Practical experience with full-scale structured sheet media (SSM) integrated fixed-film activated sludge (IFAS) systems for nitrification.

Many wastewater treatment plants in the USA, which were originally designed as secondary treatment systems with no or partial nitrification requirements, are facing increased flows, loads, and more stringent ammonia discharge limits. Plant expansion is often not cost-effective due to either high construction costs or lack of land. Under these circumstances, integrated fixed-film activated sludge (IFAS) systems using both suspended growth and biofilms that grow attached to a fixed plastic structured sheet media are found to be a viable solution for solving the challenges. Multiple plants have been retrofitted with such IFAS systems in the past few years. The system has proven to be efficient and reliable in achieving not only consistent nitrification, but also enhanced bio-chemical oxygen demand removal and sludge settling characteristics. This paper presents long-term practical experiences with the IFAS system design, operation and maintenance, and performance for three full-scale plants with distinct processes; that is, a trickling filter/solids contact process, a conventional plug flow activated sludge process and an extended aeration process.

Short-term mechanical management of cardiogenic shock.

OPINION STATEMENT: Cardiogenic shock (CS), a state of cardiac dysfunction that results in systemic hypoperfusion and end-organ dysfunction, is associated with high in-hospital mortality. Various forms of mechanical circulatory support have been used to treat CS. First employed in the 1960s, the intra-aortic balloon pump (IABP) has been a mainstay in the treatment of acute CS. However, the IABP is unable to provide adequate support in many patients, and newer technologies, including extracorporeal membrane oxygenation and percutaneous ventricular assist devices, appear to be more effective in reversing CS. These devices are also useful for supporting patients during complex percutaneous coronary intervention. Perhaps most importantly, they can be used as a bridge to decision or definitive therapy in CS patients who are potential candidates for surgical ventricular assist devices or cardiac transplantation.