Analisis Daya Tampung Beban Pencemaran di DAS Batang Merao

Abstract

Daerah Aliran Sungai (DAS) Batang Merao mengalami penurunan kualitas air akibat aktivitas manusia yang memanfaatkan dan membuang limbah. Jika dibiarkan akan menyebabkan pencemaran sungai yang terus meningkat, sehingga perlu dilakukan analisis untuk mengetahui Daya Tampung Beban Pencemaran (DTBP) DAS Batang Merao sebagai langkah antisipasi pencemaran. Penelitian ini bertujuan untuk menghitung DTBP DAS Batang Merao, serta kapasitas beban pencemaran saat ini dan lima tahun mendatang menggunakan model kualitas air QUAL2Kw berdasarkan Peraturan Menteri Lingkungan Hidup nomor 01 Tahun 2010 tentang Tata Laksana Pengendalian Pencemaran Air. Kapasitas beban pencemaran saat ini dihitung berdasarkan data pengamatan, sedangkan lima tahun mendatang berdasarkan penambahan jumlah debit limbah diffuse source dengan perhitungan laju pertumbuhan penduduk. Analisis pengujian kualitas air dilakukan pada enam segmen disepanjang DAS Batang Merao dengan parameter TSS, BOD, dan COD berdasarkan Baku Mutu Air Nasional Kelas II Peraturan Pemerintah No. 22 Tahun 2021 Lampiran IV tentang Penyelenggaraan Perlindungan dan Pengelolaan Lingkungan Hidup. Hasil validasi model dinilai dengan Nash Sutcliffe Efficiency (NSE) untuk parameter TSS, BOD dan COD adalah 0.766, 0.574, dan 0.633 yang berarti pemodelan kualitas air dapat digunakan untuk memprediksi beban pencemaran sungai. Hasil pemodelan menunjukkan untuk DAS Batang Merao memiliki DTBP parameter TSS, BOD dan COD sebesar 95,057 kg/hari, 5,739 kg/hari dan 46,774 kg/hari, sedangkan beban pencemaran kondisi saat ini sebesar 147,962 kg/hari, 10,086 kg/hari dan 60,369 kg/hari. Hal ini menunjukkan bahwa kondisi DAS saat ini kekurangan kapasitas beban pencemaran masingmasing sebesar 52,905 kg/hari, 4,347 kg/hari dan 13,594 kg/hari. Pada estimasi kondisi lima tahun mendatang yaitu tahun 2028 beban pencemaran parameter TSS, BOD dan COD sebesar 163,023 kg/hari, 11,432 kg/hari dan 69,211 kg/hari, hal ini menunjukan kapasitas beban pencemaran masing-masing parameter semakin meningkat pada tahun 2028 yaitu sebesar 67,966 kg/hari, 5,693 kg/hari dan 22,437 kg/hari. Rekomendasi strategi kebijakan dengan membuat IPAL komunal, larangan membangun rumah dibantaran sungai serta menanam vegetasi disepanjang pinggiran sungai sebagai filtrasi limbah masuk ke sungai.

The Batang Merao Watershed, a river basin, has been experiencing a decline in water quality due to human activities involving waste utilization and disposal. If left unaddressed, this trend will lead to ever-increasing river pollution. Therefore, an analysis is necessary to determine the Total Maximum Daily Loads (TMDLs) of the Batang Merao Watershed as a preventive measure against pollution. This study aims to calculate the TMDL of the Batang Merao Watershed and the current as well as the five-year future pollution load capacity using the QUAL2Kw water quality model based on the regulations outlined in the Minister of Environment and Forestry's Regulation No. 01 of 2010 regarding the Procedures for Controlling Water Pollution. The current pollution load capacity is calculated based on observational data, while the estimation for five years into the future is based on the addition of wastewater discharge from diffuse sources, considering the population growth rate. Water quality analysis was conducted in six segments along the Batang Merao Watershed using parameters TSS (Total Suspended Solids), BOD (Biochemical Oxygen Demand), and COD (Chemical Oxygen Demand) according to the National Water Quality Standards Class II as stipulated in Government Regulation No. 22 of 2021, Annex IV, regarding the Implementation of Environmental Protection and Management. model validation results are assessed with Nash Sutcliffe Efficiency (NSE) for TSS, BOD, and COD parameters are 0.766, 0.574, and 0.633, indicating that the water quality modeling can be used to predict river pollution loads. The modeling results indicate that the Total Maximum Daily Loads (TMDLs) of the Batang Merao Watershed for TSS, BOD, and COD parameters are 95,057 kg/day, 5,739 kg/day, and 46,774 kg/day, respectively. Meanwhile, the current pollution loads are 147,962 kg/day for TSS, 10,086 kg/day for BOD, and 60,369 Kg/day for COD. This indicates that the current condition of the watershed lacks pollution load capacity by 52,905 kg/day, 4,347 kg/day, and 13,594 kg/day for TSS, BOD, and COD parameters, respectively. In the estimated condition five years from now, in the year 2028, the pollution loads for TSS, BOD, and COD will amount to 163,023 kg/day, 11,432 kg/day, and 69,211 kg/day, showing an increase in the pollution load capacity for each parameter in 2028, which will be 67,966 kg/day, 5,693 kg/day, and 22,437 kg/day, respectively. Policy recommendations include implementing a communal wastewater treatment system (IPAL komunal), restrictions on building houses along riverbanks and planting vegetation along the river's edge to serve as a filter for wastewater entering the river.