Low energy costs for leachate treatment
For years, scientists and engineers have recognized the efficiency of multi-stage, flash evaporation. In very general terms, it takes approximately 700 kWh/m3 of heat energy to cause water to evaporate. This very high number is based on a single stage situation which would be analogous to a kettle on a stove. The Multiple Stage Flash process, when incorporating 15 stages (approximatel), would only require 50 to 70 kWh/m3.
The unfortunate part of this dramatic improvement in efficiency is the fact that Multiple Stage Flash units are extremely difficult to operate under ideal conditions and virtually impossible to operate if there are any fluctuations in the heat energy or in the characteristics (temperature, concentration, flow rate) of the mother fluid. In reality, each stage operates at a different pressure and temperature.
The first stage would typically be 90° C operating at half an atmosphere of pressure. The last stage would typically be operating at 35° C at 1/20th or 1/25th of an atmosphere. Each progressive stage would operate at slightly lower pressure and temperature in order to achieve the very high efficiency of evaporation. Non ideal operating conditions will cause instability in the stages. When the system is not operating in a stable condition, no progress (separation of distillate from leachate) is achieved (See diagram).
The Atlantis AutoFlash process incorporates a static, self-regulating device separating each stage from the next. This proprietary device allows the benefit of evaporation to be available to the wastewater industry with absolutely no operational difficulties.
Even more important is the fact that the low-grade, reject, waste heat can be used for driving the evaporation process. This quality of waste heat is so low, it is regarded as being available free of cost.
Further, the AutoFlash system is well applied on a landfill application generating electricity where the reject, water jacket heat from the internal combustion engine is utilized to efficiently and effectively drive the AutoFlash process. This energy source is the only heat required.
With the exception of volatile organic compounds (VOCs), the manufacturer claims that the system effectively removes 99.5% of ammonia, salts, heavy metals, BOD and COD.
This article has been abridged.