Ecological floating bed for decontamination of eutrophic water bodies: Using alum sludge ceramsite

In this study, a combined ecological floating bed (C-EFB) with alum sludge ceramsite (ASC) was designed to improve the water purification effect of traditional ecological floating beds (T-EFBs). During the ASC preparation stage, alum sludge was shaped into a ball, air-dried, and fired under 600 °C. The physical and chemical properties of the ASC meet the requirements of Artificial Ceramsite Filter Materials for Water Treatment (CJ/T229-2008). This study investigated the increased capability of this new-type artificial substrate (ASC) on the removal of chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), total phosphorus (TP), and total nitrogen (TN) from eutrophic landscape water. Compared with the T-EFB, the C-EFB owns a higher purification efficiency. The highest average efficiency of COD, NH4+-N, TN and TP removals during the four operating stages was 78.2%, 58.1%, 46.7% and 53.2%, respectively, in the C-EFB, which were all higher than those of 53.5%, 32.4%, 27.2% and 25.8%, respectively, for the T-EFB. Among them, the C-EFB showed a higher advantage in the removal of TP. The results showed that the potential benefits of utilizing ASC in seriously eutrophic bodies of water. [Display omitted] •Light and stable ASC with surface area of 253.29 ± 15 m2/g was achieved by firing process.•The C-EFB could reduce 78.2% COD, 58.1% NH4+-N, 46.7% TN and 53.2% TN from eutrophic water.•The adsorption of phosphorus by ASC packing played a key role in the TP removal.•ASC is a good carrier for both microbial development and plants growth.