• Title/Summary/Keyword: Monochloramination

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Effect of Feed Monochloramination on Performance of RO Membranes (NH2Cl 사용으로 인한 RO 막의 성능 향상)

  • Hong, Seungkwan;Reiss, Robert;Taylor, James S.;Beverly, Sharon
    • Journal of Korean Society of Water and Wastewater
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    • v.19 no.3
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    • pp.312-317
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    • 2005
  • The 15 month pilot study was performed to investigate the effect of pretreatment by monochloramine ($NH_2Cl$) on the performance of RO membranes made of cellulose acetate (CA) and polyamide (PA). Both RO membranes experienced severe biological fouling without any pretreatment during the treatment of highly organic surface water in Florida, USA. Feed monochloramination at 5 mg/L significantly minimized productivity loss by effective control of biofouling. The CA membrane did not show any structural damages by monochloramine, while the PA membrane suffered from a gradual loss of membrane integrity by chlorine oxidation, which was characterized as an increase in productivity and a decrease in selectivity. The degradation of PA membrane increased with increasing monochloramine dose.

Formation of Organic Chloramines during Monochloramination of Natural Organic Matters (천연유기물과 모노클로라민의 반응시 유기성 클로라민 생성)

  • Lee, Wontae
    • Journal of Korean Society of Environmental Engineers
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    • v.36 no.9
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    • pp.604-608
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    • 2014
  • This study investigated influence of dissolved organic nitrogen (DON) in natural organic matter (NOM) on the formation of organic chloramines upon monochloramination. Ratios of dissolved organic carbon (DOC) to DON of the 16 NOM isolates ranged from 7 to 47 mg-C/mg-N. Levels of organic chloramines maxed in 24 hours at $0.16mg-Cl_2/mg-N$ in average. The yields were relatively lower, but decay of organic chloramines were slower than those upon chlorination. Organic chloramines formed upon monochloramination decreased by 56% in average in 120 h. NOM with lower DOC/DON ratios formed more organic chloramines. NOM fractions such as hydrophobic, hydrophilic, transphilic, and colloidal did not significantly impact formation of organic chloramines. As the monochloramine doses increased, more organic chloramines were produced ($R^2=0.91$). Overestimation of disinfection capacity due to the formation of organic chloramines may not be concerns for monochloramine systems since only 6% of monochloramine could be converted to organic chloramines upon monochloramination of NOM.

Combined Effects of Metal Coagulants and Monochloramine on Polyamide RO Membrane Performance (금속성 응집제와 모노클로라민의 상호작용이 Polyamide계 RO막 성능에 미치는 영향)

  • Kim, Kyunghwa;Hong, Seungkwan;Park, Chanhyuk;Yoon, Seongro;Hong, Seongpyuo;Lee, Jonghwa
    • Journal of Korean Society of Water and Wastewater
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    • v.20 no.4
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    • pp.637-643
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    • 2006
  • The bench-scale chlorine exposure study was performed to investigate the effect of pretreatment by free chlorine and monochloramine ($NH_2Cl$) on the performance of RO membranes made of polyamide (PA). Feed monochloramination at 2mg/L did not cause significant productivity loss compared to free chlorine. However, metal coagulants reacted with monochloramine, the PA membrane suffered from a gradual loss of membrane integrity by chlorine oxidation, which was characterized as a decrease in salt rejection. Especially, RO membranes exposed to alum coagulants with monochloramine revealed the salt rejection lower than those exposed to iron coagulants. XPS membrane surface analysis demonstrated that the chlorine uptake on the membrane surface increased and carbon peaks were shifted significantly when exposed to alum coagulants with monochloramine.