PRELIMINARY ASSESSMENT OF THE FEASIBILITY OF PLANT FLOATING RAFTS IN IMPROVING AND REDUCING AGRICULTURAL WASTEWATER POLLUTION IN RICE SEED CENTER IN VINH LONG PROVINCE

Abstract

The study was conducted for preliminary evaluation of the feasibility of the floating plant raft model in controlling agricultural wastewater pollution in order to provide more information to demonstrate the solution of water treatment using plants combined with landscape creation. Four ornamental species Echinodurus cordiforlius, Cyperus alternifolius, Canna generalis and Heliconia psittacorum were grown on floating rafts with an area of ​​2 m² with a total of 6 floating rafts which were placed on the drainage canal from rice fields of the rice seed center. Water quality parameters were periodically assessed biweekly; plant growth was determined monthly and plant biomass was pruned bimonthly and determined for plant uptake N, P. The results showed that the floating rafts contributed to the absorption of nitrogen and phosphorus in wastewater. Water quality in the studied area after passing through the floating rafts tended to decrease compared to the inlet, except for location 6 because this one is located right next to the domestic wastewater discharge of workers working here, leading to a tendency for the content of pollutants to increase again. The pH and TP outlet values of all locations were within the allowable limits of table 2, level B, QCVN 08:2023/BTNMT, although DO and COD concentrations were improved after passing through the floating rafts, they still did not reach the allowable limits. The studied plants grew and developed through increased height and weight. The average initial plant height of C. generalis, H. psittacorum, E. cordiforlius and C. alternifolius was 45.0 ± 2.0; 46.0 ± 2.0; 26.0 ± 2.0 and 30.0 ± 0 cm, respectively, they were increased to 54.7; 49.1; 26.4; 57.8 cm after each month, increasing by 1.2; 1.06; 1.02; 1.9 times, respectively; with the increased corresponding plant weight was 76.4; 58.9; 7.7; 121.1 g/plant. It is estimated that after every 2 months, the plants accumulated an average of 4.37 - 29.5 g N/m² (26.2 - 177.1 g N/m²/year); 0.35 - 3.26 g P/m² (2.1 - 19.6 g P/m²/year).