Quebracho tannin acts as flocculant agent to remove surfactant as sodium dodecylbenzenesulfonate in water treatment. The feed is normally dosed with flocculant before delivery to the thickener. This eventually results in the reduction of polymer flocculant consumption in thickeners. One significant application of calcium hydroxide is as a flocculant, in water and sewage treatment. The substance also has detergent, anti-corrosive, and flocculant properties and prevents biofouling. The cost of flocculant is often a major operating cost of dewatering equipment. Water that is more brackish, or saline requires larger amounts of flocculant. A flocculant will shorten the separation time and give a cleaner soap with lower viscosity. "Chitosan", a commercial flocculant, more commonly used for water purification, is far more expensive. In a fine powder form, it can also be used as a flocculant in ponds.