Pyrolysis of Dried Biosolids for Increased Biogas Production

Parry, David L.; Lewis, F. Michael; Vandenburgh, Scott; Haug, Roger T.; Amador, Janelle

doi:10.2175/193864712811693533

Cited by 3 publications

(2 citation statements)

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“…Parry et al (2012) reported anaerobic co-digestion of APL obtained from pyrolysis of dried wastewater biosolids as well as thickened sludge; APL digestion resulted in 8% of the expected methane in a batch biochemical methane potential (BMP) test. The pyrolysis was performed at a low temperature (200 • C) and the APL generated was fed one time in a batch mode at 3.75 gCOD/L [17]. In another batch study, APL from corn stalk pyrolysis at 400 • C inhibited methanogenic activity at organic loading of 35 gCOD/L r and nutrient supplement did not improve methane production, but biochar addition helped increase methane production in the batch and semi-continuous processes [11].…”

Section: Introductionmentioning

confidence: 99%

Inhibition during Anaerobic Co-Digestion of Aqueous Pyrolysis Liquid from Wastewater Solids and Synthetic Primary Sludge

et al. 2020

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Pyrolysis can convert wastewater solids into useful byproducts such as pyrolysis gas (py-gas), bio-oil and biochar. However, pyrolysis also yields organic-rich aqueous pyrolysis liquid (APL), which presently has no beneficial use. Autocatalytic pyrolysis can beneficially increase py-gas production and eliminate bio-oil; however, APL is still generated. This study aimed to utilize APLs derived from conventional and autocatalytic wastewater solids pyrolysis as co-digestates to produce biomethane. Results showed that digester performance was not reduced when conventional APL was co-digested. Despite having a lower phenolics concentration, catalyzed APL inhibited methane production more than conventional APL and microbial community analysis revealed a concomitant reduction in acetoclastic Methanosaeta. Long-term (over 500-day) co-digestion of conventional APL with synthetic primary sludge was performed at different APL organic loading rates (OLRs). Acclimation resulted in a doubling of biomass tolerance to APL toxicity. However, at OLRs higher than 0.10 gCOD/Lr-d (COD = chemical oxygen demand, Lr = liter of reactor), methane production was inhibited. In conclusion, conventional APL COD was stoichiometrically converted to methane in quasi steady state, semi-continuous fed co-digesters at OLR ≤ 0.10 gCOD/Lr-d. Undetected organic compounds in the catalyzed APL ostensibly inhibited anaerobic digestion. Strategies such as use of specific acclimated inoculum, addition of biochar to the digester and pretreatment to remove toxicants may improve future APL digestion efforts.

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Section: Introductionmentioning

confidence: 99%

Inhibition during Anaerobic Co-Digestion of Aqueous Pyrolysis Liquid from Wastewater Solids and Synthetic Primary Sludge

et al. 2020

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“…Upflow anaerobic digesters were employed and some COD removal was achieved at low organic loading rates, whereas pyroligneous acid concentrations greater than about 10% v/v significantly inhibited methane production (Andreoni et al, 1990). Another study concluded that condensate from pyrolysis of dried wastewater biosolids was anaerobically digestible under the specific conditions studied; however, the pyrolysis temperature was low (200 • C) and only short-term, batch biochemical methane potential tests were performed with a diluted biooil which may not reproduce conditions under continuous feeding (Parry et al, 2012). Torri and Fabbri (2014), described inhibition of methanogenic batch tests seeded with unacclimated biomass, using the aqueous phase from corn stalk pyrolysis.…”

Section: Introductionmentioning

confidence: 99%

Toxicity of Various Pyrolysis Liquids From Biosolids on Methane Production Yield

2019

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Aqueous pyrolysis liquid (APL) is a high-COD byproduct of wastewater biosolids pyrolysis that is comprised of numerous complex organic compounds and ammonia nitrogen (NH 3 -N). One potential beneficial use of APL is as a co-digestate to produce more biogas in anaerobic digesters. However, some APL organics and NH 3 -N are known to inhibit methane-producing microbes. Autocatalytic pyrolysis which uses previously-produced biochar as a catalyst during biosolids pyrolysis, increases energy-rich py-gas while eliminating bio-oil production and reducing COD concentration in the APL (catalyzed APL). However, the catalyzed APL still has a high organic strength and no suitable treatment strategies have yet been identified. In this study, the methane production yields and methanogenic toxicity of non-catalyzed and catalyzed APLs were investigated. Both non-catalyzed and catalyzed APLs were produced at 800 • C from a mix of digested primary and raw waste activated sludge from a municipal water resource reclamation facility. Using the anaerobic toxicity assay, APL digester loading rates higher than 0.5 gCOD/L for non-catalyzed and 0.10 gCOD/L for catalyzed APL were not sustainable due to toxicity. The IC 50 values (APL concentration that inhibited methane production rate by 50%) for non-catalyzed and catalyzed APLs were 2.3 and 0.3 gCOD/L, respectively. Despite having significantly fewer identified organic compounds catalytic APL resulted in higher methanogenic toxicity than non-catalytic APL. NH 3 -N was not the main inhibitory constituent and other organics in APL, including 3,5-dimethoxy-4-hydroxybenzaldehyde, 2,5-dimethoxybenzyl alcohol, benzene, cresol, ethylbenzene, phenols, styrene, and xylenes as well as nitrogenated organics (e.g., benzonitrile, pyridine) ostensibly caused considerable methane production inhibition. Future research focused on pretreatment methods to overcome APL toxicity and the use of acclimated biomass to increase methane production rates during APL anaerobic digestion or co-digestion is warranted.

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Loop bioenergy production and carbon sequestration of polymeric waste by integrating biochemical and thermochemical conversion processes: A conceptual framework and recent advances

et al. 2018

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Pyrolysis of Dried Biosolids for Increased Biogas Production

Cited by 3 publications

References 0 publications

Inhibition during Anaerobic Co-Digestion of Aqueous Pyrolysis Liquid from Wastewater Solids and Synthetic Primary Sludge

Inhibition during Anaerobic Co-Digestion of Aqueous Pyrolysis Liquid from Wastewater Solids and Synthetic Primary Sludge

Toxicity of Various Pyrolysis Liquids From Biosolids on Methane Production Yield

Loop bioenergy production and carbon sequestration of polymeric waste by integrating biochemical and thermochemical conversion processes: A conceptual framework and recent advances

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