Manufacturing processes often introduce heavy metals such as Cadmium, Chrome, Zinc, Copper, Iron, Lead, and Mercury into waste water. These toxic and carcinogenic materials must be removed from waste water before it can be recycled, reused or returned to the environment. Heavy Metal Removal systems force these materials to precipitate out of solution, so they may be filtered and safely removed. Wastech has continuous heavy metal treatment systems designed for flow rates of 1, 5, 10, 25, 50, and 100 gallons per minute.  Waste streams containing dissolved heavy metals can vary widely from application to application, although the treatment concept remains the same. Dissolved heavy metals are more or less soluble in water depending on the pH of the water.

If the pH is adjusted to the point of least solubility for the particular metal being removed, it will precipitate as a solid which can then be filtered leaving clean water. Other factors such as complexing or chelating agents require pre-treatment steps to break the metals free so that they can precipitate out of solution. If the waste water has a very low concentration of metals, such as in rinse water, ion exchange may be a more appropriate solution.  Here at Wastech, we have a laboratory specifically designed for testing and optimizing heavy metal precipitation processes. When we design our heavy metal removal systems, we use the test data to develop the best treatment process for the application. At Wastech, we are process engineers, not just system manufacturers. We will stand by our designs and guarantee treatment results. 

 We can design our systems using traditional treatment methods, or using MetFloc™ chemistry. MetFloc™ HM-11 is used as a pre-treatment chemical to break complexing agents and reduce the pH prior to metal precipitation. MetFloc™ HM-12 is used to precipitate the metals. The advantage of using HM-12 is that multiple metals are removed at one time, even if the points of lowest solubility for the metals are not the same. Also, using MetFloc™, less sludge is generated than when using traditional chemistry which reduces the cost of hauling away the filtered solids. Another key benefit of using MetFloc™ is the fact that it is not sulfur based, and will not produce the “rotten egg” smell that other chemistries produce.
 

Most continuous heavy metal removal systems include a pre-treatment, treatment, flash and floc, settling, and filtration stage. The pre-treatment stage is used to remove solids or detergents, and to break any complexing agents formed with the metals so that they can precipitate during the treatment stage. The pre-treatment stage can consist of a combination of filtration and chemical treatment technologies. The treatment stage is a chemical treatment stage where a high pH solution is added to raise the pH so that the metals will precipitate out of solution. The flash and floc stage is where a polymer is added to form large flocs that are easily filtered. The settling stage usually includes a lamella clarifier where the clean water flows to the sewer, or to a final pH adjustment stage, and the solids are collected in the bottom. A final pH adjustment stage is needed if the metals precipitate at a higher pH than the upper discharge limit. The solids are then stored in a holding tank before they are filtered. Filtration can be accomplished by many different technologies including a filter press and filter cartridge housings. Wastech engineers will design every stage of the treatment process to optimize the results, while providing the lowest cost solution for the application. All Wastech continuous heavy metal removal systems are fully automated using state of the art control technologies. Control is implemented using a PLC with a touch screen HMI and our sophisticated treatment algorithms. This allows maximum flexibility to change the process parameters as well as tight control that minimizes chemical usage. We can include a variety of options including digital data logging of critical process parameters, Ethernet access to process data, communication with Building Management Systems, and even remote system access using cellular wireless technology.