COD in the presence of Perlite gets better behavior than Alum, generally this behavior changed to increase the COD removal ratio with the increasing of the amount of Perlite up to 40 mn which reached upto 92.8%. The increase of the substance weight decreases the removal efficiency. This better performance mainly refers to the change in numbers of microorganisms and the degradation of organic compounds due to the adsorbent behaviors of Perlite.