Water treatment is any process that makes water more acceptable for a specific end-use. The end use may be drinking, industrial water supply, irrigation, river flow maintenance, water recreation or many other uses including being safely returned to the environment. Water treatment removes contaminants or reduces their concentration so that the water becomes fit for its desired end-use.
Treatment for drinking water production involves the removal of contaminants from raw water to produce water that is pure enough for human consumption without any short term or long term risk of any adverse health effect. Substances that are removed during the process of drinking water treatment include suspended solids, bacteria, algae, viruses, fungi, and minerals such as iron and manganese.
Water and Wastewater Treatment Lecture. Source : NV atCEPImperial
The processes involved in removing the contaminants include physical processes such as settling and filtration, chemical processes such as disinfection and coagulation and biological processes such as slow sand filtration.
Measures taken to ensure water quality not only relate to the treatment of the water, but to its conveyance and distribution after treatment. It is therefore common practice to have residual disinfectants in the treated water in order to kill any bacteriological contamination during distribution.
World Health Organization (WHO) guidelines are a general set of standards intended to be applied where better local standards are not implemeted. More rigorous standards apply across Europe, the USA and in most other developed countries. followed throughout the world for drinking water quality requirements.
A combination selected from the following processes is used for drinking water treatment worldwide:
Pre-chlorination for algae control and arresting biological growth
Aeration along with pre-chlorination for removal of dissolved iron and manganese
Coagulation for flocculation or slow-sand filtation
Coagulant aids, also known as polyelectrolytes - to improve coagulation and for thicker floc formation
Sedimentation for solids separation, that is removal of suspended solids trapped in the floc
Filtration to remove particles from water
Disinfection for killing bacteria viruses and other pathogens.
Technologies for potable water treatment are well developed, and generalized designs are available that are used by many water utilities (public or private). In addition, a number of private companies provide patented technological solutions. Automation of water and waste-water treatment is common in the developed world. Capital costs, operating costs available quality monitoring technologies, locally available skills typically dictate the level of automation adopted.
Benefits
Biological nitrification without adding chemicals
Oxidation and nitration achieved
Biological phosphorous removal
Solids and liquids separation
Removes organics
Cost effective
Easily maintained mechanical work
Self sustaining system
Filtration System
The water is then filtered through layers of fine, granulated materials — either sand, or sand and coal, depending on the treatment plant. As smaller, suspended particles are removed, turbidity diminishes and clear water emerges.
Hardness in water is caused by certain salts. The main hardness causing ions are Calcium (Ca2+), Magnesium (Mg2+) and Bicarbonate (HCO3-). These ions or minerals are normally addressed as scale in the water causing scaling of pipes and equipment in drinking water and process water systems.
Softening units offer a water purification solution for hard water and lime scale removal.
In many applications, e.g. the preparation of drinking water, water in breweries and sodas, but also cooling water and boiler feed water, the hardness of the water is of importance.
Dhal Engineering offers water softeners and related equipment for households, laboratories and industrial applications. Water softener units are automatically regenerated with salt (NaCl). For servicing, repair or requests for water softener parts or hard water test kits.
Ultraviolet or “UV” is a type of energy found in the electromagnetic spectrum, lying between x-rays and visible light. Although we cannot see UV light or rays, we are exposed to them every time we step out into the sun. In fact, UV light is responsible for causing sunburns. Ultraviolet systems use special lamps or bulbs that emit UV light of a particular wavelength. The Ultraviolet energy attacks the genetic core of the microorganism and rearranges the DNA /RNA eliminating the microorganism's ability to function and reproduce. If the microorganism can no longer reproduce, it cannot replicate, therefore it cannot infect other organisms with which has contact. The process is simple but effective, destroying 99.99 percent of harmful microorganisms without adding chemicals to the water.
The quality or appropriateness of both the UV light and of the 'contact ', are crucial to accomplish disinfection. It is important to properly 'size' the UV based upon the application. It is equally important to use a good pre-filter to remove any dirt or debris that may be present in the raw water supply. This dirt and debris can interfere with the effectiveness of the UV rays – virtually giving the microorganism a shield to protect them when passing the UV rays. The keyword here is quality. System manufacturers strongly recommend that any pre and post filters be replaced at specified periods and that the UV lamp be replaced on an annual basis or after 9,000 hours of use -- whichever comes first.
UV systems can destroy 99.99% of harmful microorganisms without adding chemicals or changing your water’s taste or odor. It is one of the four methods of disinfection approved by the United States FDA. UV has proven to be a quick, reliable and cost effective method of disinfecting water for both point of use and point of entry.
Ultraviolet (UV) is a safe, clean, easy-to-maintain method of assuring that water is free of bacteria. UV Water Purification uses Ultraviolet light, just like sunlight, to kill micro-organisms that may be in the water. It is a proven technology that has no significant drawbacks. In some applications, its initial cost is a bit more than chlorination, but because of its low operating cost, it quickly pays for itself. It is environmentally friendly and essentially trouble-free. Most ultraviolet water treatment systems require only an annual change of lamp – as simple as changing a light bulb – and a periodic change of the filter cartridge.
Ozone was first used in water treatment in the late 1800s and ozone is more widely used in Europe and Asia.
Ozone is an unstable gas comprising of three oxygen atoms, the gas will readily degrade back to oxygen, and during this transition a free oxygen atom, or free radical form. The free oxygen radical is highly reactive and short lived, under normal conditions it will only survive for milliseconds.
Ozone is a colorless gas that has an odor similar to the smell of the air after a major thunderstorm.
Ozone has a greater disinfection effectiveness against bacteria and viruses compared to chlorination. In addition, the oxidizing properties can also reduce the concentration of iron, manganese, sulfur and reduce or eliminate taste and odor problems. Ozone oxides the iron, manganese, and sulfur in the water to form insoluble metal oxides or elemental sulfur. These insoluble particles are then removed by post-filtration. Organic particles and chemicals will be eliminated through either coagulation or chemical oxidation. Ozone is unstable, and it will degrade over a time frame ranging from a few seconds to 30 minutes. The rate of degradation is a function of water chemistry, pH and water temperature.
The formation of oxygen into ozone occurs with the use of energy. This process is carried out by an electric discharge field as in the CD-type ozone generators (corona discharge simulation of the lightning), or by ultraviolet radiation as in UV-type ozone generators (simulation of the ultraviolet rays from the sun). In addition to these commercial methods, ozone may also be made through electrolytic and chemical reactions. In general, an ozonation system includes passing dry, clean air through a high voltage electric discharge, i.e., corona discharge, which creates and ozone concentration of approximately 1% or 10,000 mg/L. In treating small quantities of waste, the UV ozonation is the most common while large-scale systems use either corona discharge or other bulk ozone-producing methods.
The raw water is then passed through a venturi throat which creates a vacuum and pulls the ozone gas into the water or the air is then bubbled up through the water being treated. Since the ozone will react with metals to create insoluble metal oxides, post filtration is required.
Reverse Osmosis Plant is widely used for removal of dissolve chemical impurities from brackish & seawater. Reverse osmosis is the process of forcing a solvent from a region of high dissolve solids concentration through a membrane to a region of low dissolve solids concentration by applying a pressure in excess of the osmotic pressure. The semi permeable membranes used for reverse osmosis have a dense polymer barrier layer in which separation takes place.
RO Plants are designed for a variety of industrial & commercial applications requiring high quality equipment with a fast delivery and competitive price. These pre-engineered, pre-assembled and factory tested units minimize installation and start-up time. With simple utility connections and easy to set up controls, the unit is ready for quick on-line service. The control system is an advanced microprocessor based system that is very easy to use
Demineralization or Deionisation is the process of removing mineral salts from water by using the ion exchange process. Impurities that remains dissolved in water dissociate to form positive and negative charged particles known as ions. An ion-exchange vessel holds ion-exchange resin of the required type through which water is allowed to pass. The selective ions in the water are exchanged with ions or radicals loosely held by the resin. In this way, the water is passed through several vessels or a mixed bed vessel so that both positive and negative ions are removed and water is dematerialized.
We, provide Wide range of custom-built Demineralization plants for industrial process water applications, with inherent design to conserve water, and save costs. Our unique design of D.M. plant ensures the maximum utilization of the effective surface area, uniform space and linear velocity across the resin bed which provides effective contact time between water and resin bed, yield salt free water for process equipment where water is being used for further application.
