| The excess sludge contains a large amount of organic matter and pathogenic bacteria,which will pose a huge threat to the environment and human health if improperly disposed.The production of short-chain fatty acids(SCFAs)from anaerobic fermentation sludge is one of the important ways of sludge resource treatment,not only achieve sludge stabilization and reduction,but also generate a large amount of organic matters.In this study,the use of potassium ferrate to couple modified steel slag was used to investigate its effect on the performance of sludge fermentation and acid production.To reveal the mechanism of slowrelease potassium ferrate to promote the production of SCFAs from sludge fermentation.The main research results are as follows:(1)Through scanning electron microscopy,X-ray photoelectron spectroscopy and X-ray diffraction analysis,it was confirmed that potassium ferrate was loaded on the surface of the modified steel slag to form a supported potassium ferrate.Subsequently,through batch experiments of sludge fermentation,it was found that both potassium ferrate and loaded potassium ferrate could significantly promote the production of short chain fatty acids(SCFAs)in fermentation sludge.However,the addition of 0.1 g/g TSS loaded with potassium ferrate had the best effect,and its cumulative acid production was up to 3160.8 ± 8.9 mg/L,which was 5.1 times that of the blank group.At the same time,the loading of potassium ferrate changed the short-chain fatty acid composition of the sludge,and the proportion of acetic acid was increased from 47 ± 1.8% in the blank reactor to 69 ± 2.6%.Compared with the blank reactor,the maximum acetic acid production increased by 1507.9 ± 45.2 mg /L.The results showed that the loaded potassium ferrate significantly improved the acid production performance of fermentation sludge.(2)The research mechanism shows that the loaded potassium ferrate promotes the lysis of sludge cells and the release of organic matter.After pretreatment with 0.1 g/g TSS loaded with potassium ferrate for 3 d,the concentrations of COD,protein and polysaccharide in the sludge fermentation broth were 1843.5 ± 55.3 mg,respectively,199.6 ± 6 mg/L,and 39.6 ±1.2 mg/L,which were 5.4,3.8,and 2.1 times that of the blank reactor,and the release of lytic cell by-products and tyrosine-like substances was enhanced,which provided better production of SCFAs.Multiple available substrates.Through the simulated water distribution experiment,it was found that the acetic acid degradation rate of the fermentation sludge during the methanation process was reduced from 25.2 ± 0.8% to 17.5 ± 0.67% in the blank group,and the methane production decreased.Although potassium ferrate loading did not affect the hydrolysis and acidification process of sludge fermentation,it inhibited the methanation of sludge,resulting in the accumulation of SCFAs.(3)In the study of the microbial community in the sludge fermentation system,it was found that Firmicutes,Proteobacteria,Bacteroidetes,Chloroflexi and Actinomycetes accounted for about 80% of the microbial community.After pretreatment with slow-release potassium ferrate,the relative abundances of Bacteroides and Petrimonas in the sludge system,which are beneficial to the dissolution of organic matter,were increased by 47.8%and 9.87% compared with the blank reactor.At the same time,the abundance of main acidproducing bacteria represented by Firmicutes and Clostridia also increased by 45.89% and45.47%.Meanwhile,Anaerolineae and Gammaproteobacteria,the main consumers of SCFAs during sludge fermentation,were inhibited under potassium ferrate loading pretreatment,and their relative abundances were only 2.13% and 6.43%,which were 7.44% and 14.22% lower than those in the blank reactor,respectively. |
PDF Full Text Request