CUBEN, A Novel Bioreactor for the Removal of Nutrients

Abstract

The applications, management and processing of wastewater have experienced an extraordinary transformation in the last two decades. Methods and terminology once the domain of disciplines like Chemical Engineering or Micro­biology, are incorporated in the academic programs of water/wastewater treatment. Terms like “aeration tank”, “tricking filter”, “retention time”, which often denoted simple physical unit operations in Civil Engineering, have been replaced by “reactor”,“fixed bed reactor”, “residence time ” and the concept of “waste” is being replaced by “resource” from where materials, heat or electric power, can be recovered, recycled or transformed. What used to be management and disposal of waste is being replaced by processing of a resources to obtain value added products. In this context, the configuration or topology of a conventional wastewater treatment plant is being replaced by that typical of a chemical engineering processing plant. This article gives a brief description of the evolution of wastewater engineering, and the unavoidable replacement of the horizontal geometry of the “tanks” by vertical reactors. These reactors offer a much smaller construction surface, exhibit a greater operational flexibility than conventional horizontal basins, and deliver equal or superior process performance. CUBEN (US Patent; Publication No. US-2012-0031836-A1) the first vertical nutrient removal bioreactor comes to meet those criteria. Its design allows the successful incorporation of processes like ANAMMOX eliminating one of the disadvantages of ANAMMOX: the presence of low dissolved oxygen concentrations (DO) in the effluent from the secondary treatment. The results presented herein show that DO can be virtually 0 mg/L in the anaerobic section, the elimination of nitrates in the anoxic stage exceeds 98% and the concentration of phosphorous in the effluent can be reduced to less than 1 mg/L without the addition of any salt or chemical. Optimization of the process with the optimum process control is underway.