Industrial Cooling Tower & Boiler Water Treatment System
EZ Water Technology Inc. offers you a comprehensive line of process equipment in the industrial market. Your project will be supported by a reliable engineering team with extensive experience in all types of industrial applications.
Our line of industrial sedimentation units offers multiple alternatives to ensure the best solution for your treatment needs. EZ Water Technology Inc. clarifiers and thickeners are used for pretreatment systems, process water, and all types of industrial wastewater. In addition to providing design support for new systems, EZ Water Technology Inc. specializes in retrofitting existing systems.
EZ Water Technology Inc. industrial filtration products complement any system requiring treatment beyond conventional clarification.
Cold Lime Softening
Hard water is water that has high mineral content. The name comes from the hard scale that forms when this water is boiled. It is not harmful to human health, but in an industrial setting, it will cause costly breakdowns in boilers, cooling towers, and other water handling equipment.
Cold lime softening is the addition of chemicals to remove the calcium and magnesium ions by precipitation. Cold (ambient temperature) lime softening is used when the mineral content of the source water ranges from 150 ppm – 500 ppm. Treatment consists of five steps: Chemical Pretreatment, Clarification, Recarbonation, Filtration and Sludge Treatment.
Sodium hypochlorite (bleach) is added to kill any living organisms that may be in the raw water.
Coagulant (usually ferric or aluminum salts) is sometimes added to aid particles to come together.The Polymer acts as a glue and turns individual particles into larger clusters. The larger particles settle faster and form a more concentrated sludge.
Softening and Clarification
Softening is the removal of calcium and magnesium from the water that could leave hard water deposits called “scale.” After the chemical pretreatment, the water flows into the softener. The softener provides a reaction zone for the hardness causing ions to precipitate. The lime and (sometimes) soda ash are added in the reaction zone just before the feed enters the clarifier. Lime is added to increase the pH to remove calcium and magnesium hardness.
Soda ash may be added to remove calcium hardness if the raw water doesn’t contain sufficient alkalinity for complete removal of hardness. Settled solids react with lime and soda ash to form larger and faster settling particles. The clarified water flows over weirs and the solids (sludge) are scraped to the center for removal and dewatering. The overflow typically has less than 10 mg/L of suspended solids. The amount of hardness remaining will depend on the water chemistry and proper chemical addition.
After softening, the pH is lowered to less than 8 to stop the softening reaction. This prevents what is called “post-precipitation” where softening continues in the pipe and eventually the pipe fills with scale. Clarifier overflow may be treated by filtration. As the water flows to the polymer may be added to improve filtration. Filtered water typically has less than 1mg/L of suspended solids. Intended use directs the stream either to a cooling tower or further filtration.
Solids underflow is pumped into a thickener. Typically, underflow solids are much denser than the clarifier feed with 3-4% solids being typical. The Polymer may be added to improve settling and clarity. The thickened underflow is sent to a belt press or other type of vacuum or pressure dewatering filter. The belt press places the solids between two belts and squeezes the water out through a series of rolls. The belt press requires an additional polymer to function properly. The resulting cake is then hauled off for disposal. The pressate and cloth wash water are pumped to the wastewater recovery sump along with the ultrafiltration system’s backwash and the R.O reject before recycling into the clarifier.
Water is a precious and crucial resource in the process of food and beverage production. From screening to tertiary treatment, biological nutrient removal to water reclamation, EZ Water Technology Inc. equipment is designed to maximize efficiencies and minimize downtime, all while meeting the ever-tightening EPA regulations.
Food Processing Wastewater
Copious wastewater is generated in food production. Effluent characteristics and constituents vary widely and require different processing technologies to achieve the required discharge limits. Discharge limits vary further by state and local regulations.
Food production plant waste streams contain large chunks which require separation. The simplest and most economic process for removing these solids is screening. A number of screen designs exist and facility layout should be a basis for the selection. Models include rotary drum screens, climber screens and channel screens with shaftless conveyors.
Screened effluent is sent to an equalization sump. It may be combined with streams not requiring screening. The various waste streams are seldom continuous in either quantity or quality. Process flows may vary by shift, by product and by cleaning schedules. Stream flow equalization is almost always advantageous. Equalizing flow rates also reduces wastewater treatment equipment size and cost.
Some plants produce high amounts of fats, oil and, grease (FOG). A dissolved air flotation (DAF) unit is an effective means of reducing the FOG and solids levels. DAFs are especially effective for food solids since most food particles float. Floating FOG and solids are skimmed from the DAF unit and recovered for disposal or sale. Skimmed solids do not require thickening.
Total suspended solids (TSS), FOG, and biological oxygen demand (BOD) are all significantly reduced by screening and DAF treatment. Nevertheless, there may still be levels of these contaminants which will require further treatment prior to discharge. Contaminant type and level determine treatment options. Waste stream volume, reuse possibilities, and available space will also influence the choice of treatment designs.
Almost all food processing facilities will require biological treatment for BOD removal. If the stream is small or BOD is low, the plant may elect to send the screened waste to a municipal treatment plant. Some wastewater will contain very high BOD (dairy, cheese, etc.) and anaerobic as well as aerobic systems will be necessary.
EZ Water Technology Inc. USA engineers water and wastewater process solutions for the power industry including water pretreatment, cooling tower makeup water treatment, and ultrafiltration pretreatment to reverse osmosis, guaranteeing SDIs less than 3. EZ Water Technology Inc. stands ready to meet deadlines and assures minimal downtime with focused service.
Power-generating stations, like other industrial wastewater producers, are facing stricter discharge requirements. This flow sheet combines many of the water treatment steps that might be encountered in converting a power station into a zero liquid discharge (ZLD) system. In this system, the final waste stream is sent to a spray dryer.
This flow sheet is a combination of several other flow sheets. The first section where the raw water enters is the service water pretreatment. The service water can be used for general water needs in the plant. The next section is demineralization for boiler feed water. The final section is the zero liquid discharge system that treats a slip stream from the cooling tower.
Not shown is water treatment necessary for drinking (potable) water and sewage.
Service Water Pretreatment – Cold Lime Softening and Clarification
In the first stage of treatment, the raw water is softened to reduce the calcium and magnesium hardness (for more information on softening see the Cold Lime Softening flow sheet). Some of the softened water is diverted to the cooling tower.
After the recarbonation, the treated water is collected in the service water storage tank. Some of the service water is sent to the demineralizing system. The rest of the water is used for backwashing filters.
The softening system includes a sludge dewatering step that is common to the entire plant. The thickener overflow is sent to the clarifier. The belt press pressate and wash water are returned to the thickener.
Boiler Feed Water – Demineralization
The softened water passes through two stages of reverse osmosis (RO) to remove the bulk of the minerals. The RO reject is sent to the ZLD system. The electrodeionization (EDI) system makes high purity water by polishing the trace contaminants left after reverse osmosis using electricity instead of chemicals.
Zero Liquid Discharge – Cooling Tower Slip Stream
The cooling tower slip stream treatment system is nearly identical to the ZLD flow sheet (a more detailed description of the process can be found on the Cold Lime Softening flow sheet). In this case, the clarifier is not used for cold lime softening, but it could be. The ZLD system shares the sludge dewatering facilities with the service water pretreatment system.
The water is clarified, filtered, and treated with reverse osmosis. The reject from the boiler feed water system may be added to the clarifier or sent to the drying system depending on the chemistry of the water. The reverse osmosis concentrate is treated with a spray dryer and the dry solids are sent to a landfill. If the concentrate stream is too large for a spray dryer, the wastewater may be sent to drying beds in areas where the evaporation rate is greater than nominal rainfall, or to an evaporator/ crystallizer system.