Colloidal fouling of RO membranes following MF/UF in the reclamation of municipal wastewater

Ning, Robert Y.; Troyer, Thomas L.

doi:10.1016/j.desal.2006.04.080

Cited by 77 publications

(49 citation statements)

References 13 publications

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“…Silica is usually represented as (SiO 2 ) n , to represent the different crystalline and amorphous forms in which this compound may exist (Ning and Troyer 2007). Colloidal silica results from the polymerisation of silica containing particles and as a result of elevated silica concentrations.…”

Section: Colloidal Foulingmentioning

confidence: 99%

Silica fouling in coal seam gas water reverse osmosis desalination

Lunevich

Sartipy

Milne

et al. 2017

Environ. Sci.: Water Res. Technol.

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i AbstractSilica precipitation and silica scale formation on membrane surfaces in RO desalination present a significant operational challenge in water purification. Silica scale formation on the membrane surface leads to flux decline, RO system productivity lost, membrane degradation, and increased cost of chemicals. In spite of the apparent simplicity of silica's composition and scale formation on the membrane surface, fundamental questions and empirical knowledge persist about the formation, solubility and behaviour of silica species during the silica polymerisation, precipitation and scale formation.The broad objective of the present study was to define conditions and factors affecting silica polymerisation and precipitation in coal seam gas (CSG) waters in Australia. The scope of the problem was narrowed to focus on dissolved silica species studied by 29 Si NMR spectroscopy, removal of silica by coagulation as pre-treatment step for RO desalination and silica fouling patterns in RO desalination for a range of salinities in both synthetic and CSG waters to develop a conceptual model of silica precipitation and deposition on the membrane surface.The CSG industry in Australia generates significant quantities of CSG water, especially during the first 3-5 years of reservoir development when the hydraulic pressure needs to be released to extract the gas from coal seam. To avoid high cost of brine treatment and residual disposal frequently requires high recovery RO desalination to treat CSG water to level acceptable for further re-use. Furthermore, CSG waters in Australia have all four critical parameters, which potentially lead to silica precipitation prior it reached the solubility limit. These parameters include medium to high salinity, medium silica concentrations, high alkalinity at pH9 and slightly elevated aluminium concentrations.Practical field, theoretical and laboratory research works have been undertaken to study industry's concerns and bring fundamental and practical solutions to the problem. In Sodium ions depress silica solubility at the same time preventing silica from deposition on the membrane surface. The majority of dissolved silica polymerised in the bulk solution and was discharged in the reject stream of the RO system. To conclude practical silica solubility or the solubility defined empirically is a key for prevention of silica polymerisation in RO desalination systems.iii

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Section: Colloidal Foulingmentioning

confidence: 99%

Silica fouling in coal seam gas water reverse osmosis desalination

Lunevich

Sartipy

Milne

et al. 2017

Environ. Sci.: Water Res. Technol.

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“…Operational cost of conventional pretreatment is lower than non-conventional pretreatment technologies but the latter is the preferred pretreatment for RO processes due to a better quality of produced water [14,15]. However, both pretreatment types have been shown inadequate in mitigating fouling on NF or RO units [16][17][18]20]. For example, due to biological growth on the membrane and impurities passing through the pretreatment [16][17][18], one study reported that severe fouling caused the feed spacers, which are spiral wound membrane elements used to separate several RO membranes [6], to be forced out of the membrane element [16].…”

Section: Introductionmentioning

confidence: 99%

“…Another study suggested that mineral scaling, which has been assumed to occur solely on tail elements in a RO system, may also occur in lead elements or any elements in the RO train where biofilm has formed [19]. Several pilot-scale and plant studies reported that colloidal fouling observed was attributed to inorganic particles, most likely in nano-and colloidal forms that were able to pass through the MF or UF unit [18,20,21].…”

Section: Introductionmentioning

confidence: 99%

“…The feedwater source and its composition and quality largely influence the fouling behavior on RO membranes [13]. For any type of application, raw water undergoes conventional pretreatment or non-conventional/membrane pretreatment (microfiltration (MF) or ultrafiltration (UF) or nanofiltration (NF)) before being fed into the RO filtration unit [14][15][16][17][18][19][20]. To prevent fouling by large and visible particles, RO feedwater needs to have turbidities of less than 1 NTU (= 1 mg/L using kaolin standard), and silt density index (SDI) of less than 4.0 [15].…”

Section: Introductionmentioning

confidence: 99%

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Effect of Biofilm on Inorganic Suspended Solids Accumulation on Reverse Osmosis Membranes

Manalo

Ohno

Okuda

et al. 2016

J. of Wat. & Envir. Tech.

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Particles and colloids in feedwater for reverse osmosis (RO) processes are typically removed by pretreatment to silt density index allowable levels to prevent accumulation on membranes. However, the accumulation is mostly caused due to combined biofouling-particulate accumulation and it is important to quantitatively understand particle accumulation as affected by biofilm. This study aims to determine the effect of biofilm on the accumulation of inorganic suspended solids on RO membranes. With the same kaolin concentration contained on the feedwater, the amount of inorganic material deposited was greater by 0.16 mg/cm 2 when secondary effluent water was used in contrast to pure water, signifying quantitative enhancement of accumulated suspended solid (SS) on the membrane. Amount of glucose in feedwater did not result in a related increase in inorganic material since deposition seemed to be influenced by biofilm coverage on a preformed biofilm, as indicated by similar biofilm percentage coverage with and without glucose in feedwater. Micrographs indicated the preferential deposition of SS on the spacer filaments and membrane areas that were covered with biofilm. This effect of biofilm on inorganic SS accumulation will be highly useful in designing pretreatment strategies by addressing biofilm control to prevent both biofilm formation and SS accumulation.

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“…For this reason it is commonly called threshold inhibition mechanism. Antifoulants for controlling colloidal fouling works on the principle of keeping the colloidal particles from coagulating or even dispersing the coagulate once formed on the membrane (Ning et al 2005;Ning and Troyer, 2007;Ning, 2009) . Colloidal iron and manganese compounds, due to their positively charged characteristics are particularly sticky on the negatively charged membranes (Ning, 2009).…”

Section: Mechanisms Of Foulingmentioning

confidence: 99%

Pretreatment for Reverse Osmosis Systems

Ning¹

2011

Expanding Issues in Desalination

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Colloidal fouling of RO membranes following MF/UF in the reclamation of municipal wastewater

Cited by 77 publications

References 13 publications

Silica fouling in coal seam gas water reverse osmosis desalination

Silica fouling in coal seam gas water reverse osmosis desalination

Effect of Biofilm on Inorganic Suspended Solids Accumulation on Reverse Osmosis Membranes

Pretreatment for Reverse Osmosis Systems

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