Purification of Forest Clear-Cut Runoff Water Using Biochar: A Meso-Scale Laboratory Column Experiment

Water

Jukka Pumpanen¹  Taija Saarela¹  Marjo Palviainen²  Elham Kakaei Lafdani³  Ari Laurén³ 

[1]Department of Environmental and Biological Sciences, University of Eastern Finland, Yliopistonranta 1 E, FI-70210 Kuopio, Finland

[2]Department of Forest Sciences, University of Helsinki, Latokartanonkaari 7, FI-00014 Helsinki, Finland

[3]School of Forest Sciences, University of Eastern Finland, Yliopistokatu 7, FI-80101 Joensuu, Finland

关键词: adsorption;    biochar reactor;    column experiment;    inorganic nitrogen;    total nitrogen;   

DOI  :  10.3390/w12020478

来源: DOAJ

【 摘 要 】

Biochar can be an effective sorbent material for removal of nutrients from water due to its high specific surface area, porous structure, and high cation and anion exchange capacity. The aim of this study was to test a biochar reactor and to evaluate its efficiency in runoff water purification and consecutive nutrient recycling in clear-cut peatland forests. The goodness of the method was tested in a meso-scale (water volume thousands of liters) reactor experiment by circulating runoff water through wood biochar-filled columns and by determining water nutrient concentrations in the column inlet and outlet. The pseudo-first and second order kinetic models were fitted to the experimental data and the adsorption rate (K_ad) and maximum adsorption capacity (Q_max) of the biochar reactor were quantified. The concentration of total nitrogen (TN) decreased by 58% during the 8-week experiment; the majority of TN adsorption occurred within the first 3 days. In addition, NO₃-N and NH₄-N concentrations decreased below the detection limit in 5 days after the beginning of the experiment. The maximum adsorption capacity of the biochar reactor varied between 0.03−0.04 mg g⁻¹ biochar for NH₄-N, and was equal to 0.02 mg g⁻¹ biochar for TN. The results demonstrated that the biochar reactor was not able to adsorb TN when the water TN concentration was below 0.4 mg L⁻¹. These results suggest that a biochar reactor can be a useful and effective method for runoff water purification in clear-cut forests and further development and testing is warranted. Unlike traditional water protection methods in peatland forestry, the biochar reactor can effectively remove NO₃-N from water. This makes the biochar reactor a promising water protection tool to be tested in sites where there is the risk of a high rate of nutrient export after forest harvesting or drainage.

【 授权许可】

Unknown