THE INFLUENCE OF NATURAL ORGANIC MATTER CHARACTERISTIC in POLLUTED RAW WATER TO THMs FORMING POTENTIAL (THMFP)

• Main Author: Rangga Sururi, Mohamad
• Format: Dissertations
• Language: Indonesia
• Subjects: Teknik saniter dan perkotaan; teknik perlindungan lingkungan
• Online Access: https://digilib.itb.ac.id/gdl/view/43988
• Institution: Institut Teknologi Bandung

There is no agreement regarding Dissolved Organic Matter (DOM) parameters that should be used as surrogate parameters for Trihalomethans Forming Potential (THMFP) in raw water. Moreover, researches related to DOM and THMFP in polluted urban rivers are still very limited. The purpose of this study is to investigate the characteristics of organic matters in polluted raw water that affect THMFP in the rainy and dry seasons. In specific, this study identified the differences during both seasons for: (i) NOM characteristics and the relationship between Total Organic Matter (TOM) and DOM; (ii) DOM sources and components in polluted raw water, (iii) formation THMFP in raw water. This study also aimed to determine the surrogate parameters for THMFP in raw water in each season as well as investigated the ability of conventional drinking water treatment plant (IPAM) in removing DOM and THMFP during both seasons, and such study was the first in Indonesia. This research was conducted at Bantar Awi intake that uses raw water from a polluted river (Cikapundung) and the Dago Pakar IPAM, owned by the PDAM of Bandung. Approximately 600 L/sec of raw water from the Cikapundung River is treated at IPAM Dago Pakar. Samples were taken during the rainy and dry seasons. Samples of raw water were obtained from the intake outlet, and specifically for study conducted at the IPAM, samples were collected from three sampling points: outlet of the intake, outlet of the secondary treatment units (coagulation - flocculation-sedimentation), and outlet of filtration unit. The measured DOM parameters included chemical oxygen demand (COD), dissolved organic compound (DOC), Chromophoric DOM (CDOM) which was measured at ? 245nm (UV254), 355nm (UV355) and as the ratio of 300nm to 400nm (UV3/4), and specific ultraviolet absorbance (SUVA). Fluorescence DOM (FDOM) were measured using fluorescence spectra with excitation wavelength of 250-600nm at 5nm intervals, and emission wavelength of 220-600nm, at 1nm interval. The sources of DOM were identified based on Biological Index (BIX) and Fluorescence Index (FI). The composition and its quantity of DOM were determined by PARAFAC. Correlation analysis was also conducted for each pair of DOM parameter and THMFP to obtain a surrogate parameter for THMFP. The results showed there were differences in the characteristics of NOM in polluted raw water during the rainy and dry seasons. The highest quantity of all organic parameters occured during the long dry season, because organic pollutants had been continously entered the water body without dilution from rain water. A good relationship between TOM and DOM (R> 0.7) was also observed, thus the quantity of DOM in the dry season can be estimated through TOM measurements. DOM of the dry season has very high hydrophobic and aromatic fractions as shown by SUVA values of >5L/mg/, but all measured DOM parameters (CDOM, DOC, COD, SUVA) are not significantly correlated with THMFP. A balanced composition between aromatic and non-aromatic compounds was found during the rainy season (SUVA between 2-4 L / mg / m), and there were significant relationships between UV355 and TTHMFP, UV355 and CHCl3FP, and SUVA and CHBrCl2FP. The results indicated the possibility of CDOM parameters as surrogate parameters for THMFP in polluted raw water in the rainy season. The ratio of these two FDOM parameters in the dry season (average FI = 0.89, and BIX = 0.89) were higher than those of the rainy season (average FI = 1.76, and BIX = 0.64), consistent with the pattern of other DOM parameters during both seasons. The values of FI and BIX may indicate the characteristic of DOM and its quantity in Cikapundung River was influenced by anthropogenic activities throughout the year. These ratios also show that the quantity of fulvic acid and protein from human activities in the dry season greater than those in the rainy season. These findings were confirmed by the results of PARAFAC analysis which identified there DOM compounds: C1 (unrecognized), C2 (humic), and C3 (protein). C1 (unrecognized) and C3 (protein) were at the highest in the dry season, while C2 (humus) was more dominant during the rainy season. The existence of C3(protein) in water body, confirming the raw water has been polluted by anthropogenic activities. The identified protein compound was tryptophan which was categorized as an aromatic protein as well as a precursor of THM, thus there was a relationship between protein (C3) and THMFP although weaker than that of UV355 and THMFP relationship in the rainy season. The high values of SUVA in the dry season were influenced by the high quantity of aromatic protein (tryptophan) in the dry season, which led poor relationship between CDOM and THMFP. This study shows the failure of conventional drinking water treatment to remove DOM optimally either during the rainy or dry season. However, its performance during the rainy season was better particularly when the water sample was dominated by the humic compounds. UV355 can possibly be a surrogate parameter for monitoring THMFP in raw water from a polluted tropical during both seasons if the quantity of humic greater than that of the protein. In the secondary treatment units during the dry season, the protein content actually increased and exceeded the humic compound, leading to non-significant relationship between the DOM parameters and and CHCl3FP.