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Stage 3, Biological Ammonia Conversion (Nitrification) The treated wastewater, which is now low in carbon but high in ammonia, flows into the third chamber of the system. This chamber is aerated in the same way as the second chamber. The rr. combination of low carbon content and high ammonia and high oxygen levels in this chamber promotes the growth of nitrifying microorganisms (Nitrosomonas and Nitrobacter). The nitrifying microorganisms convert ammonia to nitrates utilizing the oxygen in the wastewater. r To optimize the contact time and the mean cell residence time, the EnviroServer utilizes a biomedia in the aeration sections. This plastic media is used to supply a support structure for ` the establishment of a resident biofilm and is specifically developed for optimized biological growth without clogging. The main advantage is that the biomass is attached to the biomedia and does not get flushed out at high input flow rates. The biomedia also enhances the nitrification process, which requires a larger population of organisms due to the lower ` metabolic rate of the nitrifying bacteria. Stage 4, Clarification The two-stage aerobically treated wastewater, which is now high in nitrates but low in carbon (low in CBOD5) flows into the fourth chamber of the system, where clarification and settling of the suspended solids take place. Stage S, Nitrate Removal (De-Nitrification) To promote denitrification, and to remove the accumulated biomass, the wastewater is recirculated from the fourth chamber back to the first chamber. Denitrification is facilitated by . this recirculation because the bacteria in the first anoxic chamber use the oxygen from the nitrate molecule in their metabolic process,with nitrogen being released as gas in the reaction. Without recirculation, the small amount of carbon available in the secondary tank would limit the denitrification. Stage 6, Solids Removal and Destruction The recirculation of the biomass prevents accumulation of the biomass in the clarification chamber, eliminating the need for periodic removal. Removing the accumulated biomass also helps to ensure optimum clarifier performance resulting in an effluent with low suspended ` solids. The transfer of the biomass to the first compartment ensures a large vital population of microorganisms for the organic and nitrogen removal processes in the second and third chambers. The recirculation process also benefits the system in times of low loading such as vacation periods. When the water is recirculated, it carries nutrients from the first chamber into the second chamber. Thus the available nutrients are utilized to sustain the population as long as possible. In normal operation this keeps sludge build up to a minimum by helping to break up and dissolve the solids, making the nutrients available for the microorganisms. To control the build-up of sludge(dead biomass) in the system, sludge is periodically pumped from the bottom of the first chamber. The sludge is filtered through a screen inside the Thermal Processor and the water drains back to the first chamber. The Thermal Processor employs a unique thermal decomposition process to dehydrate, pyrolize and gasify the sludge. The exhaust is routed back into the liquid in the first compartment for scrubbing of the gasses. The ash from the thermal decomposition process is flushed out with the wastewater and leaves the system as dissolved and suspended solids. This feature eliminates the requirement for ` periodic removal of solids by pumping.