Study on treatment of city tail water by constructed wetland with corn straw biochar substrate

Abstract

Constructed wetland (CW) has obvious advantages in city tail water treatment. The biochar preparation from corn straw is an effective measure for improving the straw utilization. In order to improve the pollutant removal rate of CW, the city tail water treatment based on straw biochar substrate was studied. The thermogravimetric experiment of straw, characteristics test (scanning electron microscope, pore structure, element, adsorption) of biochar and city tail water treatment experiment by CW was carried out. The results show that the carbon fixation rate of straw biochar prepared at 450 °C (10 °C ⋅ min −1 , 2 h, N 2 ) was 67.72%, and the adsorption capacity of biochar exceeded 40% of the requirements of wood activated carbon adsorption standard. When the proportion of biochar in substrate was 2.95%, the mean removal rates of ammonia nitrogen, total nitrogen and nitrate nitrogen was more than 85%. This study will be conducive to reducing straw carbon emissions and improve CW technical level. • The carbon fixation rate of biochar prepared at 450 °C (10 °C ⋅ min −1 , 2 h,) was 67.72% • The adsorption of straw biochar for NH4+-N was greater than that of TP and NO3–N • Elovich equation was good to simulate the dynamic adsorption of NH4+-N, NO3–N and TP • The nitrogen removal rate was over 85% when the mass ratio of biochar was 2.95% in CW.