Phosphate Removal in Tilapia Rearing Effluent by Using CaO Catalyst Synthesized from Moaberry Pomace

Water management is essential in aquaculture to ensure food security and reduce environmental impacts. This study explores the use of calcium oxide (CaO), derived from moaberry (Antidesma thwaitesianum) pomace, for phosphate removal in tilapia farming water. The CaO catalyst was produced by calcining moaberry pomace at 950°C for seven hours, resulting in a material with over 50% CaO content, confirmed by scanning electron microscopy (SEM) and X-ray fluorescence (XRF) analyses. When introduced into water, CaO reacts to form calcium hydroxide (Ca(OH)₂), which shows significant phosphate removal ability. Under white LED light (15W, 6500K), the material also acts as a photocatalyst, generating hydroxyl radicals that enhance phosphate degradation. To apply the catalyst in a practical system, it was combined with glass powder and sodium silicate to form a composite. It was then used in a continuous-flow fixed-bed photocatalytic column. During a 120-minute treatment, the system achieved a 72% reduction in phosphate concentration at 60 minutes using a 20% CaO composite. These results demonstrate the potential of LED-assisted photocatalysis as a low-energy, environmentally friendly water treatment approach. The study highlights the value of agricultural waste utilization and green photocatalytic technology in addressing eutrophication in aquaculture. Future work should focus on improving catalyst performance, optimizing operational conditions, and evaluating long-term field applications to support sustainable aquaculture practices.