Producing biogas from agricultural residues generated during phytoremediation process: Possibility, threshold, and challenges

Cadmium Addition Effects on Anaerobic Digestion with Elevated Temperatures

“…The stimulatory effects of Cd were also found in anaerobic digestion when other crops were used as feedstocks [8,14]. A previous study found that there was no inhibitory effect on biogas production when Cd less than 1 mg/L was present in a thermophilic reactor [14]. In the present study, the available Cd concentrations in the reactor during digestion were lower than 1 mg/L as there were Cd losses due to precipitation, sorption, and formation of complexes [21].…”

“…Moreover, the impact of metals on the performance of anaerobic digestion should be considered together with temperature conditions in future research and practice.there is still lack of information about the role of Cd in biodegradation, particularly on the modification of the methanogenic pathway.The concentration of the available Cd in the reactor is greatly influenced by temperature changes. Under thermophilic conditions (55.0 ± 1.0 • C), Cd concentrations less than 1.0 mg/L were shown to be non-inhibitory to the anaerobic digestion process [14]. However, to the best of our knowledge, most of the previous research on the impacts of temperature was carried out without considering the presence of heavy metals in the reactors.The aim of this study was to examine the effect of elevated temperatures combined with the addition of Cd on the anaerobic digestion of lignocellulosic biomass.…”

“…The concentration of the available Cd in the reactor is greatly influenced by temperature changes. Under thermophilic conditions (55.0 ± 1.0 • C), Cd concentrations less than 1.0 mg/L were shown to be non-inhibitory to the anaerobic digestion process [14]. However, to the best of our knowledge, most of the previous research on the impacts of temperature was carried out without considering the presence of heavy metals in the reactors.…”

“…Previous studies reported that the toxicity of Cd influenced the efficiency and amount of CH 4 formation [9][10][11][12]. However, only few studies showed that the biogas yields during anaerobic digestion of bioenergy crops were enhanced by Cd contamination at a certain concentration range [5,8,13,14]. Cd concentrations of 2.00 ± 0.44, 39.80 ± 1.25, and 6.37 ± 0.15 mg Cd/kg biomass in the shoot of canola, oat, and wheat improved the biogas yields by 59.37%, 79.23%, and 11.34% compared to the control group under thermophilic conditions (55.0 ± 1.0 • C) [8].…”

“…TS of the substrate in the reactors was set at 8% by adding distilled water. At the beginning of fermentation, CdCl 2 solution was then added into the reactors to achieve a final concentration of 1 mg/L based on a previous study [14]. The reactors were purged with N 2 gas for 5 min to remove the oxygen.…”