Anaerobic digestion is a well-known process with a low energy requirement that is technologically easy and can be used to transform organic materials into methane from many forms of waste water, solid waste, and biomass. The effects of pretreatments for ultrasound and ozonation on organic solubilization, anaerobic biodegradability and production of biogas were elucidated in this report. The subject for comparison was two pretreatment techniques for batch anaerobic digestion for biogas recovery with the same content and experimental circumstances. At ambient temperature, anaerobic digestion experiments were performed with the solid retention time set at 25 days. The results obtained suggested that the demand for soluble chemical oxygen increased from 0.344 without pretreatment to 1.023 and 1.228 g/L with ultrasound and ozone pretreatment, respectively, whereas the biogas output yields increased by 32.3 percent and 52.9 percent over the 25 days with ultrasonic irradiation and ozonation, respectively, compared to the control case. In the case of ultrasound, ozone pretreatment, and control, the biodegradability of the organic compounds of the samples reached 55.9, 64.31, and 39.18 percent respectively, in terms of chemical oxygen demand (COD) removal efficiencies. The physicochemical characteristics of sludge flocs were studied by means of particle size scanning, which was clearly influenced by sonic and ozonate pretreatment, resulting in finer particles than in the control case. The results of this study showed that the soluble COD and ultimate yield of ozone pretreatment biogas were higher than those of pretreatment and control ultrasonics.
Manh Van Do
Institute of Environmental Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi 100000, Vietnam.
Bui Quang Minh
Center for Research and Technology Transfer, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi 100000, Vietnam.
Quoc Toan Tran
Institute of Natural Products Chemistry, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi 100000, Vietnam.
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