Modelling of tribo-electrostatic separation for industrial by-products recycling

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Computational modeling of UV-initiated advanced oxidation processes in a cross-flow photoreactor

A computational fluid dynamics (CFD) modeling study of different advanced oxidation processes (AOPs) in a UV photoreactor with a cross-flow lamp arrangement is presented in this paper. In particular, the verification and validation of three different AOP-CFD models: UV185, UV254+H2O2, and UV185+UV254+H2O2, developed in a Eulerian framework, is introduced and discussed. The AOP model was developed by coupling a comprehensive kinetic model with advanced optical models and detailed hydraulics. Oxalic acid (OXA) was chosen as model pollutant for the assessment of the AOP performance. Results revealed that the efficacy of the UV185/UV254/H2O2 process, at laminar flowrates, is superior to the other treatment processes in terms of oxalic acid degradation

Nondeterministic computational fluid dynamics modeling of Escherichia coli nactivation by peracetic acid in municipal wastewater contact tanks

Wastewater disinfection processes are typically designed according to heuristics derived from batch experiments in which the interaction among wastewater quality, reactor hydraulics, and inactivation kinetics is often neglected. In this paper, a computational fluid dynamics (CFD) study was conducted in a nondeterministic (ND) modeling framework to predict the Escherichia coli inactivation by peracetic acid (PAA) in municipal contact tanks fed by secondary settled wastewater effluent. The extent and variability associated with the observed inactivation kinetics were both satisfactorily predicted by the stochastic inactivation model at a 95% confidence level. Moreover, it was found that (a) the process variability induced by reactor hydraulics is negligible when compared to the one caused by inactivation kinetics, (b) the PAA dose required for meeting regulations is dictated equally by the fixed limit of the microbial concentration as well as its probability of occurrence, and (c) neglecting the probability of occurrence during process sizing could lead to an underestimation of the PAA dose required by as much as 100%. Finally, the ND-CFD model was used to generate sizing information in the form of probabilistic disinfection curves relating E. coli inactivation and probability of occurrence with the average PAA dose and PAA residual concentration at the outlet of the contact tank

Polarimetry for measuring the vacuum magnetic birefringence with quasi-static fields: a systematics study for the VMB@CERN experiment

We present an experimental systematics study of a polarimetric method for measuring the vacuum magnetic birefringence based on a pair of rotating half-wave plates. The presence of a systematic effect at the same frequency as the sought for magneto-optical effect inhibits the use of strictly constant magnetic fields. We characterise this systematic, discuss its origin and propose a viable workaround

Undestending and optimizing peracetic acid disinfection processes using computational fluid dynamics: the case study of Nocera (Italy) wastewater treatment plant

In this paper, a modeling study focused on optimizing the PAA disinfection performance in a full-scale contact tank currently operated at the Nocera (Italy) Wastewater Treatment Plant is presented. The disinfection process was monitored for over 2 weeks by collecting full-scale data on plant variability in flow, disinfectant demand/decay and microbial concentrations. A computational fluid dynamics (CFD) model of the contact tank describing the PAA disinfection process was developed. Four disinfection scenarios were analysed using an Eulerian-Lagrangian approach: (a) PAA disinfection under the existing conditions; (b) PAA disinfection with PAA pre-mixed prior to the contact tank; (c) PAA disinfection with PAA dosed with 8 injection points distributed over the entire length of the inlet weir; (d) PAA disinfection in an optimized plug-flow contact tank. All these scenarios were analysed for the same operating conditions, i.e. fixed flow, PAA demand/decay and inactivation kinetics. The model-based analysis clearly revealed that the optimized contact tank (scenario d) was able to achieve a much higher contact and extended between microorganisms and disinfectant thus resulting into a five-fold increase in microbial inactivation