In any copper smelter large quantities of copper slag are discarded as waste material causing space and environmental problems. This discarded slag contains important amounts of metallic values such as copper and iron. The recovery of copper values from an Indian smelter slag that contains 1.53% Cu, 39.8% Fe and 34.65% SiO ₂ was the focus of the present study. A complete investigation of the different phases present in the slag has been carried out by means of optical microscopy, Raman spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques. It is observed that iron and silica are mostly associated with the fayalite phase whereas copper is present in both oxide and sulfide phases. These oxide and sulfide phases of copper are mostly present within the slag phase and to some extent the slag is also embedded inside the oxide and sulfide phases. The recovery of copper values from the discarded slag has been explored by applying a flotation technique using conventional sodium isopropyl xanthate (SIX) as the collector. The effects of flotation parameters such as pH and collector concentration are investigated. Under optimum flotation conditions, it is possible to achieve 21% Cu with more than 80% recovery.

Stillage re-use in the fermentation stage in ethanol production is a technique used for the reduction of water and fermentation nutrients consumption. However, the inhibitory effect on yeast growth of the by-products and feed components that remains in stillage increases with re-use and reduces the number of possible recycles. Several methods such as ultrafiltration, electrodialysis and advanced oxidation processes have been used in stillage treatment prior its re-use in the fermentation stage. Nevertheless, few studies evaluating the effect of solvent extraction as a stillage treatment option have been performed. In this work, the inhibitory effect of serial stillage recycling over ethanol and biomass production was determined, using acetic acid as a monitoring compound during the fermentation and solvent extraction process. Raw palm oil methyl ester showed the highest acetic acid extraction from the aqueous phase, presenting a distribution coefficient of 3.10 for a 1:1 aqueous phase mixture:solvent ratio. Re-using stillage without treatment allowed up to three recycles with an ethanol production of 53.7 ± 2.0 g L^—1, which was reduced 25% in the fifth recycle. Alternatively, treated stillage allowed up to five recycles with an ethanol final concentration of 54.7 1.3 g L^{— 1}. These results show that reduction of acetic acid concentration by an extraction process with raw palm oil methyl ester before re-using stillage improves the number of recycles without a major effect on ethanol production. The proposed process generates a palm oil methyl ester that contains organic acids, among other by-products, that could be used for product recovery and as an alternative fuel.

Solid waste is considered an urgent environmental health issue in the Palestinian Territory. The aim of this paper was to analyse the current status of residential solid waste (RSW) management in the Palestinian Territory, with the objective of identifying windows for improvement. The study is based on a national household sample survey in the Palestinian Territory, which was conducted by the Palestinian Central Bureau of Statistics (PCBS). The results of this study revealed various interesting trends. For example, while about 90% of households in the Palestinian Territory receive solid waste collection service, about 50% of the households receive this service three times per week or less, leaving a chance for waste pile-up and litter generation. Organic waste (including food waste) was found to account for more than 90% of RSW, providing an opportunity for waste utilization through composting or biogas generation. Additional efforts are required, and some were suggested in this paper, in order to improve the current situation of Palestinian residential solid waste management.