The Influence of pH to LMW Organic formation:Aldehydes, in desinfection Process by Ozonation
Desinfection process using ozone in drinking water treatment can produce Low Molecular Wieght (LMW) organics, which can serve as substrate for a pathogenic bacterial growth and some were also carcinogenic in nature. Because ozone is unstable in water, part of ozone will react directly with dissolved solutes, while the other part may decompose before reaction. The pH of water is important because hydroxide ions initiate ozone decomposition. The aim of this research is to find out the influence of pH to ozone decomposition and also to LMW organic formation, that is, aldehydes as indicator, in desinfection process by using ozone. Due to the instability of ozone, it has to be produced on site, using an ozone generator. Ozone gas will be supplied continually into a batch system contactor with 7 liters of water. Measurements of ozone and aldehydes were done at contact time values of: 3,5 and 10 minutes at any pH condition using spectrophotometry, and GC-MS methods. Water samples were taken from a filtration unit in the Water Treatment Plan (PDAM) Dago, in the city of Bandung. The results showed that decomposition of ozone in acid pH occurred more slowly than in neutral and base pH. This research also showed that aldehyde composition (%), decreased gradually until contact time value of 10 minutes. These results were influenced by the quantity of hydrophobic natural organic matter existing in water samples. At contact time (CT) below 0,081 mg-minute/L, aldehyde can not be detected at base pH, but it can be detected at neutral and acid conditions at any range of contact time. Aldehyde formation was also influenced by the quantity and kind of existing precursors, its concentration, and the duration of contact time or ozonation. In addition, it was found that pH asserted a significant influence only for first three minutes of contact time.
Di buat oleh: Mohamad Rangga Sururi (rangsoer@yahoo.com), Dwina Roosmini, Suprihanto Notodarmojo
Kata Kunci : LMW organic, pH, ozone desinfection, aldehyde.
Keterangan : The 1st International Conference on Sustainable Infrastucture and Built Environment in Developing Countries, SABUGA ITB, Bandung – Indoensia.
The Influence of pH to LMW Organic formation:Aldehydes, in desinfection Process by Ozonation