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The CORRECT option is (d) 0.0001- 0.001µm

Easy explanation: Reverse Osmosis has a pore size range of 0.0001 – 0.001. It is by FAR the finest separation material available to industry. It is used on a large scale for the desalination and purification of WATER as it filters out EVERYTHING but water molecules, with pore sizes approaching the radius of some atoms in many CASES.

The CORRECT answer is (C) 0.001- 0.01µm

Explanation: Nanofiltration has a pore size range of 0.001-0.01um. NF membranes can filter particles up to and INCLUDING some salts, synthetic dies and sugars, however it is unable to remove most aqueous salts and metallic IONS, as such, NF is generally confined to specialist uses.

Correct option is (a) 0.1- 5µm

The best explanation: The pore size on microfiltration membranes ranges from 0.1 – 5 um, and has the LARGEST pore size of the four main membrane types. Its pores are large enough to filter out such things as bacteria, blood cells, flour, talc and MANY other kinds of FINE dust in solution. This can be contributed to its pores which are relatively large compared to other membranes; it can be operated under low pressures and THEREFORE low energy.

Right option is (C) 0.2, 4

Best EXPLANATION: The residual DISINFECTANT CONCENTRATION required is equal to or more than 0.2mg/L. This should be applied 6 hrs before the 1st USAGE.

Correct answer is (b) chemically clean a membrane filtration system

The BEST I can explain: Chlorines, acids and bases are used to chemically clean a membrane filtration system. They ENSURE MAXIMUM efficiency of the system.

The correct OPTION is (c) Air pressure HOLD test

Explanation: There are 3 MAJOR tests used to determine the INTEGRITY of a membrane filter: the Bubble Point Test, the Forward Flow Test, and the Pressure Hold Test. All three tests are based on the same physics MECHANISM that the flow of a gas through a liquid-wetted membrane under applied gas pressures.

The correct option is (b) Clarification

Easy explanation: The raw WATER reservoir would ACT as clarifier. It HELPS in clarification and reduction of fouling POTENTIAL of water FED to a membrane.

Right answer is (a) Desalination of salt WATER to produce POTABLE water

For EXPLANATION: Primary use of Membrane filtration is desalination of salt water to produce portable water in water TREATMENT. All other options are SECONDARY uses.

Right answer is (b) REVERSE flow

Explanation: Applying an external pressure to reverse the natural flow of pure solvent, thus, is reverse OSMOSIS. The process is similar to other membrane TECHNOLOGY applications. However, key differences are found between reverse osmosis and filtration. The predominant REMOVAL mechanism in membrane filtration is straining, or size exclusion, so the process can theoretically ACHIEVE perfect efficiency regardless of parameters such as the solution’s pressure and concentration.

Right OPTION is (c) FLUX

The best explanation: Flux is the rate of extraction of permeates measured as a gallon per square foot per DAY. PERMEATE is the filtrate, the liquid passing through the MEMBRANE.

Correct choice is (b) REVERSE osmosis

Easiest explanation: Reverse Osmosis has a pore SIZE range of 0.0001 – 0.001. It is by far the finest separation material AVAILABLE to industry.

The correct OPTION is (c) Straining

To elaborate: Straining has been identified as the principal mechanism that is operative in the removal of suspended SOLIDS during the filtration of SETTLED secondary effluent from BIOLOGICAL TREATMENT processes. Other mechanisms like interception and adhesion are also operative even though their effects are small and, for the most part, masked by the straining action.

The CORRECT answer is (d) NUTRITIONAL content of FEED

To explain I would say: The three qualities are: membrane filtration level selected; the characteristics of the membrane itself; and the quality of the feed water. These qualities HELP in determining percentage recovery.

Right option is (b) 4.8 gfd/psi

The BEST I can EXPLAIN: We calculated the flux to be 96 gfd. In ORDER to CALCULATE specific flux, divide the flux by the TMP 96 gfd / 20 psi. = 4.8 gfd/psi.

Right option is (b) 98GALLONS per square foot per day

To EXPLAIN: 5 GALLONS per minute multiplied by 60 minutes per hour multiplied by24 hours per day EQUALS 7200 gallons per day. 7200 gallons per day divided by75 sq. ft. = 96 gallons per square foot per day.

Right option is (d) Decrease in density of the globules

To explain: THREE factors CONTRIBUTE to this enhanced stability of HOMOGENIZED milk: a decrease in the mean diameter of the fat globules, a decrease in the size distribution of the fat globules, and an increase in density of the globules owing to the adsorption of a PROTEIN membrane.

The CORRECT answer is (a) Too soft COAGULUM

To explain: The MILK will not be suitable for the production of semi-hard or hard cheeses. This is because the coagulum will be too soft and DIFFICULT to dewater.

Correct OPTION is (a) INCREASE

The explanation: There will be an apparent increase in BACTERIAL COUNT after HOMOGENIZATION. Increase is due to the break-up of clumps and colonies of organisms.

The correct CHOICE is (d) Filtration/clarification of milk PRIOR to HOMOGENIZATION

The best explanation: To prevent the sediment formation, homogenized milk must be FILTERED or clarified, PREFERABLY before homogenization.

Right ANSWER is (c) Opaque CONTAINERS

The best explanation: HOMOGENIZED milk is more SUSCEPTIBLE to oxidized flavors caused by natural or artificial light than unhomogenized milk. To prevent the development of off-flavors, homogenized milk must be packaged in opaque containers, such as cartons, PLASTIC containers or colored bottles.

Correct choice is (a) Sediment development

The EXPLANATION: Homogenized milk may develop dark sediment at the bottom of the container after standing for 24 h. Sedimentation in homogenized milk is due to the settling of cells, FOREIGN matter and casein particles. In unhomogenized milk, these particles are USUALLY held by the FAT globules.

The correct choice is (a) Lipases

The best EXPLANATION: Homogenized MILK is more susceptible to enzyme activities, especially LIPASE action, than unhomogenized milk. Lipase can cause RANCIDITY rapidly in homogenized raw milk.

Correct ANSWER is (d) Bitter

The best EXPLANATION: Homogenized MILK has a uniform flavor throughout. Homogenized milk tastes RICHER, smoother and creamier than unhomogenized milk due to an INCREASE in the surface area of the fat globules which are uniformly distributed in milk.

The correct ANSWER is (a) Improved digestibility

Easy explanation: Homogenization has been reported to improve the digestibility of MILK due to an increase in the number and SURFACE AREA of the FAT globules.

The correct answer is (c) Whitish appearance

To elaborate: Homogenization of milk INCREASES its WHITENING POWER DUE to an increase in the number and surface area of the fat globules. Adsorption of casein micelles and serum proteins on newly created fat globules surface increases scattering of light thereby CAUSING whiter appearance.

Correct option is (a) Less than 2µ

Explanation: Homogenization LEADS to a reduction of FAT globule size to < 2 µ prevents formation of cream layer and INCREASES the surface area of the fat above 6 times.

The CORRECT choice is (d) Product demanding high viscosity

To EXPLAIN I WOULD say: Two-stage homogenization is used for PRODUCTS with a high fat CONTENT and products where high homogenization efficiency is desired.

The correct option is (a) PRODUCTS demanding a HIGH viscosity (certain cluster FORMATION).

The best I can explain: Single-stage homogenization may be used for homogenization of products demanding a high viscosity (certain cluster formation).

Right option is (b) Eddies theory

Explanation: The theory of GLOBULE disruption by turbulent eddies is based on the FACT that a lot of SMALL eddies are created in a liquid travelling at a high velocity. Higher velocity gives smaller eddies. If an eddy hits an oil droplet of its own SIZE, the droplet will break up. This theory predicts how the homogenizing effect varies with the homogenizing pressure.

Right ANSWER is (B) Eddies THEORY

The BEST I can explain: The cavitation theory, on the other hand, claims that the shock waves created when the STEAM bubbles implode disrupt the fat droplets. However, it is possible to homogenise without cavitation, but it is less efficient.

Right answer is (b) 10-25 MPa

The best I can explain: Homogenization pressure is between 10 and 25 MPa (100 – 250 bar), depending on the PRODUCT. High-pressure homogenisation procedures cause the formation of SMALL fat globules.

Correct choice is (c) 60- 70℃

To elaborate: Homogenization TEMPERATURES normally applied are 60 – 70°C, depending on the product. Processing at temperatures conducive to the partial SOLIDIFICATION of milk fat (i.e. 30 – 35°C) results in INCOMPLETE dispersion of the fat PHASE. Homogenization is most efficient when the fat phase is in a liquid state and in concentrations normal to milk.

The correct answer is (a) True

Explanation: Homogenization of cold milk, in which the fat is essentially solidified, is virtually INEFFECTIVE. Processing at temperatures conducive to the PARTIAL solidification of milk fat (i.e. 30 – 35°C) RESULTS in incomplete DISPERSION of the fat phase.

The correct OPTION is (c) 12%

To explain I would say: Cream with higher fat content than 12 % cannot normally be homogenized at the normal high PRESSURE because clusters are formed as a result of lack of membrane material (casein). A SUFFICIENTLY GOOD HOMOGENIZATION effect requires approximately 0.2 g casein per g of fat.

Correct option is (C) Homogenization

Explanation: Homogenization has become a standard industrial process, universally practiced as a means of stabilizing the fat emulsion against gravity separation. Homogenization primarily CAUSES DISRUPTION of fat globules into MUCH SMALLER ones.

The correct option is (d) Gaulin

The EXPLANATION: Gaulin, who invented the PROCESS of homogenization in 1899, described it in FRENCH as “fixer la composition des LIQUIDS”.

The correct answer is (a) True

The explanation is: When standardizing dairy PRODUCTS, the cream and milk are FIRST separated on a dairy line. The two elements are then mixed together again. However, not all of the original fat content is added back; only the exact level required for milk to be classified as SKIMMED, semi skimmed or whole.

The correct answer is (a) 2 and 35

For explanation I would SAY: 2.0 PARTS of 40% cream when MIXED with 35 parts of 3.0% milk will give 37 parts of 5% milk. Calculated USING the Pearson square method.

Right answer is (a) Continuous

Explanation: Continuous, on-line blending is much more DESIRABLE in a large-scale operation. This can be achieved on the cream separator itself by allowing sufficient cream to REMIX with the skim milk so that the MIXTURE is milk with the desired fat content; the balance cream FLOWS through the cream line into the cream tank. This requires that the separator is fitted with a STANDARDIZING device.