Evaluation of Pollutant Load Capacity and Distribution Patterns of Palm Oil Industrial Wastewater in the Kappuna River Using Mass Balance and QUAL2Kw

Abstract

Discharge of palm oil mill wastewater into water bodies requires an integrated evaluation of wastewater characteristics, treatment capacity, hydrological conditions, baseline water quality, and pollutant distribution patterns. This study aimed to evaluate the pollutant load capacity and wastewater distribution patterns of PT Kasmar Matano Persada in the Kappuna River based on the 2026 technical study document. A descriptive-evaluative approach was applied using secondary data analysis, including palm oil mill effluent (POME) and domestic wastewater characteristics, discharge rates, river and groundwater quality, seasonal river flow, mass balance calculations, QUAL2Kw modeling, wastewater treatment plant (WWTP) design, and monitoring plans. Compliance was evaluated by comparing parameter values with applicable water quality standards. POME discharge was estimated at 336 m³/day, while domestic wastewater discharge was 4.2 m³/day. The Kappuna River discharge averaged 4.90 m³/s during the dry season and 8.20 m³/s during the rainy season. Initial water quality measurements indicated BOD of 2.9 mg/L, COD of 22 mg/L, TSS of 38 mg/L, and ammonia of 0.28 mg/L, with ammonia exceeding the reference value of 0.20 mg/L. Dry-season mass balance results showed BOD of 3.0 mg/L, COD of 24.18 mg/L, TSS of 43.98 mg/L, and oil and grease of 0.5 mg/L. QUAL2Kw modeling demonstrated decreasing pollutant concentrations downstream, with a direct influence zone extending 50–80 m from the discharge point. The POME WWTP consisted of nine treatment ponds with an effective volume of 31,468 m³ and a hydraulic retention time of 93.72 days. The Kappuna River retained sufficient dilution capacity; however, several parameters showed limited compliance margins. Continuous monitoring, laboratory verification, and periodic upstream–downstream evaluations are recommended to ensure sustained environmental quality.