| The quantity of textile dyeing sludge increased very rapidly with the sustainable and fast development of textile printing and dyeing industry in China. Considering that the organic matters from sewage sludge can be conversed into valuable biochemicals such as volatile fatty acids(VFAs), anaerobic fermentation was used to textile dyeing sludge. The bioprocess strategy not only achieves the objective of controlling sludge pollution and reducing sludge volumes but also efficiently explores the resource of organic substance in sludge and reduces the toxicity. The research contents and results were shown as follows:(1) Effects of various pretreatment methods including thermo and thermo-alkaline on the solubilization of sludge and the biology toxicity were investigated.The results show that thermo can't affect acidogenesis. But heat can kill methanogens and maintain the stabilization of VFAs production. Thermo-alkaline treatment significantly increased the yields of TVFAs and acetic acid by 64% and 54%, respectively. The production rate and conversion rate were also improved. Compared with the acidogenesis from municipal sewage sludge, the anaerobic acidogenic fermentation by the textile dyeing sludge was proved feasible. The effect of biological toxicity was investigated and the results showed biological toxicity of sludge was reduced by the anaerobic fermentation. However, there is still toxic of the sludge after fermentation treatment. The effect of pretreatment on biological toxicity was not obvious.(2) In order to achieve a shorter fermentation cycles, reduce costs and increase cost-effectiveness, the effect of types of the seed sludge on the anaerobic fermentation was studied. The types of the seed sludge (sewage sludge, textile dyeing sludge and granular sludge) and the concentration of the sludge (2,6,10 gVS / L) were used to test the VFAs production. The results showed that the sludge from citric acid plant in Wuxi was the best seed sludge and the 6 gVS / L was the best concentration for the inoculation sludge.(3) In order to optimize the process parameters and improve VFA production, the effect of pH on the anaerobic acidogenic fermentation were explored. The results proved that at all pH conditions (5-10) , acetic acid was the dominant product. Alkaline conditions could enhance the acidification, and the highest concentration of TVFA, 8.21 g / L and acetic acid, 14.08 g / L can achieved, respectively.The yield of acetic acid and TVFA was 67.0% and 39.1%, respectively.The production rates were 2.41 g / L·d and 3.48 g / L·d , respectively. Compared to neutral pH condition, the yields of acetic acid and TVFA increased by 70% and 49%, and the production rate increased by 5.33 times and 5 times.(4) The effect of C/N (3.2, 20, 30, 40, 50, 60) on bio-production of organic acids was investigated. The starch was added to regulate the C/N rate and C/N can regulate the selective VFA production. C/N=30 was the optimum condition for the butyrate production. Under this condition, the highest concentration and the percentage of butyric acid was 25.33 g/L and 86.55%, and the highest concentration and yield of VFAs was 29.26g / L and 0.49g acid / gVS. The rate of production and conversion of butyric acid was a maximum value of 0.45g acid /gVS and 0.74 g acid / gVSdigest.Total production rate of TVFA and butyric acid was 2.25 g acid / L·d and 1.95 g acid / L·d.
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