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Treatment of leachate from Chania landfill using pilot scale horizontal subsurface flow constructed wetlands with gravel and biochar as substrate

Gialidis Miltiadis

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Year 2022
Type of Item Diploma Work
Bibliographic Citation Miltiadis Gialidis, "Treatment of leachate from Chania landfill using pilot scale horizontal subsurface flow constructed wetlands with gravel and biochar as substrate", Diploma Work, School of Chemical and Environmental Engineering, Technical University of Crete, Chania, Greece, 2022
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Nowadays, the protection of the environment is one of the main issues for every society. The correct treatment and management of waste contributes the most to the achievement of this goal.In order to reach this goal, it is necessary to adopt sustainable waste management procedures.Leachate, which is the subject of this diploma thesis, is the sewage that comes out of the waste landfill and can pollute the environment dangerously. For this reason, it is of great importance that leachate be treated in an environmentally friendly and at the same time low-cost way.The constructed wetlands are an effective and sustainable system that could replace and/or be combined with the existing traditional methods of waste landfill leachate treatment. And this is because the constructed wetland demands very low or even zero energy, low construction cost and easy autonomous operation compared to the traditional systems.The aim of this diploma thesis is to evaluate the treatment of the landfill leachate in constructed wetlands pilot systems with plant species of common reed (Phragmites australis) and substrate of gravel and biochar produced from olive prunnings.The selected system was a horizontal sub-surface flow constructed wetland. The landfill leachate used in the constructed wetland was collected from the landfill of Chania after the flocculation.Two constructed wetlands pilot systems were tested. The one was filled with gravel(G) and the other with gravel together with biochar (GB). There was a daily inflow supply of leachate and every week the physicochemical parameters of samples were analyzed. The inflow and outflow concentrations at the two constructed wetlands were examined and the removal of the polluting load was calculated in consideration with the physicochemical parameters pH and EC, the biological and chemical parameters COD, TSS, NH4-N, NO3-N, NO2-N, TP, PO43-P, as well as metals. BOD measurements were not performed due to its low level.Futhermore, during the experiment procedure, a daily measurement of the inflow and the outflow concentrations was recorded, for the evaluation of the evapotranspiration in the two constructed wetlands.After a five-month operation of the two wetlands and the analysis of the results, we concluded that the constructed wetland GB performed much better in the polluting load removal, showing that the use of the biochar plays a crucial role in the results of this diploma thesis.The replacement of the certain traditional processes in the landfill with horizontal sub-surface (TY HF) flow constructed wetlands using gravel and biochar as substrate materials could be a sustainable and promising alternative solution.

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