Zero Liquid Discharge (ZLD)
Zero Liquid Discharge (ZLD) is a process were waste water is completely eliminated from a system. The targets are reduction of waste water and generation of purified water for reuse. For these processes an evaporator and a crystallizer are used. The evaporator concentrates the liquid waste and the crystallizer transforms the liquid concentrate into a solid.
Further benefits:
- Recovery of valuable resources which can be sold or reused
- Cost reduction of disposal costs by reduction of waste water volume
- Reduced demand for fresh water due to recycling of water
- Reduction of transport costs for disposal along with the environmental risks
QWAIR has optimized the ZLD technique further by introduction of progressive pre treatments which are able to reduce the thermal treatment to a minimum.
Compare to competitors the amount of energy (cooling, heating and electrical energy) and chemicals is lower as well as the capital costs.
Our integrated module based and compact design with low lead time is one of the key figures of our success.
Economical treatment system for typical salty process solutions (approximate 15 t/h)
A complete thermal treatment with evaporator and crystallizer would be too expensive and from the energetic view not economic, the benefits of the single steps are used in line to guarantee a safe and economically process.
Our focus is concentrated on the reduction of thermal separation technology taking into account the pre concentration to reduce the costs and lower the amortization time. Only an integrated approach guides into an combined and economically solution.
Hereby about 30 % of the invest can be saved and about 40 % of the energy costs compare to common systems.
In this example the sediments and the insoluble parts will be removed first. The solution is filtrated by a membrane technology.
By using a pressure up to 160 bar in the modules of the combination of the different membrane technologies (UF, NF or RO) it is possible to concentrate close to crystallization. The permeate (pure water) in process water quality can be reused in the plant.
In the following step the high concentrated brine is to be dewatered further by a thermal step or a thermal centrifuge up to almost solid. This is done under reuse of all containing heat of the concentrates of about 65 °C. The containing materials can be taken out at this steps for reuse in the production.
