Zhong Fei

Application of constructed wetlands on wastewater treatment for aquaculture ponds

A group of constructed wetlands (CWs) were applied to the recirculating aquaculture system. This study assessed the performance of CWs in treating the aquaculture wastewater, examined the water quality condition of aquaculture ponds and the growth and the survival rate of “target” species (Ictalurus punctatus and Megalobrama amblycephala). The results showed that CWs were effective on reducing the concentrations of 5-day biochemical oxygen demand (BOD5, at 70.5%), total suspended solids (TSS, at 81.9%), chlorophyll a (Chl-a, at 91.9%), ammonium (NH4+, at 61.5%) and nitrate nitrogen (NO3−-N, at 68.0%). Effect of CWs on phosphate (PO43−-P) removal was relatively lower (at 20.0%). The concentrations of BOD5, TSS, Chl-a, NH4+ and TN, TP in the recirculating culture pond were significantly lower than that in the control pond(p < 0.05). CWs could help to increase total yield, survival rate of the “target” species and significantly decrease feed conversion ratio (p < 0.05).

金鱼藻(Ceratophyllum demersum)调控浮游植物捕获磷与生长的策略

水体浮游植物具有捕获利用磷的能力以及沉水植物能够显著抑制水体中藻类生长已得到国内外广泛共识，但相应的潜在机制尚缺乏深入了解.本研究选取金鱼藻（Ceratophyllum demersum）为研究对象，基于室内模拟实验，探讨了沉水植物调控浮游植物捕获磷与过度生长的机制.结果显示，尽管未种植金鱼藻的对照组上覆水中总磷、总溶解态磷和可溶性活性磷的平均浓度均显著高于种植金鱼藻的实验组（约4倍），但是两个系统中这3种磷浓度随时间的变化趋势均符合S形的对数曲线.实验组藻类密度、有效光量子产量、总碱性磷酸酶活性（TAPA）以及细颗粒碱性磷酸酶活性（细颗粒APA）也远低于对照组.此外，对照组中粗颗粒碱性磷酸酶活性（粗颗粒APA）占TAPA的44.7%，显著高于细颗粒APA.结构方程模型结果表明，对照组水体藻类密度对TAPA具有直接的正向作用，而金鱼藻的生长显著弱化了不同形态磷与APA、藻类密度、细菌动力以及光量子产量之间的相互作用.这说明沉水植物对水体浮游植物生长的调控具有多种策略.

Effect of step feeding on the performance of multi-stage vertical flow constructed wetland for municipal wastewater treatment

To investigate the effect of step feeding on the performance of multi⁃stage vertical flow constructed wetland (MS⁃VFCW) for municipal wastewater treatment, raw wastewater with four step feeding ratios (0% , 10% , 20% and 30% ) were dosed to the second stage of the MS⁃VFCW plots at a total hydraulic load of 100 mm / d. The results showed no significant differences in removal of chemical oxygen demand (COD) and total phosphorus (TP) among the four step feeding ratios, and the highest removal rates of COD and TP reached up to 87.80% and 81.17% , respectively. Most COD was removed in the first stage, with an average contribu⁃ tion of 82.18% . While the most TP was removed in the third stage, with an average contribution of 54.37% . In contrast, the differ⁃ ences in total nitrogen (TN) removal rates among the four step feeding ratios were significant, with the highest TN removal rates (61.70% ±4.48% ) under the ratio of 20% , in which the average removal contribution of each stage was 36.52% , 42.11% and 21.37% , respectively. The step feeding ratio was recommended as 20% in application of the hybrid VFCWs so as to achieve sound pollutant removal performance.

Odor compounds and the related impact factors in Tangxi River,Hefei

The spatio⁃temporal variation of odor compounds, together with water quality parameters and composition and quantity of algae, were monitored in Tangxi River, Hefei City, during 2014 2015U001001b0 The results showed that the odor in Tangxi River outbroke in summer and the highest concentration of 2⁃methylisoborneol and geosmin were 4909 and 197 ng / L,respectivelyU001001b0 Extensive algae composition analysis revealed that Cyanophyta was the dominant species in autumn and winter, while Euglenophyta, Chlorophyta or Cryptophyta were the dominant species in spring and summerU001001b0 Principal component analysis showed that the water quality was influ⁃ ent by light, organic compound, microbial activity, nitrogen and phosphorus in waterU001001b0 Additionally, significant relationships were detected between nitrogen concentration and odor compounds, which indicated that nitrogen was one of the main reasons for odor problems in Tangxi River.