Membrane technology for water production in agriculture: Desalination and wastewater reuse

The problem of water shortage affects not only human and industrial activities but also an adequate and sustainable food production. Water quality in agriculture does not have the same requirements as that of drinking water and also properly treated wastewaters can be used for irrigation. The two possible alternative sources of water for agriculture are: desalinated water and wastewater. In this paper membrane operations usually utilized for water production in agriculture are discussed. Their main advantages are: (i) their mutual compatibility which offers the possibility of combining different membrane operations to achieve the desired water qualities and (ii) their flexibility and easy scale-up which allow passing from small to large scale, from centralized to decentralized systems. The membrane technology mostly used in desalination is reverse osmosis (RO) whereas membrane bioreactors (MBRs) deal with fresh water reclamation from wastewater streams. Novel membrane technologies are described, such as forward osmosis (FO) and membrane distillation (MD), a promising prospect for agricultural water production, and the possible recovery of nutrients from saline waters and wastewaters. Nevertheless, the development of some novel technologies needs to be accelerated to reduce the costs associated with treatment and to avoid further impacts of water scarcity on food production.