Pemulihan tawas dari sludge limbah pengolahan air bersih untuk mengurangi pencemaran lingkungan perairan :: Pengolahan air bersih pada PDAM Kota Pontianak, Kalbar

ZAHARAH, Titin Anita, Prof. Dr. Sudarmadji, M.Eng.Sc

2008 | Tesis | S2 Ilmu Lingkungan

Perusahaan Daerah Air Minum (PDAM) Kota Pontianak merupakan perusahaan pemasok air bersih untuk sebagian besar masyarakat Kota Pontianak. Sungai Kapuas yang mempunyai karakteristik air gambut digunakan sebagai air baku oleh PDAM. Pada proses pengolahan air bersih PDAM menggunakan koagulan tawas untuk mengurangi kekeruhan dan warna air baku. Limbah yang dihasilkan dialirkan ke sungai, sehingga berpotensi mencemari lingkungan perairan. Penelitian ini bertujuan untuk mengkaji pemulihan tawas, serta menentukan tingkat efisiensi tawas pulihan dari limbah pengolahan air bersih PDAM Kota Pontianak. Percobaan pemulihan tawas dari limbah PDAM Kota Pontianak dilakukan dengan penambahan asam sulfat 96% (pH 2) dan kecepatan pengadukan 260 rpm. Konsentrasi tawas pulihan dinyatakan sebagai nilai absorbansi Al berdasarkan Spektrofotometer Serapan Atom (AAS). Efisiensi tawas pulihan dikaji dengan cara menggunakan tawas pulihan sebagai koagulan bahan organik dalam air gambut. Penentuan absorbansi bahan organik dilakukan menggunakan spektrofotometer UV-Vis pada panjang gelombang maksimum 254 nm. Hasil penelitian ini menunjukkan, dalam 2 gram sampel sludge kering, menghasilkan konsentrasi Al 475,472 – 652, mg/L, sedangkan tingkat efisiensi tawas pulihan 54,71% dibandingkan tawas komersil. Uji statistik menunjukkan bahwa tawas komersil mengkoagulasi lebih baik dari tawas pulihan. Untuk mengolah air baku dengan kapasitas 1.210 liter/ detik PDAM Kota Pontianak menggunakan tawas komersil ratarata sebanyak 2.092,6 Kg per hari dan menghasilkan limbah 10 liter/ detik. Berdasarkan hasil dari penelitian ini, jika PDAM melakukan pengolahan limbah dengan cara memulihkan tawasnya, maka PDAM akan menghemat memakaian tawas komersil sebanyak 327,836 Kg/ hari setara dengan 15,67%. Pengolahan limbah dengan rekoveri tawas mungkin tidak memberikan keuntungan secara ekonomi, namun mengurangi tingkat pencemaran lingkungan merupakan suatu hal yang penting dilakukan.

Water Company (PDAM) of Pontianak City is a supplier of drinking water company for the biggest part of Pontianak City residents. Kapuas river on its characteristic as peat water is used as raw water by water company. The water company uses alum coagulant in processing of drinking water especially to reduce the turbidity and colour of the water. The waste produced on the processing of drinking water was thrown to the river and contributed to water environment pollution. The objectives of this research are to examine alum recovery and to evaluate the efficiency of the recovered alum from sludge produced by water treatment at PDAM Pontianak City. The experiment of alum recovery from waste produced by water company was conducted by Sulphate acid 96% (pH 2) addition and stirring velocity of 250 rpm. The alum recovery was measured by Atomic Absorbancy Spectrometry) and stated as absorbant value. The efficiency of alum recovery was studied by using the alum recovery as organic matter coagulant in peat water. The absorbancy of organic matter was measured by spectrofotometre UV-Vis at the maximal long wave (λ) of 254 nm. The research shows that 2 gr of dry sludge sample produced Al recovery in range of 475,472 – 652, 830 mg/L. The efficiency of alum recovery was studied by using the alum recovery as organic matter coagulant in peat water. Result of the research indicates that the efficiency of alum recovery is 54,71% compared by alum commercial. The statistical test also shown that alum commercial has coagulate potential better than alum recovery. Water company of Pontianak City uses alum commercial in average of 2.092,6 Kg each day for processing of 1.210 L/s. The waste was produced by this process at debit of 10 L/s. Based on this research shows that water company will get efficiency of alum commercial about 327,836 Kg each day or equal to 15,67% if they use alum recovery on the waste processing. The waste processing conducted by alum recovery will not be profitable in economically but it can reduce the water environment pollution.

Kata Kunci : Pemulihan tawas,Pengolahan air bersih,Sludge, alum recovery, sludge, water treatment