Department of Civil and Environmental Engineering, Graduate School of Science and Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan.
Department of Civil and Environmental Engineering, Graduate School of Science and Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan.
Sci Total Environ. 2020 Jun 20;722:137854. doi: 10.1016/j.scitotenv.2020.137854. Epub 2020 Mar 10.
In Vietnam, swine wastewater is generally treated using anaerobic processes. Nevertheless, the level of pollutants in effluent after anaerobic treatment remains very high, thereby necessitating further treatment. This research was conducted to assess the applicability of duckweed (Lemna minor) for purifying wastewater collected from a household swine wastewater treatment system in Hanoi, Vietnam. After the anaerobically treated wastewater was diluted 10-fold, it was fed continuously to lab-scale stabilization ponds with and without planted duckweed at a hydraulic retention time of 5 days under ambient conditions. The chemical oxygen demand (COD), total nitrogen (T-N), and total phosphorus (T-P) concentrations in the influent were, respectively, 260-290 mg/L, 24-28 mg/L, and 1.4-1.8 mg/L. The COD, T-N, T-P removals in the pond with duckweed (74%, 84%, and 84%) were much higher than in the pond without duckweed (71%, 55%, and 58%). The duckweed greatly enhanced the first-order removal rates by 1.4, 2.0, and 3.2 times, respectively, for COD, T-N, and T-P in the ponds. Although the primary purification mechanisms in the ponds were sedimentation and adsorption, the duckweed grown with the relative growth rate of 0.07-0.16 d showed nutrient uptake activity from the wastewater. Biofilms formed on the duckweed roots apparently promoted COD removal and degradation of organic nitrogen into ammonia. Stabilization ponds planted with duckweed are anticipated for use as co-beneficial systems for wastewater treatment and biomass production.
在越南，猪废水通常采用厌氧工艺进行处理。然而，经过厌氧处理后废水中的污染物水平仍然非常高，因此需要进一步处理。本研究旨在评估浮萍（Lemna minor）用于净化越南河内家庭猪废水处理系统中收集的废水的适用性。将经过厌氧处理的废水稀释 10 倍后，在环境条件下以水力停留时间 5 天连续进料到带有和不带有浮萍的实验室规模稳定池塘中。进水的化学需氧量（COD）、总氮（T-N）和总磷（T-P）浓度分别为 260-290mg/L、24-28mg/L 和 1.4-1.8mg/L。有浮萍的池塘中的 COD、T-N 和 T-P 去除率（74%、84%和 84%）明显高于没有浮萍的池塘（71%、55%和 58%）。浮萍分别将池塘中 COD、T-N 和 T-P 的一级去除率提高了 1.4、2.0 和 3.2 倍。尽管池塘中的主要净化机制是沉淀和吸附，但相对生长率为 0.07-0.16 d 的浮萍具有从废水中吸收养分的活性。在浮萍根部形成的生物膜显然促进了 COD 的去除和有机氮降解为氨。因此，种植浮萍的稳定池塘有望作为废水处理和生物质生产的协同系统。
