Depending on the pretreatment sequence and desired cleanliness and quality of the process the quantities of water required by a mid- to large-sized pretreatment facility in metalworking can be considerable. Lack of waste water treatment capacities (and high external disposal costs for waste water) often force plant operators into a situation of water consumption management that is detrimental to overall process quality and reliability. Additionally, most chemical treatment solutions have a limited lifespan, creating yet more liquid waste to be dealt with. The installation of an on-site waste water treatment facility provides a convenient answer to these issues, giving our customers the ability to treat most if not all liquid wastes at their production site (fully automated, if desired), making them more independent from external disposal contractors and possibly allowing a higher throughput without having to accept compromises in process quality control.



Regarding waste water from metalworking processes the main pollutants encountered commonly are inorganic acids and dissolved metals, primarily iron but also more hazardous heavy metals like lead, zinc or chromium. Ever more strict environmental regulations demand adequate treatment of these waste water, customarily by chemical neutralization of the acids and concurrent removal of the metals as insoluble hydroxides. In this well-established procedure EST offers not only reliability and experience but also innovation and novelty. According to our customers’ applications we develop and provide dependable, fully automated neutralization facilities, either by continuous overflow stage neutralization for large volume homogenous waste water streams or by sequential batch reactor treatment for chemically more complex and demanding combinations of aqueous wastes.

Technical Details

  • sequential batch reactor (SBR) or continuous neutralization systems

  • customized according to the particular chemical treatment demands of the generated waste water

  • efficient removal of contaminants (acids, heavy metals, etc.) for strict compliance with local waste water discharge criteria

  • available with fully automated process control and monitoring



Chemical neutralization of waste water generally results in precipitation, the formation of solids to sequester contaminants such as metals. In addition, untreated waste water streams may already be laden with solid pollutants or oils. Capable filtration and / or sedimentation technology is needed for the separation of these compounds from the aqueous waste flow. EST provides to its reliable equipment for many types of filtration applications such as bag and cartridge filters, dewatering equipment like filter presses or band filters, oil separation systems, clarifiers or even more advanced solutions like decanter centrifuges.

Technical Details

  • removal of suspended solids from waste water by suitable filtering method (bag filter, cartridge filter, gravel / sand filter, etc.)

  • removal of solids by sedimentation (lamella clarifier)

  • backflushable systems with automatic control of backflush cycles



Some waste streams and contaminants are more challenging to treat than simply by common methods. For some types of heavy metals, toxins like hexavalent chromium, organic contaminants or chelating agents, standard neutralization and filtering do often not suffice in achieving pollutant reduction levels in compliance with the discharge criteria. Here, EST can provide the know-how and solutions for remedying waste water streams with otherwise troublesome compounds. Heavy metal removal by chelating ion exchange resins, binding or catalytic decomposition of organics and chelators by oxygen radical or UV treatment and ultrafiltration for the removal of very fine particulates are only some of the solutions offered by EST.

Technical Details

  • chromium (VI) removal by chemical reduction

  • ultrafiltration for the removal of colloids, oils, particles, etc.

  • fenton treatment of organic contaminants, phosphonates, etc.