Aplikasi QUAL2K dalam Pengembangan Model Kandungan BOD dan DO pada Sungai Ciliwung Segmen 2, R. Yanidar, et al., JTL, Vol. 5 No. 6 Des 2011, 193 - 200 193 APLIKASI QUAL2K DALAM PENGEMBANGAN MODEL KANDUNGAN BOD DAN DO PADA SUNGAI CILIWUNG SEGMEN 2 Ramadhani Yanidar, Samsu Hadi, Arief Budiman Jurusan Teknik Lingkungan, FALTL, Universitas Trisakti, Jl Kyai Tapa No.1, Jakarta 11440, Indonesia ramadhani@trisakti.ac.id Abstrak Sungai Ciliwung segmen 2 melintasi daerah Kota dan Kabupaten Bogor, dengan panjang aliran sekitar 12 km, mulai dari Kecamatan Sindang Rasa hingga Kecamatan Cibuluh. Berbagai kegiatan domestik yang berpotensi sebagai sumber pencemar, berada di sepanjang pinggiran Sungai Ciliwung. Berdasarkan hal tersebut dilakukan pengembangan model dengan memanfaatkan model QUAL2K untuk mengetahui hubungan penyebaran polutan dari sumber pencemar di sepanjang Sungai Ciliwung segmen 2 terhadap kualitas air Sungai Ciliwung. Dalam Model ini kualitas air dibatasi hanya berdasarkan parameter BOD (Biological Oxygen Demand) dan DO (Dissolved Oxygen). Beban pencemar yang dipresentasikan dalam parameter BOD sepanjang Sungai Ciliwung Segmen 2 dihitung berdasarkan data jumlah penduduk dan cakupan pelayanan sanitasi. Pengembangan model menggunakan aplikasi QUAL2K, dengan parameter utama BOD dan DO. Verifikasi model menunjukkan deviasi BOD sebesar 14% dan DO sebesar 24%. Simulasi dilakukan berdasarkan 3 skenario pengelolaan beban pencemar dan pengelolaan sungai yaitu skenario 1 peningkatan pelayanan sanitasi sebesar 50% di daerah aliran bagian hulu sungai, yang kedua dengan melakukan penggelontoran melalui Bendungan Katulampa dan yang ketiga adalah membangun instalasi pengolahan air limbah (IPAL) di kelurahan Babakan Pasar yang melayani 100% buangan air limbah domestik di 6 kelurahan di bagian hulu. Hasil simulasi menunjukkan bahwa skenario yang paling efektif adalah skenario ke 3 yaitu dengan kombinasi kebijakan, yaitu meningkatkan cakupan pelayanan sanitasi Sungai Ciliwung segmen 2 dan membangun IPAL di daerah hulu sungai. Penurunan konsentrasi BOD yang terjadi dalam skenario ini sebesar 0.4 mg/L, selain itu hasil simulasi menunjukkan bahwa pembangunan IPAL menghasilkan perubahan yang lebih berkesinambungan. Abstract QUAL2K Application in The Development of BOD and DO along the Ciliwung River Segment 2. The Ciliwung River segment 2 across the Kabupaten and Kota Bogor, the length of watershed reaches approximately 16 km from the Sindang Rasa District to the Cibuluh District. Along the Ciliwung River segment 2, there are various domestic and non domestic activities as a potential source of contaminants. This model has been developed by using the QUAL2K model to get the description of the relationship about spread of pollutants from the pollution sources at along the Ciliwung River segment 2 towards the river water quality. Therefore, efforts are needed to control and monitor river water quality. This study aims to correlate the pollutants to BOD (Biological Oxygen Demand) and DO (Dissolved Oxygen). In this model the water quality is limited only by the parameters BOD ( Biological Oxygen Demand ) and DO (Dissolved Oxygen). The BOD loading pollution were presented as a pollutan resources parameter along the Ciliwung River Segment 2, and they was calculated based on the population data and sanitation coverage. Model development using QUAL2K application, which is a software that can simulate the BOD and DO concentration. Validation of the model shows a deviation of 14 % to 24 % for BOD and DO. The simulation was performed based on 3 scenarios, which are the pollutant load management and management of the river. The first scenario is the improvement of sanitation services by 50% in the upstream watershed, the second by flushing the river through Katulampa Dam and the third is to build a wastewater treatment plant (WWTP) in the village scene of markets that serve 100% of domestic waste water discharges in 6 villages in the upper reaches. Simulation results show that the most optimum scenario is the 3 rd scenario which combination with improving the sanitation services and to built the WWTP in upstream areas. BOD concentration reduction that occurs in this scenario of 0.4 mg / L , in addition to the simulation results show that the construction of the WWTP produce more sustainable change. Keyword: BOD, Ciliwung River Segment 2, DO, Pollutant Loading, Ciliwung River Segmen2, Qual2k