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. 

 

Batch heavy metal treatment systems are a good choice when either a small volume of heavy metal laden waste is generated or the waste is a highly concentrated acid solution with dissolved metals, and would otherwise need to be hauled away. These haul off costs alone can justify installing an on-site treatment system. Batch treatment systems come in a range from 50 gallon batches up to 2,500+ gallon batches. Our standard CWT line of products offer small batch treatment in a compact footprint, while most other applications require a custom design. We can also design custom systems for For very large batch processing, or continuous flows, a continuous heavy metal precipitation system may be a better option. 

 

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. To optimize the treatment process, we test representative waste samples in our lab. This ensures that the system will be designed around real world results.

Batch heavy metal treatment systems consist of one or more treatment stages, flash and floc stage, and a filtration stage. The treatment process may include pretreatment to break any complexing or chelating agents present in the waste water. Then, the pH is raised to the point of least solubility for the metal being removed. In most cases, multiple metals must be removed from one waste stream. Traditional treatment systems require multiple treatment stages to fully remove all metals from the waste water, but using MetFloc™ chemistry, we can simplify this process and reduce the process to one step. Once the treatment is finished, the batch is mixed at high speed while a polymer is added. The polymer is used to form flocs that are easily filtered. The high speed mixing process unfolds the polymer, and then slow speed mixing allows the polymer to bond with the solids, forming a nice full floc. Once the solids have settled, the batch is filtered and the effluent is sent to the sewer or a final pH adjustment stage. A final pH adjustment stage is needed if the metals precipitate at a higher pH than the upper discharge limit.

 

Filtration is a very important part of all batch heavy metal removal systems. The treatment process may generate a small or very large amount of solids depending on the influent chemistry. A small volume of mostly rinse water from a process is more likely to generate a small amount of solid waste which can be filtered using bag filters or cartridge filters. A small volume of highly concentrated acidic waste with dissolved metals and complexing agents may produce a very large amount of solid waste during each batch process and requires a filter press for the filtration stage. Our experienced process engineers will design the most efficient and economical filtration system based on a combination of theoretical calculations and lab test results.

 

All Wastech batch 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.