Feasibility of using rural waste products to increase the denitrification efficiency in a surface flow constructed wetland

JOURNAL OF HYDROLOGY

卷:578

Article

Margalef-Marti, Rosanna¹  Carrey, Raul¹  Merchan, Daniel²  Soler, Albert¹  Causape, Jesus³  Otero, Neus^1,4 

[1] Univ Barcelona, Fac Ciincies Terra, Dept Mineral Petrol & Geol Aplicada, Grp MAiMA,SGR Mineral Aplicada Geoquim & Geomicro, C Marti & Franques S-N, E-08028 Barcelona, Spain

[2] Univ Publ Navarra, Dept Engn, IS FOOD Inst Innovat & Sustainable Dev Food Chain, Campus Arrosadia, Navarra 31006, Spain

[3] Geol Survey Spain IGME, C Manuel Lasala 44 9 B, Zaragoza 50006, Spain

[4] Generalitat Catalunya, Barcelona, Spain

关键词: Denitrification;    Constructed wetland;    Electron donor;    Isotopic fractionation;    Remediation;   

DOI  :  10.1016/j.jhydrol.2019.124035

来源: Elsevier

【 摘 要 】

A surface flow constructed wetland (CW) was set in the Lerma gully to decrease nitrate (NO3-) pollution from agricultural runoff water. The water flow rate and NO3- concentration were monitored at the inlet and the outlet, and sampling campaigns were performed which consisted of collecting six water samples along the CW flow line. After two years of operation, the NO3- attenuation was limited at a flow rate of similar to 2.5 L/s and became negligible at similar to 5.5 L/s. The present work aimed to assess the feasibility of using rural waste products (wheat hay, corn stubble, and animal compost) to induce denitrification in the CW, to assess the effect of temperature on this process, and to trace the efficiency of the treatment by using isotopic tools. In the first stage, microcosm experiments were performed. Afterwards, the selected waste material was applied in the CW, and the treatment efficiency was evaluated by means of a chemical and isotopic characterization and using the isotopic fractionation (epsilon) values calculated from laboratory experiments to avoid field-scale interference. The microcosms results showed that the stubble was the most appropriate material for application in the CW, but the denitrification rate was found to decrease with temperature. In the CW, biostimulation in autumn-winter promoted NO3- attenuation between two weeks and one month (a reduction in NO3- between 1.2 and 1.5 mM was achieved). After the biostimulation in spring-summer, the attenuation was maintained for approximately three months (NO3- reduction between 0.1 and 1.5 mM). The epsilon N-15(NO3/N2) and epsilon O-18(NO3/N2) values obtained from the laboratory experiments allowed to estimate the induced denitrification percentage. At an approximate average flow rate of 16 L/s, at least 60% of NO3- attenuation was achieved in the CW. The field samples exhibited a slope of 1.0 for delta O-18-NO3- versus delta N-15-NO3-, similar to those of the laboratory experiments (0.9-1.2). Plant uptake seemed to play a minor role in NO3- attenuation in the CW. Hence, the application of stubble in the CW allowed the removal of large amounts of NO3- from the Lerma gully, especially when applied during the warm months, but its efficacy was limited to a short time period (up to three months).

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