Characterization of Anaerobic Degradability and Kinetics of Harvested Submerged Aquatic Weeds Used for Nutrient Phytoremediation

Abstract

In this study, eight different submerged aquatic species were screened by batch biochemical methane potential and anaerobic degradability tests to identify a promising/suitable feedstock. Kinetics of the best-screened substrate were studied in a mesophilic semi-continuous experiment. The aquatic species Myriophyllum aquaticum, Egeria densa and Potamogeton perfoliatus showed relatively higher methane yields of over 400 NmL/g-VS (volatile solids). Semi-continuous operation was carried out by feeding E. densa for over 400 days. The achieved results were 33%-53% chemical oxygen demand (COD) reduction and methane yield of 126-231 NmL/g-VS with a short hydraulic retention time (HRT). Additionally, the NH4 + and PO4 3− releases from the biomass to water were found to be low (18%-27% and 2.5%-3.9%) throughout the experiment. Hydrolysis was the limiting step in the digestion of E. densa, regardless of changes in HRT (15-45 days). The acid-phase model indicated that the hydrolysis rate constant (kh) of E. densa was 0.058 one/day, which was one third lower the kh value of food waste, but quite similar to cow manure. OPEN ACCESSEnergies 2015, 8 305

Evaluation of different pretreatments on organic matter solubilization and hydrogen fermentation of mixed microalgae consortia

“…Samples for VFA and soluble COD (SCOD) analysis were prepared by centrifuging samples at 13,000 rpm for 5 min and filtering them with 0.45 mm pore-size filters. Volatile fatty acids (VFA) concentration was determined with a gas chromatograph (GC14B, Shimadzu) equipped with a flame ionization detector and a StabiliwaxR-DA capillary column (Resteck) [27]. The heating program of the column in the VFA determination is as followed: 2 min held at 100 C, then the temperature increased at a rate of 8 C min À1 until 250 C, and at 250 C maintained for 7 min.…”

Crop Characteristics of Aquatic Macrophytes for Use as a Substrate in Anaerobic Digestion Plants—A Study from Germany

“…The highest values were measured in samples from autumn harvesting where reed was the main component (34.6, 34.1 and 31.1 in samples 16, 35 and 30, respectively). Kobayashi et al [18] investigated the characteristics of eight submersed aquatic macrophytes from lakes in Japan (Hydrilla verticillata L. F. ROYLE, Potamogeton x inbaensis KADONO, P. dentatus HAGSTR., P. malaianus MIQUEL, Ceratophyllum demersum L., P. perfoliatus L., Myriophyllum aquaticum (VELL.) VERDC.…”

“…and E. densa PLANCH). The C/N ratio varied between 8.5 and 12.9, with an average of 10.3 [18]. However, the optimal C/N ratio of substrates for anaerobic fermentation ranges between 15 and 30 [19].…”

“…This is slightly higher than the values of 206 and 233 L CH4 /kg VS presented in Table 8. The eight submersed aquatic plants investigated by Kobayashi et al [18] produced methane yields of 275 (E. crappipes) to 418 L CH4 /kg VS (M. aquaticum). In the case of five submersed macrophytes from Lake Biwa in Japan analysed by Koyama et al [28] (Ceratophyllum demersum L., E. densa, E. nuttallii, Potamogeton maackianus A. BEN and Potamogeton malaianus MIQUEL), the methane yields ranged from 161.2 to 360.8 L/kg VS depending on the species being investigated.…”

Biodegradability during Anaerobic Fermentation Process Impacted by Heavy Metals

“…However, disposing the biomass residues following phytoremediation is challenging [4][5][6]. Therefore, there has been a growing interest on the development of inexpensive disposal techniques and improvements in bio-resource utilization to foster sustainability in remediation systems [7].…”