Effect Of Waste Activated Sludge Pretreated By Combination Of Potassium Ferrate And Microwave On Anaerobic Digestion

The waste activated sludge?WAS?from the municipal sewage plant is a solid organic waste which is urgently needs to be effectively disposed in our country.Anaerobic digestion is considered as an effective way of resource stabilization treatment.However,the low efficiency of anaerobic digestion restrains the wide application of anaerobic digestion technology.The oxidation-reduction potential of K₂FeO₄ under neutral or alkaline conditions is 0.72V,which has strong oxidation ability.The pretreatment of sludge with potassium ferrate can promote the anaerobically digestion of methanogenic acid.Microwave has both thermal and non-thermal effects and it is a short-term and efficient pretreatment technique.In addition,pretreatment combined with two different mechanisms can enhance the effect of single pretreatment,while K₂FeO₄ combined with microwave pretreatment for anaerobic digestion of methane production has not yet been in-depth study.So,in this study,WAS was taken as the research object,the effect of potassium ferrate pretreatment sludge and its effect on anaerobic digestion and the effect of combined with microwave pretreatment of sludge and its effect on anaerobic digestion were studied.?1?With the increase of K₂FeO₄ dosage,the better the pretreatment effect is.When the dosage of 7.5g/L was added,the breaking rate of sludge could reach 39.73%,and the suitable treatment time was 210 minutes.The effect of K₂FeO₄ combined with microwave pretreatment was better with the increase of potassium ferrate dosage,and it was better than that of pretreatment alone.The optimum treatment condition was that K₂FeO₄ added as 7.5 g/L combined with microwave irradiation for 2 min in 700 W.The maximum disintegration degree of combined pretreatment was 60.88%.It was 1.33 times higher than that of microwave pretreatment alone and 2.66 times higher than that of K₂FeO₄pretreatment alone.?2?The methane production of anaerobic fermentation was increased by different dosages of K₂FeO₄ pretreated.The optimal methanogenic condition was adding 5g/L K₂FeO₄.was increased by 22.7%compared with blank,and the production of methane was promoted mainly by increasing methane content.?3?The K₂FeO₄ combined with microwave pretreatment did not necessarily promote methane production in anaerobic fermentation.The optimal methanogenesis condition was adding 3g/L K₂FeO₄ combined with microwave 2 min pretreatment.The production of methane increased 68.31%compared with blank,48.08%higher than K₂FeO₄ alone,16.86%higher than microwave pretreatment.The results of microbial analysis showed that the increase of methane may be due to the mutual oxidation of iron-reducing bacteria and methanogenic bacteria.