Predicting calculating scaling tendency in membrane plants

Jefferies, Mike; Comstock, Dan

doi:10.1016/s0011-9164(01)00328-9

Cited by 10 publications

(4 citation statements)

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“…Although the capital expense of ion chromatography is significant, the advantages of having comprehensive on-site ion analysis are valuable for membrane processes which have a risk of (inorganic) scale formation. The ability to quickly check the Langelier Saturation Index (LSI) or Calcium Carbonate Precipitation Potential (CCPP), and adjust or initiate acid dosing could save many tens of thousands of dollars in cleaning chemicals, extend membrane life and reduce lost process time (Jefferies and Comstock, 2001). Preparation of samples for IC is similar to that of test kit chemistry, with sample filtering and dilution of concentrated wastewaters.…”

Section: àmentioning

confidence: 99%

A review of practical tools for rapid monitoring of membrane bioreactors

2016

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The production of high quality effluent from membrane bioreactors (MBRs) arguably requires less supervision than conventional activated sludge (CAS) processes. Nevertheless, the use of membranes brings additional issues of activated sludge filterability, cake layer formation and membrane fouling. From a practical standpoint, process engineers and operators require simple tools which offer timely information about the biological health and filterability of the mixed liquor as well as risks of membrane fouling. To this end, a range of analytical tools and biological assays are critically reviewed from this perspective. This review recommends that Capillary Suction Time (CST) analysis along with Total Suspended and Volatile Solids (TSS/VSS) analysis is used daily. For broad characterisation, total carbon and nitrogen analysis offer significant advantages over the commonly used chemical and biological oxygen demand (COD/BOD) analyses. Of the technologies for determining the vitality of the microbial biomass the most robust and reproducible, are the second generation adenosine-5'-triphosphate (ATP) test kits. Extracellular polymer concentrations are best monitored by measurement of turbidity after centrifugation. Taken collectively these tools can be used routinely to ensure timely intervention and smoother operation of MBR systems.

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Section: àmentioning

confidence: 99%

A review of practical tools for rapid monitoring of membrane bioreactors

2016

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“…Membrane scaling is often a slow kinetic process, and the development of scale mitigation strategies typically relies on thermodynamic solubility calculations and experimentally developed empirical relationships (5). Solubility considerations alone, especially when multiple mineral salts are of concern, are insufficient to arrive at the optimal dosing of scale-control chemicals (e.g., acid and antiscalants), given potential synergistic or antagonistic kinetic effects of membrane scale formation.…”

Section: Introductionmentioning

confidence: 99%

Reverse Osmosis Desalting of Inland Brackish Water of High Gypsum Scaling Propensity: Kinetics and Mitigation of Membrane Mineral Scaling

Rahardianto

McCool

Cohen

2008

Environ. Sci. Technol.

115

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The potential for mineral scaling that may limit the generation of new potable water resources by reverse osmosis (RO), from inland brackish water of high gypsum scaling propensity, was experimentally explored via flux decline measurements and real-time RO membrane surface imaging. Antagonistic gypsum and calcium carbonate scaling kinetics were demonstrated for high-sulfate brackish water desalting. RO scaling studies with brackish water from the California San Joaquin Valley (approximately 10 000 mg/L total dissolved solids) revealed that membrane gypsum scaling was increasingly retarded with rising bicarbonate concentrations. Crystal growth rate, fractional membrane scale coverage, and flux decline decreased by up to about 63, 78, and 73%, respectively, as the bicarbonate concentration increased, at the membrane surface, from < 0.01 to 7.81 mM, for a gypsum saturation index of 2. Inhibition of gypsum crystal growth was attributed to bicarbonate adsorption onto the crystal surfaces, and CaCO3 scaling was undetected even up to a calcite saturation index of approximately 16. Given the suppression of gypsum scaling by bicarbonate, it is essential to considerthis effect in the conventional practice of pH adjustment to suppress CaCO3 scaling. The present results suggest that antagonistic and synergistic mineral crystallization kinetics effects are important for optimizing scale-control strategies (e.g., acid and antiscalants addition to the RO feed).

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“…Due to its low solubility, calcium carbonate is the major salt which may lead to the formation of scale in the pipes [1][2][3]. The appearance and persistence of the three crystalline polymorphs, calcite, aragonite and vaterite are highly dependent on the local condition of precipitation temperature, supersaturation and the presence of additives in water.…”

Section: Introductionmentioning

confidence: 99%