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Calculation of Chemicals and Cost of Water Purification Process at Water Treatment Plant PT.XYZ

1 Balai Diklat Indrustri Medan, Ministry of Industry of The Republic of Indonesia, Medan, Indonesia
2 Department of Palm Oil Agribusiness, Politeknik Tekonologi Kimia Industri Medan, Medan, Indonesia
3 Department of Mechanical Engineering, Politeknik Tekonologi Kimia Industri Medan, Indonesia
4 PT Bina Perkasa Cemerlang, Medan, Indonesia
5 Institute of Microengineering and Nanoelectronics (IMEN), National University of Malaysia (UKM)
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Abstract

Acidic, turbid reservoir water and uncontrolled dosing raise treatment cost at palm oil mills. This study determined jar-test doses of soda ash (Na2CO3), aluminum sulfate (Al2(SO4)3), and Profloc (Poly(2-propenamide)) and calculated the chemical cost at the water treatment plant of PT XYZ located at Riau, Indonesia. Jar tests (500 mL) were run on 12 working days between 30 September and 12 October 2025 on raw water of pH 5.06–5.51 and turbidity 18–26 NTU (mean 20.6 NTU). Doses were converted to plant injection rates by pump calibration, and cost was consumption multiplied by unit price. Soda Ash B is Na2CO3 dosed through an additional injection line. Soda ash (8–14 mg/L) raised pH to a mean of 6.77, but alum then lowered it to 6.20, and only 5 of 12 selected doses reached pH 6.5–7.5. Turbidity fell by 76.5% to a mean of 4.74 NTU and decreased stepwise with alum dose, from 5.55 NTU at 10 mg/L to 4.47 NTU at 12 mg/L. Chemical cost averaged Rp288,410 per day and Rp1.80 and Rp1.67 million in the two calibration weeks. Soda ash should therefore be dosed for the post-alum pH, and alum below 11 mg/L missed the 5 NTU target.

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How to Cite

1.
Calculation of Chemicals and Cost of Water Purification Process at Water Treatment Plant PT.XYZ. EKSAKTA [Internet]. 2026 Oct. 28 [cited 2026 Oct. 29];27(05):961-73. Available from: https://eksakta.ppj.unp.ac.id/index.php/eksakta/article/view/760