Thanawat Udombua creator Thammarat Koottatep Chairperson Xue, Wenchao Examination committee Tatchai Pussayanavin Examination committee Royal Thai Government Fellowship Scholarship Donor text series technical report th Pathum Thani, Thailand Asian Institute of Technology 2021 continuing eng 70 leaves : ill. Constructed wetlands (CWs) were considered to treat effluent water from the solar septic tank afterward. Lateritic soil is suitable to select as the main material of media. However, the efficiency of lateritic soil to adsorb N and P in SST effluent still is low. Biochar has been used for soil remediations traditionally which it has benefits for plant uptake of nutrient (N and P). The rubber wood sawdust has the highest carbon. For effective biochar, the biomass was activated by 2.3M MgCl2.6H2O before a pyrolysis. Therefore, biochar can be used for combining lateritic soil to apply in the soil-based constructed wetlandsto be a Biochar-Based Constructed Wetland (BBCW). The results of media efficiency showed that yield percentage of biochar NB-300, MgB-300, NB-500, MgB-500, NB-600, and MgB-600 are 58.5, 58.36, 25.4, 40.42, 23.96, and 33.9, respectively. Biochar pyrolysis at low temperature was weight more than high temperature, and the pyrolysis at 500 o C and 600 o C, the MgBs was weight more than the NBs. The NH3-N adsorption of MgB-500 were 5.32 mg/g, which was maximum compared with other conditions. The MgB-600 and MgB-500 were the highest adsorption of TP arrived at 0.78 mg/g and 0.75 mg/g, respectively. Therefore, the MgB-500 was employed to used or applied into a constructed wetland. In addition, MgB-500 can highly adsorb NH3-N and TP for 24h and 8h, respectively from a time function experiment. The results of investigation of the BBCW show that concentrations of COD, TSS of the BBCW can remove that more than 80% and 90%, respectively. The BBCW were nutrient (N and P) removal efficiencies highly more than SBUP which was only soil as media layer. The BBCW was removal efficiency of TN were 64.14%, 65.08%, and 75.90% for HRT 12h, 24h, and 36h, respectively, which were TN removal efficiency more than BBUP which was unplanted. For design criteria, an appreciate criteria to design the BBCW to remove pollutants in SST effluent was HLR 0.09 m3 /m2 .day. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering and Management Thesis (M. Sc.) - Asian Institute of Technology, 2021 Biochar Environmental aspects Constructed wetlands Septic tanks Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B13491 http://203.159.5.9/ait-thesis/detail.php?q=B13491 210704 20260817171418.0