Abstract
The propagation of aquatic weeds including submerged macrophytes has lately been the most pressing problem in lakes, dams and reservoirs worldwide, and the treatment of the harvested phytomass has been explored. For the effective alternative treatment of submerged macrophytes, anaerobic digestion (AD) is the choice with the most potential, since it recovers biogas from wet organic waste, and the nutrient-rich digestate can be used for liquid fertilizer. Operating temperature is one of the largest factors determining AD process stability and the optimum temperature may depend greatly on the digestibility of the substrate. The present study conducted semi-continuous AD treatment of submerged macrophytes under three different operating temperature. For the substrate, a global invasive aquatic weed species Egeria densa was used. Shredded substrate was fed to completely stirred tank reactor, and it was operated at 37, 55, and 65oC. The average methane production rate at 55oC was showed a two times higher that of 37oC and 65oC. The clone analysis showed that the dominant species were quite different between AD at mesophilic and thermophilic temperature. These results suggested that the operating temperature up to 55 oC is preferable for AD of submerged macrophytes, Egeria densa.
