Eutrophication is one of the most adverse impacts of nutrient contamination of water bodies where the phosphate is considered to be the primary limiting factor. The vaterite polymorph of porous calcium carbonate nanoparticles (VPCCNPs) were synthesized and used to remove orthophosphate ions in water. In this study, the VPCCNPs were synthesized chemically, using calcium acetate and sodium bicarbonate in a water-ethylene glycol media, at a temperature of 100°C, in a reaction time of 24 hours. Synthesized nanoparticles were characterized by X-ray diffractometry to confirm that the crystalline phase of calcium carbonate formed is spherical vaterite polymorph. Scanning electron microscopy coupled with energy dispersive X-ray analysis further confirms the spherical shape of the vaterite nanoparticles and the presence of only calcium, carbon, and oxygen thus showing high purity of the synthesized calcium carbonate nanoparticles. The dynamic laser light scattering-based particle size analysis (DLS) shows the average particle size to be 25.5 nm. The Fourier transform infrared spectroscopy was used to find functional groups before and after the adsorption of phosphate by vaterite nanoparticles. The phosphate removal efficiency of synthesized nanoparticles was tested with different concentrations of phosphate solutions (2–80 mg/L), pH levels (5–12), adsorbent dosages (0.025–0.250 g), and contact times (5–120 min). Ion chromatography was used to analyse the phosphate concentrations in water samples. The maximum phosphate removal percentage of 100% was obtained with 50 mL of 2 mg/L phosphate solution and 0.15 g of the synthesized nanoparticle. Adsorption data were well fitted with the Langmuir adsorption isotherm model and the pseudo-second-order kinetic model with R2 of 0.99 and 0.98 (rate constant -0.083 g g-1 min-1), respectively. The presence of F−, NO3−, and SO42− has no effect on phosphate adsorption since 100% phosphate removal is obtained in the presence of these ions. Furthermore, the particle shows a 100% removal of orthophosphate ions available in eutrophic water regardless of the presence of many other ions in natural water bodies. The study presents a viable option for removing excess phosphate in natural water to desirable levels as a means for controlling eutrophication.

Veterinary pharmaceuticals are still unregulated and their residues in the environment have the potential to cause considerable impact on ecosystems. Water pollution due to veterinary pharmaceuticals gained worldwide attention because they deteriorate the water quality and impart a toxic effect on living organisms. Therefore, the effective aquaculture wastewater treatment for veterinary pharmaceuticals removal before releasing into the environment is necessary to prevent the risk of environmental contamination and subsequent negative health and economic impacts on both the human and aquaculture industry. This review provides an overview of currently available methods to remove veterinary pharmaceuticals available in aquaculture wastewater while reviewing some methods already studied for other types of pharmaceuticals but possible to use in aquaculture in the future and the scope of the review has been limited to aquaculture antibiotics used as veterinary medicines. Several water refinement techniques such as conventional mechanical, chemical, biological and physical wastewater treatment methods are practiced but they are not with suitable efficiency. Several studies were published covering small or special sections of water pollution by pharmaceuticals. But most of these studies have been done targeting to remove the antibiotics coming from hospital effluent, livestock or animal farm, and veterinary practices. There are very few research studies done specifically for aquaculture wastewater treatment against veterinary pharmaceuticals. Therefore, more attention and efforts must be given to this topic to be developed and to know all details concerning the toxicity of veterinary pharmaceuticals and how they can be removed from the aquaculture wastewaters.