The present work studied several ways for wastewater treatment for the waste from the pulp and paper industries including the recovery of some valuable components from this waste and reaching the acceptable environmental limits for the treatment of waste. The acidification technique showed high efficiency for the removal of solids from the black liquor. A proper treatment for the effluent produced from the pulp and paper industry that used rice straw as raw material. The dose of the alum as a coagulant has an effect on the solid process and is due to the high percentage of solids in the black liquor. Hydrochloric acid is used to control the pH of the solution and separating most of the solids from the black liquor. Sodium hydroxide can be used to remove silica from the other solids by forming sodium silicate. The amount of solids precipitated increased by increasing the stirring time, temperature, rpm of the agitator, and decreasing pH. IR spectroscopy was carried out on the solid to assign the functional groups. Thermal analysis and EDX analysis were done to study the thermal properties of the solids. A proper design of the mixer and drier is accomplished to provide high efficiency of the silica removal process.