Notice of RetractionPilot Study on Hybrid Biological Filter-Coagulation-Submerged Ultrafiltration Membrane for Drinking Water Treatment
Two parallel hybrid processes (Biological filter Coagulation/Ultrafiltration(BCUF) and Coagulation/Ultrafiltration(CUF)) for treating slightly polluted surface water were carried out in this experiment. In the process of BCUF, transverse flow water-dropping aerated biological filter was used as a primary pretreatment, and coagulation was used as the subsequent pretreatment of Ultrafiltration(UF). In the CUF process, coagulation was the unique pretreatment of UF. Turbidity was removed nearly completely in both two hybrid processes, and in the BCUF, effective ammonia nitrogen removal (87.1%) was also achieved mainly through the biological nitrification carried out in the biological filter, however, only 25.6% removal of ammonia nitrogen was achieved in the process of CUF. The removal rates of CODMn, TOC, DOC, UV254, AOC and BDOC were 55.2%, 87.8%, 71.0%, 61.1%, 91.4% and 89.3% respectively in the process of BCUF, which were much higher than that in the process of CUF. The biological pretreatment could improve the biological stability significantly and relieve the membrane fouling which made the transmembrane pressure (TMP) arising velocity lower. The pretreatment of biological filter and coagulation could remove the organic molecules in the range of 5000-500Da. Results showed the water-dropping aerated biological filter was fit for the pretreatment of UF.
Design and construction of a water potabilization membrane facility and its application to the third world countries. Preliminary tests
In many areas of underdeveloped countries population is supplied with water from rivers, lakes, etc., without applying any water treatment in most cases this water contains a certain amount of virus, bacteria and other microorganisms, which can cause several diseases. The research group of the Chemical and Nuclear Engineering Department of the Polytechnic University of Valencia (Spain) is working in the project: Design and Construction of a Water Potabilization Membrane Facility and its Application to the Third World Countries (AQUAPOT) in collaboration with the non-governmental organization Association for the Cooperation with Ecuador (ACOEC). In this project, membrane technology is proposed as an option to the current system of treatment. The object of the AQUAPOT project is the design and construction of an ultrafiltration membrane treatment unit, with spiral configuration, applicable to urban supplying systems in underdeveloped countries, which cannot guarantee an accurate disinfection of water. Before being placed definitively in Ecuador, the ultrafiltration facility has to be tested in order to prove its right operation. For so, an ultrafiltration unit similar to the one that is being constructed for being applied in Ecuador has been tested with water in much worse microbiological conditions than the water of Ecuador. The aim of this work is to describe these preliminary tests and analyze the ultrafiltration facility performance.
Ground Fault Protection for Electric Utility Generating Station Medium Voltage Auxiliary Power Systems
Most generating station designs have medium voltage auxiliary power systems with low resistance grounded neutrals.1 In order to provide even higher reliability, the auxiliary power distribution system configurations supply increasingly redundant process equipment.