Ngày nhận bài: 08-03-2017 / Ngày duyệt đăng: 04-08-2017 / Ngày xuất bản: 06-08-2025
Environmental concerns and limitations in water sources for aquaculture production are critical factors in the pursuit of wastewater treatment systems for sustainable aquaculture development. In the study, the accumulation of nitrogen components in the effluent from shrimp ponds was examined and the removal efficiency of a wastewater treatment system were evaluated for a commercial production scale. The wastewater treatment system consisted of three steps: (1) sedimentation, (2) sand-filtration, and (3) bioremediation of a high rate algal pond (HRAP), which cultivated Ulva ohnoi seaweed as a monoculture. The study showed that the discharged water from intensive shrimp ponds at the end of the production cycle contained high levels of nitrogen components. Compared to the inlet water (from reservoirs), the total nitrogen (TN) concentration in the effluent increased from 0.26 mg/l to 6.23 mg/l and was composed of 25% total particle nitrogen (TPN), 42% total ammonia nitrogen (TAN), 30% dissolved organic nitrogen (DON), and a very low proportion (approximately 3%) of oxidised nitrogen compounds (NOx). The combined treatment system effectively removed 78% of TN in the wastewater, reducing TN from 6.23 to 1.33 mgN/l. The removal efficiencies of the sedimentation pond, sand-filtration, and HRAP were 47%, 15%, and 16% TN, respectively. While the sedimentation pond mainly cleared the TPN components; the sand-filtration effectively reduced TAN and converted this compound into NOx due to its function as a habitat for nitrifying bacterial growth, and the treatment step with HRAP significantly removed both TAN and NOx in the effluent. Therefore, the treatment system integrating seaweed cultivation presented a high efficiency in removing the nitrogen components in the wastewater from intensive shrimp farms.
