TWs are finding as low-cost and also effective system to treat domestic wastewater. The aim of this study is to find suitable adsorbing material for application in an additional treatment unit where treatment wetlands do not provide sufficient PO43- reduction level. Material M1 is a fine-grained by-product of thermal treatment of carbonate-siliceous rock (opoka) with high content of calcium carbonate CaCO3 in temperature 700°C. Particular disadvantage of material M1 can be very high level of pH (11-12) and causing alkaline solution. Material M2 is lanthanum-modified bentonite (LMB) and was already used for reducing content of phosphorus compounds in lakes and other water bodies to treat effects of eutrophication process. Lanthanum-modified bentonite consists mostly SiO2 and Al2O3 (~80%). The study was conducted on effluent from small (60 pe) treatment wetland (TW) in northern Poland where Hybrid Treatment Wetland (HTW) system was provided. Sorption capacity of material M1 was low and equal 0.9 mg/g. For material M2 this parameter reached value of 2.1 mg/g. Lanthanum-modified bentonite (M2) has shown better abilities to reduce phosphates from wastewater that material M1 – material containing mostly calcium oxide. Also performed study revealed that presence of others contaminations in wastewater is causing difficulties in phosphates removal.