Waste disposal is a global concern and with the implementation of international environmental standards, trade regulations and national governing laws, waste disposal has become a mandatory requirement for sustainable development. Modern waste treatment units work by first isolating liquids from solid waste. This is usually achieved in a two-stage process whereby first the insoluble solid waste is removed using filtration techniques. Thereafter, the soluble waste is then selectively removed by either chemically displacing the dissolved substances or evaporating the liquid using thermal processes leaving behind a concentrate of the dissolved solids at the bottom. The evaporated liquid is then recovered for reuse.

However, these thermal evaporators remain resource intensive in terms of heat generation sources which are finite in nature. Therefore, heat is usually conserved by opting for multi-stage evaporation. In this way, steam generated in the first stage is utilized to raise the temperature of the next stage. This reduces the overall energy requirement of the process by up to 10 times (From 15 kW/m3 to 1.5 kW/m3). Furthermore, with the evaporation of liquid in each subsequent stage, the overall pressure in the vessel decreases such that evaporation can now easily take place at much lower temperatures I.e. 75 to 80 Deg. Cel., thereby limiting the requirement of burning additional fuel for heat generation. In the same way, heat generated from other processes can also be utilized for this purpose where the processing units are called Waste Heat Evaporators (WHE). 


The WHEs additionally benefit from removal of pressure vessels and high maintenance systems like steam boilers from the system making the overall setup compact. This drastically brings down the overall capital and Operational & maintenance cost because the setup is integrated around current plant systems. Since the complexity of the system is reduced, the need for specialist labour for operating boilers and high pressure vessels is also reduced. Descaling which is usually a menace associated with steam-run setups becomes non-existent. WHE systems make use of heat generated by flue gases and channelize them to the pipes in the evaporation chamber. In this way, the need for additional heat sources or burning fuel for heat is eliminated thereby saving costs.  Share: