景观型与蔬菜型水平潜流湿地除磷动力学模型

利用景观型和蔬菜型水平潜流湿地净化经生化处理后的生活污水尾水,进行湿地除磷动力学模型研究。对比分析不同湿地单元的除磷效率。为优化湿地除磷设计,采用一级动力学模型和Monod模型模拟除磷效果,对比模拟准确性,讨论水温、水力负荷与模型反应速率常数间关系,并建立湿地除磷模型构建式。结果表明,景观型湿地除磷能力顺序:美人蕉单元>再力花单元>鸢尾单元,蔬菜型湿地:空心菜单元>茭白单元>番茄单元,除磷效果差异归因于不同类植物的生物量区别。Monod模型(模型效率值ME:0.76～0.86)对湿地除磷的预测较一级动力学模型(ME:0.53～0.72)具有更高准确性。总磷面积去除率随水温的降低而减小,Arrhenius拟合结果表明,美人蕉(θ=1.006)、再力花(θ=1.008)和空心菜(θ=1.006)单元K_max对水温变化不敏感,水温对鸢尾(θ=1.015)和茭白(θ=1.014)单元除磷效率有较大影响。K_max20与水力负荷间存在显著正相关性,两者符合乘幂方程(R²:0.657;0.805)关系。考虑了水温和水力负荷因素的Monod模型构建式,对试验湿地除磷预测具备准确性。

Kinetic modelling of total phosphorus removal in landscape type and vegetable type horizontal subsurface-flow constructed wetlands

The studies on total phosphorus (TP) removal in landscape type and vegetable type horizontal subsurface flow wetlands were conducted. The raw water was domestic sewage which has been treated by biochemical treatment processes. The TP removal efficiency of different wetland units were compared and analysed. To optimize the design of wetlands, the first order reaction kinetics model and the Monod model were used to simulate the TP removal results and their accuracy were compared. Meanwhile, the relationship between water temperature, hydraulic loading rate (q) and the reaction coefficients were discussed. The results showed that in landscape type wetlands, the order of TP removal capacity was canna unit >thalia dealbata unit >iris tectorum unit, while it was water spinach unit >zizania unit >tomato unit in vegetable type wetland units, which was attributed to the biomass difference of different plants. The comparative evaluation between the first order kinetics model (ME: 0.53—0.72) and the Monod model (ME: 0.76—0.86) showed that the Monod model had higher accuracy in predicting the TP removal results. Decreased values of areal removal efficiency of TP were observed at lower water temperature. The K_max of canna (θ=1.006), thalia dealbata (θ=1.008) and water spinach units (θ=1.006) were insensitive to the change of water temperature. The water temperature had a great influence on TP removal efficiency of iris tectorum (θ=1.015) and zizania (θ=1.014) units. The increased values of K_max20 were observed at higher q values. The power equations (R²: 0.657; 0.805) can well reflected the relationship between K_max20 and q. The constructed Monod model, which had considered the influence of water temperature and q on K_max, gave a certain accuracy in predicting TP removal of experimental wetlands.