The operation of a facility for metalworking routinely generates considerable amounts of waste water and other liquid wastes. However, there are situations where discharge of liquid wastes may not be possible or permitted either for regulatory or ecological reasons. In other cases, high costs or limited availability of fresh water can be the prohibitive factor regarding waste water discharge and general water consumption. Investing into a Zero Liquid Discharge concept is therefore becoming attractive. EST offers individualized solutions for achieving Zero Liquid Discharge, amongst them ion exchange and reverse osmosis-based technology. Here, the focus of EST does also lie in the possibility of using low-grade waste heat from other facility processes in providing the energy required for evaporation.



Ion exchange is a well-established method for water softening and removal of ionic contaminants like acids, metals and neutral salts from a water stream by chemical absorption to a packed bed of small porous resin beads. This technology is not only suitable for the provision of softened or ultrapure process water but also for the purification of large volumes of low salt load waste water, allowing to reuse the water instead of discharging it as sewage. Ion exchange is a feasible method for treating waste waters burdened with sodium, nitrates or chlorides which cannot be readily removed or precipitated by usual neutralization techniques, accumulating these contaminants in the form of a low volume concentrated salt brine which may be either disposed of or further treated, for instance by evaporation. Whichever the definite application, EST offers the latest technology in ion exchanger systems.

Technical Details

  • frame-mounted unit

  • deionized water conductivity < 1 μS/cm

  • ion exchange resins by Purolite

  • available with automated intelligent regeneration system



Reverse osmosis systems use pressure and special membrane elements to “sieve” contaminants out of a waste water stream, creating a flow of pure water as well as an equivalent smaller amount of concentrate containing the contaminants retained by the membrane “sieve”. In ZLD applications reverse osmosis is a suitable step for the preconcentration of waste waters (and parallel provision of pure water) before further treatment steps by evaporation or other methods, allowing to reduce the total volume of the waste stream by an energy-efficient process, reducing downstream treatment costs. Using our experience in conjunction with durable membrane technology we may provide significant cost reduction in the evaporative treatment of waste water.

Technical Details

  • pre-assembled frame-mounted,

  • deionized water yield > 75 %

  • desalination rate > 97 %



Thermal treatment of waste water is an integral part of most Zero Liquid Discharge concepts. The aim of evaporator and crystallization technology is to boil away incoming waste water, often under reduced air pressure conditions to depress the boiling point, resulting in harmless steam and a solid residue of the original contaminants in the waste water stream. A majority metalworking facilities will generate some types of waste water which cannot be technologically or economically cleaned of all contaminants and dissolved salts. Further, other treatment solutions such as reverse osmosis or ion exchange may accumulate low but steady volumes of concentrated liquid wastes, necessitating either regular external disposal or evaporative post-treatment. As evaporation of waste liquids is an energy-intensive process and does often pose high demands on the materials used for the machinery used for thermal treatment we at EST do primarily focus on efficiency measures in evaporator solution design, for instance by reducing waste liquid volumes through combination with other methods and splitting waste streams prior to thermal treatment (evaporating only what really needs to be evaporated) or by methods to recuperate available waste heat from other facility processes to decrease energy costs for evaporation and crystallization. In addition, the steam generated by thermal treatment may be re-condensed and reused as high quality clean water in the facility’s processes.

Technical Details

  • energy-efficient low temperature vacuum evaporation by single-stage forced recirculation or multi-effect evaporators

  • heat supply either by integrated heat pump, external heating circuit or by waste heat recovery

  • high quality components, long lifespan, even with aggressive media

  • condensate recovery for recuperation and reuse of the evaporated water