiled for passive composting prior to land spreading to harness the nutrient value. Key concerns are uncontrolled greenhouse gas emissions, odour, losses of nutrients, and the potential for ground and surface water contamination. A sustainable management alternative is anaerobic digestion (AD), whereby organic matter in the spent bedding is converted into useable methane energy and nutrients are mobilized for subsequent recovery. However, AD technology is not currently available in Australia at a sufficiently low cost and low level of complexity for on-farm adoption. In addition, the AD characteristics of solid manure residues are not well understood, posing significant uncertainty for AD design and optimization. In response, this thesis examines a leachbed AD approach, which is particularly suitable for high solids wastes such as spend bedding, and can be cost-effective and simple to construct and operate.A pilot scale (200 L) leachbed system was constructed and operated. Spent bedding was collected from Australian piggeries and wetted with water leachate in the enclosed leachbed via two distinct operating modes: trickling and flood-and-drain. The water leachate was heated in both configurations, aimed at a 37 o C operating temperature. Results showed comparable methane recovery for both the trickling and flood-and-drain modes at 50% of the biochemical methane potential (B0 = 195 -218 L CH4 kg VSfed -1 ) in both cases. This indicated that AD performance was insensitive to the mode of leachate flow. However, the flood-and-drain leachbed did mobilise more particulates into the leachate than the trickling leachbed, which could cause a materials-handling problem with pumping of leachate onfarm. Inoculation with solid digestate from a previous leachbed (inoculum-to-substrate ratio of 0.22 on a VS basis) hastened the AD start-up, but methane recovery remained at 50 % of the Bo. Post-digestion testing indicated that methane recovery was limited by insufficient indigenous inoculum and/or by chemical inhibition.To clarify the effects of operating conditions on AD performance at high solids content, a series of batch tests were performed at smaller laboratory scale. These tested the viability of indigenous inoculum in spent bedding (from the manure component), together with the effects of operating temperature and solids concentration. Results showed that spent bedding actually did have sufficient indigenous inoculum to recover the full Bo of the spent bedding. However, to operate at higher solid loading (≥ 10 % TS content) and higher II temperatures (55 ºC), methanogenic activity could be boosted by inoculation with leachate and/or solid digestate from a former leachbed batch. The use of leachate as an inoculum would preserve leachbed volume for fresh waste and easier handling.Chemical analysis of digestat...

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Improving hydrolysis of food waste in a leach bed reactor

Cited by 68 publications

References 17 publications

Influence of ammonia in the anaerobic digestion of food waste

Influence of ammonia in the anaerobic digestion of food waste

Characterization and BMP Tests of Liquid Substrates for High-rate Anaerobic Digestion

Anaerobic treatment of solid manure residues

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