Pengaruh Suhu Kalsinasi dan Dosis Koagulan Rejected Coal untuk Menurunkan TSS, COD, TDS Limbah Tahu

Abstract

Limbah cair industri tahu mengandung pencemar tinggi seperti Total Suspended Solids (TSS), Chemical Oxygen Demand (COD), dan Total Dissolved Solids (TDS), sehingga perlu diolah sebelum dibuang ke lingkungan. Penelitian ini bertujuan memanfaatkan rejected coal sebagai bahan baku koagulan melalui variasi suhu kalsinasi dan konsentrasi H2SO4 serta mengevaluasi efektivitasnya dalam pengolahan limbah cair industri tahu. Koagulan disintesis melalui kalsinasi pada suhu 700 °C dan 900 °C, kemudian diaktivasi menggunakan H2SO4 dan diaplikasikan melalui proses koagulasi-flokulasi. Hasil penelitian menunjukkan bahwa peningkatan suhu kalsinasi meningkatkan jumlah dan ukuran pori serta menghasilkan permukaan yang lebih homogen dan hidrofobik. Peningkatan konsentrasi H2SO4 menurunkan pH dan mempengaruhi pembentukan koagulan aktif. Koagulan yang dihasilkan efektif menurunkan TSS hingga 97,3% dari 112 mg/L menjadi 3,0 mg/L, memenuhi baku mutu 200 mg/L. Penurunan COD mencapai sekitar 76,6% dari 546,7 mg/L menjadi 128,1 mg/L, dan seluruh variasi telah memenuhi baku mutu 300 mg/L. Nilai TDS meningkat dari sekitar 611 mg/L hingga lebih dari 2000 mg/L akibat ion terlarut, tetapi sebagian besar masih dalam batas baku mutu.

Industrial tofu wastewater contains high levels of pollutants such as Total Suspended Solids (TSS), Chemical Oxygen Demand (COD), and Total Dissolved Solids (TDS), so it must be treated before being discharged into the environment. This study aims to utilize rejected coal as a coagulant raw material by varying calcination temperatures and H2SO4 concentrations, as well as to evaluate its effectiveness in the treatment of industrial soybean curd wastewater. The coagulant was synthesized through calcination at 700 °C and 900 °C, then activated using H2SO4 and applied via a coagulation-flocculation process. The results showed that increasing the calcination temperature increased the number and size of pores and produced a more homogeneous and hydrophobic surface. Increasing the H2SO4 concentration lowered the pH and influenced the formation of active coagulant. The coagulant produced effectively reduced TSS by up to 97,3%, from 112 mg/L to 3,0 mg/L, meeting the quality standard of 200 mg/L. The reduction in COD reached approximately 76,6%, from 546,7 mg/L to 128,1 mg/L, and all samples met the quality standard of 300 mg/L. The TDS value increased from approximately 611 mg/L to over 2000 mg/L due to dissolved ions, but most values remained within quality standards.