Abstract
In an anaerobic digestion (AD) process, the hydrolysis phase is often limited when substrates with high concentrations of solids are used. We hypothesized that applying micro-aeration in the hydrolysis phase and the application of granular activated carbon (GAC) in the methanogenesis phase could make the AD process more efficient. A packed bed reactor (PBR) coupled with an up-flow anaerobic sludge blanket (UASB) was conducted, and its effects on methane generation were evaluated. The micro-aeration rate applied in PBR was 254 L-air/kg-Total solids (TS)-d was compared with a control reactor. Micro-aeration showed that it reduced the hydrolysis time and increased the organic matter solubilization as chemical oxygen demand (COD) increasing 200%, with a volatile fatty acids (VFAs) increment higher than 300%, compared to the control reactor (without aeration). Our findings revealed that the implementations of microaeration and GAC in the two-phase AD system could enhance methane production by reducing hydrolysis time, increasing solid waste solubilization.
Highlights
By 2012, municipal solid waste (MSW) was generated worldwide around 1300 million tons per day, and it tends to grow in 2025 up to 2200 million tons per day [1]
PBRMICRO-AERATION and up-flow anaerobic sludge blanket (UASB) can be an alternative to be used in the biodegradation of substrates with high concentrations of solids, such as OFMSW
Solubilization of organic matter is favored and it reduces the stabilization time of the UASB reactors when methanogenic microorganisms suffer from volatile fatty acids (VFAs) accumulation poisoning
Summary
By 2012, municipal solid waste (MSW) was generated worldwide around 1300 million tons per day, and it tends to grow in 2025 up to 2200 million tons per day [1]. In 2015, Mexico alone produced up to 53.1 million tons of MSW per day, which is 61.2% increased compared to the amount generated in 2003 [2]. Inadequate disposition of MSW promotes decomposition of the organic matter, producing unpleasant odors, and harmful fauna. The leachates infiltrate pollutants into the soil and groundwater, which represents a spreading potential of the contamination problem. It is necessary to look for alternatives for mitigation and final disposal to avoid environmental contamination and repercussions in ecosystems and public health
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