植物床-沟壕系统的藻类捕获功能

采用原位实验验证植物床．沟壕系统的藻类捕获功能。结果表明：该系统能够有效拦截和捕获源水藻类。在水力梯度驱动下，约35％源水进入高位小沟流经植物床内部根孔结构而汇至低位小沟。低位小沟内叶绿素a（Chl-a）浓度显著低于高位小沟（P=0．0239），其降低比例为11．1％。以植物床．沟壕系统为结构形式的根孔净化区其出水Chl-a浓度较源水整体下降了27．0％。估算该片根孔净化区捕获藻类鲜生物量约122kg／d。石臼漾湿地共含根孔净化区11片，按供水25万t／d计，估算捕获藻类鲜生物量约1100kg／d。

Algae trapping function of plant-bed/ditch systems

This case study corroborated the algae trapping function of plant-bed/ditch system through in situ field testing. Results showed that the system could effectively intercept and trap algae from source water. Under the driving of hydraulic gradients, about 35% source water flowed into the higher small ditch, and exuded through the root channel structure inside plant bed into the lower small ditch. The chlorophyll-a (Chl-a) concentration in the lower small ditch was significantly lower (P=0.0239) than that in the opposite higher small ditch. The decline percentage of Chl-a concentration amounted to 11.1 % between both sides of plant bed. The Chl-a concentration dropped down by 27.0 % at the outlet of examined root channel purification zone with plant-bed/ditch system as structure form. According to rough estimation, this patch of root channel purification zone could trap algae fresh biomass of about 122 kg/d. Shijiuyang constructed wetland contains altogether 11 patches of root channel purification zones and provides 250 000 t/d purified raw water for the drinking water plant. The total trapped algae fresh biomass reached up to about 1 100 kg/d.