Highly Efficient Treatment of Shrimp Farm Wastewater by Using the Horizontal Subsurface Flow (HSSF) Constructed Wetlands with Phragmites australis Plant

Aims: This study aimed to investigate the treatment of synthetic wastewater (low salinity) followed by actual shrimp farm wastewater (high salinity) and laboratory scale of constructed wetlands (CWs).

Study Design: A horizontal subsurface flow (HSSF) constructed wetlands, which filled by layers of sand and soil, Phragmites australis was grown as wetland vegetation for the model. The dimensions of model is 1.2 m length x 0.4 m width x 0.35 m height, that devised into three zones: inlet zone and outlet zone are 0.15m filled by soil (∅= 10 – 20 mm); the treatment zone is filled by 0.25 m of soils (∅= 5 – 10 mm) at the bottom and 0.1 m of sand at the top.

Place and Duration of Study: Environmental laboratory, Department of Environment, Hochiminh City University of Natural Resources and Environment, from January 2015 to November 2015.

Methodology: The investigation was carried out in two phases: Phase 1 was run by synthetic wastewater at two levels of loading rate; the purpose of this phase is to check the performance of wetland model at low total dissolved solids (TDS) concentration. Phase 2 was run by actual shrimp farm wastewater at low loading rate, this phase aimed to investigate the effect of high TDS concentration on the performance of constructed wetland system treating actual shrimp farm wastewater. Samples of influent and effluent were taken and analyzed such parameters of COD, TN, TP, NH4+-N, TDS by following the procedure of APHA to determine the performance of model.

Results: As a result, the average removal efficiency of COD, TN, and TP in constructed wetland model was 92.7; 95.9; and 92.77%, respectively during the phase 1. The removal efficiency of phase 2 for COD, TN, and TP was 89.39; 94.61, and 89.36%, respectively.

Conclusion: The model performed stably for treatment of both types of wastewater. The constructed wetlands model could achieve better removal efficiency in synthetic wastewater than that of shrimp farm wastewater.