Greywater Treatment In Sand And Gravel Filters

Background Enormous amounts of water are used daily in boiler water operations. However, water normally contains various levels of contaminants, dissolved solids (minerals) and dissolved gases. These contaminants cause major operational problems and damage to boilers unless they are removed or controlled on a continuing basis. Correct application of chemical treatment programs can eliminate many problems associated with boiler operations. But other problems can and do impact operations.

• Identify the historical basis for the National Pretreatment Program. • Explain the general regulatory structure of the National Pretreatment Program. • List three prohibited discharges under the National Pretreatment Program. • Describe what a categorical pretreatment standard is under the National Pretreatment Program.

This GSA Proving Ground (GPG) project assessed the performance of three alternative water treatment systems (AWT) for cooling tower water treatment applications at the Denver Federal Center (DFC) in Denver, Colorado. Cooling towers are commonly applied to water cooled chilled water plants in medium to large commercial buildings and are the point in the system where heat is dissipated to the atmosphere through the evaporative cooling process. Cooling towers also consume a large amount of water. Cooling tower related water consumption is one of largest potable water loads within buildings in the United States, with over 26% of water use associated with heating and cooling. Reducing water consumption is a priority for the General Services Administration (GSA) due to Executive Order 13693, Energy Policy Act of 1992, and regional water shortages. These factors have brought about the investigation of cost effective opportunities to reduce water use, such as AWT technologies for cooling towers. The current state of water treatment in GSA buildings is to use conventional chemical based cooling tower water treatment to maintain cooling tower water quality and contract out this specialized service to a third-party company specializing in such service.

Executive Summary The City of Grand Ledge (City) retained Fishbeck to evaluate options for the replacement of the City’s existing iron removal treatment system. Fishbeck is evaluating three options as part of this process: the installation of a new iron removal system, the installation of a new softening system, and receiving water from the adjacent Lansing Board of Water & Light (LBWL) system. This report evaluates the second option, the installation of a new softening treatment system to replace the existing iron removal system. The City’s existing iron removal plant utilizes an AERALATER® Type II-Q Packaged Iron and Manganese Removal System by General Filter (Aeralater) for iron removal. The Aeralater is at the end of its useful life, and has significant signs of deterioration. The repair of the Aeralater system was investigated as part of a prior study completed by Fishbeck, which determined that repair of the Aeralater would be costly and would give a low return on investment. The City opted to move forward assuming that the Aeralater unit would need to be replaced, rather than attempt to repair it.