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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Water Management Research » Research » Publications at this Location » Publication #339803
Research Project: Develop Water Management Strategies to Sustain Water Productivity and Protect Water Quality in Irrigated Agriculture

Location: Water Management Research

Title: Effects of vegetations and temperature on nutrient removal and microbiology in horizontal subsurface low constructed wetland for treatment of domestic sewage

Author
item ZHOU, QING - Northeast Institute Of Geography And Agronomy, Cas
item ZHU, HUI - Northeast Institute Of Geography And Agronomy, Cas
item Banuelos, Gary
item YAN, BAIXING - Northeast Institute Of Geography And Agronomy, Cas
item LIANG, YINXIU - Northeast Institute Of Geography And Agronomy, Cas
item YU, XIANFEI - Northeast Institute Of Geography And Agronomy, Cas
item CHENG, XIANWEI - Northeast Institute Of Geography And Agronomy, Cas
item CHEN, LIJIANG - Northeast Institute Of Geography And Agronomy, Cas

Submitted to: Water, Air, and Soil Pollution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/30/2017
Publication Date: 2/11/2017
Citation: Zhou, Q., Zhu, H., Banuelos, G.S., Yan, B., Liang, Y., Yu, X., Cheng, X., Chen, L. 2017. Effects of vegetations and temperature on nutrient removal and microbiology in horizontal subsurface low constructed wetland for treatment of domestic sewage. Water, Air, and Soil Pollution. 228(2017):95. doi: 10.1007/s11270-017-3280-1.

Interpretive Summary: The direct discharge of untreated domestic wastewater represents a major source of nutrients entering into aquatic environments, which may cause serious ecological problems, e.g., eutrophication. In developing countries, the treatment and reclamation of domestic wastewater has become a difficult issue especially due to the effects of worsening environmentally-unfriendly activities and increasing population. Numerous traditional technologies for domestic wastewater purification (e.g., activated sludge treatment, membrane bioreactor, and biofilm process, etc.) have been widely applied for domestic sewage treatment in many countries. However, low-cost and easily managed technologies such as constructed wetlands (CWs) may be a more practical alternative for wastewater treatment in rural areas of developing countries, e.g., China. The efficient removal of nutrients can be achieved through a series of biotic and abiotic processes, especially those occurring around the rhizosphere of vegetation used in CWs. In this study, we compared different CWs (e.g., polyculture, monoculture, and no vegetation) for their abilities to clean simulated domestic sewage. Our results showed that CWs with vegetation (especially polyculture) have a higher removal efficiency of organic compounds and nutrients than those CWs without plants. Among the different CWs, the CW with polyculture was the best strategy for treating the simulated domestic sewage. In this regard, the vegetated CWs reduced total nitrogen and phosphorus loss by plant uptake, while the roots provided surface and organic carbon for bacteria to thrive. These bacteria likely contributed to additional removal of nitrates in the water. The multi-interaction among nitrogen, phosphorus, and organic carbon in CW with polyculture is complex but our study shows that its use should be further investigated in future field studies.

Technical Abstract: The direct discharge of untreated domestic wastewater represents a major source of nutrients entering into aquatic environments, which may cause serious ecological problems, e.g., eutrophication. In this regard, low-cost and easily managed technologies such as constructed wetlands (CWs) provide a good alternative for wastewater treatment in rural areas of developing countries, e.g., China. In this study, four bench-scale CWs were established for treatment of domestic sewage treatment. The CWs were cultivated with polyculture (Canna indica + Lythrum salicaria), monoculture (Canna indica), monoculture (Lythrum salicaria) and unplanted control, respectively. The removal efficiency of each type of CW was evaluated by three experiments as affected by vegetation, nutrient loading rates, and temperature. Results of Experiment 1 with different vegetation indicated that nutrient removal of NH +-N, total nitrogen (TN)and total phosphorous (TP) was greater in polyculture (Canna indica and Lythrum salicaria) than those in monoculture and unplanted control. The removal percentages of NH +-N, TN, and TP were 99.3%, 98.0%, and 94.5%, respectively, in polyculture. In experiment 2 with different NH +-N loading rates, NH +-N was almost completely removed (99.5%) in polyculture for both NH +-N loading rates (8.2 g m-2 and 13.6 g m-2, respectively). Additionally, the reduction of TP and chemical oxygen demand (COD) in CWs with vegetation (for polyculture or monoculture) was relatively stable, however, unplanted control exhibited high fluctuation in removal percentages of TP and COD. In Experiment 3 with different temperatures ranging from 8.9 to 25.5°C, the removal percentages of NH4+-N, NO +-N, TN and TP tended to decrease with a decrease of temperature in all CWs. A sharper decline in the removal percentage of NO3+-N of all CWs (> 39%) was observed at low temperature (8.9°C). Additionally, the microbial biomass of unplanted control decreased with a decrease in temperature, while microbial biomass of CWs with vegetation tended to increase from 19.8 to 25.5°C. In conclusion, CW cultivated with polyculture was more efficient for the purification of domestic sewage as compared to CW monoculture or unplanted control. This study could provide useful information for enhancing the efficiency of CWs, as well as future design, application, and operation management of CWs.