The effect of pH on anaerobic fermentation of primary sludge at room temperature

Wu, Haixia; Yang, Dianhai; Zhou, Qi; Song, Zhoubing

doi:10.1016/j.jhazmat.2009.06.146

Cited by 98 publications

(32 citation statements)

References 28 publications

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“…Alkaline conditions are expected to lead to more soluble protein and carbohydrate generation. At the same time, the methanogenic activity is inhibited resulting in enhanced SCFAs production (Wu et al, 2009). The optimum pH has been found to be in the range of 9-11 and can be maintained with the use NaOH and Ca(OH) 2 (Su et al, 2013;Wu et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…At the same time, the methanogenic activity is inhibited resulting in enhanced SCFAs production (Wu et al, 2009). The optimum pH has been found to be in the range of 9-11 and can be maintained with the use NaOH and Ca(OH) 2 (Su et al, 2013;Wu et al, 2009). However, this practice is not desirable in full-scale plants, since it increases the cost and the environmental impact of the process.…”

Section: Introductionmentioning

confidence: 99%

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Recovery of volatile fatty acids from fermentation of sewage sludge in municipal wastewater treatment plants

Longo

Katsou

Malamis

et al. 2015

Bioresource Technology

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Recovery of volatile fatty acids from fermentation of sewage sludge in municipal wastewater treatment plants

Longo

Katsou

Malamis

et al. 2015

Bioresource Technology

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“…AD operation at depressed pH have been recommended to increase P solubility (Banister, Pitman et al 1998, Chen, Jiang et al 2007, Wu, Yang et al 2009, Bi, Guo et al 2012 and to avoid any deposition-precipitation in the digester. However, low pH conditions can impact on methane production (Beccari, Bonemazzi et al 1996, Gerardi 2006) by accumulating VFA.…”

Section: Phmentioning

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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“…Jako kluczowe wymienia się takie parametry, jak: hydrauliczny czas zatrzymania, pH i temperaturę. Wyszczególnione parametry decydują nie tylko o efektywności fermentacji, ale i o formie uzyskiwanych produktów, w tym LKT bądź rozpuszczonych białek i węglowodanów [13][14][15][16].…”

Section: Wprowadzenieunclassified

Acid Fermentation of Primary Sludge Subjected to Sonication

Pastuszka

Grosser

Kamizela

2017

Eng. Prot. Environ.

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Organic carbon is the main source of energy and matter necessary for the development of micro-organisms. Removing the suspension from the wastewater in the primary settling tank causes a reduction in the concentration of organic compounds and their hydrolysis products including volatile fatty acids (VFA). As a result, the ratio of organic matter to nitrogen and phosphorus in wastewater after sedimentation is lower than in raw wastewater. Volatile fatty acids, especially acetic acid, are the most desirable and assimilable form of organic carbon. In biological wastewater treatment processes, the content of easily biodegradable organic carbon significantly influences the rate and efficiency of denitrification and dephosphorylation. There are a many of solutions that increase the content of organic matter, including VFA, in wastewater. The basic solutions include sedimentation time reduction, and in particular the use of the concepts of active primary settling tank with acid fermentation process. Other technological solutions are based on the use of acid fermentation in fermentors or special thickeners. The rate of acid fermentation process, leading to the formation of VFA is dependent on many factors. The basic limiting factors include content of biodegradable organic substance and temperature. The aim of the study was to evaluate the possibility of using sonication to intensify the production of volatile fatty acids from primary sludge in acid fermentation. The aim of the study was also to determine the combined effect of sonication time (sonication energy) and temperature of acid fermentation on the yield of volatile fatty acids. During the study, VFA generation was inhibited by the increase in sonication energy. The most effective acid fermentation, due to the production of LKT, was carried out under conditions of psychrophilic temperature i.e. 20°C.

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The effect of pH on anaerobic fermentation of primary sludge at room temperature

Cited by 98 publications

References 28 publications

Recovery of volatile fatty acids from fermentation of sewage sludge in municipal wastewater treatment plants

Recovery of volatile fatty acids from fermentation of sewage sludge in municipal wastewater treatment plants

Enhanced phosphorus solubility during anaerobic digestion

Acid Fermentation of Primary Sludge Subjected to Sonication

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