零价铁和微波预处理组合强化污泥厌氧消化

Enhancement for Anaerobic Digestion of Waste Activated Sludge Based on Microwave Pretreatment Combined with Zero Valent Iron

以中温(100℃)常压的微波预处理结合零价铁投加为对象,考察了低投加量5. 19～41. 51 g·kg^(-1)(以TS计)、高投加量83. 35～853. 46 g·kg^(-1)(以TS计)下的零价铁对微波预处理污泥厌氧消化的进一步强化作用.结果表明,微波预处理与零价铁组合可使污泥厌氧消化产甲烷潜势提升17%～23%.零价铁对微波预处理后污泥厌氧消化具有一定的促进作用,且提升了厌氧消化初期(1～4 d)产甲烷速率,零价铁投加量为31. 13 g·kg^(-1)(以TS计)时,产甲烷潜势提升了7. 42%,反应第2 d的产甲烷速率提高了11. 02%.高投加量的零价铁并未表现出更好的强化效果.零价铁促进了厌氧消化初期溶解性有机物的释放,投加量为31. 13 g·kg^(-1)(以TS计)时,溶解性蛋白质较单独预处理组提高21. 16%,并且零价铁投加加快了乙酸、异丁酸、异戊酸的消耗.零价铁的投加,导致上清液中的磷酸根和硫酸根浓度降低,相应地,上清液中铁元素的浓度反而下降,说明零价铁的形态转化后,易与磷酸盐、硫反应形成沉淀,这可能是铁投加作用效果不明显的重要原因.

In this study,we investigated the enhanced performance after addition of zero valent iron(ZVI)under different dosages(low range of 5.19-41.51 g·kg-1 TS and high range of 83.35-853.46 g·kg-1 TS),combined with microwave(MW)pretreatment for anaerobic digestion(AD)of waste activated sludge(WAS).The results demonstrated that the methane production potential of WAS could be increased by 17%-24%with the addition of ZVI combined with MW pretreatment,and especially the methane production rate was enhanced in the initial days(1-4 d).ZVI addition could further improve the enhanced performance of AD under MW pretreatment.Compared with the performance of AD with only MW pretreatment,the methane production potential was increased by 7.42%,and methane production flow rate at 2 d was increased by 11.02%with 31.13 g·kg-1 TS of ZVI addition.However,the higher dosage of added ZVI did not show further enhanced performance.It was concluded that ZVI addition promoted the release of dissolved organics at the initial stage of AD.For instance,soluble proteins were increased by 21.16%with the ZVI addition of 31.13 g·kg-1 TS compared with pretreated WAS without ZVI addition.Furthermore,ZVI addition accelerated the degradation of acetic acid,iso-butyric acid,and iso-valeric acid,and led to a significant reduction of orthophosphate and sulfate in the supernatant of the digested sludge.The concentration of iron in the supernatant decreased even with a high dosage of ZVI.Thus,the formation of precipitate that occurred due to reactions between iron and orthophosphate or sulfate,may be the main reason for the lack of enhanced performance even with high dosage of ZVI addition.