Pencemaran logam berat pada badan air yang merupakan sumber air baku menjadi isu penting dalam teknologi pengolahan air bersih. Saat ini, sebagian besar pengolahan air bersih masih mempergunakan metode konvensional yaitu koagulasi-flokulasi-sedimentasi (KFS). Akan tetapi, metode tersebut belum cukup efektif dalam menyisihkan logam berat dari air baku. Sementara itu, teknologi membran filtrasi diketahui mampu menyisihkan molekul hingga ion termasuk logam berat. Salah satu logam berat yaitu tembaga (Cu) dengan konsentrasi tinggi sebesar 0,07 mg/L yang melebihi batas baku mutu PP Nomor 22 Tahun 2021 tentang Penyelenggaraan Perlindungan dan Pengelolaan Lingkungan Hidup terkandung dalam sedimen Danau Salam Universitas Indonesia (UI). Oleh karena itu, diperlukan sebuah studi untuk mengkaji efisiensi penyisihan logam Cu dan dosis optimum dari koagulan pada proses KFS serta proses kombinasi dengan ultrafiltrasi (UF) dan mikrofiltrasi (MF). Pada seri pertama eksperimen, air Danau Salam yang mengandung 2 ppm tembaga dalam bentuk tembaga (II) sulfat digunakan sebagai umpan. Eksperimen jar test dan filtrasi vakum dilakukan pada skala laboratorium pada tekanan konstan 0,7 bar menggunakan membran filter PES 0,03 m dan glass microfiber 1,2 m. Parameter kualitas air berupa kekeruhan, Total Dissolved Solid (TDS), dan Cu terlarut, diuji di setiap percobaan untuk mengetahui kinerja sistem KFS dan kombinasi (KFS-UF dan KFS-MF). Hasil penelitian menunjukkan bahwa 80,55 ± 0,14% Cu dieliminasi melalui proses KFS-UF dan 76,45 ± 0,64% Cu melalui KFS-MF pada dosis alum optimum 70 mg/L. Meskipun demikian, dosis koagulan alum dapat dikurangi hingga ±50% (30 mg/L) dengan tetap memperoleh penyisihan Cu yang tinggi, yaitu sebesar 88,2 ± 1,13% melalui proses KFS-UF dan 87,35 ± 1,84% melalui KFS-MF.

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Heavy metal pollution in water bodies, which are the source of raw water, is an essential issue in water treatment. Currently, most water treatment plants operate by using conventional methods, i.e., coagulation-flocculation-sedimentation (CFS). However, this method is less effective in removing heavy metals. Meanwhile, membrane filtration methods are able to remove pollutants effectively from water, even ions, including dissolved metals. Heavy metals copper (Cu) in the sediments of Lake Salam of Universitas Indonesia (UI) was found at higher concentrations of 0.07 mg/L in comparison to the Government Regulation No. 22 of 2021 on Implementation of Environmental Protection and Management. Therefore, a study is needed to examine the efficiency of Cu removal in the CFS process combined with ultrafiltration (UF) and microfiltration (MF) at the optimum alum dose. In the first series of experiments, Lake Salam water containing two ppm copper in the form of copper (II) sulfate was used as feed. Jar test and vacuum membrane filtration experiments were performed at a laboratory scale at a constant pressure of 0.7 bar using 0.03 μm PES and 1.2 μm glass microfiber membrane filter. Water quality parameters, such as turbidity, Total Dissolved Solid (TDS), and dissolved Cu, were tested in each experiment to determine the performance of the CFS and hybrid systems (CFS-UF and CFS-MF). The results showed that 80.55 ± 0.14% of Cu were eliminated through the CFS-UF process and 76.45 ± 0.64% Cu through CFS-MF in the optimum alum dose of 70 mg/L. However, the coagulant dosage can be reduced to ±50% (30 mg/L) while still obtaining high Cu removal, which was 88,2 ± 1,13% through the CFS-UF process and 87.35 ± 1.84% through CFS-MF.