Volume 10, Issue 4 (December 2025)
J Environ Health Sustain Dev 2025, 10(4): 2843-2858 |
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Ethics code: IR.IUMS.REC.1402.027
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Kowsari M H, Yeganeh M, Ansari M, Abdolahi Nejad B, Hasham Firooz M, Farzadkia M. Comparative Efficiency of Mesophilic Anaerobic Digestion and Aerated Static Pile Composting in the Stabilization of Municipal Wastewater Sludge. J Environ Health Sustain Dev 2025; 10 (4) :2843-2858
URL: http://jehsd.ssu.ac.ir/article-1-1062-en.html
URL: http://jehsd.ssu.ac.ir/article-1-1062-en.html
Mohammad Hasan Kowsari 
, Mojtaba Yeganeh , Mohsen Ansari , Behnaz Abdolahi Nejad , Masoumeh Hasham Firooz , Mahdi Farzadkia *
, Mojtaba Yeganeh , Mohsen Ansari , Behnaz Abdolahi Nejad , Masoumeh Hasham Firooz , Mahdi Farzadkia *
Research Center for Environmental Health Technology, Iran University of Medical Sciences, Tehran, Iran & Department of Environmental Health Engineering, School of Public Health, Iran University of Medical Sciences, Tehran, Iran
Abstract: (97 Views)
Introduction: Stabilization of municipal wastewater sludge is a critical requirement for mitigating environmental and public health risks. This study provides a comparative evaluation of mesophilic anaerobic digestion (AD) and aerated static pile (ASP) composting for sludge stabilization at Iran’s largest municipal wastewater treatment plant, with a focus on process efficiency, hygienic quality, and end-product usability.
Materials and Methods: Laboratory-scale experiments were conducted using batch mesophilic anaerobic digestion (35 °C, 24 days) and aerated static pile composting. The composting process employed sludge conditioned with bulking and amendment agents under controlled aeration, including a 6-day thermophilic phase within a 30-day operational period. Process performance was assessed based on volatile solids reduction, pathogen inactivation, and biogas production.
Results: ASP composting demonstrated superior stabilization and hygienization performance, achieving more than 50% volatile solids reduction and over 3-log fecal coliform reduction, resulting in compost meeting USEPA Class A standards. In contrast, anaerobic digestion achieved approximately 40% volatile solids reduction and produced 5405 mL of biogas, yielding biosolids classified as USEPA Class B.
Conclusion: While mesophilic anaerobic digestion offers the advantage of renewable energy recovery, aerated static pile composting provides a more hygienically robust pathway for producing stabilized, high-quality compost suitable for agricultural applications. The findings highlight that the selection of sludge treatment technology should be context-driven, balancing priorities between energy generation and the production of sanitized, agriculturally valuable biosolids.
Materials and Methods: Laboratory-scale experiments were conducted using batch mesophilic anaerobic digestion (35 °C, 24 days) and aerated static pile composting. The composting process employed sludge conditioned with bulking and amendment agents under controlled aeration, including a 6-day thermophilic phase within a 30-day operational period. Process performance was assessed based on volatile solids reduction, pathogen inactivation, and biogas production.
Results: ASP composting demonstrated superior stabilization and hygienization performance, achieving more than 50% volatile solids reduction and over 3-log fecal coliform reduction, resulting in compost meeting USEPA Class A standards. In contrast, anaerobic digestion achieved approximately 40% volatile solids reduction and produced 5405 mL of biogas, yielding biosolids classified as USEPA Class B.
Conclusion: While mesophilic anaerobic digestion offers the advantage of renewable energy recovery, aerated static pile composting provides a more hygienically robust pathway for producing stabilized, high-quality compost suitable for agricultural applications. The findings highlight that the selection of sludge treatment technology should be context-driven, balancing priorities between energy generation and the production of sanitized, agriculturally valuable biosolids.
Type of Study: Original articles |
Subject:
Environmental Health, Sciences, and Engineering
Received: 2025/10/8 | Accepted: 2025/11/20 | Published: 2025/12/25
Received: 2025/10/8 | Accepted: 2025/11/20 | Published: 2025/12/25
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