Wastewater generated from pulp and paper production still contains pollutants and contaminants, so appropriate and economical materials are needed to reduce pollutants by using adsorbents from bottom ash. This study examines the characteristics of bottom ash and pulp and paper wastewater, the effect of stirring time, stirring speed, and adsorbent activation temperature on decreasing environmental parameters of wastewater. The synthesis of bottom ash as an adsorbent was carried out by heating at 100 and 200 °C for 1 hour. The wastewater treatment process with maximum yield occurs at a stirring speed of 100 rpm for 50 min. The use of bottom ash without heating as an adsorbent in the pulp and paper wastewater treatment process has reduced TSS 77.5%, COD 85.72%, chloride 26.9%, TDS 1143 ppm, and EC 2180 s/cm, which have met the environmental quality standards.