Membrane operations for water recovery in power plants

Materials & Technologies for Performance Improvement of Cooling Systems in Power Plants (acronym MATChING) is an H2020 EU-funded project,started in March 2016 and scheduled for 42 months. MATChING goal is to reduce water demand and improve energy efficiency of cooling systems in the energy sector through the use of advanced and nano-technology based materials. All technological areas of plant cooling systems are affected: cooling tower, steam condenser, cooling water circuit and water conditioning. To increase available effective water supply at reasonable costs, alternative water sources are exploited: different membrane based technologies are used to re-cycle or re-use municipal, process and blow down waters. In MATChING project, ITM-CNR is involved in various tasks. One of this is water recovery from the plume of cooling tower through membrane assisted condenser. The latter is a new membrane technology that allows recovering water from humidified waste gaseous streams. In details, the waste gaseous stream (e.g., the plume of the cooling tower) at a certain temperature is fed to the membrane condenser module kept at equal or lower temperature. The hydrophobic nature of the microporous membranes is exploited for promoting water vapor condensation and recovery. Moreover, ITM-CNR is also involved in the development and lab-scale testing of different MF, UF, NF, RO and MD systems for the treatment and reuse of the wastewaters available on power plants. In particular, ITM-CNR is involved in the treatment of the flue gas desulfurization (FGD) wastewater. Laboratory tests have been carried out considering four possible scenarios: 1) MD applied directly on wastewater; 2) pre-treatment units (pressure driven membranes) coupled to MD; 3) MD for treatment of high concentrated salt solutions coming from RO; 4) an integrated process MF or UF + NF or RO. In this work, the results achieved in the first 30 months of the project, in terms of membrane performance (productivity and water quality), will be presented. It will be shown that the amount of produced high purity water can be increased from around 60 to more than 80% when the RO brine is further concentrated via MD. This work was supported by the EU Project H2020 "Materials & Technologies for Performance Improvement of Cooling Systems in Power Plants (acronym MATChING)" (GA 686031).