EFFECTIVENESS OF CHLORINE-BASED DISINFECTION ON ON-SITE SYSTEM TREATMENT OF DOMESTIC WASTEWATER

• Main Author: F Pangaribuan, Arisa
• Format: Theses
• Language: Indonesia
• Subjects: Teknik saniter dan perkotaan; teknik perlindungan lingkungan
• Online Access: https://digilib.itb.ac.id/gdl/view/78204
• Institution: Institut Teknologi Bandung

Domestic wastewater contains nutrients, organic matter, suspended solids, and pathogens. In general, domestic wastewater is treated at on-site treatment plants in Indonesia. Domestic wastewater treatment on-site system is designed to remove solids, organic compounds, and nutrients, while pathogen removal efficiency has not been systematically evaluated. For the bacteriological content of effluent wastewater not to pollute the environment, disinfection is necessary. Disinfection of wastewater will destruct microorganisms, specifically pathogenic microorganisms. One widely applied disinfection method is chlorine-based disinfection using chlorine tablets. This study conducted an analysis related to the efficiency of removal of Escherichia coli parameter by chlorine tablet disinfectants and concurrently safe for the environment. The study was conducted with a septic tank reactor as on-site wastewater treatment system to treat domestic wastewater followed by a disinfection unit using TCCA chlorine tablet disinfectant. Variations in contact time were carried out, which are 45 minutes, 30 minutes, and 15 minutes. Before disinfection, the reactor treatment result shows E. coli removal by 99.84% but with the final concentration of E. coli in effluent which is still relatively high. For this reason, it was confirmed that disinfection became mandatory to remove E. coli, so that effluent can be discharged safely to water bodies and not increase the risk of spreading the disease. By disinfection, removal of E. coli in all measurements resulted in 100% removal efficiency, whether at 45-minute, 30- minute, or 15-minute contact time variations. In the seventh measurement of the 15- minute contact time variation. Examination of the distribution of data allowance for the time variations shows that the data is not normally distributed because the data values tend to be uniform. So, there is no need to check the best contact time of the treatment. With relatively similar efficiency results in all time variations tried, it was concluded that the application of one TCCA tablet with a contact time of 15 minutes was enough to remove the E. coli content. However, the use of this disinfectant should be followed by dechlorination. This is due to chlorine residual in effluent which are classified as high and dangerous if directly discharged into water bodies. The highest total chlorine residual at a concentration of 12.5 mg/l with the highest free chlorine residual was 2.9 mg/l. Dechlorination application through the addition of Na2SO3 at ratio of 1.8-2 mg/(mg/l) residual was shown to reduce chlorine concentration until a safe concentration to discharge into the environment.