Effectiveness of domestic wastewater treatment using a Bio-hedge water hyacinth wetland system

Abstract

Constructed wetland applications have been limited by a large land requirement and capital investment. This study aimed to improve a shallow pond water hyacinth system by incorporating the advantages of engineered attached microbial growth technique (termed Bio-hedge) for on-site domestic wastewater treatment. A laboratory scale continuous-flow system consists of the mesh type matrix providing an additional biofilm surface area of 54 m 2 /m 3. Following one year of experimentation, the process showed more stability and enhanced performance in removing organic matter and nutrients, compared to traditional water hyacinth (by lowering 33%-67% HRT) and facultative (by lowering 92%-96% HRT) ponds. The wastewater exposed plants revealed a relative growth rate of 1.15% per day, and no anatomical deformities were observed. Plant nutrient level averaged 27 ± 1.7 and 44 ± 2.3 mg N/g dry weight, and 5 ± 1.4 & 9±1.2 mg P/g dry weight in roots and shoots, respectively. Microorganisms immobilized on Bio-hedge media (4.06 × 10 7 cfu/cm 2) and plant roots (3.12 × 10 4 cfu/cm) were isolated and identified (a total of 23 strains). The capital cost was pre-estimated for 1 m 3 /d wastewater at 78 US$/m 3 inflow and 465 US$/kg BOD 5 removed. This process is a suitable ecotechnology due to improved biofilm formation, reduced footprint, energy savings, and increased quality effluent.