Dinamika Sifat Kimia Air Daerah Sulfat Masam
Date
2022-07-18Author
Zahra, Ismi Aulia
Sumawinata, Basuki
Oktariani, Putri
Metadata
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Pada Oktober 2015 dan November 2019, air Sungai Segah di Kabupaten Berau secara spektakuler menjadi jernih ketika sebelumnya tampak berwarna coklat dan keruh. Selain airnya yang jernih, beberapa flok hasil proses flokulasi juga terlihat mengambang di beberapa bagian sungai. Hasil investigasi awal di sepanjang Sungai Segah, menunjukkan bahwa fenomena air jernih ini bermula dari perkebunan kelapa sawit milik Perusahaan A dan B. Sejak itu, media massa setempat gencar menyebarkan informasi tentang kegiatan pemupukan atau tumpahan pupuk di sungai tersebut oleh perkebunan kelapa sawit yang menyebabkan air jernih di sepanjang Sungai Segah. Pernyataan media massa lokal itu tampaknya dipertanyakan, karena harga pupuk yang mahal dan debit air di Sungai Segah tinggi. Penyebab terjadinya fenomena air jernih di Sungai Segah adalah adanya air asam yang banyak mengandung aluminium terlarut (273 ppm), hasil dari proses oksidasi pirit pada tanah sulfat masam di area perkebunan kelapa sawit. Selama musim kemarau yang panjang, pirit di tanah sulfat masam teroksidasi, dan ketika hujan deras, air asam yang mengalir ke sungai menyebabkan ikatan di antara partikel-partikel lumpur dan mengakibatkan air sungai menjadi jernih. Diperlukan beberapa upaya untuk meningkatkan pH air asam seperti penambahan zat basa dan pembilasan rutin dengan membuka pintu air perkebunan secara berkala yang akan mengalirkan air tidak asam dari perkebunan ke sungai. Penelitian ini bertujuan untuk mengetahui apakah upaya-upaya yang dilakukan dapat menurunkan aluminium terlarut dalam air asam, guna mencegah terjadinya flokulasi yang menyebabkan penjernihan air di Sungai Segah. Beberapa sampel air dari air parit perkebunan dianalisis kadar aluminium terlarut dan pH-nya pada tiga waktu yang berbeda, yaitu pada bulan Agustus 2020, Januari 2021, dan Agustus 2021. Hasil penelitian menunjukkan kecenderungan penurunan kadar aluminium terlarut diikuti dengan peningkatan pH. Kandungan aluminium terlarut tertinggi adalah 19,08 ppm, dan pH air mendekati netral pada pengukuran akhir. Dengan demikian, dapat disimpulkan bahwa upaya perbaikan dapat mengurangi kandungan aluminium terlarut dalam air untuk mencegah terjadinya penjernihan air di Sungai Segah. In October 2015 and November 2019, the water of Segah River in Berau Regency spectacularly became clear when it was appeared brown and muddy before. Besides clear water, some flocs which was the result of flocculation process were spotted floating in some part of the river. The initial investigation result along the Segah River, showed that the clear water phenomenon was started from the palm oil plantation owned by Company A and Company B. Since then, the local mass media aggressively shared the information about fertilization activity or spilled fertilizer on the river by an oil palm plantation caused clear water along Segah River. The statement of those local mass media seems questionable, since fertilizer was costly and the flow rate of water in Segah River is high. The cause of clear water phenomenon in Segah River was the acidic water that contained large amount of soluble aluminum (273 ppm), a result of pyrite oxidation process on acid sulfate soil in the oil palm plantation area. During a long dry season, pyrite in the acid sulfate soil was oxidized, and when the heavy rainfall came, acidic water flowed to the river caused bonding among the particles of the mud and created clear water in the river. Some efforts are needed to increase the pH of acidic water such as addition of alkaline substance and routine flushing by periodically opening the plantation water gate which will flow the not acidic water from the plantation to the river. This research aimed to observe if some efforts that mentioned before could reduce the soluble aluminum in acidic water, in order to prevent the flocculation that caused clear water in Segah River. Some water samples from the plantation ditch water were analyzed for its soluble aluminum content and pH at three different time, they were in August 2020, January 2021, and August 2021. The result showed a decreasing trend of soluble aluminum content followed by pH increasement. The highest soluble aluminum content was 19.08 ppm, and the water's pH was close to neutral at the final measurement. Thus, it can be concluded that improvement efforts could reduce the soluble aluminum content in the water to prevent clear water in Segah River.