Hydrolysis-acidification of excess sludge and its effect on sludge reduction in A-A/O system

2011 ◽  
Author(s):  
X.Q. Cao ◽  
Z.L. Zhao ◽  
W.S. Yang
Keyword(s):  
Sludge Reduction ◽  
Excess Sludge ◽  
Hydrolysis Acidification

Evaluation of Sludge Reduction Mechanisms in ‘Sonolysis-Cryptic Growth’ Wastewater Treatment System

2015 ◽  
Vol 768 ◽  
pp. 108-115
Author(s):  
Pan Yue Zhang ◽  
Tian Wan ◽  
Guang Ming Zhang
Keyword(s):  
Wastewater Treatment ◽  
Organic Load ◽  
Sludge Reduction ◽  
Excess Sludge ◽  
Operation Condition ◽  
Reduction Mechanisms ◽  
Residual Sludge ◽  
Cryptic Growth ◽  
Load Increase

‘Sonication - cryptic growth’ technology can reduce 30-80% excess sludge in wastewater treatment systems. Various mechanisms contribute to the sludge reduction but the role of each one is unclear. This paper quantitatively studied the potential mechanisms in ‘sonication - cryptic growth’. The operation condition was: every day 20% sludge was sonicated under 1.2 Wml-1 for 15 min and then returned to the wastewater treatment reactor for cryptic growth. The results showed that under such conditions, ‘sonication - cryptic growth’ reduced the excess sludge by 57.3% and the effluent met the national discharge standard. Multiple mechanisms were involved in the process. Detailed analysis showed that the ‘lysis-cryptic growth’ mechanism was the most important one and accounted for 49.1% of sludge reduction. Biodegradation of residual sludge was the second important one and contributed 19.5%. Other potential mechanisms included the altered microbial community, longer sludge retention time, and accumulation of persistent materials. But organic load increase had virtually no impact.

scholarly journals Enhancement of performance and biodegradability kinetics of aerobic-anaerobic sludge digestion

2020 ◽  
Vol 167 ◽  
pp. 01010 ◽  
Author(s):  
Boonchai Wichitsathian ◽  
Jareeya Yimratanabovorn ◽  
Watcharapol Wonglertarak
Keyword(s):  
Organic Matter ◽  
Removal Efficiency ◽  
Aeration Rate ◽  
Anaerobic Sludge ◽  
Sludge Reduction ◽  
Excess Sludge ◽  
Sludge Digestion ◽  
Anaerobic Sludge Digestion ◽  
Aerobic Sludge ◽  
Biodegradable Organic Matter

The excess sludge problem from a wastewater treatment plant is a great concerned due to the high cost of sludge management accounting for about 20% to 50% of the total operating cost. Therefore, sludge reduction is critical. Currently, aerobic and/or anaerobic sludge digestions are widely used in the industries for treating the excess sludge. The objective of this research was to study the effects of aeration rate and temperature on the excess sludge reduction by using the aerobic-anaerobic digestion system in the laboratory. The aeration rates of 1.0, 0.5, and 0.1 volume air per volume slurry per minute (vvm) at the room temperature and the thermophilic temperature (55 ± 2°C) were investigated. The results showed that the highest removal efficiency of aerobic sludge digestion was obtained at the thermophilic temperature and aeration rate of 1.0 vvm. The removal efficiency of organic matter in terms of COD, total solids (TS) and volatile solids (VS) were 34.76%, 33.01% and 43.45%, respectively. Consequently, the highest specific growth rate of microorganisms was 0.39 per hour and the substrate removal rate was 0.55 milligram CODremoved per milligram VSS per hour. Furthermore, slowly biodegradable organic matter was hydrolyzed to readily biodegradable organic matter and inert soluble organic matter. When the sludge effluent from aerobic sludge digestion was feed to the anaerobic sludge digestion, the removal efficiency of organic matter in terms of COD, TS and VS were increased by 25%, 17% and 28%, respectively. Moreover, the obtained methane production rate in the anaerobic sludge digestion was approximate 0.234 m3/kg COD removed.

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