Yonglan Tian

Ecophysiological characteristics and biogas production of cadmium-contaminated crops.

The present study proposes a novel strategy to get a rational production of biogas of the biomass residues from phytoremediation. This study investigates physiological responses, cadmium (Cd) accumulation and biogas production from canola, oat and wheat in pot and batch experiments. The results indicate that (1) aerial biomasses for canola, oat and wheat were enhanced by 5 mg Cd/kg soil by 19.41%, 8.78% and 3.38%, and the upper limit of Cd concentration that canola, oat and wheat can tolerate for aerial biomass production were 50, 10 and 10 mg Cd/kg soil; (2) canola accumulates more Cd than oat and wheat in its aerial parts; (3) cumulative biogas yields were 159.37%, 179.23% and 111.34% of the control when Cd in the shoot were 2.00±0.44, 39.80±1.25 and 6.37±0.15 mg Cd/kg biomass for canola, oat and wheat. Phytoremediation in cooperation with bioenergy production provide new insights for both soil remediation and energy research.

Morphological Responses, Biomass Yield, and Bioenergy Potential of Sweet Sorghum Cultivated in Cadmium-Contaminated Soil for Biofuel

This study was performed to assess morphological responses, biomass yield and bioenergy potential during the entire growth period (167 days) of sweet sorghum with different Cd stress, i.e. 0, 1, 5, 10, 30, 50, and 100 mg/kg in pot experiments. The results showed that the morphological characteristics of sweet sorghum, i.e. shoot length, leaf length and leaf numbers were not significantly changed with the Cd concentration ≤ 5 mg/kg in the soil. The aerial biomass of sweet sorghum treated by 10 mg/kg Cd was 82.71% of the control test, and was reduced to 70.67% when the Cd concentration in the soil was increased to 30 mg/kg. The root was the main location site of Cd in the sweet sorghum, thus the reutilization of the aerial biomass would not be seriously influenced. The predicted ethanol yields was 3.65, 3.05, 3.14, 2.69, 1.15, and 0.41 t/y/hm2 for 1, 5, 10, 30, 50, and 100 mg/kg Cd concentration, respectively. Due to its high biomass production and Cd accumulation capacity, sweet sorghum is a good candidate for bio-energy production in Cd-contaminated (<30 mg/kg) soil.

Adsorption of methylene blue from aqueous solutions onto sintering process red mud

Abstract The adsorption behavior of methylene blue (MB) dye from aqueous solutions onto sintering process red mud (SRM) and its hydrochloric acid-activated product (ASRM) was investigated in a batch system. The results showed that equilibrium was reached after a contact time of 60 min for both adsorbents. The optimum pH for MB adsorption was 10.0 for SRM and 9.0 for ASRM. The removal of the dye increased with increasing initial dye concentration and adsorbent amount, whereas it decreased with increasing ionic strength. The effect of temperature on adsorption was also investigated; the adsorption of MB on SRM and ASRM samples was spontaneous and followed an endothermic process, based on the analysis of thermodynamic parameters, including enthalpy (ΔH), entropy (ΔS), and free energy (ΔG) changes. The adsorption of MB followed pseudo-second-order kinetics, with a coefficient of correlation ⩾ 0.9999. The adsorption process was better described by the Langmuir isotherm model than Freundlich model, with a maxim...

Research on anaerobic digestion of corn stover enhanced by dilute acid pretreatment: Mechanism study and potential utilization in practical application

The utilization of lignocelluloses for biogas production is limited for several aspects, and an efficient pre-treatment is essential to increase the enzyme accessibility of cellulose. This research focused on the mechanism of biogas production and biodegradation properties under the treatments with different acid agents, including sulfuric acid (H2SO4), acetic acid (CH3COOH), and phosphoric acid (H3PO4). The H3PO4 pretreated corn stover was then co-digested with cow dung in a pilot test to investigate the performance of acid pretreatment in practice. The results showed that the main compositions of corn stover were cellulose, hemicellulose, and lignin, and their proportions in the corn stovers were increased after the acid pretreatments. This hence increased the final biogas yields (up to 40.75%), methane content, and promoted the biodegradation process. More significantly, the acid pretreatments delayed the appearance of the peak value of the biogas yield for 3 to 8 days depending on the acid concentrations. This study proposed that the dilute weak acid pretreatment, especially H3PO4 pretreatment, efficiently enhanced the biogas production by increasing the degradation of hemicellulose. Further on, the H3PO4 pretreatment also improved the stability of fermentation, which would benefit the biogas generation in practice. This research contributes to a better understanding of the mechanism of acid influence on enhancing the biogas generation and substrate biodegradation, and provides pratically sound guidance for reclamation of lignocellulosic materials.

How does copper stress influence the relationships among the anaerobic co-fermentation parameters?

The presence of heavy metals influences the efficiency of anaerobic fermentation and results in the variations of the relationships among the fermentation parameters. In this study, the impacts of elevated Cu2+ concentrations on relationships among biogas properties, process stability, substrate biodegradation, and enzyme activity were analysed by Pearson correlation analysis based on the experimental data of a mesophilic anaerobic co-fermentation with mixed acid pretreated Phragmites australis straw and raw cow dung as feedstocks. The results showed that in the absence of Cu2+, the cumulative biogas yields were positively related to pH values (0.780, p < 0.05) and negatively related to oxidation-reduction potential values (−0.909, p < 0.01) and cellulase activity (−0.937, p < 0.01). The coenzyme F420 activity was negatively related to volatile fatty acid (VFA) concentrations (−0.756, p < 0.05). In the presence of 30 mg/l Cu2+, correlation coefficients between the cumulative biogas yields and pH values, ammonia nitrogen (NH4+-N), VFA, chemical oxygen demand, hemicellulose, and cellulose were higher than the control group, indicating the efficient hydrolysis, acidogenesis, and acetogenesis stages. High Cu2+ concentrations (500 mg/l) resulted in almost completely different impacts on these relationships from the low Cu2+ concentrations, especially on the hydrolysis stage.The presence of heavy metals influences the efficiency of anaerobic fermentation and results in the variations of the relationships among the fermentation parameters. In this study, the impacts of elevated Cu2+ concentrations on relationships among biogas properties, process stability, substrate biodegradation, and enzyme activity were analysed by Pearson correlation analysis based on the experimental data of a mesophilic anaerobic co-fermentation with mixed acid pretreated Phragmites australis straw and raw cow dung as feedstocks. The results showed that in the absence of Cu2+, the cumulative biogas yields were positively related to pH values (0.780, p < 0.05) and negatively related to oxidation-reduction potential values (−0.909, p < 0.01) and cellulase activity (−0.937, p < 0.01). The coenzyme F420 activity was negatively related to volatile fatty acid (VFA) concentrations (−0.756, p < 0.05). In the presence of 30 mg/l Cu2+, correlation coefficients between the cumulative biogas yields and pH values, a...

Process analysis of anaerobic fermentation of Phragmites australis straw and cow dung exposing to elevated chromium (VI) concentrations

Anaerobic fermentation is considered as a cost-effective way of biomass waste disposal. Chromium (Cr) is one of the heavy metals that often been blamed for unsatisfactory operation or failure of anaerobic fermentation. The impact of Cr (added as K2Cr2O7) on mesophilic anaerobic fermentation of Phragmites australis straw and cow dung was demonstrated by investigating the biogas properties, process stability, substrate degradation and enzyme activities during the fermentation process. The results showed that 30, 100 and 500 mg/L Cr6+ addition increased the cumulative biogas yields by up to 19.00%, 14.85% and 7.68% respectively, and brought forward the daily biogas yield peak. Meanwhile, the methane (CH4) content in the 30 (52.47%) and 100 (40.57%) mg/L Cr6+-added groups were generally higher than the control group (37.70%). Higher pH values (close to pH 7) and lower oxidation-reduction potential (ORP) values in the Cr6+-added groups after the 15th day indicated the better process stability compared to the control group. Taking the whole fermentation process into account, the promoting effect of Cr6+ addition on biogas yields was mainly attributable to better process stability, the enhanced degradation of lignin and hemicellulose, the transformation of intermediates into VFA, the higher coenzyme F420 activities and the efficient generation of CH4. These results demonstrate that an appropriate addition of Cr6+ could enhance the anaerobic fermentation which support the regulations utilizing of the Cr6+ contaminated biowaste.