Kajian Kualitas Air dalam Upaya Pengendalian Pencemaran di Sungai Deli, Kota Medan, Sumatera Utara

Abstract

Pencemaran lingkungan merupakan permasalahan krusial dan menjadi tantangan yang dihadapi masyarakat di tengah pesatnya perkembangan zaman. Hal ini disebabkan oleh peningkatan laju urbanisasi, perubahan penggunaan lahan, serta meningkatnya kebutuhan sektor domestik, industri, dan pertanian sehingga memberikan tekanan besar secara berkelanjutan terhadap daya dukung lingkungan. Sungai Deli mengalami pergeseran fungsi menjadi tempat pembuangan umum melalui aktivitas masyarakat kota Medan. Pencemaran di sungai Deli terjadi secara berkelanjutan akibat masuknya berbagai jenis limbah ke perairan sehingga akumulasi limbah semakin bertambah dan mengakibatkan kerusakan ekosistem perairan. Penelitian ini bertujuan menganalisis kualitas air sungai Deli dengan metode perhitungan Indeks Pencemaran (IP) dan Canadian Council of Ministers of the Environment Water Quality Index (CCME-WQI) serta menentukan strategi pengelolaan pencemaran sungai Deli dengan metode Analitycal Hierarchy Process (AHP). Pengambilan contoh air dilakukan pada 4 stasiun pengamatan (hulu, tengah, dan hilir) di sungai Deli kota Medan dan dilakukan pengulangan sebanyak 3 kali (6 Februari, 29 Februari, dan 26 Maret 2024). Parameter kualitas air yang dianalisis sebanyak 13 parameter yaitu suhu, pH, Biological Oxygen Demand (BOD), Dissolved Oxygen (DO), Chemical Oxygen Demand (COD), Total Suspended Solid (TSS), ammonia, fosfat, salinitas, fenol, minyak dan lemak, logam berat kadmium (Cd), timbal (Pb), dan seng (Zn). Data primer diperoleh dari pengambilan dan analisis contoh air serta wawancara dengan perwakilan instansi dan masyarakat, sedangkan data sekunder berasal dari sumber resmi daring (website) dan literatur. Hasil perhitungan dengan metode IP menunjukkan bahwa hulu dan tengah sungai tergolong pada kategori tercemar ringan, sedangkan bagian hilir sungai tergolong tercemar sedang. Namun, hasil ini tidak sepenuhnya mencerminkan kondisi pencemaran aktual karena selain parameter logam berat (Pb, Zn, Cd), BOD, dan TSS melewati ambang batas baku mutu, pada Sungai Deli bagian kota hingga hilir ini juga terdapat sampah. Hilir sungai mengalami tingkat pencemaran tertinggi akibat akumulasi beban pencemaran yang terbawa dari bagian hulunya dan kemungkinan pengaruh kondisi pasang air laut. Selain itu, keberadaan sampah padat yang melimpah di seluruh segmen sungai — yang tidak tercakup dalam perhitungan IP — semakin memperjelas bahwa metode ini belum mampu merepresentasikan kondisi pencemaran secara menyeluruh. Hasil perhitungan menggunakan metode CCME-WQI lebih menunjukkan kondisi kualitas air berdasarkan data yang ada, yakni secara umum menunjukkan kondisi kualitas air Sungai Deli yang tergolong buruk di semua stasiun yang diamati. Diagram hierarki dalam pengambilan keputusan pengelolaan pencemaran sungai Deli memiliki elemen aktor (masyarakat, pemerintah, dan industri), elemen kriteria (sosial-budaya, biologi-teknologi, dan hukum-kelembagaan), dan elemen alternatif sebagai strategi yang ditawarkan menjadi solusi permasalahan pencemaran di sungai Deli. Analisis dengan metode AHP menghasilkan strategi pengelolaan berupa penegakan regulasi lingkungan terkait larangan membuang sampah ke sungai dan pengolahan limbah cair industri, pengawasan dan pemantauan kualitas air sungai oleh industri dan dinas lingkungan hidup pemerintah daerah, peningkatan pengelolaan sampah oleh pemerintah dan warga, peningkatan kesadaran masyarakat, serta restorasi dan konservasi sungai oleh pemerintah dan masyarakat di daerah aliran sungai Deli.

Environmental pollution is a crucial problem and a challenge faced by society amidst the rapid development of the times. This is due to the increasing rate of urbanization, changes in land use, and increasing needs of the domestic, industrial and agricultural sectors, which put great ongoing pressure on the environmental carrying capacity. The Deli River has undergone a change in function to become a public waste disposal site through the activities of the Medan City community. Pollution in the Deli River occurs continuously due to the entry of various types of waste into the waters so that the accumulation of waste continues to increase and causes damage to the aquatic ecosystem. This study aims to analyze the water quality of Deli River using Pollution Index (IP) calculation method and Canadian Council of Ministers of the Environment Water Quality Index (CCME-WQI) and to determine pollution management strategy of the Deli River using the Analytical Hierarchy Process (AHP) method. Water sampling was carried out at 4 observation stations (upstream, midstream, and downstream) in the Deli River in Medan, and was repeated three times (February 6, February 29, and March 26, 2024) in the Deli River, Medan City and repeated 3 times on February 6, February 29, and March 26, 2024. The water quality parameters analyzed were 13 parameters, namely temperature, pH, Biological Oxygen Demand (BOD), Dissolved Oxygen (DO), Chemical Oxygen Demand (COD), Total Suspended Solid (TSS), ammonia, phosphate, salinity, phenol, oil and fat, heavy metals cadmium (Cd), lead (Pb), and zinc (Zn). Primary data was obtained from water sample collection and analysis, interviews with representatives of agencies and the community, while secondary data was obtained from official online sources (websites) and literature. The results of calculations using IP method showed that the upstream and midstream of the river are classified as lightly polluted, while the downstream is classified as moderately polluted. However, these results do not fully reflect the actual pollution conditions. In addition to heavy metal parameters (Pb, Zn, Cd), BOD, and TSS exceeding the quality standard threshold, Deli River in the city of Medan to the downstream area also contains rubbish. The downstream of the river experienced the highest levels of pollution due to the accumulated pollution load carried over from the upstream and the possible influence of tidal conditions. Furthermore, the presence of abundant solid waste throughout the river segment— not included in the IP calculation—further clarifies that this method is not capable of representing the overall pollution conditions. The results of calculations using the CCME-WQI method better show the condition of water quality based on existing data, namely generally showing the condition of the Deli River water quality which is classified as poor at all observed stations. The hierarchy diagram in decision-making for managing pollution in the Deli River has actor elements (community, government, and industry), criteria elements (socio-cultural, biological-technological, and legal-institutional), and alternative elements as strategies offered as solutions to pollution problems in the Deli River. Analysis using the AHP method resulted in a management strategy in the form of enforcing environmental regulations related to the prohibition of waste disposal into rivers and processing industrial liquid waste, supervision and monitoring of river water quality by industry and the local government environmental service, improving waste management by the government and residents, increasing public awareness, and and river restoration and conservation by the government and community in the Deli River.