Integrated Constructed Wetlands Technology for treating Household Piggery Wastewater in Binh Dinh Province, Vietnam
摘要
This study integrated an air flotation and settling (AFS) tank, anaerobic/oxic (A/O) tank, moving bed biofilm reactor (MBBR) with a constructed wetland (CW) for removing high levels of COD (834–1981 mg/L), BOD5 (302–886 mg/L), TN (102.4–398.2 mg/L) and coliforms (2.1 × 105–4.5 × 105 CFU/100 mL) from the effluent of a biogas digester processing piggery wastewater. The plants Eichhornia crassipes and Ipomoea aquatica were used in the CW to improve the pollutant removal effiency. From April 18 to July 30, 2024, the experiment was conducted, during which the integrated AFS–A/O–CW system achieved removal efficiencies of 74.2 ± 5.9% for TSS, 82.6 ± 8.2% for COD, 86.7 ± 5.3% for BOD₅, 79.1 ± 8.6% for NH₄⁺, 65.2 ± 10.7% for TN, and 94.5 ± 3.2% for coliforms. Through 16S rRNA gene metabarcoding analysis, 14 genes and 16 phyla were detected in the mixture of sludge and wastewater in the aerobic zone of A/O tanks that contributed to the reduction of NH4+, TN, COD and BOD5 in the piggery wastewater. The weight of Eichhornia crassipes (n = 7) after a 3-month period increased from 17.5 ± 2.3 g to 86.3 ± 9.7 g, while the average weight of Ipomoea aquatica (n = 7) after a period of one month increased from 6.3 ± 0.6 g to 17.4 ± 3.6–22.7 ± 4.7 g. Following the treatment by the integrated AFS tank, A/O tanks, MBBR and CW system, the final treated water quality met the specifications set out by the Vietnam National Technical Regulation on livestock effluent discharge [QCVN62-MT:2016/BTNMT].