Solids Control in Sludge Pretreatment

Sludge pretreatment by mechanical, chemical or thermal methods before anaerobic digestion has been applied to increase the digestability of excess sludge. Pretreatment processes rely on their ability to disrupt cell membranes and to release organic materials from the cells into the aqueous phase. Pretreatment by mechanical disintegration has grown rapidly in recent years in parallel with the advances in technology. Ultrasonic sludge disintegration –one of the most commonly used mechanical pretreatment methods- enables the occurrence of cavitation bubbles for the break-up of microorganism cells to extract intracellular materials. The purpose of this study was to conduct disintegration experiments to optimize sonication parameters and to operate subsequent batch anaerobic digesters to examine the effect of food to microorganism ratio (F/M) in sonicated and unsonicated samples. Results showed that high sonication powers and longer treatment times were effective in sludge disintegration in terms of soluble chemical oxygen demand release. Sonicated sludge digested in batch reactors with higher initial F/M ratio caused higher methane generations, higher sludge reductions and had better dewatering characteristics.

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Identification of recalcitrant compounds after anaerobic digestion with various sludge pretreatment methods

Post Treatments of Anaerobically Treated Effluents ◽

10.2166/9781780409740_0283 ◽

2019 ◽

pp. 283-302

Keyword(s):

Anaerobic Digestion ◽

Sludge Pretreatment ◽

Recalcitrant Compounds

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Thermal hydrolysis sludge pretreatment

10.1016/b978-0-323-85223-4.00022-1 ◽

2021 ◽

pp. 391-398

Author(s):

Kine Svensson

Keyword(s):

Thermal Hydrolysis ◽

Sludge Pretreatment

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Transformation of dissolved organic matters produced from alkaline-ultrasonic sludge pretreatment in anaerobic digestion: From macro to micro

Water Research ◽

10.1016/j.watres.2018.05.044 ◽

2018 ◽

Vol 142 ◽

pp. 138-146 ◽

Cited By ~ 45

Author(s):

Dan Lu ◽

Keke Xiao ◽

Yun Chen ◽

Yan Ni Annie Soh ◽

Yan Zhou

Keyword(s):

Anaerobic Digestion ◽

Organic Matters ◽

Sludge Pretreatment ◽

Dissolved Organic Matters

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Use of anaerobic hydrolysis pretreatment to enhance ultrasonic disintegration of excess sludge

Water Science & Technology ◽

10.2166/wst.2015.587 ◽

2015 ◽

Vol 73 (5) ◽

pp. 1190-1196

Author(s):

Xianjin Li ◽

Tong Zhu ◽

Yang Shen ◽

Tianyu Chai ◽

Yuanhua Xie ◽

...

Keyword(s):

Energy Consumption ◽

Cell Walls ◽

Oxygen Demand ◽

Biochemical Properties ◽

Excess Sludge ◽

Disintegration Rate ◽

Sludge Characteristics ◽

Sludge Pretreatment ◽

Combined Pretreatment ◽

Reducing Energy

To improve the excess sludge disintegration efficiency, reduce the sludge disintegration cost, and increase sludge biodegradability, a combined pretreatment of anaerobic hydrolysis (AH) and ultrasonic treatment (UT) was proposed for excess sludge. Results showed that AH had an advantage in dissolving flocs, modifying sludge characteristics, and reducing the difficulty of sludge disintegration, whereas UT was advantageous in damaging cell walls, releasing intracellular substances, and decomposing macromolecular material. The combined AH–UT process was an efficient method for excess sludge pretreatment. The optimized solution involved AH for 3 days, followed by UT for 10 min. After treatment, chemical oxygen demand, protein, and peptidoglycan concentrations reached 3,949.5 mg O2/L, 752.5 mg/L and 619.1 mg/L, respectively. This work has great significance for further engineering applications, namely, reducing energy consumption, increasing the sludge disintegration rate, and improving the biochemical properties of sludge.

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Pretreatment followed by anaerobic digestion of secondary sludge for reduction of sewage sludge volume

Water Science & Technology ◽

10.2166/wst.2013.154 ◽

2013 ◽

Vol 67 (11) ◽

pp. 2527-2533 ◽

Cited By ~ 15

Author(s):

Naoki Abe ◽

Yue-Qin Tang ◽

Makoto Iwamura ◽

Shigeru Morimura ◽

Kenji Kida

Keyword(s):

Anaerobic Digestion ◽

Sewage Sludge ◽

Thermal Treatment ◽

Low Pressure ◽

Gas Production ◽

Wet Oxidation ◽

Thermophilic Anaerobic Digestion ◽

Sludge Pretreatment ◽

Secondary Sludge ◽

Digestion Efficiency

The influence of two pretreatment methods, thermal treatment and low-pressure wet oxidation, on the sludge digestion efficiency was examined. Batch thermophilic anaerobic digestion was used to evaluate the effectiveness of the pretreatment methods in terms of volatile suspended solids (VSS) digestion efficiency and gas production. The results showed that the gas production was not proportional to the VSS degradation efficiency of either thermal treatment or low-pressure wet oxidation. Low-pressure wet oxidation treatment at 150 °C along with 40% of the theoretical oxygen required to oxidize organic carbon gave the highest gas production and the VSS digestion efficiency of 77% at a VSS loading rate of 8 g l−1 d−1. The digestion efficiency was about 30% higher than that of thermophilic anaerobic digestion without sludge pretreatment. Sewage sludge could be treated effectively at a high VSS digestion efficiency with this pretreatment followed by thermophilic anaerobic digestion.

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