(545ac) Sorption Characteristics of Nitrogen and Phosphorus Onto Biochar from Aqueous Solution

Nitrogen (N) and phosphorus (P) pollution in water has created a serious concern worldwide due to its adverse effects on the environment. N and P concentrations have increased in water due to the discharge from point and non-point sources. High N concentration causes various health problems such as methemoglobinemia, or blue baby syndrome. On the other hand, P is one of the limiting nutrients to control eutrophication in natural ecosystems. Eutrophication causes excessive algal growth, known as algal bloom, which has various detrimental effects such as increase of water treatment cost, decrease of oxygen content and recreational use of water. Different technologies are available to remove N and P from water. Among these, the adsorption process has proven to be an effective and low-cost technique for the removal of these pollutants. Nowadays, biochar as an adsorbent has received significant attention because of its distinctive characteristics. Therefore, this study focuses on the removal of N and P from aqueous solution by batch adsorption experiments using biochar derived from wood chips (spruce, pine, and fir). Sorption characteristics of N and P onto biochar were evaluated as a function of biochar dosages, initial concentrations of N and P, and pH using synthetic water. At the end of each batch test, samples were collected and analyzed to determine the residual NH₄⁺-N and P concentrations using a HACH DR 2800 Spectrophotometer. Results demonstrated that N removal increased to 80% with the increase of biochar dosage at 100 g/L whereas N removal decreased with the increase of initial N concentration. The highest N removal was achieved in a pH range from 4 to 6. In case of P removal, the percentage of P removal increased consistently with the increase of biochar dosages except at the end of the test. The highest P removal was 60% at a biochar dosage of 80 g/L. P removal deteriorated with the increase of initial P concentration. The maximum P removal was obtained at a pH value of 2. The sorption isotherm followed the Langmuir model for both N and P sorption onto biochar. The sorption kinetics of N and P onto biochar followed a second order kinetic model. This study indicated that biochar has the potential to remove both N and P from aqueous solution. Further experiments are in progress to investigate the removal mechanism of N and P onto biochar using Fourier Transform Infrared (FTIR) Spectroscopy.