The Use of Expanded Clay Aggregate for the Pretreatment of Surface Waters on the Example of a Tributary of Lake Klasztorne Górne in Strzelce Krajeńskie

The paper presents a proposal for the treatment of river water based on expanded clay (ceramsite). It is a lightweight mineral aggregate containing components relative to phosphorus adsorption (calcium, iron, manganese, aluminum). A pilot plant on a fractional technical scale was built on a nutrient rich (phosphorus up to 0.4 mg dm⁻³, nitrogen up to 10.0 mg dm⁻³), small (mean annual flow about 0.04 m³ s⁻¹), natural watercourse (Młynówka River, a tributary of the Otok Channel, Noteć basin, the municipality of Strzelce Krajeńskie). The monitoring included quantitative and qualitative measurements of the water stream in 2014–2015. On the basis of the examinations, the calculated effectiveness of ceramsite filters in removing major contaminants from water was: for total nitrogen 5–6%, phosphorus 12–16%, and for suspensions 17–29%. The effectiveness of the treatment is highly influenced by hydraulic load, so this type application on a full-scale should occupy a sufficiently large volume. Taking into account simplicity of performance, ease of operation and low cost of construction and maintenance, such pretreatment plants based on expanded clay would seem to be a promising tool for the protection of surface waters in catchments of small rivers and streams.