Water treatment using nanoporous graphene membrane for irrigation system in Davao City

Abstract

This research focuses on the efficiency of using nanoporous graphene membranes in treating water that flows in the irrigation system of Davao City. The very main source of water for irrigation is the rivers classified as D in the DENR Water Classification. However, direct disposal of waste to the river may contaminate the water in the irrigation which may affect livestock farming, crop production, and other agricultural sectors depending on the irrigation. In the worst case, contaminants and toxic chemicals can cause death. To prevent this from worsening, a treatment plant in the inlet of irrigation is proposed to ensure the flowing water is safe. An innovative composition of Nanofilter by combining reduced graphene oxide and polyvinyl alcohol cross-linked using glutaraldehyde. To verify the outcome mixture/solution for reduced graphene oxide in comparison to the ideal rGO based on the previous studies, SEM analysis is performed. After the completion of crosslinking rGO and PVA, the resulting nanofiber which is a Nanofilter will be used to filter water. A raw water sample is collected from the irrigation in Calinan, Davao City. The treatment process takes place. The samples of raw and treated water were secured for quality tests based on the DENR Water Quality Criteria for Irrigation under D classification. The result showed that the raw did not meet the Dissolved Oxygen (DO) level and biochemical oxygen demand (BOD) which resulted in 1mg/L and 43mg/L. Only the pH value passed with a result of 7.2. On the contrary, the treated water passed the requirements of DENR Irrigation water quality criteria. The results are 7.0 for pH, 3mg/L for dissolved oxygen and the biochemical oxygen demand is 10mg/L. Based on these results the raw water compared to treated water has significantly improved and met the desired values of DENR parameters in assessing the irrigation water quality. In the end, a design of a water treatment plant situated in the inlet of the irrigation is proposed with a capacity of 3.25 m3 and discharge rate of 0.056 cu.m per second to prevent the contaminants from flowing in the irrigation by integrating Nanoporous Graphene Membrane.