The so-called “short-term flow” protocol is widely applied in experimental flow-induced crystallization studies on polymers in order to separate the nucleation and subsequent growth processes [Liedauer et al. Int. Polym. Proc. 1993, 8, 236–244]. The basis of this protocol is the assumption that structure development during flow can be minimized and the rheological behavior, i.e., the viscosity, does not change noticeably. In this work we explore the validity of this assumption for short but strong flows and reveal the structure formation during the early stages of crystallization. Viscosity and structure evolution of an isotactic polypropylene (iPP, M w ≈ 365 kg/mol and M w/M n = 5.4) melt at 145 °C are measured during the short-flow period (0.2–0.25 s) using the combination of a slit rheometer and fast X-ray scattering measurements. For high enough (apparent) shear rates (≥240 s–1) a viscosity rise during flow is observed; i.e., the condition for “short-term flow” is not satisfied. With a time delay with respect to the viscosity rise, the development of shish is observed at a position halfway the length of slit, along the flow direction, by means of ultrafast time-resolved SAXS measurements. Depending on the shear rate, these shish are detected during (shear rates ≥ 400 s–1) or after flow (240 s–1 ≤ shear rates < 400 s–1). For even lower shear rates of 160 and 80 s–1, the viscosity does not change significantly, and instead of shish, oriented row nuclei (X-ray undetectable) are generated. These two shear conditions qualify as short-term flow. A full understanding of the coupled flow and crystallization phenomena requires that the transient and nonhomogeneous behaviors, both in flow and in flow gradient direction, have to be taken into account. This can only be done by a full numerical model, and therefore, the results presented in this paper also provide a valuable data set for future numerical studies.

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This study demonstrates a comparison of energy usage, land footprint and volumetric requirements of municipal wastewater treatment with aerobic granular sludge (AGS) and conventional activated sludge (CAS) at a full‐scale wastewater treatment plant characterized by large fluctuations in nutrient loadings and temperature. The concentration of organic matter in the influent to the AGS was increased by means of hydrolysis and bypassing the pre‐settler. Both treatment lines produced effluent concentrations below 5 mg BOD7 L‐1, 10 mg TN L‐1, and 1 mg TP L‐1, by enhanced biological nitrogen‐ and phosphorus removal. In this case study, the averages of volumetric energy usage over one year were 0.22 ± 0.08 and 0.26 ± 0.07 kWh m‐3 for the AGS and CAS, respectively. A larger difference was observed for the energy usage per reduced P.E., which was on average 0.19 ± 0.08 kWh P.E.‐1 for the AGS and 0.30 ± 0.08 kWh P.E.‐1 for the CAS. However, both processes had the potential for decreased energy usage. Over one year, both processes showed similar fluctuations in energy usage, related to variations in loading, temperature, and DO. The AGS had a lower specific area, 0.3 m2 m‐3 d‐1, compared to 0.6 m2 m‐3 d‐1 of the CAS, and also a lower specific volume, 1.3 m3 m‐3 d‐1 compared to 2.0 m3 m‐3 d‐1. This study confirms that AGS at full‐scale can be compact and still have comparable energy usage as CAS.