Combined wastewater feed directly into final clarification – advantage for receiving rivers

With a view to a reduction of the discharge from combined water outflow, the increase of the influent to a wastewater treatment plant can be an efficient solution, for cases in which the discharge concentration of the wastewater treatment plant would not deteriorate significantly as a result. Through bypassing the aeration with combined water and a direct feed of the combined water into the final clarification (Mina-Process) the specific sludge volume loading, which is significant to the efficiency of the final clarification, will not be raised. But the adsorption capability of the aerated sludge, the sedimentation effect of the final clarification, and the partial recirculation over return-sludge can be used for an elimination of suspended solids, chemical oxygen demand (COD), ammonia and phosphate from the combined wastewater. In large-scale tests in Wilhelmshaven (160,000 PE), removal efficiencies for the elimination in the bypass of 75% of COD, 60% of ammonia and 89% of suspended solids were reached. In comparison with conventional procedures for combined water treatment (e.g. storage volumes, soil filter) the Mina-Process has the possibility to achieve a highly efficient and economical combined water treatment by using the capability of existing clarifiers.