Low pH anaerobic digestion of waste activated sludge for enhanced phosphorous release

Latif, Muhammad Asif; Mehta, Chirag; Batstone, Damien J.

doi:10.1016/j.watres.2015.05.062

Cited by 113 publications

(61 citation statements)

References 24 publications

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“…Such COD values are comparable with the ones of other organic materials typically used as anaerobic digestion substrate [84][85][86], pointing out stillage organic potential to be transformed into methane. Anaerobic digestion can thus convert over 50% of the by-product COD to biogas, which may be used as fuel within the plant [89].…”

Section: The Combination Of Bioethanol and Biogas Production Processessupporting

confidence: 65%

Combined Biogas and Bioethanol Production: Opportunities and Challenges for Industrial Application

Cesaro

Belgıorno

2015

Energies

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Abstract:In the last decades the increasing energy requirements along with the need to face the consequences of climate change have driven the search for renewable energy sources, in order to replace as much as possible the use of fossil fuels. In this context biomass has generated great interest as it can be converted into energy via several routes, including fermentation and anaerobic digestion. The former is the most common option to produce ethanol, which has been recognized as one of the leading candidates to substitute a large fraction of the liquid fuels produced from oil. As the economic competitiveness of bioethanol fermentation processes has to be enhanced in order to promote its wider implementation, the most recent trends are directed towards the use of fermentation by-products within anaerobic digestion. The integration of both fermentation and anaerobic digestion, in a biorefinery concept, would allow the production of ethanol along with that of biogas, which can be used to produce heat and electricity, thus improving the overall energy balance. This work aims at reviewing the main studies on the combination of both bioethanol and biogas production processes, in order to highlight the strength and weakness of the integrated treatment for industrial application.

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Section: The Combination Of Bioethanol and Biogas Production Processessupporting

confidence: 65%

Combined Biogas and Bioethanol Production: Opportunities and Challenges for Industrial Application

Cesaro

Belgıorno

2015

Energies

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“…Total solids (TS), VS, COD, SCOD, VFA and, elemental concentrations and microbial analysis were measured according to the protocol given in Latif, Mehta et al (2015). Biogas composition (CH4 and CO2) was measured using a Shimadzu GC-2014, Japan gas chromatograph (GC) equipped with a Valco GC valve (1 mL sample loop), a HAYESEP Q 80/100 packed column (2.4 m length; 1/8" outer diameter, 2 mm inner diameter) and a thermal conductivity detector (TCD).…”

Section: Analytical Techniquesmentioning

confidence: 99%

“…The B0 values presented for CI experiments therefore represent the calculated contribution of the effluent sludge only and should be directly comparable to the NI results. The data was compared by degradability (B0) and first order hydrolysis coefficient (khyd) as previously described in Latif, Mehta et al (2015).…”

Section: Residual Biochemical Methane Potentialmentioning

confidence: 99%

Enhanced phosphorus solubility during anaerobic digestion

Latif¹

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Worldwide phosphorus (P) consumption has increased massively over the last century, to overcome soil nutrient constraints, and to feed an increasing population with an increasing level of urbanization.However, current P reserves are limited and are expected to deplete in 50-120 years. Hence, new techniques to source P from alternative resources are essential. Waste streams are the largest alternative resource of P, with much of the organic wastes containing P treated by anaerobic digestion (AD). However, P recovery from the digested waste streams is limited by in-reactor P precipitation, and inaccessibility of soil available P in sludge biosolids. In-reactor P precipitation increases the operational costs of a treatment facility due to scaling and precipitation, there are strong advantages in being able to recover P as a purified mineral product. In such circumstances, keeping high PO4 concentration during AD is vital to enhance its recovery post AD.This thesis aims to assess two different techniques to enhance PO4 concentration during AD from waste activated sludge (WAS): low pH and high pressure (enabling low pH). Low pH single stage AD was tested in both batch and continuous mode. In the batch study, biochemical methane potential tests were conducted for 51 days at a pH range of 5.0 to 7.2 in two separate sets (two different WAS samples collected from municipal WWTP). Low pH (< 5.7) caused a significant loss in the methane potential (B0) of up to 33%, with 3.6 times increase in PO4 concentration compared to the neutral pH (7 -7.7), but with no major change in methane production rate coefficient (khyd). The loss in methane yield was mainly due to decrease in hydrolytic capability rather than inhibition of methanogenesis with volatile fatty acids (VFAs) being < 300 mgCOD L -1 and soluble COD < 1300 mgCOD L -1 even at low pH. While pH did not influence the acetoclastic community (Methanosaeta dominated), it was the primary driver for the remaining community, and caused a loss of diversity and shift to Clostridia.To validate the results from batch conditions, continuous low pH AD was performed using similar substrate and pH conditions. The influence of the pH on PO4 concentration was similar in continuous and batch. It was found that the low pH (5.5) caused a significant increase in PO4 concentration up to 79% of the total P, while methane yield was reduced by 50%. VFAs and SCOD concentrations increased from 40 to 504 mg L -1 and 600 to 2017 mg L -1 respectively, as the pH was reduced from 7.0 to 5.5. Higher concentration of propionic acid (370 -430 mg L -1 ) was recorded at low pH (< 5.5).The reduction in methane yield was associated with a shift in microbial community and decreased destruction of particulate organics. Acidogens dominated at low pH (< 6.0), while methanogens decreased by 88% at pH 5.5 compared to neutral pH. Apart from the loss in methanogenic and hydrolytic capacity, continuous acid dosing to maintain low pH condition was identified as a key limitation with this technology. To assess an...

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“…Industrial, 1992bIndustrial, , 2010 Para realizar la preparación del sustrato, se definió una concentración recomendada por Browne y Murphy (2014), menor al 10% de SV en base al contenido de sólidos totales, comúnmente utilizado para digestores CSTR. En este estudio se tomó la decisión de iniciar con 7% de SV por considerar que condiciones de baja carga pueden resultar en un crecimiento prolífico de bacterias que consumen ácido en el reactor de fermentación, lo que provoca un aumento en el pH (Grimberg et al, 2015) y que una sobrecarga orgánica provocaría una caída de pH e inhibición de la reacción (Latif et al, 2015Zhang et al, Información Tecnológica -Vol. 28 Nº 1 2017 2014), lo que se refleja en una producción de biogás mínima o nula.…”

Section: Caracterización Y Preparación Del Sustratounclassified

Adaptación de Inóculos Durante el Arranque de la Digestión Anaerobia con Residuos Sólidos Orgánicos

Nakasima-López¹,

Taboada-González²,

Aguilar-Virgen³

et al. 2017

Inf. tecnol.

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ResumenEn este estudio se analizó la adaptación de dos inóculos, tomados en una industria láctea y una industria cervecera, en digestores anaeróbicos de mezcla completa (CSTR). El estudio es necesario porque en el uso de la tecnología anaeróbica, el arranque del sistema es crítico y lento, y para acelerar el tiempo de arranque de un digestor anaeróbico, se recurre a la inoculación. Se caracterizaron los residuos de alimentos y los inóculos, se alimentaron los digestores a una misma concentración y composición del residuo orgánico, y se analizó la reacción de degradación durante 150 días. La adaptación del inóculo dos (industria cervecera) al residuo orgánico fue más rápida y estable en el proceso de degradación, lo que dio un mayor rendimiento de biogás y concentración de metano (48.3%). Sistemas de digestión operando con un pH por debajo de 6.5 producen biogás con bajo contenido de metano. Palabras clave: biogás; CSTR; digestión anaeróbica; inóculos; arranque Inoculum Adaptation During Start-up of Anaerobic Digestion of Organic Solid Waste AbstractIn this study, the adaptation of two inoculums, taken from a dairy industry and a brewing industry, in continuous anaerobic flow stirred digesters (CSTR) was analyzed. The study is needed because in the use of anaerobic technology, the start-up of the system is critical and slow and inoculation is used to speed up the start-up time in anaerobic digesters. The food waste and inoculums were characterized, the digesters were fed at the same concentration and composition of organic waste, and degradation reaction was analyzed during 150 days. The adaptation inoculum two (brewing industry) to the organic residue was faster and more stable in the degradation process, resulting in a higher yield of biogas and methane concentration (48.3%). Digestion systems operating with a pH below 6.5 produce biogas with low methane content.

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Low pH anaerobic digestion of waste activated sludge for enhanced phosphorous release

Cited by 113 publications

References 24 publications

Combined Biogas and Bioethanol Production: Opportunities and Challenges for Industrial Application

Combined Biogas and Bioethanol Production: Opportunities and Challenges for Industrial Application

Enhanced phosphorus solubility during anaerobic digestion

Adaptación de Inóculos Durante el Arranque de la Digestión Anaerobia con Residuos Sólidos Orgánicos

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