Phycoremediation encompasses microalgae as a sustainable treatment system by integrating the wastewater treatment with bioenergy recovery. However, transforming this technology to real time from lab scale is limited due to temperature and cell volume (inoculum size). Thus, the present study aims to investigate the influence of inoculum size (10%–30% v/v) and temperature condition (25°C–35°C) for the growth of five microalgal species in paddy-soaked wastewater (PSWW), using response surface methodology (RSM). The optimal conditions for better biomass production and wastewater treatment were found to be at 25°C and 30% inoculum size. Among five selected microalgae, Chlorella pyrenoidosa exhibited maximum dry biomass content (831 mg=L) with greater (>90%) removal on ammonical nitrogen (NH3-N) and phosphates (PO4-P) at a rate of 0.025 and 0.006 mg P=mg of dry biomass, respectively, with significant p value (p < 0.05). Similar results were obtained for Chlorella vulgaris and Scenedesmus obliquus (an indigenous sp.) with more than 80% removal efficiency. However, at higher temperatures, Chlorella pyrenoidosa exhibited better results when other strains failed to maintain biomass production and removal on NH3-N and PO4-P. This study demonstrated that phycoremediation is a viable option upon selecting appropriate strains and conditions imminent for scale-up applications. © 2019 American Society of Civil Engineers.