DESIGN PROPOSAL PRE-CHLORINATION PROCESS IN WATER TREATMENT (STUDY CASE: WTP 2 PT. JABABEKA INFRASTRUKTUR, CIKARANG)

Abstract

PT Jababeka Infrastruktur's Water Treatment Plant (WTP) 2 is a water treatment facility that aims to serve clean water needs. This company uses an open system where chlorine is injected directly into the raw water intake, this allows for waste of chlorine which is wasted due to evaporation. The current injected dose in pre-chlorination is 7 - 7.5 mg/L with a residual chlor of 0.7 mg/L. The residual chlor, according to WHO, is still outside the standard criteria, where the standard set is in the 0.2 - 0.5 mg/l range. The dose injected in pre-chlorination should be more optimal because, in the secondary data of the WTP 2 laboratory test report, the content of nitrate, nitrite, ammonia, and total iron parameters is low. This study aims to determine the chlorination breakpoint graph pattern formed, determine the chlorine dose breakpoint in the water treatment process, and recommend the optimum dose of pre-chlorination and pre-chlorination system with a closed basin. This study used laboratory analysis on raw water samples. Then, the water samples were given chlorine treatment with a dose range of 0 – 15 mg/L. After being treated, the samples were analyzed for pH, turbidity, ammonia, nitrate, nitrite, and total iron. The chlorination breakpoint graph is linear, as evidenced by the low reducing agent. The breakpoint was achieved at 0.9 mg/L of chlorination dose for raw water turbidity 30.5 NTU. The recommended optimum dose in the breakpoint dose range of 1.1 mg/L. The pre-chlorination unit is a two-line chlorination unit with a closed design with a mixer inside.