Duckweed was used to treat effluent from a shrimp farm in a batch wise and recirculation system. The result showed that duckweed could efficiently remove nutrients in the effluent, especially ammonia, which seemed to be the preferred nitrogen source of the plant. Red tilapia was used in the recirculation system and showed high potential in removal of uneaten shrimp feed.

The uptake of dissolved nutrients by microalgae is the primary way to remove nitrogen in aquaculture systems. Many authors have studied the use of microalgae to treat wastewater from aquaculture. However, excessive microalgae accumulation may cause high levels of organic matter and suspended solids in the final effluent. Thus, an efficient way to remove excess algae is needed in wastewater treatment. In this study, the potential of the filamentous cyanobacterium, Oscillatoria okeni, and the green alga, Chlorella vulgaris, to remove nitrate-nitrogen from tilapia-pond effluent was assessed. The results indicated that C. vulgaris exhibited higher specific rate of growth and rate of nitrate utilization than O. okeni. However, O. okeni has the advantage over C. vulgaris in solid-liquid separation by filtration and sedimentation after treatment.

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Oxytetracycline (OTC), widely used as an antibiotic substance in aquaculture, has an adverse effect on environmental and public health. The aim of this paper was to demonstrate that OTC can be removed by hydrogel films composed of β‐cyclodextrin/carboxymethylcellulose (β‐CD/CMC) with esterification‐crosslink method. Oxytetracycline adsorption experiments were performed with an initial pH of 1–12 and an initial concentration of 10–500 mg/L. The experimental data were fitted with Langmuir and Freundlich isotherms and compared using linear and nonlinear models. The experimental results indicate that OTC's adsorption capacity depends on the active β‐cyclodextrin content. The optimal pH was around 8.

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