Agro-based wastewater profile by biological treatment of pond treatment system in Kulai, Johor

Abstract

Agro-based wastewater industries tremendously impact the environment when discharged into rivers. The oil palm industry is one such industry, and its daily operations to produce palm oil generate large amounts of wastewater, called palm oil mill effluent (POME). A high organic content of POME is continuously produced, and its production increases annually. The challenge of the POME treatment system is to meet the required effluent standards, and the color of the POME is difficult to remove. Due to several advantages, the ponding system is the preferred conventional wastewater treatment method for POME. Therefore, this study aimed to investigate the performance characteristics of the ponding system in relation to color-causing compounds. This study collected POME samples from cooling, anaerobic, facultative, and two algae (aerobic) ponds. The physicochemical characteristics of the samples were measured in the influent and effluent of each pond, including the pH, biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), volatile suspended solids (VSS), total phosphorus (TP), total nitrogen (TN), ammoniacal nitrogen (AN), total organic carbon (TOC), color, oil and grease (O&G), carotene, phenolics, and tannin-lignin. Pollutants in POME were statistically analyzed for their relationships. To evaluate the efficiency of the ponding system, pollutant removal was measured for each biological treatment pond. The results showed that the biological treatment system removed 70-90% of the pollutants, with the final effluent meeting the acceptable standards for TN and AN parameters. However, removing color-causing compounds in POME, particularly phenolics (0.955, P = 0.003) and tannin-lignin (0.969, P = 0.001), remains a challenge in the treatment process. These compounds had the strongest correlation with color, with low removal rates observed in the facultative ponds due to floating sludge formation. Further analysis of the POME samples showed that carotene, which had the lowest presence in POME, was not significantly correlated with color (0.649, P = 0.163). This study can be useful for tertiary treatment, and additional treatment methods may be necessary to improve the effluent quality by polishing biologically treated POME.