Optimasi Pembubuhan Dosis Aluminium Sulfat Berdasarkan Variasi Kekeruhan Air Baku Pada Proses Koagulasi Dengan Metode Jar test di IPA TSM Perumda Air Minum Tirta Pawan Kabupaten Ketapang - R.Gagak Eko Bhaskoro; Nitis Aruming Firdaus; Rita Fiyani (Jurnal Green Growth dan Manajemen Lingkungan, 2025)
Koagulasi merupakan proses penting dalam pengolahan air minum untuk menghilangkan partikel koloid penyebab kekeruhan. IPA Tirta Sarana Mulia Kabupaten Ketapang menggunakan aluminium sulfat sebagai koagulan. Penelitian ini bertujuan menentukan putaran jar test berdasarkan kondisi eksisting, dosis optimum aluminium sulfat berdasarkan variasi kekeruhan air baku, debit pembubuhan, serta efisiensi biaya koagulan. Metode yang digunakan adalah metode kuantitatif dengan pendekatan trial and error menggunakan jar test pada variasi kekeruhan 10–50 NTU. Hasil menunjukkan kecepatan putaran optimal 200 rpm selama 7 detik di pipa, 100 rpm selama 1,2 menit di bak koagulasi, dan 40–20 rpm selama 5–12 menit di bak flokulasi. Dosis optimum aluminium sulfat sebesar 1 mg/l (10 NTU) hingga 10 mg/l (50 NTU). Setiap variasi kekeruhan menghasilkan persamaan regresi power dengan nilai R² mendekati 1, yang digunakan untuk menentukan debit dan stroke pompa secara akurat. Efisiensi biaya berkisar 92%–17% dengan penghematan Rp 91.831.450 – Rp 16.696.627. Penyesuaian dosis berdasarkan kekeruhan terbukti efektif secara teknis dan ekonomis. Kata kunci: Koagulasi, Aluminium Sulfat, Jar test Abstract Coagulation was an important process in drinking water treatment to remove colloidal particles that caused turbidity. The Tirta Sarana Mulia (TSM) Water Treatment Plant in Ketapang Regency used aluminum sulfate as a coagulant. This study aimed to determine the jar test rotation based on existing conditions, the optimum dose of aluminum sulfate according to variations in raw water turbidity, the dosing flow rate, and the cost efficiency of the coagulant. The method used was a quantitative method with a trial-and-error approach using a jar test at turbidity variations of 10–50 NTU. The results showed that the optimal stirring speed was 200 rpm for 7 seconds in the pipe, 100 rpm for 1.2 minutes in the coagulation tank, and 40–20 rpm for 5–12 minutes in the flocculation tank. The optimum dose of aluminum sulfate ranged from 1 mg/L (10 NTU) to 10 mg/L (50 NTU). Each turbidity variation produced a regression equation with an R² value close to 1, which was used to determine the dosing flow rate and pump stroke accurately. The cost efficiency ranged from 92% to 17% with savings of IDR 91,831,450 – IDR 16,696,627. The adjustment of dosage based on turbidity proved to be technically and economically effective. Keywords: Coagulation, Aluminium Sulfate, Jar test