Application of response surface methodology (RSM) for optimization of ammoniacal nitrogen removal from palm oil mill wastewater using limestone roughing filter

Abstract

The creation of very pollute palm oil mill waste water has resulted in semiserious environmental hazards. The reason for the current study is to test the optimal removal of ammonia nitrogen (NH3-N) from palm oil mill waste water by filtration using inexpensive filters media in place of current methods, to remove ammonia nitrogen from palm oil mill effluent. A series of batch and column studies were conducted using a different particle size of limestone (4, 12 and 20 mm) at various filtration rates of 20 ml/min, 60 ml/min and 100 ml/min. An experimental model design was conducted using Central Composite Design (CCD) in Response Surface Methodology (RSM). RSM was used to calculate the outcomes of process variables and their role in reaching ideal conditions. Equilibrium isotherms in this study were evaluated using the Langmuir and Freundlich isotherm. Using statistical analysis, the NH3–N removal model proved to be very significant with very low probability values (0.0001). The column study showed that ideal NH3-N removal was attained using a lower flow rate and smaller sized limestone (LS). The ideal conditions found when using 4 mm limestone and a 20 ml/min flow rate. This resulted in 45.3% removal of NH3–N which was seen in the predicted model, and fit well with the laboratory results (45%). The adsorption isotherm data fit the Langmuir isotherm.