The residence time distributions (RTDs) of continuous solution copolymerization tank reactors connected in series are evaluated experimentally to analyze features related to the fluid dynamics of this class of reactors. For this purpose, tracer step experiments are carried out in lab‐scale polymerization tank reactors to provide experimental data for analysis of the quality of mixing and evaluate associated macromixing effects. Besides, mathematical models are developed to describe the RTD data obtained experimentally. Based on a compartmental approach, perfect mixing tanks, tanks with stagnant zones, tanks with crossflow, and tanks in series with backflow models were proposed. Particularly, the analysis of the available experimental data and of mathematical models indicate that the flow features of these systems are strongly associated with the established degree of mixing, presenting significant non‐ideal flow behavior, usually neglected in most modeling and experimental studies.

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The on-line monitoring of the droplet/particle size distributions is very important to ensure the quality and applicability of various products in heterogeneous systems. For this reason, the main objective of the present work was to study the usage of the focused beam reflectance measurement (FBRM) technique for monitoring of liquid-liquid dispersions (styrene dispersion in aqueous solutions) and suspension polymerization of styrene. To do better understand the FBRM technique in these systems, the effects of surfactant concentrations, agitation speed and ambient light were evaluated during the in-line monitoring of average chord lengths and chord-length distributions (CLD) at different operation conditions in batch experiments. In addition, a preliminary investigation of the optimal probe position was conducted in the polymerization experiments. It is shown that the FBRM technique is sensitive to variations of particle sizes in the characteristic ranges of particle diameters of typical styrene suspension polymerizations, being useful for monitoring and also control applications that require the on-line characterization of CLD in real time in liquid-liquid dispersions and polymerization systems. POLYM. ENG. SCI., 56:309-318, 2016.

Summary This work studies the use of Focused Beam Reflectance Measurements (FBRM) for monitoring of size distributions in liquid‐liquid (styrene‐water) dispersions and styrene suspension polymerizations performed in stirred tanks. The effects of the suspending agent concentration, stirring rate and presence of external light sources on the FBRM performance were evaluated during the in‐line monitoring of average size chords and chord length distribution (CLD). It can be stated that FBRM is sensitive to variations of particle sizes and, therefore, that FBRM is suitable for evaluation of CLDs in real time in suspension polymerization systems.

Sewage-water treatment comprehends primary, secondary, and tertiary steps to produce reusable water after removing sewage contaminants. However, a sewage-water treatment plant is typically a power and energy consumer and produces high volumes of sewage sludge mainly generated in the primary and secondary steps. The use of more efficient anaerobic digestion of sewage water with sewage sludge can produce reasonable flowrates of biogas, which is shown to be a consolidated strategy towards the energy self-sufficiency and economic feasibility of sewage-water treatment plants. Anaerobic digestion can also reduce the carbon footprint of energy sources since the biogas produced can replace fossil fuels for electricity generation. In summary, since the socio-economic importance of sewage treatment is high, this review examined works that contemplate: (i) improvements of sewage-water treatment plant bioenergy production and economic performances; (ii) the exploitation of technology alternatives for the energy self-sufficiency of sewage-water treatment plants; (iii) the implementation of new techniques for sewage-sludge management aiming at bioenergy production; and (iv) the implementation of sewage-water treatment with bioenergy production and carbon capture and storage.