Although groundwater is more reliable and clean water resource when it is used as a drinking water, it is difficult to treat once it is polluted. One of the most important pollution paremeters in groundwater is nitrate which might be discharged by domestic or industrial wastes, agricultural activities, fertilizers and animal wastes. Even though denitrification, ion exchange, reverse osmos are widely used treatment methods for nitrate removal, biological treatment methods have effectively been also used. Nitrate removal from groundwater by microalgae is used as an alternative method in biological treatment methods. On the other hand, there are some topics which need to be investigated about chemical compositon of groundwater and microalgae growth.