Summary Fossil fuel is scanty and negatively affects the earth by inducing climate change. As a result, alternative and renewable energy (RE) sources are being investigated to replace fossil fuel. Wind and solar energy are leaders in the RE market, but huge and accessible other energy sources such as salinity gradient power (SGP) exist and need to be collected to contribute to the global energy demand. SGP is mainly extracted with reverse electrodialysis (RED) and pressure retarded osmosis (PRO) systems. The applicability of RED‐SGP in a natural environment is the current challenge due to the low power density and the high Levelized cost of energy (LCOE) of the process. The properties of the ion‐exchange membranes (IEMs), the spacers, the feed solutions characteristics and salinity, and the electrodes are among the most important parameters that control the performance of RED‐SGP processes. New highly selective, conductive, and cost‐effective membranes are required to improve RED performance and reduce the produced energy cost. Alternatives feed solutions such as wastewaters and brine from desalination plants as well as hybrid RED such as RED combined to electrodialysis (ED), reverse osmosis (RO), or membrane distillation (MD) will result in cost‐effective water treatment and SGP extraction.

a b s t r a c tLandfill leachate is a high-strength wastewater with high concentration of harmful pollutants and is produced in almost all countries with high variation in constituents. In this study, a modified direct contact membrane distillation (DCMD) has been used to investigate the treatability of raw and pretreated landfill leachate. Two different hydrophobic membranes, polytetrafluoroethylene (PTFE) and polyvinylidene difluoride membranes with two different pore sizes (0.22 and 0.45 µm, respectively) were used and performed at three various delta temperatures (∆T); 30°C, 40°C and 50°C. The rejection efficiencies for conductivity, COD, sulfate, alkalinity and hardness were approximately 85%, 99%, 95%, 90% and 98%, respectively, with raw leachate and 99%, 98%, 92%, 85% and 98%, respectively, with pretreated leachate, while NH 4 + -N removal efficiency was about 70% and 92% for raw and pretreated leachate, respectively. The highest transmembrane fluxes (TMF) were obtained at a ∆T of 50°C with 0.45 µm pore size of PTFE membrane. The highest TMF with raw leachate was 9.87 L/m 2 h while it was 15.54 L/m 2 h with pretreated leachate. Contact angles and Fourier transform infrared spectroscopy were used to evaluate the resistance of the membranes to wetting and fouling.

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A large amount of textile waste is generated every year around the globe. The textile product made from natural fibers might be vermicomposted and used as fertilizer. The present study aimed to research an integrated system of pre-composting (pathogen kill) and vermicomposting with various levels of post-consumer cotton waste to determine if this addition has any effects on the composting process. A vermicompost bin was constructed and filled with feedstocks mixed with post-consumer cotton textile waste at a 25:1 C:N ratio, and operated for three months at approximately 70% moisture content, with four composting trials with 0 g (control), 100 g, 200 g, and 300 g of textile waste. The pre-composting stage reached a temperature ranging from 40 °C to 50 °C, able to neutralize the pathogens. All four trials resulted in final compost with C: N ratios around 14, proving that post-consumer cotton textile waste did not affect the vermicomposting process, and was successfully used as a carbon source by worms to produce a healthy and mature compost. This indicates a sustainable option for the recovery of textile waste that is being decomposed in landfills.

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A lab‐scale reverse electrodialysis module was constructed to highlight the optimal feed solutions concentration, the flow rate and their importance in improving the power density in reverse electrodialysis. The results showed that the increase of the feed solutions flow rate is beneficial by augmenting the power output, but too high flow rate harms the process performance. Even though the highest power density (0.54 W/m2) was obtained at 60 mL/min with 4 and 428 mm feed solutions, the optimal flow rate determined by this study was 30–45 mL/min. It has been discovered that the variation of NaCl concentration in the low compartment was more sensible in affecting the reverse electrodialysis performance compared to the high compartment solution. The NaCl concentration of 6 and 684 mm appeared to be the optimal values for low compartment and high compartment solutions, respectively, for high performance and efficient power generation with reverse electrodialysis using seawater and river. When 1/3 of the minimum flow rate of the Ceyhan River running into the Mediterranean Sea is operated in the reverse electrodialysis system, at least 17.18 × 106 KWh electrical energy was estimated to be generated per year, with a power density of 0.705 m2/W.