The economics membrane distillation (MD) and common seawater desalination methods including multi effect distillation (MED), multistage flash (MSF) and reverse osmosis (RO) are compared. MD also has the opportunity to enhance RO recovery, demonstrated experimentally on RO concentrate from groundwater. MD concentrated RO brine to 361,000 mg/L total dissolved solids, an order of magnitude more saline than typical seawater, validating this potential. On a reference 30,000 m 3 /day plant, MD has similar economics with other thermal desalination techniques, but RO is more cost effective. With the inclusion of a carbon tax of $23 per tonne carbon in Australia, RO remained the economically favourable process. However, when heat comes at a cost equivalent of 10% of the value of the steam needed for MD and MED, under a carbon tax regime, the cost of MD reduces to $0.66/m 3 which is cheaper than RO and MED. The favour to MD was due to lower material cost. On low thermally, high electrically efficient installations MD can desalinate water from low temperature (<50°C) heat sources at a cost of $0.57/m 3 . Our assessment has found that generally, MD opportunities occur when heat is available at low cost, while extended recovery of RO brine is also viable.

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The optimal use of tris-2-ethylhexylamine to recover hydrochloric acid and metals from leach solutions and comparison with other extractants'The optimal use of tris-2-ethylhexylamine to recover hydrochloric acid and metals from leach solutions and comparison with other extractants, Journal of Environmental Chemical Engineering https://doi. Highlight More than 96% HCl may be extracted by single stage extraction with dilute TEHA.  Mn, Li, Fe, and HCl can be separated at optimal conditions of extraction, stripping and scrubbing  Recovery of HCl will solve disposal problem of HCl bearing effluents. AbstractThis paper describes the use of TEHA for HCl recovery from a leach solution generated by a hydrometallurgical plant. Four organic extractants were tested including TEHA, Alamine 336, Cyanex 923 and TBP. TEHA organic system performed best in terms of acid extraction, stripping and scrubbing efficiency. The successive extraction shows that more than 99 % HCl was extracted after three stages of extraction. Scrubbing tests with different A/O ratios at different temperatures were conducted to identify the optimal conditions to separate HCl, Mn and Fe. After scrubbing the loaded organic solution at an A/O ratio of 1:4 and 22°C, 94-100% of entrained metals were removed in a single contact with only 5.2% acid lost in the loaded scrub liquor. It was found that the phase disengagement time was in the range of 2-4 min for both extraction and stripping, indicating reasonable fast phase separation. Based on these results from batch tests, it can be expected that after optimisation in a counter current circuit consisting of extraction, scrubbing, selective and bulk stripping, nearly all metals and HCl would be recovered and recycled.

Biofuel is a sustainable alternative to conventional marine fuels; the key issues in promoting the use of biofuel in marine transportation are addressed.

The purpose of this study is to evaluate a life cycle assessment of straight vegetable oil (SVO) and biodiesel addressing alternative upstream pathways. The pathways are SVO and biodiesel produced in the United Kingdom (UK) using European rapeseed and also, SVO and biodiesel produced in the UK using soybean grain and soybean oil imported from Argentina. Four environmental impact categories have been assessed using the SimaPro (ReCiPe life-cycle impact assessment) method: this includes global warming potential (GWP); acidification; eutrophication and particulate matter. Rapeseed based biofuel had the lowest emission impact in terms of GHG emissions. Significant greenhouse gas (GHG) emissions can result from land use change due to the expansion and cultivation of soybean in Argentina. When land use change is not considered, the soy based biofuel system has the lowest GHG impact with more than 70% GHG emission reduction. The GHG emission at cultivation stage far outweighs the impacts of the other life-cycle stages irrespective of the feedstock used for the biofuel production systems. The use of fertilizers and associated soil emissions are the main contributors. The environmental impacts of biofuel can be reduced by avoiding land use change, improving soil management practices and yield, and also optimizing transportation routes. Effective implementation of options for biofuels production were explored to improve sustainability in shipping. et al., 2018). The risk of indirect land use change has led some to

This paper describes for the first time the use of direct contact membrane distillation (DCMD) for acid and water recovery from a real leach solution generated by a hydrometallurgical plant. The leach solutions considered contained H2SO4 or HCl. In all tests the temperature of the feed solution was kept at 60 °C. The test work showed that fluxes were within the range of 18-33 kg/m(2)/h and 15-35 kg/m(2)/h for the H2SO4 and HCl systems, respectively. In the H2SO4 leach system, the final concentration of free acid in the sample solution increased on the concentrate side of the DCMD system from 1.04 M up to 4.60 M. The sulfate separation efficiency was over 99.9% and overall water recovery exceeded 80%. In the HCl leach system, HCl vapour passed through the membrane from the feed side to the permeate. The concentration of HCl captured in the permeate was about 1.10 M leaving behind only 0.41 M in the feed from the initial concentration of 2.13 M. In all the experiments, salt rejection was >99.9%. DCMD is clearly viable for high recovery of high quality water and concentrated H2SO4 from spent sulfuric acid leach solution where solvent extraction could then be applied to recover the sulfuric acid and metals. While HCl can be recovered for reuse using only DCMD.