Laercio Mantovani Frare

Influence of chemical composition on biochemical methane potential of fruit and vegetable waste

This study investigates the influence of chemical composition on the biochemical methane potential (BMP) of twelve different batches of fruit and vegetable waste (FVW) with different compositions collected over one year. BMP ranged from 288 to 516LNCH4kgVS-1, with significant statistical differences between means, which was explained by variations in the chemical composition over time. BMP was most strongly correlated to lipid content and high calorific values. Multiple linear regression was performed to develop statistical models to more rapidly predict methane potential. Models were analysed that considered chemical compounds and that considered only high calorific value as a single parameter. The best BMP prediction was obtained using the statistical model that included lipid, protein, cellulose, lignin, and high calorific value (HCV), with R2 of 92.5%; lignin was negatively correlated to methane production. Because HCV and lipids are strongly correlated, and because HCV can be determined more rapidly than overall chemical composition, HCV may be useful for predicting BMP.

Methane potential of fruit and vegetable waste: an evaluation of the semi-continuous anaerobic mono-digestion

ABSTRACT The anaerobic digestion (AD) of a high diversity blend of fruit and vegetable waste (FVW) generated in tropical conditions as a single substrate was performed. A continuously stirred tank reactor (CSTR) operated in semi-continuous regime was used for AD. The reactor performance was monitored with gradually increasing organic loading rates (OLRs) from 0.5 up to 5.0 gVS L–1 d–1. The biochemical methane potential (BMP) of FVW determined by batch bottles was 360 LN CH4 kgVS–1, with a biodegradability of 79%. A stable pH with an adequate level of buffering capacity was observed during the entire experiment. Methane yield indicated the best performance at an OLR of 3.0 gVS L–1 d–1, with 285 LN CH4 kgVS–1 added, reaching 79% of BMP. At an OLR over 3.0 gVS L–1 d–1 accumulation of volatile fatty acids (VFA) was detected; in particular, propionic acid was monitored, and a decreased methane yield was detected. Biogas production rate was 1.55 LN L–1 d–1 and showed linear increase according to increases in the OLR. GRAPHICAL ABSTRACT

Velocity Simulation of an Electrochemical Reactor for Textile Wastewater Treatment

A limitation for the use of electrocoagulation for wastewater treatment is its complexity, since the process is affected by many variables, including the hydrodynamics in the reactor. This paper aimed to present a simulation, through Computational Fluid Dynamics (CFD), of the flow and velocity field of a bench scale electrocoagulation reactor for textile wastewater treatment, with the goal of selecting the best design for the cell, which consists in a continuous, multiple parallel plate reactor. Six scenarios were proposed combining the different values for the two studied variables: electrode width (7 cm, 9 cm and 11 cm) and number of electrodes (5 pairs or 6 pairs). The CFD simulations were carried out within the software COMSOL Multyphysics, which solved the Navier-Stokes equations for the incompressible, laminar, steady-state conditions. The results showed that from the scenarios, the best for the desirable conditions within the reactor (good mixture, low velocity profile and few stagnant zones) were the configurations with 5 pairs of 7 cm wide and 6 pairs of 9 cm wide electrodes. A definitive design for the reactor will possibly be achieved in future studies which will include simulations for the concentration profile.