Preparation of high acidity coefficient slag wool fiber with blast furnace slag and modifying agents

Preparation of high acidity coefficient slag wool fiber with molten slag and modifying agents is considered to be a positive approach for value-added utilization of blast furnace slag. In order to achieve the multi-purposes of fiber-forming, energy saving, and waste heat recovery, the modifying agents that can improve the acidity coefficient of slag effectively, economically, and environmentally were investigated. Three agents with different acidity coefficients were adopted to modify slag and manufacture wool fibers. The effect of agent and slag proportion on the melting temperature and viscosity of molten slag was studied at a fixed acidity coefficient of 1.8 and 2.0. The results indicate that the sample modified with high acidity coefficient agent and high slag proportion has lower melting temperature and viscosity. The effect of agent and slag temperature on the fiber diameter was also investigated when the acidity coefficient of slag is 2.0. At a fixed slag proportion of 50 wt.%, the mean diameter decreases with increasing temperature and decreasing viscosity coefficient. Besides, the temperature drops caused by the addition of agents and energy consumption of samples for heating the slag were also analyzed.

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.