The effect of salinity on waste activated sludge alkaline fermentation and kinetic analysis

The effect of salinity on sludge alkaline fermentation at low temperature（20°C） was investigated, and a kinetic analysis was performed. Different doses of sodium chloride（Na Cl, 0–25 g/L） were added into the fermentation system. The batch-mode results showed that the soluble chemical oxygen demand（SCOD） increased with salinity. The hydrolysate（soluble protein, polysaccharide） and the acidification products（short chain fatty acids（SCFAs）, NH＋4–N, and PO_4^（3-）–P） increased with salinity initially, but slightly declined respectively at higher level salinity（20 g/L or 20–25 g/L）. However, the hydrolytic acidification performance increased in the presence of salt compared to that without salt.Furthermore, the results of Haldane inhibition kinetics analysis showed that the salt enhanced the hydrolysis rate of particulate organic matter from sludge particulate and the specific utilization of hydrolysate, and decreased the specific utilization of SCFAs. Pearson correlation coefficient analysis indicated that the importance of polysaccharide on the accumulation of SCFAs was reduced with salt addition, but the importance of protein and NH＋4–N on SCFA accumulation was increased.

Effect of the addition of organic carbon sources on nitrous oxide emission in anaerobic-aerobic(low dissolved oxygen)sequencing batch reactors

The effect of additional organic carbon sources on the production of nitrous oxide(N_(2)O)in anaerobicaerobic(low dissolved oxygen)real wastewater treatment system was investigated.In this paper,three laboratoryscale sequencing batch reactors(SBRs)(SBR-1,SBR-2 and SBR-3)were operating under an anaerobic-aerobic(low dissolved oxygen,0.15-0.45 mg·L^(-1))configuration.The SBRs were‘long-term cultured’respectively with a single municipal wastewater sample,sodium acetate,and a waste-activated sludge alkaline fermentation liquid as the additional carbon sources of real wastewater.Off-gas analysis showed that N_(2)O was emitted into the atmosphere during the aerobic(low dissolved oxygen)period in the three SBRs,and the order of N_(2)O emission rate was SBR-2>SBR-1>SBR-3.It was observed that the higher poly-β-hydroxyvalerate fraction of polyhydroxyalkanoates,the lower glycogen transformation and less nitrite accumulation was in SBR-3,while the opposite behavior was observed in SBR-2.Further research indicated that the interaction of the factors above potentially affected the N_(2)O emission in the anaerobic-aerobic(low dissolved oxygen)system.

Delignification of disposable wooden chopsticks waste for fermentative hydrogen production by an enriched culture from a hot spring

Hydrogen （H2） production from lignocellulosic materials may be enhanced by removing lignin and increasing the porosity of the material prior to enzymatic hydrolysis. Alkaline pretreatment conditions, used to delignify disposable wooden chopsticks （DWC） waste, were investigated. The effects of NaOH concentration, temperature and retention time were examined and it was found that retention time had no effect on lignin removal or carbohydrate released in enzymatic hydrolysate. The highest percentage of lignin removal （41%） was obtained with 2% NaOH at 100℃, correlated with the highest carbohydrate released （67 mg/gpretreated DWC） in the hydrolysate. An enriched culture from a hot spring was used as inoculum for fermentative H2 production, and its optimum initial pH and temperature were determined to be 7.0 and 50℃, respectively. Furthermore, enzymatic hydrolysate from pretreated DWC was successfully demonstrated as a substrate for fermentative H2 production by the enriched culture. The maximum H2 yield and production rate were achieved at 195 mL H2/g total sugarsconsumed and 1 16 mL Hz/（L.day）, respectively.