Thesis (B.S.) -- Cagayan State University, 2022.
Includes bibliographical references.

This study investigated the optimum condition for phosphate and nitrate removal from wastewater using Lemna minor -based phytoremediation process. Response Surface Methodology (RSM) with Central Composite Design (CCD) was employed as the experimental design, in which two factors including light intensity (74.75 - 145.25 μE/m2) and exposure time (3.18 -8.82 hours) were involved in the study, while two responses were investigated, namely phosphate removal efficiency and nitrate removal efficiency for a phytoremediation period of 21 days. Through numerical optimization, the highest PO43- removal efficiency of 86.61% (initial phosphate concentration = 1.419 mg/L) was obtained at the following optimum condition: light intensity of 110 μE/m2 and exposure time of 6 hours. The highest NO3-removal efficiency of 75.36% (initial nitrate concentration=2.76 mg/L) was obtained at the following optimum condition: light intensity of 74.75 μE/m2 and exposure time of 6 hours. The actual data obtained from the wastewater treatment was used to build a model. The model for 21 days phytoremediation was Y1 = -211.9+ 6.11A +36.9B -0.03289A2 - 1.28B2 -0.3396AB. Plant growth rate for 21 days of phytoremediation by duckweeds is measured to be 0.58g for maximum growth rate with a condition of 85 μE/m2 for light intensity and 8 hours for exposure time. The minimum growth rate was measured to be 0.23g with a condition of 74.75 μE/m2 for light intensity and 6 hours for exposure time. Findings in the duckweed's growth rate revealed that nutrient concentration and light intensity have a significant interaction effect on Lemna growth under optimal growth conditions.

Keywords: wastewater treatment; Lemna minor; phytoremediation; nutrient removal.