The Effect of Light-Emitting Diodes Illumination Period and Light Intensity on High Rate Algal Reactor System in Laundry Wastewater Treatment

Wastewater that contain high concentration of nutrients can create instability in water ecosystem if left untreated. Laundry wastewater contain nutrients with high concentration. Nutrients that commonly found in laundry wastewater are nitrogen and phosphorus. This study had a purpose to determine the effect of illumination period and light intensity for the removal of Chemical Oxygen Demand (COD), Nitrogen-ammonia (NH3-N), and phosphate (P) content using Chlorella vulgaris in High Rate Algal Reactor (HRAR) treatment. Variables that used were exposure period of 12 and 24 hours and light intensity of 2000-3000 Lux, 4000-5000 Lux, and 6000-7000 lux. Parameters tested in this study were COD, Nitrogen-ammonia, phosphate to determine the efficiency of nutrient removal and Chlorophyll α to determine the condition of algae development. Results showed that the highest nutrient removal obtained by the reactor with 24 hours illumination period with light intensity of 6000-7000 Lux that able to remove 54.63% of COD, and 22.15% of P. The 12 hours of illumination period was better to remove NH3-N up to 50.07%. Based on the result of statistic test, illumination period did not significantly influence the removal efficiency of COD, NH3-N and P shown by P-value >0.05, while light intensity was significantly affect the removal of COD and NH3-N showed by P value