There are three main types of volcano-composite or strato, shield and dome. Composite Volcanoes. Composite volcanoes, sometimes known as strato volcanoes, are steep sided cones formed from layers of ash and [lava] flows.The eruptions from these volcanoes may be a pyroclastic flow rather than a flow of lava.A pyroclastic flow is a superheated mixture of hot steam, ash, rock and dust.omposite volcanoes, sometimes known as strato volcanoes, are steep sided cones formed from layers of ash and [lava] flows. The eruptions from these volcanoes may be a pyroclastic flow rather than a flow of lava. A pyroclastic flow is a superheated mixture of hot steam, ash, rock and dust.
Desalination plants typically use reverse osmosis, a process that pushes saltwater through a membrane to create purified, drinking water. But in addition to being costly, and energy-intensive, reverse osmosis can negatively impact the environment.
Desalination is far more expensive than using water from land supply sources. The cost is very high and so it cannot be afforded by everyone who needs it, but because the desalinisation technology is improving fast, so the costs are beginning to fall, making it more affordable to countries and islands that need it.