The Development of Nitrogen and Phosphorus Removal System on Eutrophication in Water Bodies Using Floating Plants

The nitrogen-phosphorus removal model was set up and monitored during in 3 weeks, which divided to 3 periods including 0-day, 14-day and 21-day of detention times. The model was closed water system with eutrophication in greenhouse, temperature and light intensity were controlled within 25-35 °C and 150-200 micromole/sec (8.30 a.m. - 4.30 p.m. daily), respectively. Each closed water system was 10 liters of water tank and filled with plankton blooming water. This experiment was divided into 2 phases: first period was determined and selected experimental system, which was contained and combined in different types of floating plants, such as Salvinia cucullata, Pistia stratiotes and Lemna perpusilla; and second period was monitored the efficiency of selected floating plant system (Pistia stratiotes and Lemna perpusilla, 15 grams for each floating plant) for nitrogen-phosphorus treatments; and combining with other water treatments, such as photosynthesis bacteria (PSB) and Hoagland's nutrient solution. The finding was shown that Salvinia cucullata and Lemna perpusilla were most water parameter qualities improvement, including DO, pH, Turbidity, BOD, TSS, PO43-, total phosphorus and total nitrogen (mg/l). However, Salvinia Cucullata were poor growing along with experimental period when compared to Pistia stratiotes, thus, it was used in second period of study.

All floating plant systems in the first phase were represented water treatment and clearly remediation, which indicated by turbidity (<0.1 mg/l), total suspended solid (1 mg/l) and total phosphorus (<0.1 mg/l). The other parameters were also met to standard, however, the systems were unable to eliminate nitrogen, which may due to the limitation on adsorbing of nutrient conditions from atmosphere. The second period had indicated nitrogen and phosphorus reduction of Pistia stratiotes and Lemna perpusilla by 21.96% and 75.15%, respectively. Floating plants combined with photosynthesis bacteria were increased in nitrogen and phosphorus reduction (66.47% and 63.03%, respectively). The assessment of phytoplankton community structure on water quality were calculated as Applied Algal Research Laboratory-Phytoplankton (AARL-PP) score. Pediastrum was the most represented group of the phytoplankton community followed by the Blue green algae including Gleocapsa, Golenkinia and Kirchneriella, which were indicated as moderately polluted by using dominant phytoplankton species.