Dissertation
Dissertation > Environmental science, safety science > Processing and comprehensive utilization of waste > General issues > Wastewater treatment and utilization

Influence of Hydraulic Retention Time and Wastewater Concentration by the Plants in Constructed Wetland

Author DiXu
Tutor QiuLing
School Northwest University of Science and Technology
Course Agricultural Biological Environmental and Energy Engineering
Keywords Constructed wetlands Wetland plants Hydraulic retention time Influent concentration Purifying effect
CLC X703
Type Master's thesis
Year 2009
Downloads 156
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In recent years, water shortage and water pollution seriously hampered the country's economic and social development, the impact on people's lives and even a threat to human health. Artificial wetlands as a water purification effect, investment running costs low ecological wastewater treatment technology, the role of physical, chemical and biological treatment of sewage by a wide range of applications. The plant plays a key role as an important part of the artificial wetland. This article through simulation of artificial wetlands system, research to explore the six kinds of wetland plants in the hydraulic dwell time and influent concentration such as impact factors conditions of sewage treatment effects test and record a wetland plants in growth status and system matrix nitrification denitrification intensity get the following results: (1) select cattails, yellow iris, willow, reed, Lythrum vegetables and calamus test wetland plants studied HRT were 1,2,3,4,5,6 d purification plant pollutants effect. The results show that the HRT = 4d, wetland plant systems CODcr of pollutants BOD5, TP, TN, NH 4 -N and NO 3 - -N average removal rate were 92.3%, 97.2%, 93.2%, 77.2%, 95.9% and 97.8%, respectively, higher than the treatment effect of hydraulic retention time. Removal of cattail system CODcr best removal rate was 95.9%; the willow system of TP removal efficiency of 99.6%, better than other plant systems; the TN removal works best calamus system, the removal rate reed system was 92.4%; remove NH 4 -N showed advantages, the removal rate of 98.1%; addition to the cattail systems, other plant systems NO < sub> 3 - -N of the removal of more than 95%. ⑵ respectively configured low, medium, and high concentrations of sewage as influent of the system, HRT = 4d system of wetland plants to different concentrations of sewage purification effect. The results show that, at low concentrations, higher of calamus and willows system on the removal efficiency of COD cr , 95.3% and 94.8%, respectively; reed system of BOD 5 removal rate, 94.1%; wetland plants TP has a better purification effect, the removal rate of 90%; the reeds and calamus system of TN, NH / sub> . < / sup>-N removal rate reached 96.7%, 95.6% and 93.7%, 95.8%. At moderate concentrations, the the cattails system COD cr and the NH 4 -N removal rates were 94.4% and 92.2%, higher than the other plant systems, BOD 5 , TP, TN removal best plant systems with low concentrations of the same. Under conditions of high concentration sewage the cattail systems of of CODcr of BOD5 removal best willow system removed the highest TP removal, calamus and Typha system the TN effect of the best, the NH 4 highest -N removal cattails and willows. Plant removal rate is higher than the high concentration, low concentrations of sewage wastewater removal efficiency. ⑶ through wetland plants during the test the growth status of the study, the results showed that, Lythrum test late emergence wilt phenomenon and other wetland plants growth well, new branches grow, plants significantly change high becomes large. The growth of cattails and reeds height variation increased the 157cm and 136cm; cattail fresh weight increase most 498.8g; wetland plants after harvest moisture content was significantly lower than prior to planting. ⑷ matrix nitrification and denitrification strength test studies have shown that nitrification and denitrification strength of each system matrix than in late July when the trial began (end of June) and end (end of August); comparison between wetland plant systems, the cattails system matrix nitrification the highest intensity of the highest intensity, willow plants denitrification. ⑸ willow as a new type of artificial wetland plants to sewage good purifying effect, TP, TN removal efficiency reached 99.6% and 91.2%, respectively, and grow well in the sewage can overwinter growth and improve artificial wetland treatment effect in winter reduce long-term operating costs. Finally, willows, cattails, reeds and iris and other plants in constructed wetland project and recommendations focus on wetland plants.

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