Evidence of Improved Seawater Quality using a Slow Sand Filtration

Abstract

In recent years water treatment methods under pressurized systems have been considered as the optimum high-rate filtration techniques. Unpressurized-slow sand filtration can be the cheapest and most efficient method, among others. This research aims to test the performance of a reliable seawater filtration system, using three different iterations. The filters have been designed considering many types of filtration layers such as sand, gravel, palm chlorophyll and other layers. The results of routine tests showed that the seawater pH, and TSS, and conductivity in the Gulf of Oman are relatively high. The pH values were decreased from 9.4 to 8.4 (filter 1), 9.0 (filter 2), and 8.7 (filter 3). Filter three has a reduced value of conductivity from 13.06 to 12.81 Ms/cm while a slight increase in filters 1 and 2. The TSS values were significantly reduced from 12.42 mg/L to 1.682 mg/L (filter 1), 2.478 mg/L (filter 2), and 1.200 mg/L (filter 3). This reflects the efficiency for each filter for this parameter is 86.5% for filter 1, 80% for filter 2, while 90.3% for filter three. Water velocity through each layer was monitored using Darcy law where the water of filter three has the longest residence time and slowest flow per time. The fastest flow was in filter one with an average of 0.5 L/minutes, filter two has an average flow of 0.088 L/minutes, while filter 3 has a flow rate of 0.026 L/minutes. The third filter has provided the best performance according to the results. Statistical analysis was conducted to understand the correlation between different parameters. As per Pearson correlation, there is a significant correlation between pH and conductivity values for 19 samples (0.989), while the correlation with TSS is relatively weak (0.364).