Integrated dewatering and stabilization system as an environmentally friendly technology in sewage sludge management in Poland

Abstract

Sludge treatment reed beds (STRBs) are an environmentally friendly technology which provides integrated dewatering and stabilization of sewage sludge. STRBs do not require the use of chemicals to improve the dewatering process. STRB is both, a low-emission and a low-energy-consuming method. After the stabilization process, sludge is characterized by the chemical composition similar to that of humus. The aim of the paper is to present the comprehensive data from Waste Water Treatment Plant (WWTP) in Gniewino (Poland) where the sewage sludge is dewatered and stabilized in a STRB.Research and literature reports indicate that sewage sludge treated in STRB is dewatered, which results in an increase in the dry matter (dm) (from 1.1% to 15.5%) and stabilization due to the decrease in the content of the organic matter (from 71.2% of the dm to 52.4% of the dm). Likewise, thanks to the high concentration of nutrients (TKN concentration − 3.64% of the dm and P concentration − 3.54% of the dm) and the low concentration of heavy metals (below permissible values for the agricultural use) after the time of stabilization, safe and valuable product can be recycled to the environment. Reject water (RW) generated during this process has relatively stable and much better properties in comparison to these which are generated in high technologies for sludge treatment. Thus, recycling the RW from the slugde dewatering in STRB represents a very low internal pollution and should not alert the treatment proceses of wastewater.