Asian Journal of Biology

Objective: Indonesian State Oil Company processes crude oil into fuel oil, non-fuel fuel and petrochemical, this activity produces waste that allows pollution of the Donan river. herefore, this study aims to analyze the quality of Donan streams based on water chemical - physical quality, and the plankton and benthos diversity conditions, due to the impact of waste discharged from the installation of wastewater treatment units from cilacap state oil companies.

Methodology: This research was conducted by analyzing water samples with Atomic Absorption Spectrophotometer method. Water sampling is done at point 2 sampling points is at sampling point A = holding basin output 39 and B = holding basin output 66 - 49.

Results: Based onBiological Oxygen Demand (ppm) analysis between 5.5 ppm - 7.2 ppm. Chemical Oxygen Demand concentration (ppm) between 33.6 ppm - 33.7 ppm. While the concentration of Dissolved Oxygen (ppm) between 6.0 ppm - 5.9 ppm. The results of heavy metal chromium analysis with concentrations between 0.04 ppm - 0.05 ppm. Free chlorine concentration with concentration of 0.04 ppm - 0.05 ppm. While the concentration of H₂S was 0.2 ppm . and the fluoride concentration was 0.88 ppm - 1.01 ppm. Based on the quality standards stipulated by Regulation of the Minister of Environment No. 19 of 2010 and Regional Regulations of Central Java, No. 5 of 2012 shows that the Donan river on the verge of polluted. Plankton analysis was found as the dominant species of Coscinodiscus sp and Nitzschia sp which is a bio-indicator of pollutant. The waters are contaminated lightly.