IJEP 45(5): 457-463 : Vol. 45 Issue. 5 (May 2025)
1. University of Phayao, Programme in Environmental Health, School of Public Health, Phayao 56000, Thailand
2. University of Phayao, Programme in Occupational Health and Safety, School of Public Health, Phayao 56000, Thailand
Abstract
A large portion of waste-activated sludge (WAS) is produced annually by many community wastewater treatment systems in Thailand. This research is interested in studying the feasibility of anaerobic co-digestion of waste-activated sludge with cow dung (CD) by using the central composite design (CCD) to determine the number of biochemical biogas production (BBP) experiments. The response surface methodology (RSM) was applied to evaluate and optimize optimum co-digestion between WAS and CD. The weight of CD has a significant impact on the biogas yield (BY). The highest BY of 174 mL/g total solids (TS) was achieved for WAS: CD co-digestion ratio of 1.5:3.2 by weight within 20 days, at the carbon to nitrogen ratio of 24. By adding the WAS into the system, there was a relative improvement in the system stability. This ratio was led to test in the pilot continuous stirred tank reactor (CSTR); the maximum BY increased by 23.95% compared with the biochemical biogas potential (BBP) experiment. Moreover, the CSTR digestion system could be completed within a shorter time of 15 days. The obtained biogas also has a methane content of approximately 58.82%, which is worth the investment. Therefore, the co-digestion of WAS with CD was the promised alternative for biogas production. Additionally, this can offer a lot of benefits to the community, such as waste-to-energy conversion, cost reduction by minimizing the WAS to landfill, greenhouse gas emission (GHG) reduction from the WAS landfill, etc. However, it needs further study to improve the co-digestion efficiency from the anaerobic co-digestion of waste-activated sludge with cow dung.
Keywords
Waste-activated sludge, Cow dung, Biogas, Anaerobic co-digestion, Activated sludge
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