Development of the short Creative Expression Interest Scale based on item response theory.

This study develops a short Creative Expression Interest Scale (CEIS) among Chinese freshmen based on the perspective of item response theory (IRT). Nine hundred fifty-nine valid Chinese freshmen participated in the Creative Expression Interest survey. Researchers applied the initial data for unidimensionality, item fit, discrimination parameter, and differential item functioning to obtain a short CEIS. The results show that the Short CEIS meets the psychometric requirements of the IRT. Pearson correlation coefficient of theta between the short and long CEIS is 0.922. The marginal reliability of the short CEIS is 0.799. These indicate that the short CEIS developed in this study among Chinese freshmen, meets the psychometric requirements. Although the Short CEIS can eliminate redundant, uninformative items, save time, and improve the quality of data collection. However, the validity of this short scale needs further validation.

[Start-up of a thermophilic anaerobic sludge digester].

Anaerobic digestion is one of the most widely-used technologies of the sludge reduction and stabilization, in which thermophilic digestion has advantage of fast stabilization. But it is lack of operation experience in China. Thus start-up of a thermophilic anaerobic sludge digester treating excess activated sludge was investigated. The digester was an internal circulation anaerobic sludge digester. It belongs to upflow reactor and its hydrodynamic conditions can be controlled by backflow biogas. A multistep strategy was applied to the start-up to enhance anaerobic bacteria to adapt the changes of temperature, reactor and treated sludge, including: to feed the digester with easily-degraded glucose to enhance bacteria reproduce at the first beginning with COD organic loading of 2.4 kg/(m3 x d); to accelerate the internal circulation; to control pH within a optimal range; to gradually increase excess sludge flow rate as well as to initiate pydrohydrolysis to enhance hydrolysis. The start-up took 63 days and when it finished, the VSS organic loading reached 1.60 kg/(m3 x d), the average VSS biogas rate was 0.51 L/g, i. e. 15.3 m3/m3 sludge (96% water content), VSS and SS removals were 60.8% and 45.8%. This shows that the strategy is valid.