<![CDATA[The Manunggal River, which flows through the districts of Gondokusuman, Pakualaman, and Umbulharjo in Yogyakarta City, has shown significant pollution levels. According to water quality monitoring conducted by the Yogyakarta City Environmental Service at the Mangkukusuman Bridge point, the concentrations of COD, BOD, and Nitrite exceed the Class II quality standards stipulated in the Yogyakarta Governor Regulation No. 20 of 2008, with recorded values of 31.14 mg/L, 10.88 mg/L, and 0.59 mg/L, respectively. This study aims to evaluate the effectiveness of papaya seed powder (Carica papaya L.) in reducing COD, BOD, and Nitrite concentrations in the river water. This experimental research employed a Pretest-Posttest Control Group Design, with data analyzed using effectiveness percentages and one-way ANOVA. Water samples were collected from the Manunggal River at the Mangkukusuman Bridge monitoring point in Baciro Yogyakarta. The results indicate that the application of papaya seed powder at concentrations of 6 g/L, 6.5 g/L, and 7 g/L inadvertently increased COD and BOD levels by 41.24%, 51.10%, and 55.93%, respectively. Conversely, the treatment succeeded in reducing Nitrite levels by 31.96%, 42.80%, and 31.81%. These findings suggest that while papaya seed powder (Carica papaya L.) is ineffective in lowering COD and BOD likely due to its organic content it demonstrates a capacity to reduce Nitrite concentrations, although the final levels still did not comply with the required water quality standards. ABSTRAK Sungai Manunggal yang melintasi Kecamatan Gondokusuman, Pakualaman, dan Umbulharjo Kota Yogyakarta ini, berdasarkan pemantauan kualitas air di titik Jembatan Mangkukusuman yang dilakukan Dinas Lingkungan Hidup Kota Yogyakarta, menunjukkan konsentrasi COD, BOD, dan nitrit yang melebihi baku mutu kelas II menurut Peraturan Gubernur DIY Nomor 20 Tahun 2008, yaitu COD 31,14 mg/L, BOD 10,88 mg/L, dan nitrit 0,59 mg/L. Penelitian ini bertujuan untuk mengetahui efektivitas serbuk biji pepaya (Carica papaya L.) dalam menurunkan konsentrasi COD, BOD, dan nitrit dalam air sungai. Penelitian ini merupakan experiment research menggunakan penelitian Pretest-Posttest Control Group Design, kemudian dihitung persentase efektivitasnya. Sampel yang digunakan adalah air Sungai Manunggal dengan titik pantau Jembatan Mangkukusuman di Banciro, Kota Yogyakarta. Hasil penelitian menunjukkan bahwa serbuk biji pepaya pada konsentrasi 6 gr/L, 6,5 gr/L, 7 gr/L justru menaikkan COD dan BOD sebesar 41,24%, 51,10% dan 55,93%. Namun, dapat menurunkan nitrit sebesar 31,96%, 42,80%, dan 31,81%. Hal ini menunjukkan bahwa serbuk biji pepaya (Carica papaya L.) tidak efektif untuk menurunkan COD dan BOD, namun dapat menurunkan konsentrasi nitrit dalam air sungai meskipun belum memenuhi standar baku mutu.]]>
