Enhancing bullfrog farming sustainability: circular water management through effluent treatment.

Ensuring effective wastewater treatment is crucial for promoting sustainable water use and reducing environmental pollution in intensive bullfrog aquaculture. This study presents the design and implementation of an integrated treatment system, composed of a flotation tank, a biochemical tank, and constructed wetlands, aimed at facilitating the reuse of treated effluent. The system, operated under optimal conditions-at a flow rate of 250 m³/h, hydraulic retention time of 6 h, and aeration intensity of 2,000 m³/h-demonstrated significant removal efficiencies. Specifically, the biochemical tank reduced chemical oxygen demand (CODCr), ammoniacal nitrogen, and total phosphorus by 70%, 43%, and 42%, respectively. After a month of continuous operation, the system achieved higher removal rates of 71.7% for CODCr, 83% for ammoniacal nitrogen, and 86.7% for reactive phosphorus, rendering the treated water suitable for reuse in bullfrog farming. However, total nitrogen removal remained relatively low, and reactive phosphorus slightly exceeded discharge standards, indicating areas for further optimization. Despite these limitations, this innovative system enhances water recycling, supports circular water management strategies, and provides a practical solution for reducing water consumption and minimizing aquaculture's environmental footprint.