Water Flashcards
Hard water
Is high in minerals or ions. Water hardness is mainly calcium and magnesium cations, along with bicarbonate, carbonate, sulphate, chloride or nitrate anions.
- high in calcium and magnesium salts
Soft water
Is low in ions
Ions
Are an atom, or group of atoms, that has a net positive charge (cation) or negative charge (anion). Anions and cations when combined are called salts so we can also say that hard water is high in calcium and magnesium salts
70% of the earths surface is water
97% of the earths water is saltwater in oceans
2% is fresh water in ice caps
0.6% is ground water (boreholes and springs)
0.4% is fresh surface water (rivers, lakes, reservoirs)
Surface water (rivers, lakes, reservoirs)
Typically soft, with low mineral content.
Higher level of organic material, open to pollution from cities l, towns and agricultural run off.
Borehole (ground water)
Has a mineral content because it is situated in bedrock which is rich in iron and calcium. Contains lower lever of contaminants and organic material because it is filtered as it passes through the earths layers.
An aquifer
Is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials (gravel, sand l, or silt)
Municipal water (treated water)
Surface water and/or ground water that is treated at a municipal treatment works before being supplied to the brewery.
Produce water
Interacts with the product
Process water
Assists in ttyhe functioning of various production processes
Service water
Provides water to non-production (service) systems
Filtration (screening)
Filter through metal grills/ screens to filter out larger or smaller particles, depending on the mesh size
Filtration (coagulation and sedimentation)
Chemical coagulants, such as aluminium or ferric chloride, reduce time for solids to coagulate or flocculate out
Sand filtration
Remove turbidity, algae, and microorganisms.
Cartridge filtration
Polymer fibres wound into a spiral that traps particles. Used for water with low levels of suspended solids.
Membrane filtration
Semi permeable membrane
1. Microfiltration
2. Untrafiltration
3. Nanofiltration
4. Reverse osmosis
Microfiltration
Removed Down to 0.1um
- yeast, solids, colloids, most bacteria
Untrafiltration
Removed particles down to 0.01um
- viruses, colloids, large organic compounds (such as proteins)
Nanofiltration
Removes particles down to roughly 0.001 um
-removes organic compounds including trihalomethanes, THM and some salts
Reverse osmosis
Removes particles down to 0.0001um
- removed most dissolved ions and molecules
Carbon filtration
Removes free chlorine and most organic contaminants.
- organic halogenated compounds can affect colour and taint flavour and aroma
Free chlorine
Often added to municipal water to make it safe to drink.
Halogen compounds (such as chlorine, fluorine, bromine, and iodine) combine with organic material to produce organic halogenated compounds such as trihalomethanes (THMs) and chlorophenols. These compounds can colour the beer and produce taste or odour taints.
Sterilisation, chlorine dioxide
Kills microbial cells by oxidising them. Unlike free chlorine does not produce flavour taints, non corrosive, and non toxic.
Ozone
Produced by passing a flow of air or oxygen through a high voltage field, causing three atoms of oxygen to bond together.
Can kill bacteria by oxidising their cell membrane.
-no residue and oxidises compounds - leaving no off flavour
UV - light
UV light at 200-280 nm destroys DNA of microbes.
- is non corrosive, leaves no residue taints
-lacks killing potential.
Sterile filtration
Is a form of micro filtration using a pore size between 0.2-0.45um to remove Bacteria and yeast.
We can check our source water’s hardness using soap. Hard water collapses soap lather (foam) as it forms insoluble salts of fatty acids, which then precipitate. So, if you can get a good lather of soap bubbles in the water, the water is soft. If you struggle to form a lather of soap bubbles, then the water is hard. Needless to say breweries use more sophisticated analyses than these to test the water they aim to brew with!
Permanent hardness
- non-carbonate salts eg sulphates, chlorides, nitrates cannot be boiled out
- will decrease pH
Removing permanent hardness
-ion exchange
-anion and cation exchange sites
- reverse osmosis
- concentrates dissolved materials on one side up to 98%
Temporary hardness
- carbonate and bicarbonate salts of calcium and magnesium, can be boiled out.
-will raise pH
Removing temporary hardness
- can be boiled out, but leaves scaling
-lime/calcium hydroxide additions + bicarbonates = calcium carbonate- will precipitate out! - or acid treatments to release co2 and form calcium salts
Removal of hardness by ion exchange
The ion exchange system is made up of vessels that contain special resin beads (made of polymer) that have an anion (negative ion) or cation (positive ion) attached to them. Water flows through the resin beads, where the undesirable ions in the water are exchanged with the desirable ions attached to the resin. Once the resin beads have become saturated with the undesirable ions, they are regenerated, usually by washing them through with mineral acids or sodium hydroxide.
Hard water removal by reverse osmosis
O smosis is the diffusion of water across a semi-permeable membrane, from water containing less dissolved material to water containing more dissolved material. Osmosis aims to balance the concentration on either side of the membrane – moving water from the side with most water, to the side with less water. It should result in a similar concentration of material dissolved in the water on either side of the membrane. So, for reverse osmosis to take place, we need to apply enough pressure on the concentrated side, to prevent osmosis and concentrate the dissolved material even more.
RO can remove more than 98% of dissolved minerals.
Calcium effect on beer quality
+ decreases mash/wort pH, stabilises enzymes, precipitates o slate, improves true formation, aid yeast flocculation.
- low pH decreases extraction of hip bittering compounds.
Magnesium
+ similar to calcium (but not as effective)
- similar to calcium (but not as effective). High concentrations can also have a laxative effect on the consumer
Sodium
+low levels contribute a full and sweet mouthfeel
- high levels contribute a salty/sour flavour.
Sulphate
+ some breweries believe it can help to emphasise hop character and dryness.
- high levels cause astringent and unpleasant bitterness, as well as being a precursor to ‘sulphury’ off flavours
Chloride
+ some brewers believe it helps to give beer body and fullness, as well as sweetness. Emphasis on malt character
- high levels can inhaibit the yeast and give a salty taste.
Zinc
+ vital yeast nutrient at low levels
- high levels can cause astringent flavours and be toxic to yeast
Iron/magnesium
+ none
- oxidation catalyst affecting beer stability (flavour and haze), metallic flavour, and may inhibit yeast activity and hence fermentation.
Carbonated/bicarbonates
+ low levels can help increase the mash and wort pH if using darker malts.
- high levels increase pH and cause scale on heating surfaces
Pilsner type lagers
-soft water, low mineral content
-sulphates= chlorides for a balanced flavour
- low calcium ion level for pH
Ales (bitters, pale ales)
- sulphates > chlorides to bring out butter flavours
- low in carbonates to help balance some coloured malts (which tend to reduce pH)
- higher calcium to reduce pH and balance the carbonates.
Milds, stouts, porters
- chlorides > sulphates for enhanced fullness and sweetness
- medium level of carbonates to balance the higher coloured malt input
- calcium to help balance the carbonated and drop the pH
