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Enhanced Deep Utilization of Low-Organic Content Sludge by Processing Time-Extended Low-Temperature Thermal
Tingjiao Liu1, Chunshan Wu1, Yulan Wang2
1College of Environmental Science and Engineering and Key Laboratory of Pollution Control and Resource Recycling of Fujian Province, Fujian Normal University, Fuzhou 350007, China.
ACS Omega
|November 8, 2021
Summary
Extended low-temperature thermal hydrolysis pretreatment significantly boosts methane production from sewage sludge. This cost-effective method enhances sludge digestion and resource recovery, offering a sustainable solution for waste management.
Area of Science:
- Environmental Engineering
- Biotechnology
- Waste Management
Background:
- Sewage sludge treatment relies on anaerobic digestion for stability and resource recovery.
- Low organic content in sludge limits methane production, necessitating pretreatment methods.
- Thermal hydrolysis is a common pretreatment, but high temperatures increase energy costs.
Purpose of the Study:
- To investigate the effectiveness of extended low-temperature (90 °C) thermal hydrolysis for enhancing anaerobic digestion of low-organic content sludge.
- To determine the optimal pretreatment time for maximizing methane production and economic feasibility.
- To assess the impact of this pretreatment on sludge dewatering and heavy metal stability.
Main Methods:
- Low-organic content sludge was pretreated using thermal hydrolysis at 90 °C for varying extended contact times.
- Solubilization of organic matter (proteins and carbohydrates) was analyzed.
- Anaerobic digestion was performed, and methane production was measured (mL/gVS).
- Energy balance calculations and dewatering properties were evaluated.
Main Results:
- Extended contact time at 90 °C significantly promoted the solubilization of proteins and carbohydrates.
- Methane production increased by up to 5.56 times compared to untreated sludge, reaching 294.73 mL/gVS after 36 hours of pretreatment.
- Extended thermal hydrolysis time proved more economically feasible than increasing temperature, based on energy balance.
- Sludge dewatering properties and heavy metal stability were improved.
Conclusions:
- Low-temperature thermal hydrolysis with prolonged contact time is an effective and economical pretreatment for enhancing anaerobic digestion of low-organic content sludge.
- This method improves methane yield, sludge dewaterability, and heavy metal immobilization.
- The findings support advanced utilization of treated sludge, contributing to sustainable waste management.
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