Anaerobic digestion of Chinese cabbage waste was investigated through a pilot-scale two-stage digester at a mesophilic temperature of 37 °C. In the acidification digester, the main product was acetic acid, with t...Anaerobic digestion of Chinese cabbage waste was investigated through a pilot-scale two-stage digester at a mesophilic temperature of 37 °C. In the acidification digester, the main product was acetic acid, with the maximum concentration of 4289 mg·L-1on the fourth day, accounting for 50.32% of total volatile fatty acids. The oxidation reduction potential(ORP) and NH+4-N level decreased gradually with hydraulic retention time(HRT)of acidification. In the second digestion phase, the maximum methanogenic bacterial concentration reached9.6 × 1010ml-1at the organic loading rate(OLR) of 3.5–4 kg VS·m-3, with corresponding HRT of 12–16 days.Accordingly, the optimal biogas production was 0.62 m3·(kg VS)-1, with methane content of 65%–68%. ORP and NH+4-N levels in the methanizer remained between- 500 and- 560 m V and 2000–4500 mg·L-1, respectively. Methanococcus and Methanosarcina served as the main methanogens in the anaerobic digester.展开更多
The occurrence and development mechanism of internal local corrosion has always been a controversial topic,and especially under flow conditions.In this paper,an improved high shear force loop was experimentally used,a...The occurrence and development mechanism of internal local corrosion has always been a controversial topic,and especially under flow conditions.In this paper,an improved high shear force loop was experimentally used,and local flow field is induced by simulating corrosion defects on the surface of X80 pipeline steel specimens.The characteristics of corrosion products deposited on the surface of specimens in CO2-saturated NACE solution were investigated by means of electrochemical impedance spectroscopy(EIS),scanning electron microscopy(SEM),X-ray diffraction(XRD),and energy dispersive spectrometry(EDS).The 3D micromorphology of the corrosion test surface after remove the corrosion scale used to measure the size of localized corrosion pit.Under the influence of local defects,the wall shear stress(WSS)and turbulent kinetic energy of local flow fields enhanced significantly,and pressure fluctuations in local flow field were induced.The results showed that the characteristics of surface corrosion products varied with flow velocity.The corrosion scales formed in various regions of specimens with defects exhibited different surface micro-morphologies and chemical compositions.Overall,these data offer new perspectives for better understanding the mechanisms behind local corrosion.展开更多
基金the National Science-Technology Support Plan of China(2014BAD02B04)
文摘Anaerobic digestion of Chinese cabbage waste was investigated through a pilot-scale two-stage digester at a mesophilic temperature of 37 °C. In the acidification digester, the main product was acetic acid, with the maximum concentration of 4289 mg·L-1on the fourth day, accounting for 50.32% of total volatile fatty acids. The oxidation reduction potential(ORP) and NH+4-N level decreased gradually with hydraulic retention time(HRT)of acidification. In the second digestion phase, the maximum methanogenic bacterial concentration reached9.6 × 1010ml-1at the organic loading rate(OLR) of 3.5–4 kg VS·m-3, with corresponding HRT of 12–16 days.Accordingly, the optimal biogas production was 0.62 m3·(kg VS)-1, with methane content of 65%–68%. ORP and NH+4-N levels in the methanizer remained between- 500 and- 560 m V and 2000–4500 mg·L-1, respectively. Methanococcus and Methanosarcina served as the main methanogens in the anaerobic digester.
基金supported by the National Natural Science Foundation of China with(No.51774314)Natural Science Foundation of Shandong Province with grant number(No.ZR2018MEM002)the Fundamental Research Funds for the Central Universities(No.19CX05001A)for financial support。
文摘The occurrence and development mechanism of internal local corrosion has always been a controversial topic,and especially under flow conditions.In this paper,an improved high shear force loop was experimentally used,and local flow field is induced by simulating corrosion defects on the surface of X80 pipeline steel specimens.The characteristics of corrosion products deposited on the surface of specimens in CO2-saturated NACE solution were investigated by means of electrochemical impedance spectroscopy(EIS),scanning electron microscopy(SEM),X-ray diffraction(XRD),and energy dispersive spectrometry(EDS).The 3D micromorphology of the corrosion test surface after remove the corrosion scale used to measure the size of localized corrosion pit.Under the influence of local defects,the wall shear stress(WSS)and turbulent kinetic energy of local flow fields enhanced significantly,and pressure fluctuations in local flow field were induced.The results showed that the characteristics of surface corrosion products varied with flow velocity.The corrosion scales formed in various regions of specimens with defects exhibited different surface micro-morphologies and chemical compositions.Overall,these data offer new perspectives for better understanding the mechanisms behind local corrosion.
