Fresh water may come from either a surface or ground source and typically contains less than 5 000ppm TDS.

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1 WATER PURIFICATION & FILTRATION With in-house specialist engineers Enbitec offers turnkey solutions for any water purification and filtration needs that our clients may require. Enbitec designs, constructs, supplies and maintains water purification and filtration plants that are suitable to the commercial & industrial market. Our services and solutions include prefiltration, Micro Filtration, Ultra Filtration, Reverse Osmosis & Disinfection systems. TYPES OF WATER Fresh Water Fresh water may come from either a surface or ground source and typically contains less than 5 000ppm TDS. Brackish Water Brackish water contains between and ppm of TDS. Its sources can either be natural fresh water alone or mixed with seawater. Brackish water differs from open seawater in the biological activity. Within harbors, bays and estuaries differences can exist in the amount and type of constituents present in the water. The main constituents are the salinity and the silt. Extensive seasonal variation in these is observed. Potable Water Potable water is natural fresh water that is made safe for drinking purposes by filtration, extensive treatment and/or disinfection. World Health Organisation (WHO) issues the guidelines for the allowable limits of various constituents in potable water. Many countries also have their own standards. Distilled or Demineralized Water Cooling Water The minerals can be removed by Reverse Osmosis, distillation or Ion Exchange processes. Water quality is described by specific conductivity. When the specific conductivity reduces to <0.1µs/cm (Microsiemens Per Centimeter), it is expressed in resistivity (MΩ.cm) for ultra pure water. Cooling water implies that treatment against excessive scaling or corrosion has been applied to. This may include anything from natural water to seawater and may comprise either an open- or closed- loop system or a once through system Boiler Feed Water Process Water Service Water The feed water make-up for boiler is always softened or demineralized. Based on boiler pressure it is also subsequently de-aerated It may include recovered steam condensate This is a general term commonly used to describe water used for process purposes in the industry This can be from simple filtered water to several times purified ultra pure water (UPW). This is a term used to describe water used for general purposes such as washing, flushing, cleaning of process equipment, floor washing and gardening.

2 Waste Water By definition waste water is any water that is discarded after use. Water that results from industrial process or manufacture of goods are classed as industrial waste water Industrial waste water contains contaminants that are specific to the industry and unit operations. Domestic Sewage The waste water from residence and institutions carrying human waste, washing water, food preparation wastes, laundry waste and other waste products are classed as domestic or sanitary sewage. Waste water from shops/stores and community service establishment, termed commercial wastes are included in the sanitary or domestic sewage category if their characteristics are similar to household flows. Grey & Black Water Seawater Grey water is the waste water that comes from the laundry, kitchen, bathroom faucets, baths and showers. Black water is the waste water that comes from the toilet and garbage disposal Thus municipal domestic sewage is the mixture of grey and black water. Seawater typically contains about ppm TDS or 3.5% salinity. The salinity may be reduced due to dilution by rivers with fresh water or concentrated by solar evaporation in others. Seawater contains some specific impurities such as Boron, Barium, Strontium and marine organisms. COMMON WATER PROBLEMS Whether fed from a municipal source, a borehole, a river, or the ocean, all water supplies contain dissolved mineral salts, microbiological contaminants and other materials. The amounts present determine the final analysis of the water, and ultimately whether the water is suitable for its intended application. In order to provide quality water for domestic and industrial use, the impurities that exceed acceptable levels have to be identified. Water treatment equipment should never be installed without a water analysis. In this section, we discuss common water problems, how to identify them, the affects they can have on drinking and process water, and the most effective ways we can treat them. Bacteria & Viruses The human body contains certain amounts of coliform and E. coli bacteria. In normal concentrations, these bacteria are not harmful. Most E. coli are harmless. Some strains, however, may cause illness such as diarrhea, cramps, nausea, headaches or other symptoms. The presence of E. coli or fecal coliform in a drinking water sample may indicate human or animal fecal contamination. There are a number of methods for effective bacteria removal, including Chlorination, Ultraviolet Disinfection, Ozonation, Reverse Osmosis and certain types of Filtration. Fluoride Fluorides in water can be harmful to humans and animals, depending on the concentration. Excess amounts of fluoride in the water can cause a condition known as endemic dental fluorosis during the period of tooth formation. This condition leads to dark brown staining of teeth. Conversely, low concentrations of fluoride (such as those found in most toothpastes) help protect against tooth decay. The most effective way to remove fluoride is using Reverse Osmosis.

3 Iron & Manganese Iron is a problem usually associated with borehole water supplies. Iron can be found in 2 states. Water containing Ferrous iron is usually clear when it comes out of the ground, but becomes cloudy or red when it comes into contact with air, converting the iron to its Ferric state. Traces of ferric iron can often be seen through the red stains found on basins, baths, toilets and staining on laundry. Manganese is usually found in the same water supplies as iron. Even small concentrations of manganese can cause brown or black stains to appear. Specialized Iron Removal Filters can be used to remove iron & manganese from water supplies. Nitrates In most water supplies, the presence of excessive nitrate levels is as a result of pollution by organic matter. Usually, excessive nitrates are only found in borehole supplies. An example would be where a borehole and a septic tank are too close to one another. Concentration of nitrates in excess of 10 ppm in drinking water supplies can cause cyanosis (blue baby). Cyanosis results on a poisoning of the blood, decreasing its ability to effectively carry oxygen through the body. Nitrate removal is most effectively carried out using a Reverse Osmosis System, usually combined with a Water Softener. ph The ph scale is used to express the acidity or alkalinity of water. The ph scale ranges from 0 to 14. A ph of 7.0 is neutral, indicating a balance between acidity and alkalinity. Values below 7.0 indicate increasing acidic strength. Conversely, values above 7.0 indicate increasing alkaline strength. Waters with ph below 7.0 tend to cause iron or copper pick-up in piping systems and often lead to staining problems. Blue or green staining will be seen if the piping is copper, and red or brown stains can be expected if the piping is iron. The lower the ph, the greater the tendency of the water to cause corrosion. Excess acidity in water is treated by neutralizing the acidity the through the addition of alkaline minerals. ENBITEC s Filter Systems can be filled with neutralizing media, which slowly dissolves as the water passes over the media bed, adding a small amount of hardness to the water. This additional water hardness may mean that a water softener is recommended. The ideal ph range is Sodium Sodium can be found in almost all water supplies. Low concentrations of sodium have no effect on the taste or quality of drinking water, but as the sodium levels increase, the water will become more corrosive, and the taste will become unpleasant. Usually taste starts becoming apparent at around 500 ppm of sodium. Sodium can be removed using a Reverse Osmosis process, Deionization process, or by Distillation. Sulphates Excessive levels of sulphates will often lead to a metallic or medicine-like taste, and will act as a laxative. Sulphate removal is usually as a result of a Reverse Osmosis, Deionization, Distillation process. Taste & Odours Tastes and odours are generally considered as the same problem, except for tastes caused by mineral salts. For example, water with high chloride content will have a salty taste but will probably not have any odour. A properly treated water supply should contain no trace of objectionable taste or odour. There are a number of tastes and odours that may exist in your water supply. Most often, these are caused by excessive chlorine, but can also include a musty or mouldy smell, or oil, gas or rotten egg odours. For each

4 different type of bad taste or odour there is likely to be a different set of distinct problems and recommendations for treatment. Chlorine, mouldy or musty tastes and odours can usually be removed using an Activated Carbon Filter. Rotten eggs smells result from traces of hydrogen sulphide in the water, and will usually need to be oxidized or ozonized to effectively remove them. Total Dissolved Solids Total Dissolved Solids (TDS) is the name given to the sum of all the mineral compounds dissolved in a water supply. For the most part, TDS is made up of calcium, magnesium and sodium. High TDS levels can lead to a number of problems, ranging from a salty or brackish taste, to a decrease in the effectiveness of Water Softeners and other water treatment equipment. For domestic and most industrial water supplies, the maximum recommended TDS level is 500 ppm. Reverse Osmosis is the most commonly used process for the reduction of Total Dissolved Solids. Total Hardness Excess hardness is one of the most common water problems on any water supply. While a hard water supply can be used for most domestic applications, it is unsuitable for industrial use. Using hard water can result in: Excess use of detergents and other cleaning chemicals. Scale build-up on heating elements and in industrial heating and cooling systems. Reduced lifespan of heating systems. Higher electrical costs. White deposits on glass, vehicles and other smooth surfaces in contact with water. Whilst there are a number of scale removal systems available, hard water can be most effectively treated using an Ion Exchange Water Softeners. Water softeners use an ion exchange process to remove the majority of calcium and magnesium ions from the water supply. During the exchange process, the calcium and magnesium ions are replaced by sodium ions, generated from a sodium chloride/water solution (brine) made in the system s brine tank. For domestic purposes, the recommended hardness levels are ppm. For industrial purposes, hardness should not exceed 50ppm WATER PURIFICATION & FILTRATION METHODS Water Purification/Filtration is the process of removing undesirable chemicals, materials, and biological contaminants from contaminated water. The goal is to produce water fit for a specific purpose. Most water is purified for human consumption (drinking water) but water purification systems may also be designed for a variety of other purposes, including meeting the requirements of medical, pharmacology, chemical and industrial applications. Membrane Filtration Processes MICROFILTRATI ULTRAFILTRATI NANOFILTRATIO REVERSE

5 1. Microfiltration Microfiltration usually serves as a pre-treatment for other separation processes such as ultrafiltration, and a post-treatment for granular media filtration. The typical particle size used for microfiltration ranges from about 0.1 to 10 µm. In terms of approximate molecular weight these membranes can separate macromolecules generally less than 100,000 g/mol. The filters used in the microfiltration process are specially designed to prevent particles such as, sediment, algae, protozoa or large bacteria from passing through a specially designed filter. More microscopic, atomic or ionic materials such as water (H2O), monovalent species such as Sodium (Na+) or Chloride (Cl-) ions, dissolved or natural organic matter, and small colloids and viruses will still be able to pass through the filter. 2. Ultrafiltration Ultra filtration is a membrane filtration process similar to Reverse Osmosis, using hydrostatic pressure to force water through a semi-permeable membrane. Suspended solids and solutes of high molecular weight are retained in the so called retentate, while water and low molecular weight solutes pass through the membrane in the permeate. This separation process is used in industry and research for purifying and concentrating macromolecular solutions, especially protein solutions. Ultrafiltration is not fundamentally different from microfiltration or nanofiltration except in terms of the size of the molecules it retains - it is defined by the Molecular Weight Cut Off (MWCO) of the membrane used. Common applications for ultra-filtration systems are food & beverage processing, pharmaceutical use, municipal, borehole and surface water treatment. 3. Reverse Osmosis Explaining the process Reverse osmosis is a complicated process which uses a membrane under pressure to separate relatively pure water (or other solvent) from a less pure solution. When two aqueous solutions of different concentrations are separated by a semipermeable membrane, water passes through the membrane in the direction of the more concentrated solution as a result of osmotic pressure. If enough counter pressure is applied to the concentrated solution to overcome the osmotic pressure, the flow of water will be reversed. Water molecules can form hydrogen bonds in the reverse osmosis membrane and fit into the membrane matrix. The water molecules that enter the membrane by hydrogen bonding can be pushed through under pressure. Most organic substances with a molecular weight over 100 are sieved out, i.e., oils, pyroxenes and particulates including bacteria and viruses. Salt ions, on the other hand, are rejected by a mechanism related to the valence of the ion. Ions are repelled by dielectric interactions; ions with higher charges are repelled to a greater distance from the membrane surface. The nominal rejection ratio of common ionic salts is 85-98%. The majority of the commercially manufactured Reverse O osmosis (RO) membranes are usually made from cellulose acetate, polysulfonate, and polyamide. The membrane consists of a skin about 0.25 microns and a support layer about 100 microns. The skin is the active barrier and primarily allows water to pass through. The amount of dissolved solids in water produced by reverse osmosis is approximately a constant percentage of those in the feed water. For example, when the feed water contains 300 ppm total dissolved solids (TDS), the product water may have 15 to 30 ppm (95% and 90% rejection ratio respectively). A RO system design is based on a certain range of feed water TDS, the percentage of rejection and percentage of recovery desired. For a given system, the higher the percentage of recovery or the lower the percentage of rejection, the poorer the quality of product water becomes.

6 A Reverse Osmosis Membrane pore is smaller than the diameter of a human hair APPLIED PRESSURE PURE WATER MEMBRANE 4. Pre-treatment Various methods exist for effective pre-treatment. The objective of pre-treatment is to remove contaminants from raw water that will affect the stability and performance of the main treatment process and to remove contaminants that will affect performance of clients main process. Pre Treatment Methods Coagulation Coagulation is the addition of chemicals to change the properties of these contaminants so they increase in size and can then be removed by flotation, filtration and settling. Coagulation is the process that destabilises the particles by neutralising surface charges and forms micro floc. Flocculation is the aggregation of microflocs into larger aggregates (Flocs) Flocculation Flocculation is the agglomeration of destabilized particles into a large size floc which can effectively be removed by sedimentation or flotation Addition of flocculating chemicals may help formation of the floc. Filtration Two main types of filter media are employed - surface filter, a solid sieve which traps the solid particles, and a depth filter, a bed of granular material which retains the solid particles as it passes. The first type allows the solid particles, i.e. the residue, to be collected intact; the second type does not permit this. However, the second type is less prone to clogging due to the greater surface area where the particles can be trapped. Also, when the solid particles are very fine, it is often cheaper and easier to discard the contaminated granules than to clean the solid sieve. Filter media can be cleaned by rinsing with solvents or detergents. Alternatively, in engineering applications, such as water treatment plants, they may be cleaned by backwashing. Self-cleaning screen filters utilize point-of-suction backwashing to clean the screen without interrupting system flow.

7 Filtration Types Depth Filtration 5. Disinfection Surface Filtration Disc Filtration Bag Filters and Strainers Cartridge Filters Multimedia Filters Dual media Filters Multi Media Filters Multi Grade Filters Disinfection vs Sterilization Disinfection (Large Scale) Selective destruction or inactivation of pathogenic organisms Sterilization (Small scale) Complete destruction of all organisms Types of disinfection & sterilization Chlorination The primary purpose of chlorination is to disinfect water before it is used for drinking or other uses. Other purposes of chlorination are taste/odour control, prevention of algae growth, iron/manganese oxidation and destruction of hydrogen sulfide. Ozone Ozone is one of the strongest commercially available oxidizing agents and is commonly used for the treatment of water in municipal and industrial process applications. The special advantage is in the environmentally friendly way in which it works, without the formation of harmful chlorinated by-products. Ultra Violet Disinfection UV radiation can be an effective disinfection method. Disinfection using UV radiation is commonly used in wastewater treatment applications and is finding an increased usage in drinking water treatment. Many bottlers of spring water use UV disinfection equipment to sterilize their water.