RESUMEN

Stormwater treatment requires effective control measures and development of low-cost and high-efficiency technologies. An integrated system is developed by combining a baffled vertical-flow constructed wetland (BVFCW) and a scenic water body for stormwater quality control purpose. The objectives of the study are to compare the pollutant removal performance of the full-scale integrated system with four groups of wetland-to-scenic water body area ratios (WSARs) including 1/11, 2/11, 3/11, 4/11 and investigate its treatment efficiency. Results show that the system performs better in the removal of chemical oxygen demand (COD), total nitrogen (TN), ammonia nitrogen (NH4+-N), nitrate-nitrogen (NO3-N), and total phosphorus (TP) at the WSAR of 4/11 than that at 3/11 in sixteen-day operation, while it reaches the highest total nitrogen (TN) removal efficiency of 74.0% at the WSAR of 2/11 due to relatively rich carbon source and high influent TN concentration. The integrated system may prove the most effective COD removal at the WSAR of 4/11 for four-time aerobic/anaerobic alternating conditions, a longer flow path and more time to contact with substrates, although the influent COD is lower than that at 2/11 and 1/11. After sixteen-day operation, BVFCW achieved COD removal rate of 90.3%, NH4+-N removal rate of 85.7%, NO3-N removal rate of 68.6%, and TP removal rate of 52.5% at the WSAR of 4/11. At the WSAR of 1/11, effluent met the Class IV requirements in Chinese standards after one-week operation, while effluent met the Class III requirements under the rest conditions. Since effluent in all WSARs met the standards, WSARs of 1/11 and 2/11 were recommended.

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RESUMEN

In consideration of severe eutrophication of scenic water caused by pollutants released from sediments in summer, calcium peroxide (CaO2) was adopted as the slow release peroxide to improve the water quality in a field experiment of 600 m2. The effect of CaO2 on the overlying water, interstitial water, sediment, and sediment microorganisms of scenic water was studied. Results for two months indicated that the dissolved oxygen (DO) concentration of the overlying water in the test zone was 3.78 times that in the control zone; the oxidation-reduction potential (ORP) in the overlying water and sediment increased significantly (p = 0.002 and p = 0). Meanwhile, CaO2 could effectively inhibit the release of nitrogen (N) and phosphorus (P) from the sediment and could obviously reduce the concentrations of N and P in the overlying water by enhancing the microbiological action. Moreover, the average concentrations of total nitrogen and total phosphorus in the overlying water of the test zone were 46.27% and 50.51% of those in control zone, respectively, and the concentrations of N and P in the interstitial water decreased during the entire experiment. In addition, CaO2 decreased the relative abundance of anaerobic bacteria in the sediment, whereas it increased that of aerobic bacteria and promoted the appearance of the functional bacteria, such as Nitrospirae and Thermodesulfoba. In conclusion, CaO2 can improve the DO and ORP in the eutrophic water effectively and change the microbial community in the sediment to a certain extent, thereby controlling the pollutants released from the sediment and reducing the N and P concentrations in the overlying water. Thus, CaO2 can effectively realize the purification and restoration of the severely eutrophic scenic water.

RESUMEN

Six micro-polluted landscape water bodies were selected to explore the relationship between water quality and the nirS-Type denitrifier community structure and diversity with an Illumina high-throughput sequencing technique. The results of a physico-chemical analysis of the water bodies showed that the Fengqing Park (FQ) and Laodong Park (LD) water bodies were classified as inferior Ⅴ water quality, the Qujiang Park (QJ), Mutasi Park (MTS), and Xinjiyuan Park (XJY) water bodies were classified as Ⅴ water quality, and the Yongyang Park (YY) water quality was classified as Ⅳ. The TN values varied from 1.21 mg·L-1 to 6.50 mg·L-1, with the lowest value found in YY and the highest in FQ (P<0.05). TP was significantly higher in LD (0.10 mg·L-1) and significantly lower in QJ[0.02 mg·L-1 (P<0.05)]. The NH4+-N in LD was 4.44 times higher than that in QJ and FQ (P<0.01). Illumina high-throughput sequencing revealed that the denitrifier community composition was significantly different among the six water bodies, and Paracoccus sp., Pseudomonas sp., and Rubrivivax sp. were the dominant genus species. A principle component analysis (PCA) indicated that the nirS-Type denitrifier communities of XJY and MTS were mainly regulated by NH4+-N and the permanganate index, LD and FQ were significantly influenced by NO3--N, NO2--N, TN, TP, and DO, and YY was significantly influenced by pH value. Our results showed that nirS-Type denitrifier communities were regulated by different water quality indicators.

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