The effects of feed solution temperature on pore size and trace organic The effects of feed solution temperature on pore size and trace organic contaminant rejection by the nanofiltration membrane NF270 contaminant rejection by the nanofiltration membrane NF270
A B S T R A C TThis study aimed to elucidate key factors governing the rejection of trace organic contaminants (TrOCs) by nanofiltration (NF) and reverse osmosis (RO) membranes. The rejection of 16 selected hydrophilic and hydrophobic TrOCs by an NF and an RO membranes was evaluated at different solution pH values using a cross-flow NF/RO filtration system. An analytical technique consisting of solid phase extraction followed by gas chromatography and mass spectrometry detection was used for the analysis of the TrOCs. In general, rejection increased in the order of decreasing membrane permeability, increasing molecular weight (or equivalent molecular width) of the TrOCs, and increasing hydrophilicity. Adsorption of hydrophobic TrOCs to the membrane could be observed based on a mass balance calculation. However, the correlation between adsorption and log D value (the logarithm of the octanol-water distribution coefficient) of the TrOCs (which indicates their hydrophobicity) observed in this study was rather weak. This is due to the adsorption being not only dependent on hydrophobicity, but also on other physicochemical aspects of TrOCs and the membrane material, such as molecular size, charge of the compounds, pore size, charge, and surface roughness properties of the membranes. Therefore, the results suggest that these factors may also govern the adsorption (and subsequently rejection) of TrOCs to NF/RO membranes.
This study investigated the effect of microbial inoculant (Emuniv) on composting of biodegradable domestic solid wastes for over 30 days. Three different types of treatments were used for the composting of source separated domestic solid waste. The results showed that the use of microbial inoculant in the composting of domestic solid wastes enhanced the biodegradation of composted organic material, which is evident from the considerable changes in temperature, moisture content and volume reduction with time. The compost treatments with Emuniv inoculant recorded higher temperature for the duration of composting phases, compared to treatment without Emuniv inoculant. Whereas, the moisture content and volume reduction of all treatments was showed a decreasing trend during the composting process. The larger reduction was seen in the treatments with Emuniv inoculant. Additionally, according to the results of analysis of variance (ANOVA), there was a statistically significant difference in temperature, moisture content and volume reduction between treatments. Moreover, the utilisation of microbial inoculant in composting was also can improve the quality of final compost product as reflected by the total nitrogen and available phosphorus contents in the compost product were higher than in the control.
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