Study on the Purification of Pollutants from Rainfall Runoff by Prefabricated Improved Multi-aggregate Ecological Concrete (IMAEC) Revetment

Ecological revetment can purify rainfall runoff, thus reducing river pollution. Aiming at the problems of complex construction of traditional ecological concrete (TEC) revetment, short seepage path, poor cleaning ability and poor treatment ability of large flow rainfall runoff, multi-aggregate filter ecological concrete and multi-aggregate planting ecological concrete were prepared using adsorption materials as coarse aggregate, and a prefabricated improved multi-aggregate ecological concrete (IMAEC) revetment was designed. The seepage characteristics of the IMAEC revetment and the purification effect of different packing layers on rainfall runoff were explored through laboratory simulation tests. Then, the purification effect and engineering benefit of the IMAEC revetment in practical engineering were analyzed. The results showed that the IMAEC revetment had a rapid seepage rate, no overflow, and outstanding permeability. The seepage path and hydraulic residence time (HRT) of the revetment were prolonged, and the water permeated evenly. The average removal rates of ammonia nitrogen (NH 3 -N), total phosphorus (TP) and chemical oxygen demand (COD) for the IMAEC revetment at 3.5 × 10 –4 m 3 /s, 6.5 × 10 –4 m 3 /s and 9.6 × 10 –4 m 3 /s flows were 64%, 51% and 42%. The planting ecological concrete layer and filter ecological concrete layer in the IMAEC revetment make outstanding contributions to the purification of runoff. With the increase in runoff flow, the contribution rate of the planting ecological concrete layer to pollutants gradually decreased, while the contribution rate of the filter ecological concrete layer gradually increased. The removal rates of NH 3 -N, TP and COD reached 76%, 54% and 51% in the engineering application of the IMAEC revetment. Article Highlights The seepage characteristics and purification effect of IMAEC revetment are improved. IMAEC revetment removes pollutants through a plant-filler-microbial coupling. Ecological concrete layers have a great contribution to the purification of pollutants. IMAEC revetment shows good engineering benefit in engineering application.