Papers by Author: Yu Fang Yu

Abstract: This study aims to find out the optimum extraction time varied from 5 min to 60 min for extracellular polymeric substances (EPS) from sewage sludge pretreated at 80 °C. The change of the contents of EPS and its components under different time limit were recorded and compared. The results showed: the contents of soluble protein, TOC, soluble sugar and DNA was increased by 579.17 mg/l, 514.25 mg/l, 132.79 mg/l, and 34.69 mg/l, respectively, with the increase of thermal pre-treatment time during the process, and the DNA content increased the least, which indicating that the effect of thermal pre-treatment at 80 °C on cell lysis of sewage sludge was small. The EPS content, as a whole, was increased with the increase of thermal pre-treatment time. By analyzing the experimental data with the Analytic Hierarchy Process Model, which was used to identify the optimum thermal pre-treatment time of extracting EPS, the results showed that the effectiveness of EPS extraction from sludges was 30 min>60 min>50 min>20 min>40 min>10 min>5 min. Therefore, the 30 min was choosed as the optimum thermal pre-treatment time.

Abstract: Great attention has been paid to the increasing amount of municipal sludge generated from wastewater treatment plants due to its potential risks to the surrounding environment. The municipal sludge, which mainly composed of polysaccharides, proteins as well as abundant groups of microorganisms, has been proved to be a promising biological material for hydrogen production by anaerobic fermentation. The tests systematically investigated the effects of initial pH on bio-hydrogen production from alkaline pretreated municipal sludge. The results showed that both hydrogenogen and methanogen were inhibited at the initial pH 2 to 4, which resulted in little hydrogen production. The methanogen inhibition was obvious by the rate of 94-98 % at the initial pH 5. The relatively high hydrogen production appeared at the initial pH 5 during the fermentation using the alkaline pretreated sludge at pH=12.0, and the corresponding pH at the end of fermentation was from 5.0 to 6.0, which was good for hydrogen production from saccharide. The hydrogenogen and methanogen could be promoted and the lag phase for hydrogen production could be shorten at the initial pH 6 to 10, however the corresponding hydrogen production was quite low. It also could be concluded that the alkaline pretreated sludge with initial pH 12.0 gave the highest hydrogen production, and the initial pH 12.0 for the alkaline pretreated sludge could inhibit methanogen growth and meanwhile maintain a high activity of the hydrogenogen.

Abstract: This paper investigated the influence of the inoculation volume of dewatering sludge on thermophilic anaerobic digestion in residue of fermentative hydrogen production using combined sludge and food waste in batch experimental systems. The inoculum to residue ratios were 10%, 30%, 50%, 70%, 90%, respectively. The results showed that the biogas production increased with the inoculation volume except for 90%,and the optimum inoculation volume was 70%.