Research of Nutrients Absorption by Different Types of Aquatic Plants
Date Issued
2016
Date
2016
Author(s)
Cheong, Hong-Hoi
Abstract
Using natural ecosystems to improve water quality is an important technology for the future circulating water treatment. The benefits of using aquatic plants to purify water quality are low cost, low pollution, zero energy consumption, high efficiency, improving the ecological environment and sustainable development. In this study observes the situation of plants absorbing nutrients with four different types of aquatic plants: emergent plants (Cyperus involucratus Rottb), floating-leaved plants (Nymphoides cristata (Roxb.) O. Kuntze), floating plants (Pistia stratiotes Linn), submerged plant (Egeria densa Planch), in three different concentrations of water (hydroponic water, lake water, pure water). The results showed that submerged plants (Egeria densa Planch) had better absorption of nutrients in the first 14 days. They could absorb 125.351 mg phosphate (PO43-), 0.795 mg nitrite (NO2-), 11.081 mg ammonium (NH4+) and 12.816 mg calcium ion (Ca2+) per kilogram per day. They also had significant reduction of cation base on two points. First, the whole plant, including roots, stems and leaves can absorb nutrients. Second, when submerged plants photosynthesis under the water, they produced large amounts of hydroxide ions and bicarbonate ions increasing the water pH value and binding more cations settlement. Moreover, submerged plants increased dissolved oxygen in water. Secondary, floating plants (Pistia stratiotes Linn) had effectively reduced the conductivity of the water and could absorb 19.578 mg nitrate (NO3-), 1.719 mg nitrite (NO2-) and 14.823 mg Chloride (Cl-) per kilogram per day. Floating plants reduced dissolved oxygen and pH. They just formed a complementary relationship with the submerged plants. The third, emergent plants (Cyperus involucratus Rottb) had a good nutrient absorption capacity, slope consolidation and algae growth inhibition. Finally, floating-leaved plants (Nymphoides cristata (Roxb.) O. Kuntze) had no significant effect in nutrient absorption and they reduced the water pH and dissolved oxygen. Hence it is not recommended in water purification. In addition, this study found out that the higher nutrient concentration, the faster the absorption rate. It also found out that four different types of aquatic plants had been absorption stagnation after 14 days. This study aimed to quantify the rate of nutrient revenue and expenditure of aquatic plants and the effect of aquatic plants on water purification. It can provide a data base for future reference improving water quality in the construction design. Hoping that it can achieve the most effective improvement by rational allocation of the proportion of four different types of aquatic plants.
Subjects
aquatic plants
water purification
nutrient absorption
ecological engineering
water environment
Type
thesis
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