INNOVATIVE REUSE OF DEWATERED ALUM SLUDGE IN ENGINEERED WETLAND FOR WASTEWATER TREATMENT: A WIN-WIN TECHNIQUE

摘要

During the past six years at University College Dublin (UCD), Ireland immense efforts have been taken to study the reuse of dewatered alum sludge, a by-product from water purification industry, as a resourceful material in environmental and civil engineering. This paper reports a first pilot-scale study of the newly developed novel engineered wetland system, which employed alum sludge as main substrate for animal farm wastewater treatment in Ireland. The pilot-scale alum sludge-based wetland system consists of four identical wetland compartments in series designed with a total treatment surface area of 3.42 m2. Dewatered alum sludge collected from a local water treatment plant was used as a main substrate and the depth of total substrate in each compartment was kept 0.75 m. Hydraulic loadings of up to 0.29 m3/m2.d and organic loading of 150.8 g-BOD5/m2.d have been applied for the entire system. Results acquired from the field experiment revealed that the average removal efficiencies up to 94.6% for phosphorus, 73% for COD, 64% for TN and 70% for SS were achieved in the novel system. It has been observed that the system is capable for nitrification and denitrification. The reuse of dewatered alum sludge as main substrate discernibly enhanced the P immobilization. This novel wetland system proved to be efficient to treat high strength wastewater as compared with the conventional constructed wetland system. Notably, the system is a showcase to offer a novel reuse alternative for the alum sludge to compete with landfill, and this novel approach claims to be a win-win technique.