Liquid state bioconversion continuous bioreactor of sewage sludge treatment: Determination and evaluation of mixed fungi growth kinetics

Liquid state bioconversion (LSB), a bioremediation and biodewatering process was applied for sewage sludge treatment in this study. The LSB process is a non-hazardous, safer and environmentally friendlier method for ultimate sludge management and disposal compared to the other available technologies. The system presented in this study was developed by using mixed fungi of Aspergillus niger and Penicillium corylophilum to treat sewage sludge in a LSB bioreactor. This research was conducted in order to study the LSB process on continuous system in terms of kinetic coefficients determination. For the continuous LSB process, a mathematical model was developed from the basic principles of material balance based on Monod equation. By investigating the kinetics of substrate utilisation and biomass growth, the kinetic coefficients of growth yield coefficient (Y), specific microorganism decay rate (Kd), half saturation constant (Ks) and maximum specific growth rate (μmax) were found to be 0.79 g VSS g COD−1, 0.012 day−1, 1.78 g COD L−1 and 0.357 day−1, respectively

Stability enhancement of MWCNT/water nanofluids using PVA surfactant

Nanofluids are prepared by dispersing MWCNT into aqueous polyvinyl alcohol (PVA) suspensions used as base fluids. This paper investigates the effectiveness of PVA as surfactant in stabilising MWCNT/water nanofluids. The stability of nanofluids is measured by Zetasizer Nano-ZS of only the stable samples. The morphology of carbon nanotube (CNT) and its interaction with PVA dispersant was analysed using SEM and in order to observe the dispersion characteristics of all samples, image analysis was carried out using TEM. The results demonstrated that zeta potential is affected by the concentration of CNT (0.01-0.1 wt.%). The zeta potential values (-19.96 mV to -33.3 mV) increased with an increase in CNT concentration. The SEM and TEM results showed that the amount of PVA added to each CNT concentration is sufficient to provide maximum stability to the CNT-water nanofluids, no excessive agglomerations or significant clusters of PVA are observed from the surface of CNT