Effects of alkali, autoclaving, and Fe+ autoclaving pretreatment on anaerobic digestion performance of coking sludge from the perspective of sludge extracts and methane production

Visible light assisted FeOOH/CeO2/C deep degradation of organic matter in coking wastewater

In order to degrade hard-to-degrade organic pollutants such as amines, phenols, naphthalenes, pyrroles and pyridazines in coking wastewater, the nano-FeOOH/CeO₂/C composite catalysts (FCHCoke) were prepared. Firstly the catalysts were characterized by XRD, TEM, BET, BJH and UV/Vis/NIR. Then UV-Vis and GC-MS were used to detect the products in the degradation process of organic pollutants, respectively. The results showed that the average pore size of FCHCoke was 2-6 nm and the carrier coke enhanced the ability of the catalyst to absorbs visible light. Each intermittent light exposure for 2 h showed a better photodegradation. Under the intermittent irradiation of visible light of for a total of 8 h, 100µg۰mL^-1aniline and phenol were completely degraded. Dihydronaphthalene, esters, pyrrole, pyridazine, oxime and macromolecular alkanes in coking wastewater were also completely degraded. The acidity of pH=6 is more suitable for the photodegradation reaction of the catalyst. Organic degradation is the result of a combination of chemical catalysis and photocatalysis.

A shift from anaerobic digestion to dark fermentation in glycol ethylene fermentation

Anaerobic digestion of aqueous glycol ethylene was tested. The process lasted two cycles of 7 days, but after the second cycle, high hydrogen production occurred shift to dark fermentation. The biogas production lasted 14 days, obtaining peak values of hydrogen, and then rapidly stopped. In investigations, the following were checked: dependence of hydrogen, methane and hydrogen sulphide in the process. Mixtures of water with glycol ethylene mass ratio from 0.6 to 0.85 were substrates in experiments. The highest methane production was for water ethylene 0.7 ratio 2.85 L of methane with a yield of 178 mL of methane/g VSS (volatile suspended solids) of glycol ethylene. The optimal ratio of water and glycol ethylene was 0.85 25.5 mL of hydrogen (giving yield 1.71 mL of hydrogen/g VSS of glycol ethylene) and 1.71 mL of hydrogen sulphide emission for a 0.6 ratio. Popular polymer industry wastes, glycol ethylene, can be utilised by anaerobic digestion.