Treatment of African catfish, Clarias gariepinus wastewater utilizing phytoremediation of microalgae, Chlorella sp. with Aspergillus niger bio-harvesting

[Display omitted] •Microalgae phytoremediation could serve as sustainable aquaculture wastewater treatment.•Phytoremediation of Chlorella sp. at various inoculation dosage 0–60% (v/v) were evaluated.•Optimum dosage of 30% (v/v) achieved 98.7% ammonia and 92.2% orthophosphate removal.•Bio-flocculant Aspergillus niger yield 97% Chlorella sp. harvesting efficiency.•Co-cultivation of Chlorella sp. with A. niger provide environment-friendly treatment. This study focuses on the evaluation of the performance of Chlorella sp. in removing nutrient in aquaculture wastewater and its correlation with the kinetic growth of Chlorella sp. The treatment was applied with various Chlorella sp. inoculation dosage ranging from 0% to 60% (v/v) of wastewater. The optimum inoculation dosage was recorded at 30% (v/v) with effluent concentration of ammonia and orthophosphate recording at 0.012mgL−1 and 0.647mgL−1, respectively on Day 11. The optimum dosage for bio-flocculation process was obtained at 30mgL−1 of Aspergillus niger with a harvesting efficiency of 97%. This type of development of phytoremediation with continuous bio-harvesting could promote the use of sustainable green technology for effective wastewater treatment.