title: Pollutant removal by horizontal subsurface flow constructed wetlands in Lithuania.
abstract: Horizontal subsurface flow constructed wetlands recently have been developed in Lithuania. They ensure the efficient removal of nutrients and organic matter. This article analyses BOD5 and N and P removal efficiency with respect to filter loads. To achieve a normative wastewater treatment level according to BOD5 (25 mg O2 l(-1), loads of filters should not exceed 5.8 g m(-2) day(-1), that is, the treatment of wastewater produced by population equivalent requires a filter area of 10.5 m2. After treatment in filters total N of wastewater contains 55-85% of mineral N. Nitrite-N and nitrate-N make up 0.1% and 3.0% on average; the other part is composed of ammonia-N. Increasing total N concentrations contained in water outflow predetermine higher ammonia-N amounts. If water outflow contains 10 mg l(-1) of total N, ammonia-N makes up 51.5%; if it contains 40 mg l(-1), then ammonia-N makes up 81.0%. The average total nitrogen removal efficiency is 37-44%. P removal is affected by the physico-chemical characteristics of sand and qualitative composition of phosphorus contained in wastewater. P removal up to 2 mg l(-1) from domestic and other wastewater of similar composition requires no higher than 0.15 g m(-2)/day(-1) load of filters according to total P.
authors.affiliation: Water Management Institute, Lithuanian University of Agriculture, Kedainiai, Lithuania. v.gasiunas@water.omnitel.net
authors.forename: Valerijus
authors.initials: V
authors.lastname: Gasiunas
authors.forename: Zenonas
authors.initials: Z
authors.lastname: Strusevicius
authors.forename: Marija-Sigita
authors.initials: MS
authors.lastname: Struseviciene
mesh_terms: D000641:Ammonia; D017753:Ecosystem; D004779:Environment Design; D005374:Filtration; D008097:Lithuania; D009584:Nitrogen / Q000302:isolation & purification*; D010758:Phosphorus / Q000302:isolation & purification*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014872:Water Movements
chemical_list: D010758:Phosphorus; D000641:Ammonia; D009584:Nitrogen