ATAD, THE FAR COUNTRY: IMPROVEMENTS TO THE 3rd, 2nd GENERATION ATAD YIELD BETTER THAN EXPECTED RETURNS

The 2nd generation ATAD design continues to evolve and improve, providing superior sludge stabilization and solids reduction, as well as significant energy savings compared to aerobic digestion. The BG ATAD is the third municipal, 2nd generation ATAD to be built. The design incorporates many design improvements from the original design, including:Parallel reactors that allow for continuous feeding followed by 24 hour isolation.Improved foam controlTemperature phased nitrification in a covered nitrification tank. The pasteurized ATAD sludge is cooled by a radiator and a heat exchanger from 150°F to 95°F.Improved nitrogen removal by controlling aeration by pH.Use of the nitrification tank in the odor control system. ATAD off gas flows through the nitrification tank, removing 50% of the ammonia in the gas.An improved biofilterOpen-topped liquid storage tanks for the digested and cooled biosolids prior to land applicationThe ATAD was put on line in April, 2005. It reached thermophilic temperatures within 7 days. There were, as usual, a few of the usual start-up problems, but nothing serious. The ATAD performance has been even better than expected:75% VS reductionNo fecal coliforms detected in the ATAD, nitrification tank or storage tanks.No odors.A power reduction of 450 Hp, reducing electric costs by over 100,000/yr.The project was on time and on budget and has been a success.