Enhanced nutrient removal from aquaculture wastewater using optimized constructed wetlands: A comprehensive screening of microbial complexes, substrates, and macrophytes

Abstract

Constructed wetlands (CWs) are widely used to treat wastewater from aquaculture, and their efficiency largely depends on active components like microbes, substrates, and macrophytes. This study screened various commercial microbial complexes, substrates, and macrophytes for their effectiveness in removing nitrogen and phosphorus from pond wastewater contaminated with fish feed and excreta (CPW). Four microbial complexes (MC1, MC2, MC3, and MC4) were screened, two substrate types (zeolite and ceramsite), and five common macrophytes—Pontederia crassipes (PC), Myriophyllum aquaticum (MA), Canna indica (CI), Typha latifolia (TL), and Phragmites australis (PA). Screening evaluation included COD, total nitrogen (TN), ammonium nitrogen (AN), nitrate nitrogen (NN), and total phosphorus (TP) removal. Among microbial complexes, MC3 at 1.0 g/L (MC3-T2) exhibited the highest efficiency in COD (56 %), TN (66 %), AN (51 %), NN (69 %), and TP (59 %) removal. Screening of macrophytes showed that MA was most efficient with a decrease of 61 % COD, 91 % TN, 62 % AN, 84 % NN, and 69 % TP. Similarly, between both substrates, zeolite most effective, with 50–25 % COD, 12–7 % TN, 44–28 % AN, 71–47 % NN, and 45–19 % TP removal over six periods. Based on these findings, four artificial CWs were developed, with CW-2 (which carries MA, CI, MC3-T2, and zeolite) showed the highest removal of COD (57–43 %), TN (29–11 %), AN (65–28 %), NN (87–69 %), and TP (80–47 %) over eight periods. The development of CWs by utilizing these optimal components (particularly CW-2) provides highly effective solutions for excessive nutrients removal from CPW. This innovative approach presents a promising alternative for mitigating eutrophication and enhancing wastewater treatment processes.